JP2018046369A - antenna - Google Patents

Abstract

An antenna capable of performing multiplex communication of OAM waves while suppressing a decrease in reception level is provided. The antenna has a plurality of types of array antennas. The type of the array antenna is indicated by the OAM wave mode and the transmission / reception type of transmission or reception. Each array antenna is composed of a plurality of antenna elements arranged on the circumference. The circumference in which the antenna elements are arranged is concentric and has the same diameter for a plurality of array antennas. A plurality of array antennas with different transmission / reception types may share at least some antenna elements, and a plurality of array antennas with different OAM wave modes may share at least some antenna elements. A plurality of antenna elements constituting one array antenna are arranged at equal intervals on the circumference. [Selection] Figure 10

Description

  The present invention relates to an antenna.

  1 to 4 are diagrams showing characteristics of OAM (Orbital Angular Momentum) waves. 1 shows the characteristics of the OAM wave in the OAM mode L0, FIG. 2 shows the characteristics of the OAM wave in the OAM mode L1, FIG. 3 shows the characteristics of the OAM wave in the OAM mode L2, and FIG. 4 shows the characteristics of the OAM wave in the OAM mode L3. Indicates. Hereinafter, the OAM mode is also simply referred to as “mode”. The radio waves having different orbital angular momentum as shown in FIGS. 1 to 4 (modes L0, L1, L2, L3,...) Can be made to correspond to different signals and multiplexed. As shown in FIGS. 1 to 4, when comparing changes in the phase in the same distance from the transmission side, the phase is the same in mode L0, but in mode L1, the phase rotates once from 0 to 360 °, and L2 2 rotations and L3 3 rotations (see, for example, Non-Patent Documents 1 and 2). It is considered that the wireless communication capacity can be greatly increased by multiplexing such OAM waves in several modes (for example, see Non-Patent Documents 1, 2, and 3).

  The peak of OAM wave radiation used in this wireless communication spreads conically in the direction from the transmission side to the reception side. Moreover, the spread of the conical peak in the radiation differs depending on the selected OAM mode (OAM wave mode). As the difference, as shown in the level distributions of FIGS. 1 to 4, it can be confirmed that as the OAM wave mode becomes higher order, the circular radiation peak at a position away from the transmission side by the same distance spreads more. . Considering the characteristics of such OAM waves, it is necessary to devise the arrangement of transmission / reception antennas.

  FIG. 34 is a diagram showing the arrangement of antenna elements in multiplex transmission / reception according to the prior art (for example, Non-Patent Document 3). As shown in the figure, each of the antenna 980 and the antenna 990 has a plurality of types of array antennas that radiate OAM waves. The array antenna is composed of a plurality of antenna elements arranged on the circumference. The type of array antenna is represented by a combination of transmission / reception type of transmission (radiation) or reception and the OAM mode. When at least one of the transmission / reception type and the OAM mode is different, the type of the array antenna is different. This figure shows a case where the transmitting antenna 980 and the receiving antenna 990 each have two array antennas.

  When one antenna is provided with a plurality of types of array antennas, the antenna elements constituting each array antenna have the same center in the plurality of types of array antennas, and on a circumference with a different radius for each of the plurality of types of array antennas. Placed in. In the figure, in the antenna 980, the antenna element 981 of the first array antenna is arranged on the circumference C1, and the antenna element 982 of the second array antenna is concentric with the circumference C1 and smaller than the circumference C1. It arrange | positions at the periphery C2. In the antenna 990, the antenna element 991 of the first array antenna is arranged on the circumference C3, and the antenna element 992 of the second array antenna is concentric with the circumference C3 and smaller than the circumference C3. Is placed on top. The array antenna composed of antenna elements arranged on these separate circumferences emits or receives OAM waves of different modes. By handling OAM waves of different modes in this way, multiplex communication is realized. Further, the difference between the antenna element 981 and the antenna element 982 and the antenna element 991 and the antenna element 992 may be a difference in OAM wave mode handled as described above, or may be a difference between transmission and reception. . Hereinafter, an array antenna that radiates (transmits) an OAM wave is also referred to as a “transmission-side array antenna”, and an array antenna that receives an OAM wave radiated from the transmission-side array antenna is also referred to as a “reception-side array antenna”. Hereinafter, the antenna element is also referred to as “element”, and the antenna element of the receiving array antenna is also referred to as “reception element”.

Yan Yan, et al., “High-capacity millimetre-wave communications with orbital angular momentum multiplexing”, Nature communications, 5, 2014, p.1-9 Yan Yan, "High-Capacity Millimeter-wave Communications with Orbital Angular Momentum Multiplexing", EE Festival Presentation, USC Optical Communications Laboratory, 2014 Zhengyi Li, Yoji Ohashi and Kazumi Kasai, "A Dual-channel Wireless Communication System by Multiplexing Twisted Radio Wave", Proceedings of the 44th European Microwave Conference, (Italy), 2014, p.235-238

The problems of the prior art will be described using two types of conventional transmission / reception antennas shown in FIGS.
Each of the two antennas shown in FIG. 35 has a transmission-side array antenna and a reception-side array antenna in which antenna elements are arranged on concentric circumferences having different sizes. The diameter of the circumference where the transmission side array antenna is arranged is smaller than the diameter of the circumference where the reception side array antenna is arranged. This is because the peak of the OAM wave radiated from the antenna element of the transmitting side array antenna spreads in a conical shape, so that the antenna element of the receiving side array antenna is spread on the circumference having the larger diameter. This is because OAM waves can be received more effectively.

  The transmission-side antenna shown in FIG. 36 has two transmission-side array antennas in which antenna elements are arranged on circumferences of concentric different sizes, and the reception-side antenna has concentric circumferences of different sizes. It has two receiving side array antennas on which antenna elements are arranged. In the transmission-side antenna, the antenna elements of the transmission-side array antenna that handles OAM waves in the transmission mode L1 are arranged on a small-diameter circumference, and the antenna elements in the transmission-side array antenna that handles OAM waves in the transmission mode L2 are It is arranged on the circumference of the large diameter. Similarly, in the receiving-side antenna, the antenna elements of the receiving-side array antenna that handles the OAM wave in the receiving mode L1 are arranged on the circumference of a small diameter, and the antenna of the receiving-side array antenna that handles the OAM wave in the receiving mode L2 The elements are arranged on a large diameter circumference. The reason for assigning different modes to the large and small circumferences is that the radiation spread angle differs depending on the OAM wave mode. That is, in the case of the same conditions, the mode L2 has a larger spread of radiation in the OAM wave than the mode L1, so that there is a rational point in handling the mode L2 with the antenna elements on the outer circumference.

  Incidentally, in these two conventional examples shown in FIGS. 35 and 36, there is a deviation amount in the direction of the receiving element with respect to the radiation peak, as indicated by an arrow in a dotted circle. In particular, when the antenna elements of the transmission side array antenna are arranged on a circle having a small diameter, like the transmission side array antenna of the transmission mode L1 shown in FIG. The amount of deviation in the direction increases. If the “out-of-direction amount” is large as described above, the reception level is naturally greatly reduced, so that a transmission signal cannot be received, and wireless communication using an OAM wave may not be possible.

  In view of the above circumstances, an object of the present invention is to provide an antenna capable of performing multiplex communication of OAM waves while suppressing a decrease in reception level.

  One aspect of the present invention is an antenna having a plurality of array antennas each having a different type indicated by a combination of an OAM (Orbital Angular Momentum) wave mode and a transmission / reception transmission / reception type. Each has a plurality of antenna elements arranged on the circumference, and the circumference on which the antenna elements are arranged is concentric and has the same diameter with respect to the plurality of array antennas.

  One aspect of the present invention is the antenna described above, wherein a plurality of the array antennas having different transmission / reception types share at least a part of the antenna elements, and each of the array antennas configures the array antenna. The antenna elements are arranged at equal intervals on the circumference.

  One embodiment of the present invention is the above-described antenna, wherein a plurality of the array antennas having different OAM wave modes share at least a part of the antenna elements, and each array antenna includes a plurality of the array antennas. The antenna elements are arranged at equal intervals on the circumference.

  According to the present invention, it is possible to provide an antenna that can perform multiplex communication of OAM waves while suppressing a decrease in reception level.

It is a figure which shows the characteristic of the OAM (Orbital Angular Momentum) wave of mode L0. It is a figure which shows the characteristic of the OAM wave of mode L1. It is a figure which shows the characteristic of the OAM wave of mode L2. It is a figure which shows the characteristic of the OAM wave of mode L3. It is a figure which shows the table | surface of the spreading angle of the radiation | emission of an OAM wave when the aperture diameter of an array antenna differs in the same transmission mode. It is a figure which shows the table | surface of the radiation spread angle of an OAM wave when the aperture diameter of an array antenna is the same and transmission modes differ. It is a figure which shows the list of a peak direction when changing a transmission mode and an aperture diameter. It is a figure which shows the radiation pattern of an OAM wave when the aperture diameters of an array antenna differ in the same transmission mode. It is a figure which shows the radiation pattern of an OAM wave when the aperture diameter of an array antenna is the same and transmission modes differ. It is a figure which shows the element arrangement | positioning in the multiplex transmission / reception by 1st Embodiment. It is a figure which shows the deletion effect of the deviation | shift amount in a receiving element direction with respect to a radiation peak when using the antenna by 1st Embodiment. It is a figure which shows the effect of element arrangement | positioning by 1st Embodiment. It is the graph which expanded the facing direction of the radiation pattern. It is a figure which shows the structure of the communication apparatus by the side of transmission by 1st Embodiment. It is a figure which shows the structure of the communication apparatus of the receiving side by 1st Embodiment. It is a figure which shows the numerical example of the case where the transmission of the OAM wave of multiple modes is directly received using the communication apparatus by 1st Embodiment. It is a figure which shows the multiplex transmission / reception system of the OAM wave by 1st Embodiment. It is a figure which shows the fall of the received power level when it remove | deviates from a radiation peak. It is a figure which shows the reception level change of the multiplexed OAM wave in the multiplex transmission / reception system by 1st Embodiment. It is a figure which shows the reception level change of the multiplexed OAM wave in the multiplex transmission / reception system by 1st Embodiment. It is a figure which shows the case which reflects and receives transmission of the OAM wave of multiple modes by the modification of 1st Embodiment. It is a figure which shows the case where transmission of the OAM wave of multiple modes by 2nd Embodiment is received directly. It is a figure which shows arrangement | positioning of the antenna element by 2nd Embodiment. It is a figure which shows arrangement | positioning of the antenna element by 2nd Embodiment. It is a connection block diagram in the communication apparatus by 2nd Embodiment. It is a figure which shows the phase value set to each antenna element by 2nd Embodiment. It is a connection block diagram in the communication apparatus by 2nd Embodiment. It is another connection block diagram in the communication apparatus by 2nd Embodiment. It is a figure which shows the multiplex transmission / reception system of the OAM wave by 2nd Embodiment. It is a figure which shows the reception level change of the multiplexed OAM wave in the multiplex transmission / reception system by 2nd Embodiment. It is a figure which shows the reception level change of the multiplexed OAM wave in the multiplex transmission / reception system by 2nd Embodiment. It is a figure which shows arrangement | positioning of the antenna element in the multiplex transmission / reception by 3rd Embodiment. It is a figure which shows the connection structure in the communication apparatus by 3rd Embodiment. It is a figure which shows arrangement | positioning of the antenna element in the multiplex transmission / reception by a prior art. It is a figure which shows the deviation | shift amount of the receiving element direction with respect to the radiation peak by a prior art. It is a figure which shows the deviation | shift amount of the receiving element direction with respect to the radiation peak by a prior art.

OAM waves can be multiplexed using multiple modes. In order to generate this multiplexed OAM wave, the antenna has a plurality of array antennas. In each array antenna, antenna elements are arranged on the circumference. In the prior art, antenna elements are arranged on a plurality of circumferences for each mode, or antenna elements are arranged on different circumferences for transmission and reception. In the present embodiment, a multi-mode antenna element or a transmission / reception antenna element is arranged on the same circumference (on the maximum circumference of all the array antennas to be multiplexed). As a result, the spread of the OAM wave is suppressed, and the OAM wave multiplex transmission / reception in which the receiving element direction viewed from the transmission is reduced as much as possible from the spread of the OAM wave is realized.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
The characteristics of OAM (Orbital Angular Momentum) waves shown in FIGS. 1 to 4 will be described in detail with specific examples of radiation peaks and phases in each mode. In the following, four types of radio waves are listed by combining the normal radio wave (mode L0) shown in FIG. 1 and the three types of OAM waves of modes L1, L2, and L3 shown in FIGS. explain.

  First, the electric field intensity distribution (intensity level distribution) of each type of radio wave will be described. As shown in FIG. 1, a normal radio wave has a strong circular center, and as shown in FIGS. Then, the center is a weak ring shape. Comparing the diameters of the circular rings whose intensity levels are peaks in the annular level distribution of the OAM wave in each mode, it can be confirmed that the peaks spread from the center in the order of modes L1, L2, and L3. In addition, the phase change is uniform in normal radio waves, but in OAM waves, there is a change of 1 to 3 rounds at 0 to 360 ° with respect to the central angle according to modes L1 to L3.

  5 and 6 are tables showing the spread angle of the radiation of the OAM wave with respect to two different parameters. These two types of parameters are the transmission mode of the OAM wave and the diameter of the transmission side array antenna in which the antenna elements that generate and radiate the OAM wave are arranged on the circumference, that is, the length of the opening diameter of the transmission side array antenna. is there. FIG. 5 shows the difference in the spread angle of the OAM wave when the aperture diameter of the transmitting array antenna is different in the same transmission mode of the OAM mode L ± 1. FIG. 6 shows the difference in spread angle when the transmission side array antenna has the same aperture diameter of 4λ and the transmission mode of the OAM wave is different. This opening diameter is 4λ, and “λ” indicates a wavelength. On the other hand, the spread angle is an angle at which the peak of the intensity level of the radiated radio wave spreads in a conical shape.

  As can be seen from FIG. 5, when the condition is the same transmission mode of the OAM mode L ± 1, the aperture diameter, which is the diameter in which the antenna elements of the transmitting-side array antenna are arranged on the circumference, is short from λ to 2λ,. As the length increases, the spread angle decreases in the reverse order of 34 °, 17 °,..., 8 °. On the other hand, as shown in FIG. 6, when the condition is that the aperture diameter is the same diameter 4λ (λ is the wavelength), the OAM wave is increased as the low OAM mode L ± 1 increases to L ± 2,. The spread angle also increases in order of 8 °, 14 °,..., 25 °.

  The numerical values shown in FIGS. 5 and 6 are obtained from simulation results shown in FIGS. 8 and 9 described later. When the two parameters listed in FIGS. 5 and 6 affect the spread angle of the OAM wave, the following examination is performed in FIG. 10 described later. That is, two relatively simple modes L ± 1 and ± 2 are multiplexed, and the size (aperture diameter) of the transmitting-side array antenna is limited to a maximum of 4λ. In the case of the conventional case A shown in FIG. 34, the size of the transmitting array antenna that handles the mode L ± 1 is 2λ, and the mode L ± 2 is The size of the transmission side array antenna to be handled is 4λ. On the other hand, in the present embodiment shown in FIG. 10 described later, the size of the transmission side array antenna that handles the mode L ± 1 and the size of the transmission side array antenna that handles the mode L ± 2 are both 4λ.

  FIG. 7 is a diagram showing a list of peak directions when the transmission mode and the aperture diameter are changed. The list shown in the figure covers modes L ± 1, L ± 2,..., L ± 4, L ± 5. Furthermore, in the table shown in FIG. 6, when antenna elements are arranged on the circumference of the transmitting-side array antenna that radiates OAM waves, the aperture diameter D, which is the diameter of the circumference where these antenna elements are arranged, is λ. , 2λ,..., 4λ,. That is, the list shown in FIG. 7 shows the numerical value of the spread angle of the emission peak of the OAM wave as the peak direction that changes depending on the combination of these different OAM modes and aperture diameters. As a whole, the entire list shown in the figure tends to increase the spread angle in the peak direction when the OAM mode is higher than the low-order OAM mode. In the same OAM mode, the peak spread angle tends to decrease as the aperture diameter increases. The spread angle of the OAM wave under the conditions shown in FIGS. 5 and 6 (the aperture diameters λ to 4λ in the mode L1 and the modes L1 to L4 in the aperture diameter 4λ) are respectively surrounded by the symbols A1 and A2 in the list. Is included in the range.

  FIG. 8 is a diagram showing a radiation pattern of OAM waves when the aperture diameter of the transmission side array antenna is different in the same transmission mode, and FIG. 9 is a diagram when the aperture diameter of the transmission side array antenna is the same and the transmission mode is different. The radiation pattern of an OAM wave is shown. The radiation patterns shown in FIGS. 8 and 9 are the results of simulating the radiation pattern on the condition that 16 antenna elements, which are microdipoles having a length λ / 20, are arranged on the circumference. In this simulation, the used frequency is f = 5.2 GHz (wavelength λ = 5.8 cm).

  First, FIG. 8 shows a radiation pattern of a transmitting-side array antenna in which antenna elements are arranged on a circumference having a diameter (opening diameter) different from λ, 2λ, 3λ, and 4λ when the transmission mode is mode L1. In these cases, it can be seen that the peak direction indicated by the arrow is narrowed as the opening diameter increases. Next, FIG. 9 shows a radiation pattern when antenna elements are arranged on the circumference of the same 4λ diameter (same aperture diameter) and the transmission mode is changed to modes L1, L2, L3, and L4. It can be seen that the peak direction indicated by the arrow expands as the mode becomes higher. The list of FIG. 7 is a summary of the results of the spread angle under the condition of combining various modes and the aperture diameter of the transmitting-side array antenna by simulation as shown in FIG. 8 and FIG.

  FIG. 10 is a diagram showing an element arrangement in an antenna that performs multiplex transmission / reception in the present embodiment. Each of the transmitting-side antenna 100 and the receiving-side antenna 200 shown in the figure has a plurality of array antennas. The transmitting-side antenna 100 has two transmitting-side array antennas having different OAM modes, and the receiving-side antenna has two receiving-side array antennas having different OAM modes. One antenna may include a transmitting-side array antenna and a receiving-side array antenna that have the same or different OAM modes. In the antenna 100, the antenna element 101 and the antenna element 102 constitute an array antenna of a different type. The circumference where the antenna element 101 is arranged and the circumference where the antenna element 102 is arranged are a circumference C5 which is concentric and has the same diameter. Similarly, in the antenna 200, the antenna element 201 and the antenna element 202 constitute different types of array antennas. The circumference where the antenna element 201 is arranged and the circumference where the antenna element 202 is arranged are a circumference C5 of a concentric and the same diameter circle.

  The prior art antenna has been described with reference to FIG. 34. The circumference C5 of the two array antennas included in each of the antennas 100 and 200 shown in FIG. 34 is the circumference C3 of the array antenna outside the antenna 990 shown in FIG. Is the same diameter. That is, the aperture diameter of the array antenna outside the antenna 990 shown in FIG. 34 is considered to be the same as the aperture diameter of the array antenna included in each of the antennas 100 and 200 shown in FIG. In the case of this condition, the antennas 100 and 200 shown in FIG. 10 have an array in which at least one of the OAM wave mode and the transmission / reception type is different on the circumference of the largest diameter in the antenna 100 and 200 shown in FIG. Since the antenna element of the antenna is arranged, the spread of the radiation peak due to the OAM wave can be suppressed. That is, in the transmission-side array antenna, the antenna element is arranged on the circumference of the largest diameter, thereby suppressing the spread of the radiation peak, which is a problem in the prior art. Furthermore, by arranging antenna elements on the circumference of the largest diameter in the receiving side array antenna, it is aimed to receive at an angle as close as possible to the radiation peak determined by the OAM mode and the aperture diameter on the transmitting side.

  FIG. 11 is a diagram illustrating the effect of deleting the amount of deviation in the receiving element direction with respect to the radiation peak when the antenna of this embodiment is used. As shown in the figure, the antenna element of the mode L1 array antenna and the antenna element of the mode L2 array antenna are arranged on the same circumference in both the transmission side antenna and the reception side antenna. The antenna element 101 is an antenna element that constitutes the transmission-side array antenna in the transmission mode L1 in the antenna 100 shown in FIG. 10, and the antenna element 102 constitutes the transmission-side array antenna in the transmission mode L2 in the antenna 100 shown in FIG. Antenna element. The antenna element 201 is an antenna element that constitutes a reception-side array antenna in the reception mode L1 in the antenna 200 shown in FIG. 10, and the antenna element 202 constitutes a reception-side array antenna in the reception mode L2 in the antenna 200 shown in FIG. Antenna element.

  The amount by which the receiving-side array antennas of the transmission modes L1 and L2 deviate from the radiation peaks of the OAM waves generated by the transmitting-side array antennas of the transmission modes L1 and L2 is small. In particular, with respect to the radiation peak of mode L1, the amount of the peak direction deviating from the direction toward the antenna element 201 on the receiving side is small as shown in the ranges of B1 and B2. This point will be supplemented with examples with specific numerical values in FIGS. 12 and 13 described later. Thereafter, the configuration of the transmitting / receiving apparatus (FIGS. 14 and 15 to be described later), the result of the simulation of multiplexing using the OAM wave (FIG. 18 to be described later), and additional examination based on the verification experiment of the multiplexing using the OAM wave (FIGS. 17, 19, and 20 described later) will be described.

  FIG. 12 is a diagram for explaining the improvement of the off-peak amount, which is an effect of the element arrangement of the present embodiment. In the figure, the following cases are assumed as specific numerical examples. First, the frequency f used for wireless communication is 5.2 GHz (wavelength λ = 5.76 cm). In the antenna on the transmission side, antenna elements are arranged on the circumferences of the respective transmission-side array antennas having a diameter of 4λ and a diameter of 6λ, and the OAM waves of mode L1 and mode L2 are radiated from the respective transmission-side array antennas. In the antenna on the receiving side, the receiving element is arranged on a circumference (radius 2λ = 11.53 cm and 3λ = 17.29 cm) of the same size as that of the transmission, and the mode L1 of the receiving side array antenna having the radius 2λ is set. An OAM wave is received, and an OAM wave of mode L2 is received by a receiving side array antenna having a radius of 3λ. The distance d between the transmitting side array antenna and the receiving side array antenna is 1.8 m.

In this case, first, consider a case where a mode L2 OAM wave is radiated from a transmitting-side array antenna having a diameter of 6λ. The OAM wave of mode L2 with an aperture diameter of 6λ has a radiation spread angle of 9 ° (reference A3 in the list of FIG. 7). The radius of the receiving side in this peak direction 9 ° is d · tan (9 °) = 28.50cm, the direction of the receiving element is ^{tan -1 (3λ / d) =} tan -1 (0.096) = 5.5 It can be calculated as °. Therefore, the off-peak amount of the transmitting array antenna having a diameter of 6λ and the mode L2 is 9−5.5 = 3.5 °.

Next, consider a case where a mode L1 OAM wave is radiated from the other array antenna having a diameter of 4λ. The OAM wave of mode L1 with an aperture diameter of 4λ has a radiation spread angle of 8 ° (symbol A4 in the list of FIG. 7). At the peak direction of 8 °, the radius on the receiving side is d · tan (8 °) = 25.29 cm, and the direction of the receiving element is tan ⁻¹ (2λ / d) = tan ⁻¹ (0.064) = 3.7 °. Can be calculated. Therefore, the off-peak amount of the transmission side array antenna having the diameter of 4λ and the mode L1 is 8−3.7 = 4.3 °.

  Here, if the arrangement of the receiving elements that receive the OAM wave of the mode L1 is changed from the circumference of the diameter 4λ to the circumference of the same diameter 6λ as the receiving element that receives the mode L2, the mode L1 Is reduced to 8−5.5 = 2.5 ° (Improved deviation 1).

Further, when the arrangement of the antenna elements of the transmitting-side array antenna that transmits the OAM wave of mode L1 is changed from the circumference of the diameter 4λ to the circumference of the diameter 6λ similarly to the receiving-side array antenna, the spread angle becomes 6 Changes to (° A5 in the list of FIG. 7). At this peak direction of 6 °, the radius on the receiving side is d · tan (6 °) = 18.91 cm, and the direction of the receiving element is tan ⁻¹ (3λ / d) = 5.5 ° as described above. Due to this change in the spread angle, the amount of deviation from the direction of the receiving element can be further reduced to 6-5.5 = 0.5 ° (improved amount of deviation 2).

  FIG. 13 is a diagram showing a graph in which the facing direction of the radiation pattern is enlarged. The horizontal axis of the graph shown in the figure is an azimuth angle [°] that is an angle with respect to the direction in which the plane on which the transmitting array antenna is arranged faces, and the vertical axis is a gain [dB] of the signal strength level. The parameter of this graph is a combination of the diameter (opening diameter) of the transmitting-side array antenna in which the antenna elements are arranged on the circumference and the transmission mode of the OAM wave. In the figure, (4λ, L1), (6λ, L1), and (6λ, L2), which are combinations of the diameters (opening diameters) 4λ and 6λ of the transmitting array antenna and the OAM wave transmission modes L1 and L2, The radiation pattern when used as a condition is shown. In each graph, the peak direction and the intensity level of the peak are (8 °, 14.7 dB), (6 °, 14.4 dB), and (9 °, 13 dB). Here, the amount of deviation of the direction of the receiving element with respect to the peak direction of the OAM wave in the mode L1 described with reference to FIG.

  First, when the transmitting / receiving array antenna had an aperture diameter of 4λ, the direction of the receiving element was 3.7 °. It can be seen from the graph of FIG. 13 that the signal intensity level at this time is considerably low. Here, the direction of the receiving element becomes 5.5 ° by changing the diameter of the receiving array antenna from 4λ to 6λ (the same aperture diameter as that of the receiving array antenna in mode L2), so the same parameters (4λ, L1 ) Also increases the intensity level and improves the gain (improvement of outliers 1). Further, if the transmitting-side array antenna is also 6λ (the same aperture diameter as that of the receiving-side array antenna in mode L2), the graph of parameter (4λ, L1) in FIG. Even at .5 °, the gains are further increased (improvement of outlier 2).

The configuration of a communication apparatus using an antenna that performs multiplex transmission / reception in this embodiment will be described with reference to FIGS. 14 and 15.
FIG. 14 is a diagram illustrating a configuration of the communication device 300 on the transmission side. The transmission-side communication apparatus 300 includes M transmission signal generation apparatuses 301, M demultiplexers 302 having N ports, M × N phase shifters 303, and antennas 310. The phase adjustment amount of the phase shifter 303 is variable depending on the setting. The antenna 310 has M × N antenna elements 311. The components of the communication device 300 are connected in the order of the transmission signal generation device 301, the duplexer 302, the phase shifter 303, and the antenna element 311. Here, M is the number of modes in which OAM waves are multiplexed, and N is the number of elements used to transmit an OAM wave of one mode, that is, the number of elements constituting one transmitting side array antenna.

  Among the M types of transmission modes to be multiplexed, the transmission signal generation device 301 that generates a signal to be transmitted in the m-th transmission mode (m is an integer of 1 to M) is referred to as a transmission signal generation device 301-m. The duplexer 302 connected to the transmission signal generation device 301-m is referred to as a duplexer 302-m. The phase shifter 303 connected to the n-th port (n is an integer of 1 to N) of the duplexer 302-m is referred to as a phase shifter 303-mn and is connected to the phase shifter 303-mn. The antenna element 311 is referred to as an antenna element 311-mn. The antenna elements 311-m-1 to 311-m-N constitute an array antenna that transmits an OAM wave in the m-th transmission mode. All the antenna elements 311-1-1 to 311-MN are arranged on a circumference having the same diameter as that of the maximum-size transmitting-side array antenna as described above with reference to FIG.

  In the above configuration, the transmission signal generation device 301-m outputs the generated signal to the duplexer 302-m. The demultiplexer 302-m demultiplexes the signal input from the transmission signal generation device 301-m into N ports and outputs the demultiplexed signals to the phase shifters 303-m-1 to 303-m-N. The phase shifter 303-mn adjusts the phase of the signal input from the n-th port of the duplexer 302-m based on the transmission mode, and outputs it to the antenna element 311-mn. The antenna element 311-mn radiates the signal input from the phase shifter 303-mn.

  FIG. 15 is a diagram illustrating the configuration of the communication device 400 on the receiving side. The communication device 400 on the reception side includes an antenna 410, M × N phase shifters 421, M multiplexers 422 having N ports, and M received signal demodulation devices 423. The antenna 410 has M × N antenna elements 411. The phase adjustment amount of the phase shifter 421 is variable depending on the setting. The components of the communication device 400 are connected in the order of an antenna element 411, a phase shifter 421, a multiplexer 422, and a received signal demodulation device 423. M is the number of modes in which OAM waves are multiplexed, and N is the number of elements used to receive one mode of OAM waves, that is, the number of elements constituting the receiving side array antenna.

  The n-th (n is an integer not less than 1 and not more than N) antenna element 411 that receives an OAM wave in an m-th mode (m is an integer not less than 1 and not more than M) is described as an antenna element 411-mn. The phase shifter 421 connected to the antenna element 411-mn is referred to as a phase shifter 421-mn. The multiplexer 422 in which each of the N ports is connected to the phase shifters 421-m-1 to 421-m-N is referred to as a multiplexer 422-m, and the received signal is connected to the multiplexer 422-m. The demodulator 423 is referred to as a received signal demodulator 423-m.

The antenna element 411-mn outputs the received signal to the phase shifter 421-mn. The phase shifter 421-mn adjusts the phase of the signal input from the antenna element 411-mn based on the reception mode, and outputs it to the nth port of the multiplexer 422-m. The multiplexer 422-m multiplexes the signals input from the phase shifters 421-m-1 to 421-m-N and outputs the combined signals to the received signal demodulator 423-m. The received signal demodulator 423-m demodulates the signal input from the multiplexer 422-m.
Up to this point, the same symbols M and N are used for the number of components so that the configuration on the reception side shown in FIG. 15 is matched with the transmission side in FIG. However, transmission / reception does not necessarily require the same number of corresponding components.

  As described above, in contrast to the transmission-side apparatus configuration shown in FIG. 13, in the reception-side apparatus configuration shown in FIG. 14, a multiplexer is substituted for the demultiplexer, and a reception signal demodulation is substituted for the transmission signal generation apparatus. It is the structure provided with the apparatus. The arrangement of the antenna elements 311 included in the antenna 310 shown in FIG. 13 is the arrangement of the antenna elements 101 and 102 of the antenna 100 shown in FIG. 10 and the arrangement of the antenna elements 101 and 102 of the array antenna on the transmission side shown in FIG. . That is, the antenna elements 311 of different types of array antennas are all arranged on the same circle. Similarly, the arrangement of the antenna elements 411 of the antenna 410 shown in FIG. 14 is the same as the arrangement of the antenna elements 201 and 202 of the antenna 200 of the present embodiment shown in FIG. 10 and the antenna elements of the array antenna on the receiving side shown in FIG. Assume that 201 and 202 are arranged. That is, the antenna elements 411 of different types of array antennas are all arranged on the same circle. As a result, as described below, the problems in the prior art in which antenna elements are arranged on different circumferences corresponding to a plurality of modes and transmission / reception are eliminated, and the advantages of the present embodiment are derived.

(1) The aperture diameter of the transmitting array antenna is as large as possible in any mode, and the spread angle of the OAM wave is small. In other words, directivity is high.
(2) The position (arrangement) of antenna elements is simple.
(3) The number of elements can be reduced and the manufacturing cost of the antenna can be reduced.

  In the second embodiment to be described later, one antenna is used by using a hybrid to multiplex input signals to the transmitting-side antenna element or to demultiplex the received signal from the receiving-side antenna element. The device shares multiple modes. In a third embodiment to be described later, when the antenna performs two-way communication, a communication signal is input / output by a circulator and transmission / reception is shared by one antenna element.

  FIG. 16 is a diagram illustrating specific numerical examples in the case of directly receiving transmission of OAM waves in a plurality of modes using the communication apparatus of the present embodiment. In the numerical example shown in the figure, as conditions for transmission / reception using a plurality of modes for OAM waves, the distance d between transmission / reception is 1.8 m, the frequency is 5.2 GHz, the aperture diameter D is 4λ (= 23 cm), and the multiple mode Is mode L1, L2 (, L3). The transmission-side array antenna and the reception-side array antenna have the same aperture diameter (same diameter) D (= 4λ), and on the transmission side, antenna elements 311 for each mode are arranged on a concentric circumference. In the figure, the antenna elements 311 of the modes L1, L2 (, L3) are described as antenna elements 311-1, 311-2, 311-3. The peak directions in the transmission modes L1, L2 (, L3) are 8 ° and 14 ° (, 20 °) spread angles from the transmission side, and therefore the radius of 0.25 m and 0.45 m at the position of the reception side array antenna. , Spread out into a 0.65m circle. Since the aperture diameter of the receiving array antenna is 23 cm with respect to the peak spread in each of these transmission modes, the antenna element on the receiving side has a direction of 3.9 ° (≈4 °) when viewed from the transmitting side. Therefore, the difference between the direction of the receiving element from the transmission side and the peak direction of each mode L1, L2 (, L3) is 4 °, 10 ° (, 16 °).

  FIG. 17 is a diagram showing an OAM wave multiplex transmission / reception system according to this embodiment. In the figure, the transmission side has the same configuration as the communication device 300 shown in FIG. 14, and the reception side has the same configuration as the communication device 400 shown in FIG. Note that M = 2 and N = 4. However, the reception side further includes a network analyzer 501, and the transmission side includes a network analyzer 502. On the receiving side, a spectrum analyzer 503 is used as the received signal demodulator 423.

  In the verification experiment using the multiplex transmission / reception system shown in the figure, the used frequency is 5.2 GHz (wavelength: 5.765 cm), and the OAM wave modes are L1 and L-1. The elements of the transmission side antenna and the reception side antenna are 8 elements in total, with 4 elements for mode L1 and 4 elements for mode L2, and the aperture diameter of the array antenna for transmission and reception is 4λ (23.06 cm).

  The two transmission signal generation devices 301-1 and 301-2 that are signal sources (SG) generate transmission signals and output them to the demultiplexers 302-1 and 302-2, respectively. These two transmission signals have different modes used for transmission from L1 and L-1. The transmission signals output from the transmission signal generators 301-1 and 301-2 are distributed to four ports by the two demultiplexers 302-1 and 302-2, respectively. The 2 × 4 phase shifters 303-1-1 to 303-1-4, 303-2-1 to 303-2-4 adjust the phase of the transmission signal and transmit two sets of four elements included in the antenna 310. Output to the side array antenna. The antenna elements 311-1-1 to 311-1-4 of the transmission side array antenna in mode L1 are the same as the antenna elements 311-2-1 to 311-2-4 of the transmission side array antenna in mode L-1. It arrange | positions on the circumference of diameter 4lambda.

  A phase is set at 5.2 GHz in the phase shifter 303 inserted immediately before each antenna element 311. The phase set in the phase shifter 303 is determined by the position and mode on the circumference of the antenna element 311 to which the phase shifter 303 is connected. That is, the phase shifter 421 includes 0 [°], 45 [°], 90 [°],..., −45 (315) [°] for the mode L1 and 0 [°], −45 for the mode L-1. [°], −90 [°],..., 45 (−315) [°] are set by the network analyzer 501. Further, in order to evaluate whether or not the OAM wave to be multiplexed can be separated, the transmitting-side antenna 310 is rotated around the vertical axis (Z-axis). This rotation angle is α [°].

  The reception side array antenna of the opposing antenna 410 is symmetrical with the transmission side array antenna. OAM signals received by the antenna elements 411-1-1 to 411-1-4, 411-2-1 to 411-2-4 of the receiving side array antenna are phase shifters 421-1-1 to 421-1-1. 4, 421-2-1 to 421-2-4, and is aggregated for each mode by the multiplexers 422-1 and 422-2. The two signals aggregated for each mode are output to a spectrum analyzer 503 as a received signal demodulator. In the phase shifter 421, the phase is set at 5.2 GHz for each antenna element 411 connected by the network analyzer 502. The mode used for reception is selected by changing the phase setting of the phase shifter 421.

  FIG. 18 is a diagram illustrating a decrease in the reception power level when the emission peak is deviated. This figure shows a pattern result simulating the intensity level of ± 180 ° in front of the transmitting side array antenna. The analysis conditions are as follows: use frequency is 5.2 GHz, 8 elements are arranged at equal intervals on the circumference as a transmission side array antenna, the aperture diameter which is the diameter of the transmission side array antenna is 4λ (λ is the wavelength), and transmission / reception distance Is 1.8 m. Further, the phase of each antenna element is set by increasing the phase by 45 ° (= 360 ÷ 8) in the order of arrangement on the circumference of adjacent elements so as to transmit the OAM wave mode L1.

  From the simulation results shown in the figure, the level drop due to the difference from the received power level (8.27 dB) at the peak in the 8 ° direction to the 4 ° direction (received power level: 4.98 dB) corresponding to the position of the receiving element is It is only 3.29 dB. Considering this level reduction, it can be seen that the OAM wave can be transmitted and received with the transmitting and receiving side array antennas having the same diameter facing each other.

  19 and 20 are diagrams showing changes in the reception level of multiplexed OAM waves in the multiplex transmission / reception system shown in FIG. In this system, mode L1 is set for the four antenna elements of the transmitting array antenna, mode L-1 is set for the four antenna elements of another transmitting array antenna, and mode L1 is set for the four antenna elements of the receiving array antenna. , Mode L-1 is set for four antenna elements of another receiving-side array antenna.

  FIG. 19 shows reception of an OAM wave transmitted with mode L1 set to four antenna elements of the transmitting side array antenna and mode L-1 set to four antenna elements of another transmitting side array antenna. The result of the receiving peak intensity obtained by receiving with the four antenna elements of the side array antenna is shown. On the other hand, FIG. 20 shows an OAM wave transmitted with mode L1 set for the four antenna elements of the transmitting side array antenna and mode L-1 set for the four antenna elements of another transmitting side array antenna. The result of the receiving peak intensity obtained by receiving with the four antenna elements of the receiving side array antenna for which is set.

  When the transmission / reception antenna elements are in the same mode as shown in the graph of B1 in FIG. 19 (mode L1 for both transmission and reception) and the graph of B3 in FIG. 20 (mode L-1 for both transmission and reception). In the direction in which transmission and reception are opposite (transmission rotation angle α = 0 [°]), the reception peak intensity is about −40 dB. On the other hand, as shown in the graph of symbol B2 in FIG. 19 (transmission mode L-1 and reception mode L1) and the graph of symbol B4 in FIG. 20 (transmission mode L and reception mode L-1). In addition, when the transmitting and receiving antenna elements are in different modes, the received peak intensity is low at less than −60 dB in the same facing direction. That is, as shown in the graph of FIG. 19, when the transmission / reception array antennas face each other in the case of the same mode L1 for transmission and reception and the case of different mode L-1 (transmission) vs. L1 (reception), reception is performed. The level difference is> 20 dB. Also, as shown in the graph of FIG. 20, the array antenna for transmission / reception is different between the case where the antenna elements for transmission / reception are the same mode L-1 and the case where the mode L1 (transmission) is different from L-1 (reception). When facing each other, the reception level difference is> 30 dB. As shown in FIGS. 19 and 20, there is a level difference exceeding 20 dB between the signal intensity received in the same mode as the transmission side and the signal intensity received in a mode different from the transmission side. From this, the receiving antenna can identify the received signal from the transmitting antenna by the OAM wave mode, so that multiplex communication using the OAM wave is possible.

(Modification of the first embodiment)
FIG. 21 is a diagram illustrating a case where the reception-side antenna reflects and receives transmission of a multi-mode OAM wave. As shown in the figure, a plurality of reflectors 450 are arranged in a ring shape in front of the array antenna on the transmission side. In the figure, as the three reflecting plates 450, the reflecting plates 450-1, 450-2, and 450-3 are arranged in a ring shape so that the centers of the rings coincide. The diameter of the ring-shaped reflecting plate 450 is determined by the spread angle in each mode and the distance to the transmitting-side array antenna. Here, a necessary distance is secured from the transmitting-side array antenna to the reflecting plate 450 in order to generate an OAM wave. Furthermore, the inclination of each ring-shaped reflecting plate 450 is half of the above-described spread angle. In this way, by installing a plurality of ring-shaped reflectors 450 in a concentric manner, OAM waves are propagated in parallel from the respective spreads. A plurality of ring-shaped reflectors that are symmetrical with the transmission-side reflection plate 450 and a reception-side array antenna are also provided facing the reception side. Thus, the OAM wave radiated from the transmitting array antenna propagates in parallel on the transmitting ring-shaped reflecting plate, and the parallel propagated OAM wave is received by the receiving array antenna by the receiving reflector. Bent to the optimal angle to receive.

  As specific numerical examples shown in FIG. 21, the frequency used is 75 GHz, the aperture diameter D of the array antenna is D = 4λ (= 16 mm), and the distance d between the transmitting-side array antenna and the reflector 450 is 12 cm. When the transmission modes to be multiplexed are the modes L1, L2 (, L3), the spread angles in the respective modes are 8 °, 14 ° (, 20 °), so that the reflectors 450-1, 450-2 (, 450- The ring radius of 3) is 17 mm and 30 mm (, 44 mm), and the inclination of the reflector is 4 ° and 7 ° (, 10 °), respectively. The OAM wave can be propagated in parallel by setting the numerical value of the inclination of the reflectors 450-1, 450-2 (, 450-3) to half the previous spread angle. The receiving side also includes the same array antenna as the transmitting side and a plurality of ring-shaped reflecting plates that are symmetrical to the reflecting plates 450-1, 450-2 (450-3) placed in front of the transmitting side antenna. Thus, each array antenna in the reception mode L1, L2 (, L3) on the reception side is reflected by the reflection plates 450-1, 450-2 (, 450-3) on the transmission side and propagated in parallel. OAM waves can be received. If the peak level is propagated in parallel by having a plurality of ring-shaped reflectors shown in FIG. 21 on both the transmitting and receiving sides, the peak level is theoretically received in all modes of the multiplexed OAM waves. It can be secured regardless of the position, and the transmission / reception distance can be further extended.

[Second Embodiment]
In this embodiment, antenna elements are shared by array antennas of different OAM modes.

  FIG. 22 is a diagram illustrating a case in which transmission of a multi-mode OAM wave is directly received. In contrast to FIG. 16 in the first embodiment, in FIG. 22, the arrangement of antenna elements for a plurality of modes multiplexed in the array antenna is examined in detail.

  In FIG. 16, six elements are assigned to each of the OAM wave modes L1, L2, and L3, and a total of 18 elements are arranged on the same circumference to configure the transmitting antenna. The conditions for configuring the antenna on the transmitting side are to have an array antenna for each mode for transmission only and to have the number of elements necessary to generate an OAM wave corresponding to the mode. When the modes are L1, L2, L3,..., Li,..., And the number of modes is L = 1, L = 2, L = 3,. The minimum number of elements required when generating a wave is 2 | L | +1, and a corresponding number of elements is required in the higher-order mode. Here, since the mode L3 requires at least 7 elements, the mode L3 cannot be realized with the 6 elements shown in FIG. In addition, the diagonal length of each antenna element is shorter than the length obtained by dividing the circumference of the transmitting-side array antenna by the number of elements, that is, the size of each antenna element is small in FIG. is there. In addition, as a condition, when antenna elements in a plurality of modes are arranged on the same circumference, the antenna elements are arranged at equal intervals in each mode. For example, in FIG. 22, the antenna elements 351 for mode L1 are arranged at equal intervals for every two elements jumped, but the antenna elements 352 for mode L2 are mixed with one element jump and adjacent elements at equal intervals. is not. In other words, it is required that all antenna elements can be arranged on the circumference within the range of the target array antenna. A case that does not satisfy these conditions is shown in FIG. 22, and the following two items can be cited as problems to the first embodiment.

(A) The antenna elements are not arranged at equal intervals for each mode. That is, the antenna elements arranged on the same circumference are unequal intervals for each mode.
(B) A multi-mode antenna element cannot be arranged. For example, in FIG. 22, the antenna element 351 of mode L1 and the antenna element 352 of L2 can be arranged, but the antenna element of mode L3 cannot be arranged. In higher order modes, a corresponding number of elements is required.

  FIG. 23 and FIG. 24 show the arrangement of antenna elements as a countermeasure for solving the problem with respect to the first embodiment. In this measure, the antenna elements are shared by a plurality of array antennas to reduce the number of elements. Reduction of the number of elements solves the problem shown in FIG. 22 ((a) elements arranged on the same circumference are unequally spaced for each mode, and (b) antenna elements cannot be arranged with multiple modes). .

  In the measure (a) shown in FIG. 23, the antenna elements arranged on the circumference of the antenna are reduced by sharing the same antenna element between different modes for transmission and reception. In FIG. 23, there are three types of modes, L1, L2, and L3, as OAM waves. In each of these modes, 4 elements, 8 elements, and 8 elements are used only on the transmission side. For this reason, if antenna elements are not shared, a total of 20 elements are required. Therefore, if four antenna elements 601 sharing all these three modes and four antenna elements 603 sharing mode L2 and mode L3 are combined, there are eight elements, and there are separate antenna elements for transmission and reception. The total is 16 elements. Therefore, four elements are reduced compared to the case where the antenna element is not shared. The four antenna elements 602 shown in the figure are receiving antenna elements sharing three types of modes L1, L2, and L3, and the four antenna elements 604 share two types of modes L1 and L2. It is a receiving antenna element. In this way, different types of antenna elements 601, 602, 603, and 604 can be arranged at equal intervals in FIG. For example, mode L1 is arranged with three elements skipped, and mode L2 and mode L3 are arranged with one element skipped.

  The measure (b) shown in FIG. 24 aims to further reduce the number of elements than the measure (a) shown in FIG. 23 by sharing the same antenna element for transmission and reception between different modes. In FIG. 23 described above, the total of the transmission side and the reception side is 2 × 8 elements, for a total of 16 elements. On the other hand, in FIG. 24, since transmission / reception is shared by the same antenna element, the half of FIG. In the figure, an antenna element 611 is an antenna element that shares transmission / reception of three types of modes L1, L2, and L3, and an antenna element 612 is an antenna element that shares transmission / reception of two types of modes L1 and L2. It is. As shown in the figure, the antenna elements for mode L1 are arranged at equal intervals by skipping one element, and the antenna elements for mode L2 and mode L3 are equally spaced by all eight elements constituting the array antenna. .

  In addition, about the countermeasure (a) which shares an antenna element between different modes shown in FIG. 23, a structure is shown in FIG. 25 immediately after this, and a verification experiment and its result are shown in FIG. 29 and FIG. Further, a measure (b) for sharing the antenna element shown in FIG. 24 for transmission and reception will be described with reference to FIG. 32 in the third embodiment.

  The element arrangement (modification) and the set phase of the antenna element in the multiplex transmission / reception in this embodiment will be described with reference to FIGS. In FIG. 25 and FIG. 26, all antenna elements are shared by array antennas of all modes to be multiplexed.

  FIG. 25 is a connection configuration diagram in a communication device 650 having antenna elements for different transmission and reception. In the figure, only the configuration on the transmission side of the communication device 650 is shown. The communication device 650 includes M transmission signal generation devices 651, M demultiplexers 652 having N ports, M × N phase shifters 653, N hybrid multiplexers 654, and antennas 660. And have. The phase adjuster 653 has a variable phase adjustment amount. The antenna 660 includes N antenna elements 661 for transmission.

  N antenna elements 661 that radiate signals are connected to N hybrid multiplexers 654, respectively. Each of the N hybrid multiplexers 654 is connected to M phase shifters 653 having a mode number. That is, there are a total of M × N phase shifters 653. Each phase shifter 653 is connected to M transmission signal generators 651 through M demultiplexers 652 having N-port outputs. Note that the hybrid multiplexer 654 allows a signal to pass between the input and the output, and blocks the signal between a plurality of inputs.

  Hereinafter, the m-th transmission signal generation device 651 is referred to as a transmission signal generation device 651-m (m is an integer of 1 to M), and the duplexer 652 connected to the transmission signal generation device 651-m This is described as a demultiplexer 652-m. The phase shifter 653 connected to the n-th port (n is an integer not smaller than 1 and not larger than N) of the duplexer 652-m is referred to as a phase shifter 653-mn, and the phase shifters 653-1-n to 653- The hybrid multiplexer 654 connected to M-m is referred to as a hybrid multiplexer 654-n. The antenna element 661 connected to the hybrid multiplexer 654-n is referred to as an antenna element 661-n.

  The transmission signal generation device 651-m outputs the generated transmission signal to the duplexer 652-m. The demultiplexer 652-m demultiplexes the transmission signal input from the transmission signal generation device 651-m to N ports and outputs the demultiplexed signals to the phase shifters 653-m-1 to 653-m-N. The phase shifter 653-mn adjusts the phase of the transmission signal input from the branching filter 652-m based on the transmission mode, and inputs it to the hybrid multiplexer 654-n. The hybrid multiplexer 654-n multiplexes the transmission signals whose phases are adjusted by the phase shifters 653-1-n, 653-2-n,..., 653-Mn to the antenna element 661-n. Output. The antenna element 661-n radiates the signal input from the hybrid multiplexer 654-n.

  The receiving-side communication device is configured by replacing three elements in the connection configuration shown in FIG. That is, the communication device on the reception side includes a hybrid duplexer instead of the hybrid multiplexer, a multiplexer instead of the duplexer, and a reception signal demodulation device instead of the transmission signal generation device. This is similar to the description of the reception-side communication apparatus in FIG. 15 with respect to the transmission-side communication apparatus in FIG. 14 described above. However, as described in FIG. 15, the number of components on the receiving side does not have to be the same so as to match the transmitting side. Transmission / reception may be realized as different numbers of components.

  FIG. 26 is a diagram showing phase values set in the antenna elements 661 shown in FIG. Antenna elements # 1, # 2, # 3,..., #J,..., #N shown in the figure are antenna elements 661-1 to 661-1 included in the antenna 660 in the connection configuration of the communication device 650 on the transmission side shown in FIG. 661-N, which are arranged on the same circumference. The number N of elements required for the antenna 660 is calculated based on the highest order mode Lmax. As described in the explanation of FIG. 22, the number N of antenna elements is, in particular, as a condition of the transmitting-side array antenna that generates the OAM wave mode Lmax (when Lmax is considered as a specific order of the OAM mode). N ≧ 2Lmax + 1 is required. And the phase corresponding to the several mode to multiplex is set to the signal output to each antenna element # 1- # N arrange | positioned on the same periphery.

  When the number M of modes to be multiplexed (M ≦ 2Lmax + 1), the OAM wave mode L is L0, L ± 1, L ± 2,..., L ± i,. In such a case, the phase corresponding to the OAM wave mode of the antenna element # 1 is 360 / N [°] in the mode L1, 720 / N [°] in the mode L2,..., 360 · Lmax / N [ °] is set. As the phase corresponding to the antenna element # 2, 720 / N [°] is set in the mode L1, 1440 / N [°] in the mode L2,... 720 · Lmax / N [°] in the mode Lmax. Further, as a phase corresponding to the antenna element #j, 360 j / N [°] in the mode L1, 720 j / N [°] in the mode L2,..., 360 j · Lmax / N [°] in the mode Lmax are set. The phase corresponding to antenna element #N is 360 (N−1) / N [°] in mode L1, 720 (N−1) / N [°] in mode L2,..., 360 (N in mode Lmax. -1) Lmax / N [°] is set.

27 and 28, a configuration example in which the reduction of the device configuration due to the difference in the number of elements used in each mode is compared with an example in which the reduction is not performed is compared with an example in which the reduction is supported.
FIG. 27 is a connection configuration diagram of the communication device 650 configured with a sufficient number of elements and functional elements. The communication device 650 is an example of a configuration that does not support element reduction. On the other hand, FIG. 28 is a connection configuration diagram in the communication device 680 in which the number of elements is appropriately set and the number of components is reduced.

  The configuration on the transmission side of the communication device 650 shown in FIG. 27 is the same as the configuration of the communication device 650 shown in FIG. 25, and only the configuration on the transmission side is shown. The communication device 650 includes M transmission signal generation devices 651-1 to 651-M, M duplexers 652-1 to 652-M having N ports, and M × N phase shifters 653-1. -1 to 653-MN, N hybrid multiplexers 654-1 to 654-N, and an antenna 660. The antenna 660 includes N transmission antenna elements 661-1 to 661-N.

  On the other hand, the communication device 680 shown in FIG. 28 is composed of the same elements as the communication device 650 shown in FIG. 27, and in particular, the number of elements N is also the same as that of the communication device 650. The communication device 650 is the same as the communication device 650 in that M transmission signal generation devices 651 are provided. Elements constituting the communication device 680 are, in order of signal flow, a transmission signal generation device 651 that generates a transmission signal, a demultiplexer 682 that branches the transmission signal generated by the transmission signal generation device 651, and a distributed transmission signal. A phase shifter 683 that adjusts and sets the phase according to the mode of the OAM wave, a hybrid combiner 684 that combines the phase-adjusted OAM wave transmission signals of a plurality of modes, and an antenna 690 having N antenna elements 691 It is. The N antenna elements 691 are referred to as antenna elements 691-1 to 691-N, respectively.

  In the figure, only the configuration on the transmission side of the communication device 680 is shown. In the configuration on the receiving side, the transmitting-side array antenna is used as it is as the receiving-side array antenna, a hybrid duplexer is provided instead of the hybrid multiplexer, the phase shifter is used as it is, and the multiplexer is used instead of the duplexer. And a reception signal demodulating device instead of the transmission signal generating device. This is also the relationship between the communication device 300 on the transmission side shown in FIG. 14 and the communication device 400 on the reception side shown in FIG. 15, or the configuration on the reception side when only the configuration on the transmission side in the communication device 650 in FIG. It is the same as the description regarding.

  Here, the communication apparatus 680 shown in FIG. 28 is different from the communication apparatus 650 shown in FIG. 27 in that the mode allocation method sharing the antenna element 691 is different. In communication device 650 shown in FIG. 27, all antenna elements 661-1 to 661-N share a plurality of modes. On the other hand, in the communication device 680 shown in FIG. 28, some of the N antenna elements 691 are shared in a plurality of modes. That is, some of the antenna elements 691 are shared by the higher-order mode and the lower-order mode, and the remaining other antenna elements 691 are used only by the higher-order mode. As described with reference to FIGS. 22 and 25, when the modes are L1, L2, L3,..., Li,..., The number of modes L = 1, L = 2, L = 3,. Then, since the minimum number of elements necessary for generating the mode L OAM wave is 2 | L | +1 as described above, an appropriate number of elements with a margin can be secured. And assign it to the component. In this way, the number of shared elements is set more appropriately according to the multiple modes to be multiplexed. The elements constituting the transmission / reception apparatus are reduced as shown in FIG. 27 to FIG. 28, and the manufacturing cost of the transmission / reception apparatus can be reduced by this reduction.

For example, the communication device 680 has an array antenna of M types of transmission modes, and the array antenna of the m-th type (m is an integer greater than or equal to 1 and less than or equal to M) includes N antenna elements 691 of the antenna 690. and used among _{N m} antenna elements 691 of the number _{(N m} ≦ N). Of the N antenna elements 691, Z (Z <N, Z is an integer) are shared by a plurality of modes of array antennas, and the remaining (NZ) antenna elements 691 are array antennas of one mode. Used by. Each of the antenna elements 691 shared by the array antennas in the plurality of modes is connected to the hybrid multiplexer 684. Therefore, the communication device 680 can reduce (NZ) multiplexers compared to the communication device 650.

As described above, the communication device 680 includes the same M transmission signal generation devices 651-1 to 651-M as the communication device 650 illustrated in FIG. The duplexer 682 connected to the transmission signal generation device 651-m that generates a signal to be transmitted in the m-th mode is referred to as a duplexer 682-m. Demultiplexer 682-m has a _{N m-number} of ports. The demultiplexer 682-m n-th phase shifter 683 (n is the following integer 1 or more _{N m)} is connected to the port, referred to as a phase shifter 683-m-n. With such a configuration, the communication device 680 can reduce Σ (N−N _m ) phase shifters compared to the communication device 650. The phase shifter 683-mn of the transmission mode sharing the antenna element 691 outputs a signal whose phase is adjusted to the hybrid multiplexer 684 connected to the antenna element 691 used in the m-th transmission mode. The phase shifter 683-mn in the transmission mode that does not share the antenna element outputs a signal whose phase is adjusted to the antenna element 691 used in the transmission mode.

  FIG. 29 is a diagram illustrating an OAM wave multiplex transmission / reception system according to the present embodiment. In the figure, the transmission side has the same configuration as the communication device 650 shown in FIGS. 25 and 27, and M = 2 and N = 4. On the receiving side, the antenna 750 is replaced with the antenna 660, the hybrid multiplexers 654-1 to 654-4 of the communication device 650 are replaced with the hybrid demultiplexers 761-1 to 761-4, and the phase shifter is variable. Instead of 653-1-1 to 653-1-4 and 653-2-1 to 653-2-4, phase shifters 762-1-1 to 762-1-4 and 762-2-1 having variable phases are available. 762-2-4 is replaced with duplexers 652-1 and 652-2 having four ports, and multiplexers 763-1 and 763-2 having four ports are replaced with transmission signal generating devices 651-1 and 651-. In this configuration, a spectrum analyzer 764 serving as a received signal demodulating device is provided instead of 2. The mode used for reception is selected by changing the phase setting of the phase shifters 762-1-1 to 762-1-4 and 762-2-1 to 762-2-4. The antenna 750 includes four antenna elements 751-1 to 751-4 for multiplexing and receiving a plurality of modes, and has the same configuration as the antenna 660 on the transmission side.

  On the transmission side, a hybrid multiplexer 654 multiplexes transmission signals of a plurality of modes, and radiates OAM waves of different modes through the same antenna element 661. The frequency used is 5.2 GHz (wavelength: 5.765 cm), the number of elements included in the antenna 660 and the antenna 750 is four elements, the aperture diameter of the array antenna of the antenna 660 and the array antenna of the antenna 750 is 4λ (23.06 cm), The OAM wave modes are L1 and L-1. The distance between transmission and reception is 1.8 m, and the spread angle is 8 °. The phase shifters 653-1-1 to 653-1-4 and the phase shifters 762-1-1 to 762-1-4 have 0 [°], 90 [°], 180 [°], and −90 [ [°], the phase shifters 653-2-1 to 653-2-4 and the phase shifters 762-2-1 to 762-2-4 have 0 [°], −90 [°], 180 with respect to the mode L-1. [°] and 90 [°] are set. In addition, in order to evaluate whether the multiplexed OAM wave can be separated, the transmitting antenna 660 is rotated around the vertical axis (Z axis). This rotation angle is α [°].

  On the receiving side, multiplexed OAM wave reception signals received by the same antenna elements 751-1 to 751-4 correspond to the respective modes via the hybrid demultiplexers 761-1 to 761-4. The phase shifters 762-1-1 to 762-1-4 and 762-2-1 to 762-2-4 are divided and passed. In this way, the transmitting side transmits OAM waves multiplexed using the same antenna elements, and the receiving side receives multiplexed OAM waves using the same antenna elements, thereby reducing the number of elements. be able to.

30 and 31 are diagrams showing changes in the reception level of multiplexed OAM waves in the multiplex transmission / reception system shown in FIG.
In FIG. 30, the mode L1 and the mode L-1 are set in the four antenna elements of the transmitting antenna, and the OAM wave radiated by combining is set to the mode L1 and the mode L1 of the receiving antenna. The result of reception peak intensity obtained for mode L1 by demultiplexing after reception by four antenna elements is shown. On the other hand, FIG. 31 shows that the mode L1 and the mode L-1 are set for each of the four antenna elements of the transmission side array antenna, and the combined OAM wave is radiated to the mode L-1 and the mode of the reception side array antenna. The result of reception peak intensity obtained for mode L-1 by demultiplexing after reception by four antenna elements with L-1 set is shown.

  As shown in the graphs D1 and D2 in FIG. 30, when the signal on the transmitting side has an OAM wave mode L1 and the receiving side also receives the signal in the same mode L1, and the mode on the transmitting side OAM wave is L-1. The reception level difference from when the signal is received in the mode L1 at which the reception side is different is> 20 dB. Similarly, as shown in the graphs of D3 and D4 in FIG. 31, when the signal on the transmitting side has an OAM wave mode of L-1, and the receiving side also receives the signal in the same mode L-1, the OAM on the transmitting side The reception level difference from the case where the signal having the wave mode L is received in the mode L-1 on the receiving side is> 20 dB. Therefore, in comparison with the case where the number of elements constituting the array antenna (eight) is large without using the hybrid duplexer / hybrid multiplexer shown in FIG. 19 and FIG. 20, in FIG. 30 and FIG. It has been proved that signal separation can be realized by multiplexing with OAM wave mode L ± 1 even with half the number of elements (four). The reduction in the separation level can be improved by arranging antenna elements with the same number of elements on the circumference, so there are restrictions on the size of the array antenna, and under the condition that antenna elements with the same number of elements are arranged on the circumference, the hybrid It is effective to share an antenna element using a duplexer and a hybrid multiplexer.

[Third Embodiment]
In the present embodiment, a measure for solving the problem of the first embodiment shown in FIG. 24 of the second embodiment (sharing antenna elements and reducing the number of elements) is shown. In the third embodiment, a transmission / reception configuration connected to the array antenna will be described as a measure (b) for sharing the same antenna element in the transmission / reception shown in FIG. As can be seen from FIG. 24, in addition to reducing the number of elements by sharing antenna elements arranged on the same circumference between array antennas of different modes in the previous second embodiment, transmission and reception are shared. By doing so, the number of elements can be further reduced, which leads to multiplexing that uses more OAM wave modes.

The element arrangement in the multiplex transmission / reception according to the present embodiment will be described with reference to FIGS. 32 and 33.
FIG. 32 is a diagram showing the arrangement of antenna elements in multiplex transmission / reception according to the present embodiment. As shown in the figure, the antenna 810 uses the antenna element 811 on the circumference of the concentric circle and the same diameter to share the antenna element for transmission and reception. This figure shows a state where eight antenna elements 811 originally arranged on the same circumference and four shared antenna elements 811 are arranged one by one. Further, in the figure, the antenna 810 having the antenna element 811 arranged on the circumference is the same for both transmission and reception, but it is not necessarily the same.

  FIG. 33 is a diagram illustrating a connection configuration in the communication apparatus 800. As described above, the communication device 800 that performs transmission / reception shares the antenna element 811 for transmission / reception. Assuming that the number of multiplexing is M and the number of elements is N, the communication device 800 includes M transmission signal generation devices 801, M reception signal demodulation devices 802, M circulators 803, M demultiplexing / A multiplexer 804, M × N phase shifters 805, N hybrid demultiplexers / multiplexers 806, and an antenna 810 are provided. The antenna 810 includes N antenna elements 811. The N antenna elements 811 are referred to as antenna elements 811-1 to 811-N, respectively. As described above, the communication apparatus 800 includes the multiplex number M transmission signal generation apparatuses 801 and reception signal demodulation apparatuses 802, and a circulator 803 connected to the transmission signal generation apparatuses 801 and reception signal demodulation apparatuses 802. The circulator 803 is connected to M × N variable phase shifters 805 via M demultiplexers / multiplexers 804. In the phase shifter 805, the phase of the signal is adjusted and set in accordance with the mode in which the OAM wave is multiplexed. Phase shifter 805 is connected to N antenna elements 811 via N hybrid demultiplexers / multiplexers 806. In the circulator 803, the input and output directions of signals are determined in order, and signals in the input to output directions are not allowed to pass in the reverse order.

  The configuration on the receiving side with respect to the configuration on the transmitting side of the communication device 800 shown in FIG. 33 is the configuration of the communication device 400 on the receiving side in FIG. 15 with respect to the communication device 300 on the transmitting side in FIG. The communication device 650 of FIG. 28 and the communication device 680 of FIG.

  Hereinafter, the transmission signal generation device 801 that generates a signal to be transmitted in the m-th mode (m is an integer of 1 to M) is referred to as a transmission signal generation device 801-m, and is received in the m-th mode. The received signal demodulator 802 that demodulates the signal is referred to as a received signal demodulator 802-m. The circulator 803 connected to the transmission signal generator 801-m and the received signal demodulator 802-m is described as a circulator 803-m, and the demultiplexer / multiplexer 804 connected to the circulator 803-m is demultiplexed / combined. It is described as a waver 804-m. The phase shifter 805 connected to the n-th port (n is an integer of 1 to N) of the demultiplexer / multiplexer 804-m is referred to as a phase shifter 805-mn. The hybrid demultiplexer / multiplexer 806 connected to the phase shifters 805-1-n to 805-Mn and the antenna element 811-n is referred to as a hybrid demultiplexer / multiplexer 806-n.

  The transmission signal generation device 801-m outputs the generated transmission signal to the circulator 803-m. The circulator 803-m outputs the transmission signal input from the transmission signal generation device 801-m to the demultiplexer / multiplexer 804-m. The demultiplexer / multiplexer 804-m demultiplexes the transmission signal input from the circulator 803-m to N ports and outputs the demultiplexed signals to the phase shifters 805-m-1 to 805-m-N. The phase shifters 805-m-1 to 805-m-N adjust the phase of the transmission signal input from the n-th port of the demultiplexer / multiplexer 804-m based on the mth mode, Output to the wave / multiplexer 806-n. The hybrid demultiplexer / multiplexer 806-n multiplexes the transmission signals input from the phase shifters 805-1-n to 805-Mn and outputs the combined signal to the antenna element 811-n. The antenna element 811-n radiates the transmission signal input from the hybrid demultiplexer / multiplexer 806-n.

  On the other hand, the antenna element 811-n outputs the received signal to the hybrid demultiplexer / multiplexer 806-n. The hybrid demultiplexer / multiplexer 806-n distributes the reception signal input from the antenna element 811-n to the phase shifters 805-1-n to 805-Mn. The phase shifter 805-mn adjusts the phase of the received signal input from the hybrid demultiplexer / multiplexer 806-n based on the mth mode, and the nth of the demultiplexer / multiplexer 804-m. Output to the port. The demultiplexer / multiplexer 804-m multiplexes the reception signals input from the phase shifters 805-m-1 to 805-m-N and outputs the multiplexed signal to the circulator 803-m. The circulator 803-m outputs the received signal input from the demultiplexer / multiplexer 804-m to the received signal demodulator 802-m. The reception signal demodulator 802-m demodulates the reception signal input from the circulator 803-m.

  The advantage of the configuration of the communication apparatus 800 shown in FIG. 33 is that the number of elements included in the antenna can be reduced because the antenna element is shared in the OAM wave mode in which the antenna elements are multiplexed and / or is shared in transmission and reception. is there. Thereby, when arranging antenna elements on the same circumference, the restriction on the number of elements can be eliminated.

  According to the embodiment described above, the antenna that performs wireless multiplex communication using an OAM wave has a plurality of different types of array antennas. The type of the array antenna is represented by an OAM wave mode and a transmission / reception transmission / reception type. The antenna elements constituting each of the plurality of array antennas included in the antenna are arranged on the same circumference. That is, antenna elements having different OAM wave modes, antenna elements that transmit OAM waves, and antenna elements that receive OAM waves are arranged on the same circumference.

  In addition, the antenna elements arranged on the same circumference in the antenna that performs the OAM wave multiplex communication described above perform one or both of transmission and reception of the OAM wave. That is, the antenna includes a transmitting-side array antenna that transmits (radiates) OAM waves, and a receiving-side array antenna that receives OAM waves. The antenna element of the transmitting-side array antenna and the receiving-side array Use at least a part of the antenna elements of the antenna. In each array antenna, the antenna elements are arranged at equal intervals.

  In addition, the antenna elements arranged on the same circumference in the antenna that performs the OAM wave multiplex communication described above perform one or both of transmission and reception of the OAM wave. The antenna has a plurality of array antennas on the transmission side that transmit OAM waves of different OAM modes, and at least some of the antenna elements are shared by the plurality of array antennas on the transmission side. Alternatively, the antenna has a plurality of receiving-side array antennas that receive OAM waves of different OAM modes, and at least some of the antenna elements are shared by the plurality of receiving-side array antennas. The antenna may include both a plurality of transmitting side array antennas sharing at least some antenna elements and a plurality of receiving side array antennas sharing at least some antenna elements. In each of the transmitting side array antenna and the receiving side array antenna, the antenna elements are arranged at equal intervals.

  According to the embodiment described above, an antenna that has a plurality of different types of array antennas and performs wireless multiplex communication using an OAM wave includes the direction of the radiation peak of the OAM wave from the array antenna on the transmission side, and the reception side. By reducing the amount of deviation of the array antenna from the direction of the antenna element, a decrease in reception level is suppressed. By suppressing the decrease in the reception level, multiplex transmission / reception using the OAM wave can be performed more reliably.

  Further, by sharing antenna elements for transmission and reception or antenna elements of different modes, the number of elements of the array antenna can be reduced. For this reason, the problem of physically disposing antenna elements of different types (different at least one of OAM mode and transmission / reception type) at equal intervals on the same circle with the conventional number of elements can be solved. .

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  It can be used for an antenna that transmits and receives OAM waves in a multiplexed manner.

DESCRIPTION OF SYMBOLS 100, 200 ... Antenna 101, 102, 201, 202 ... Antenna element 300 ... Communication apparatus 301-1 to 301-M ... Transmission signal generation apparatus 302-1 to 302-M ... Demultiplexer 303-1-1-1 to 303- M-N ... phase shifter 310 ... antennas 311-1-1 to 311-MN, 311-1 to 311-3 ... antenna elements 351 and 352 ... antenna element 400 ... communication device 410 ... antenna 411-1-1 to 411-MN ... Antenna elements 421-1-1 to 421-MN ... Phase shifters 422-1 to 422-M ... Multiplexers 423-1 to 423-M ... Received signal demodulation devices 450-1 to 450- -3 ... reflectors 501, 502 ... network analyzer 503 ... spectrum analyzer 601, 602, 603, 604, 611, 612 ... antenna element 650 ... communication device 65 -1 to 651-M ... transmission signal generators 652-1 to 652-M ... demultiplexers 653-1-1 to 653-MN ... phase shifters 654-1 to 654-N ... hybrid multiplexer 660 ... Antennas 661-1 to 661-N ... Antenna element 680 ... Communication devices 682-1 to 682-M ... Demultiplexers 683-1-1 to 683-M _M ... Phase shifter 684 ... Hybrid multiplexer 690 ... Antenna 691-1 to 691-N antenna element 750 antenna 751-1 to 751-4 antenna element 761-1 to 761-4 hybrid demultiplexer 762-1-1 to 762-2-4 phase shifter 763 -1, 763-2 ... multiplexer 764 ... spectrum analyzer 800 ... communication devices 801-1 to 801-M ... transmission signal generation devices 802-1 to 802-M ... received signal demodulation devices 803-1 to 80-80 3-M ... circulators 804-1 to 804-M ... multiplexers 805-1-1 to 805-MN ... phase shifters 806-1 to 806-N ... multiplexers 810 ... antennas 811-1 to 811- N ... Antenna elements 980, 990 ... Antennas 981, 982, 991, 992 ... Antenna elements

Claims (3)

An antenna having a plurality of different array antennas, each of which is indicated by a combination of an OAM (Orbital Angular Momentum) wave mode and a transmission / reception transmission / reception type,
Each of the plurality of array antennas includes a plurality of antenna elements arranged on a circumference,
The circumference on which the antenna element is arranged is concentric and the same diameter for a plurality of the array antennas,
An antenna characterized by that. In the plurality of array antennas having different transmission / reception types, at least some of the antenna elements are shared,
A plurality of the antenna elements constituting the array antenna for each array antenna are arranged at equal intervals on the circumference.
The antenna according to claim 1. In the plurality of array antennas having different OAM wave modes, at least some of the antenna elements are shared,
A plurality of the antenna elements constituting the array antenna for each array antenna are arranged at equal intervals on the circumference.
The antenna according to claim 1.