JP2017009530A - Antenna device - Google Patents

Abstract

An antenna device capable of reducing the amount of reflected power with respect to an incoming wave from a radar is obtained. A dielectric tube is provided which is bent so that both ends thereof are in the same direction and in which an ionizing gas is enclosed. Electrode terminals 3 are respectively provided at both ends of the dielectric tube 1, and at least one value of excitation voltage and excitation current is controlled and supplied from the plasma excitation power source 4 to the electrode terminals 3. The high frequency signal generator 5 is supplied with a high frequency signal for operating the dielectric tube 1 as an antenna. The plasma frequency in the plasma state of the dielectric tube 1 is set to a frequency lower than the frequency of the radio wave used by the radar. [Selection] Figure 1

Description

  The present invention relates to an antenna device capable of reducing the amount of power reflected by radio waves arriving at an antenna.

As a conventional antenna device, when the external power supply is turned on, the ionizing gas in the dielectric tube becomes a plasma state. By supplying high-frequency power in this state, the dielectric tube operates as an antenna. When the power is turned off, the ionizing gas in the dielectric tube changes from the plasma state to the normal state, the high frequency conductivity is lost, and the dielectric tube appears to be electrically transparent to the high frequency. (For example, see Patent Document 1).
Further, in Patent Document 1, the shape of the dielectric tube is configured to be bent to realize a low scattering cross-sectional area, while other members such as wiring also have a scattering cross-sectional area as a whole device. The configuration to be implemented so as not to increase is shown.

JP 2010-148025 A

  The conventional antenna device is mounted so that the shape of the antenna is bent and the scattering cross section of other members necessary for exciting the plasma does not affect the antenna characteristics. In such a conventional antenna device, a low scattering cross-sectional area when not in use can be realized, and when there are a plurality of antennas that are arranged close to each other and used for switching, mutual interference can be reduced. There has been a problem that consideration has not been given to reducing the amount of reflected power in the.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an antenna device capable of reducing the amount of reflected power with respect to an incoming wave from a radar.

  In the antenna device according to the present invention, both ends of the antenna tube are bent in the same direction, and a dielectric tube in which an ionizing gas is sealed is provided. The first is provided inside the dielectric tube and at both ends of the dielectric tube. The electrode terminal and the second electrode terminal are connected to the first electrode terminal and the second electrode terminal, and at least one of the excitation voltage and the excitation current is controlled to maintain the ionizing gas in the plasma state. A high frequency signal generator for supplying a high frequency signal to at least one of the first electrode terminal and the second electrode terminal and operating the dielectric tube as an antenna. The plasma frequency to be in the plasma state is lower than the frequency of the radio wave used by the radar.

  In the antenna device of the present invention, the plasma frequency to be set to the plasma state is set to a frequency lower than the frequency of the radio wave used by the radar, so that the amount of reflected power with respect to the incoming wave from the radar can be reduced.

It is a block diagram which shows the antenna apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the frequency characteristic of reflected electric power when a plane wave is entered into plasma. It is a block diagram which shows the antenna apparatus by Embodiment 2 of this invention. It is a block diagram which shows the antenna apparatus by Embodiment 3 of this invention. It is a block diagram which shows the antenna apparatus by Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a block diagram showing an antenna apparatus according to Embodiment 1 of the present invention.
The illustrated antenna device includes a dielectric tube 1, a moving body surface 2, an electrode terminal 3, a plasma excitation power source 4, a high frequency signal generator 5, and a cover 6.

  The dielectric tube 1 is filled with an ionizing gas, is bent in a U shape so that both ends are close and both ends are in the same direction, and both ends thereof are in the vicinity of the movable body surface 2, that is, It is arranged on the moving body surface 2 with a minute interval. The electrode terminals 3 are provided at both ends inside the dielectric tube 1 as first and second electrode terminals, respectively. The plasma excitation power source 4 is connected to each of the electrode terminals 3 and generates an excitation voltage or an excitation current that excites the ionizing gas into a plasma state. The high frequency signal generator 5 supplies a high frequency signal to at least one of the electrode terminals 3 in order to operate the dielectric tube 1 as an antenna. The cover 6 is disposed so as to cover the dielectric tube 1 and plays a role of protecting the dielectric tube 1.

  The dielectric tube 1 has been described as having both ends disposed in the vicinity of the moving body surface 2, but a ground conductor is provided on the moving body surface 2, and both ends of the dielectric tube 1 are close to each other on the ground conductor. You may comprise so that it may arrange | position.

  Moreover, you may comprise the array antenna apparatus which consists of a some antenna element by using the antenna apparatus of FIG. 1 as an antenna element. When configuring such an array antenna device, at least some of the components of the antenna element may be shared. For example, each of the plasma excitation power source 4 and the high-frequency signal generator 5 may be shared by two or more antenna elements. The cover 6 may also be mounted so as to cover two or more dielectric tubes 1. As described above, when configuring the array antenna apparatus, it is possible to reduce the circuit scale and cost by sharing at least a part of the components.

  FIG. 2 is a diagram illustrating frequency characteristics of reflected power when a plane wave is incident on plasma. The result when the plasma is turned on is indicated as “plasma ON”, and the result when the plasma is not turned on is indicated as “plasma OFF”. Plasma ON is indicated by a solid line, plasma OFF is indicated by a broken line, and the vicinity of the frequency where the reflected power of plasma ON and plasma OFF is the same value is the “plasma frequency”. At a frequency lower than the plasma frequency, the plasma ON shows higher reflected power than the plasma OFF, and the difference in reflected power amount between the plasma ON and the plasma OFF is large. For this reason, it behaves as a metal when plasma is turned on, and as a dielectric when plasma is turned off, and when used as an antenna, it appears as metal to the radar.

On the other hand, above the plasma frequency, the amount of reflected power is the same for plasma ON and plasma OFF. For this reason, both plasma ON and plasma OFF behave as dielectrics, and even when used as an antenna, they are observed as a dielectric by the radar, and the amount of reflected power looks lower than that of a normal antenna.
Therefore, by making the plasma frequency lower than the frequency used by the radar, it is observed from the radar as a dielectric.

  For example, when the mobile body on which the antenna device of Embodiment 1 is installed is an aircraft, the antenna device is mounted on the surface of the aircraft body. Here, a radio wave having an X-band frequency is generally used for a radar mounted on an aircraft. Therefore, by setting the plasma frequency of the plasma generated in the dielectric tube 1 to be lower than the frequency of the X band, the X band frequency becomes a characteristic similar to that of the dielectric, and the amount of reflected power is reduced. It is possible to operate as an antenna that is difficult to observe from a radar using a frequency of.

  Here, the radio wave of the X band frequency used in the radar mounted on the aircraft is taken as an example. However, the radio wave is not limited to an application object such as an aircraft and a radio wave of the frequency band such as the X band. By observing from the radar that uses the radio wave of that frequency band by setting the plasma frequency to be lower than the frequency of the radio wave corresponding to the radio wave of the frequency band used by various radars depending on the application target Can be operated as a difficult antenna.

  Further, as a method for adjusting the plasma frequency, for example, the control is performed by the excitation voltage or the excitation current according to the second embodiment described later or the control by the pressure or density of the ionizing gas according to the third embodiment. Not only the method but also other control methods may be applied.

  As described above, according to the antenna device of the first embodiment, the dielectric tube in which both ends are bent in the same direction and the ionizing gas is sealed inside, the dielectric tube inside the dielectric tube, and the dielectric tube The first electrode terminal and the second electrode terminal provided at both ends of the first electrode terminal, and the first electrode terminal and the second electrode terminal are connected to each other, and at least one of the excitation voltage and the excitation current is controlled. A high frequency signal is supplied to at least one of the first electrode terminal and the second electrode terminal, and the dielectric tube serves as an antenna, and a plasma excitation power source for maintaining the ionizing gas in a plasma state High frequency signal generator, and the plasma frequency to be in the plasma state is lower than the frequency of the radio wave used by the radar. The reflected power amount can be reduced even when using the antenna, therefore, it can be operated as an antenna it is difficult to observe from the radar for.

  Further, according to the antenna device of the first embodiment, since the ground conductor is provided on the surface of the moving body and the dielectric tube is positioned on the ground conductor, as the antenna device mounted on the moving body, It can be operated as an antenna that is difficult to observe from the radar.

  Further, according to the antenna device of the first embodiment, since the dielectric tube is positioned on the surface of the moving body, the antenna device mounted on the moving body is an antenna that is difficult to observe from the radar. It can be operated.

  Further, according to the antenna device of the first embodiment, since the moving body is an aircraft, it can be operated as an antenna device of an aircraft that is difficult to observe from a radar.

  In addition, according to the antenna device of the first embodiment, the frequency of the radio wave used by the radar is set to the X band frequency, so that it is operated as an antenna that is difficult to observe from the radar using the X band. Can do.

  Further, according to the antenna device of the first embodiment, since the dielectric cover that covers the dielectric tube is provided, the dielectric tube can be protected.

  Also, according to the antenna device of the first embodiment, the antenna device is used as an antenna element, and a plurality of antenna elements are arranged to form an array configuration, so that the amount of reflected power with respect to incoming waves from the radar is reduced as an array antenna device. Can be made.

Embodiment 2. FIG.
In the first embodiment, an antenna device has been described in which a frequency lower than the frequency of the radio wave used by the radar is set as the plasma frequency and operated as an antenna that is difficult to observe from the radar.
In FIG. 2 described in the first embodiment, the pressure or density of the ionizing gas enclosed in the dielectric tube 1 and the excitation voltage or excitation current supplied to excite the ionizing gas into the plasma state are set in advance. In addition, the frequency characteristics of reflected power measured by changing the frequency were shown, but at least one of the excitation voltage and the excitation current supplied to excite the ionizing gas into the plasma state should be changed. However, the plasma frequency can be adjusted and the characteristics of the reflected power can be controlled.

  From this point of view, in the second embodiment, the plasma frequency is set in accordance with the frequency of the radio wave actually coming from the radar, and the plasma frequency is set by changing the excitation voltage or the excitation current supplied to the plasma excitation power source. An antenna device to be described will be described.

3 is a block diagram showing an antenna apparatus according to Embodiment 2 of the present invention.
The antenna device according to the second embodiment includes a dielectric tube 1, a moving body surface 2, an electrode terminal 3, a plasma excitation power source 4a, a high frequency signal generator 5, a cover 6, a radio wave receiving device 7, a data analysis unit 8, a plasma setting. The unit 9 is provided. Here, since the dielectric tube 1, the movable body surface 2, the electrode terminal 3, the high-frequency signal generator 5, and the cover 6 are the same as those of the first embodiment shown in FIG. Omitted.

  The radio wave receiving device 7 is a radio wave receiving means for receiving radio waves arriving at the antenna device. The data analysis unit 8 is a processing unit that analyzes the frequency f of the incoming radio wave received by the radio wave receiver 7. The plasma setting unit 9 excites the ionizing gas into a plasma state so that the plasma frequency of the plasma excited in the dielectric tube 1 is set to a frequency lower than the frequency f of the incoming radio wave analyzed by the data analysis unit 8. This is a processing unit that calculates an excitation voltage or an excitation current to be supplied for this purpose and instructs the plasma excitation power source 4a to supply the excitation voltage or the excitation current. The plasma excitation power source 4a is basically the same as the plasma excitation power source 4 of the first embodiment, but generates an excitation voltage or an excitation current instructed from the plasma setting unit 9 to bring the ionizing gas into a plasma state. It is configured to excite.

  In the antenna device of the second embodiment configured as described above, first, the radio wave receiving device 7 receives a radio wave such as a radar wave arriving at the own device. When the radio wave receiving device 7 receives an incoming radio wave, the data analysis unit 8 performs frequency analysis and calculates the frequency f. Next, the plasma setting unit 9 supplies the plasma frequency excited in the dielectric tube 1 based on the frequency f analyzed by the data analysis unit 8 so as to set the plasma frequency to a frequency lower than the frequency f. The excitation voltage or excitation current to be calculated is calculated and instructed to the plasma excitation power source 4a. As a result, the plasma excitation power source 4a excites the ionizing gas in the dielectric tube 1 into a plasma state at a frequency lower than the frequency f.

  In the above example, the value of either the excitation voltage or the excitation current is controlled. However, both values of the excitation voltage and the excitation current may be controlled.

  Moreover, although the dielectric tube 1 demonstrated that the both ends were arrange | positioned in the vicinity of the mobile body surface 2, a ground conductor was provided in the mobile body surface 2, and both ends of the dielectric tube 1 approached on the ground conductor. You may comprise so that it may arrange | position.

Furthermore, an array antenna apparatus including a plurality of antenna elements may be configured using the antenna apparatus of FIG. 3 as an antenna element. When configuring such an array antenna device, at least some of the components of the antenna element may be shared. For example, the radio wave receiver 7, the data analysis unit 8, and the plasma setting unit 9 do not need to be provided in the same number as the plurality of antenna elements, and may be configured to share one set. Each of the plasma excitation power supply 4a and the high-frequency signal generator 5 may be shared by two or more antenna elements. The cover 6 may also be mounted so as to cover two or more dielectric tubes 1. As described above, when configuring the array antenna apparatus, it is possible to reduce the circuit scale and cost by sharing at least a part of the components.
A plurality of radio wave receivers 7 may be installed in the reception direction.

  As described above, according to the antenna device according to the second embodiment of the present invention, the radio wave receiver that receives the radio wave used by the radar, the data analysis unit that analyzes the frequency of the radio wave received by the radio wave receiver, A radar that receives an incoming radio wave by its own device, since it has a plasma setting unit that instructs the plasma excitation power source at least one of an excitation voltage and an excitation current with a plasma frequency lower than the frequency analyzed by the data analysis unit Observability from can be reduced.

Embodiment 3 FIG.
In the second embodiment, the antenna device that changes the excitation voltage or the excitation current supplied to excite the ionizing gas into the plasma state so as to set the plasma frequency in accordance with the frequency of the actually arrived radio wave. explained. On the other hand, by changing the pressure or density of the ionizing gas instead of changing the excitation voltage or the excitation current, the plasma frequency can be adjusted and the characteristics of the reflected power can be controlled.

  In the third embodiment, an antenna device that changes the pressure or density of ionizing gas so as to set the plasma frequency in accordance with the frequency of the radio wave actually coming from the radar will be described.

FIG. 4 is a block diagram showing an antenna apparatus according to Embodiment 3 of the present invention.
The antenna device according to Embodiment 3 includes a dielectric tube 1a, a moving body surface 2, an electrode terminal 3, a plasma excitation power source 4, a high frequency signal generator 5, a cover 6, a radio wave receiving device 7, a data analysis unit 8, a plasma setting. Part 10 and an ionizing gas adjusting part 11. Here, the moving body surface 2, the electrode terminal 3, the plasma excitation power source 4, the high frequency signal generator 5 and the cover 6 are the same as those in the first embodiment shown in FIG. The analysis unit 8 has the same configuration as that of the second embodiment shown in FIG.

The dielectric tube 1a is similar to the first embodiment and the second embodiment in that an ionizing gas is sealed inside and both ends thereof are disposed in the vicinity of the moving body surface 2. The second embodiment is different from the first and second embodiments in that the pressure or density can be adjusted.
The plasma setting unit 10 excites the ionizing gas into a plasma state so that the plasma frequency of the plasma excited in the dielectric tube 1a is set to a frequency lower than the frequency f of the incoming radio wave calculated by the data analysis unit 8. This is a processing unit for calculating the pressure or density of the ionizing gas and instructing this value to the ionizing gas adjusting unit 11. The ionizing gas adjusting unit 11 is an adjusting unit for adjusting the pressure or density of the ionizing gas in the dielectric tube 1 a to a state instructed by the plasma setting unit 10.

  The ionizing gas adjusting unit 11 includes, for example, an accumulating unit 111 that accumulates an ionizing gas, and a control valve 112 that is provided between the accumulating unit 111 and the dielectric tube 1a and adjusts the pressure or density of the ionizing gas. Composed. The control valve 112 adjusts the pressure or density of the ionizing gas in the dielectric tube 1a to be the pressure or density instructed from the plasma setting unit 10. The accumulating unit 111 may be a cylinder that accumulates an ionizing gas, for example.

  In the antenna device of the third embodiment configured as described above, first, the radio wave receiving device 7 receives a radio wave such as a radar wave arriving at the own device. When the radio wave receiving device 7 receives an incoming radio wave, the data analysis unit 8 performs frequency analysis and calculates the frequency f. Next, the plasma setting unit 10 sets the plasma frequency of the plasma excited in the dielectric tube 1 to a frequency lower than the frequency f based on the frequency f analyzed by the data analysis unit 8. The pressure or density of the ionizing gas in the body tube 1a is calculated, and this value is instructed to the ionizing gas adjusting unit 11. The ionizing gas adjusting unit 11 adjusts the ionizing gas in the dielectric tube 1a so that the instructed ionizing gas pressure or density is obtained. Thereby, the plasma excitation power source 4 excites the ionizing gas in the dielectric tube 1a into a plasma state at a frequency lower than the frequency f.

  In the above example, the pressure or density of the ionizing gas in the dielectric tube 1a is controlled. However, both the pressure and density values of the ionizing gas may be controlled. For example, control such as “increase the pressure value and decrease the density value” is also possible.

  Further, the dielectric tube 1a has been described as having both ends disposed in the vicinity of the moving body surface 2, but a ground conductor is provided on the moving body surface 2, and both ends of the dielectric tube 1 are close to each other on the ground conductor. You may comprise so that it may arrange | position.

Furthermore, an array antenna apparatus including a plurality of antenna elements may be configured using the antenna apparatus of FIG. 4 as an antenna element. When configuring such an array antenna device, at least some of the components of the antenna element may be shared. For example, the radio wave receiver 7, the data analysis unit 8, and the plasma setting unit 10 do not need to be provided in the same number as the plurality of antenna elements, and may be configured to share one set. Each of the plasma excitation power source 4, the high-frequency signal generator 5, and the ionizing gas adjustment unit 11 may be shared by two or more antenna elements. The cover 6 may also be mounted so as to cover two or more dielectric tubes 1a. As described above, when configuring the array antenna apparatus, it is possible to reduce the circuit scale and cost by sharing at least a part of the components.
A plurality of radio wave receivers 7 may be installed in the reception direction.

  As described above, according to the antenna device according to Embodiment 3 of the present invention, the radio wave receiving device that receives the radio wave used by the radar, the data analysis unit that analyzes the frequency of the radio wave received by the radio wave receiving device, An ionizing gas adjusting unit that adjusts at least one of the pressure and density of the ionizing gas inside the dielectric tube, and a pressure and density of the ionizing gas that has a plasma frequency lower than the frequency analyzed by the data analysis unit. Since the plasma setting unit for instructing at least one of the values to the ionizing gas adjustment unit is provided, it is possible to reduce the observability from the radar that receives the incoming radio wave in its own device.

Embodiment 4 FIG.
In the second embodiment, an antenna device that changes an excitation voltage or an excitation current supplied to excite ionizing gas into a plasma state so as to set the plasma frequency in accordance with the frequency of radio waves actually coming from the radar. Explained. In the third embodiment, the antenna device that changes the pressure or density of the ionizing gas so as to set the plasma frequency in accordance with the frequency of the radio wave actually coming from the radar has been described.

  Here, both the control of the second embodiment and the control of the third embodiment may be combined, and this will be described below as a fourth embodiment. That is, the antenna device of the fourth embodiment controls the excitation voltage or the excitation current supplied to excite the ionizing gas into the plasma state so as to set the plasma frequency in accordance with the frequency of the actually arrived radio wave. And controlling the pressure or density of the ionizing gas.

FIG. 5 is a configuration diagram illustrating an antenna device according to the fourth embodiment.
An antenna device according to Embodiment 4 of the present invention includes a dielectric tube 1a, a moving body surface 2, electrode terminals 3, a plasma excitation power source 4a, a high-frequency signal generator 5, a cover 6, a radio wave receiving device 7, and a data analysis unit 8. , An ionizing gas adjusting unit 11 and a plasma setting unit 12. Here, the moving body surface 2, the electrode terminal 3, the high-frequency signal generator 5, and the cover 6 are the same as those in the first and second embodiments shown in FIGS. 1 and 3, and the plasma excitation power source 4a. The radio wave receiving device 7 and the data analyzing unit 8 are the same as those in the second embodiment, and the dielectric tube 1a and the ionizing gas adjusting unit 11 are the same as those in the third embodiment shown in FIG. Since it is the same, the same code | symbol is attached to a corresponding part and the description is abbreviate | omitted.

  The plasma setting unit 12 excites the ionizing gas into a plasma state so that the plasma frequency of the plasma excited in the dielectric tube 1a is set to a frequency lower than the frequency f of the incoming radio wave calculated by the data analysis unit 8. The excitation voltage or excitation current to be supplied and the pressure or density of the ionizing gas are calculated, the excitation voltage or excitation current is calculated in the plasma excitation power source 4a, and the pressure or density of the ionizing gas is calculated in the ionizing gas. It is a processing unit that instructs the adjustment unit 11. In addition, the ionizing gas adjustment part 11 is comprised from the storage means 111 and the control valve 112, for example like the ionizing gas adjustment part 11 of Embodiment 3. FIG.

  In the antenna device of the fourth embodiment configured as described above, first, the radio wave receiving device 7 receives a radio wave such as a radar wave arriving at the own device. When the radio wave receiving device 7 receives an incoming radio wave, the data analysis unit 8 performs frequency analysis and calculates the frequency f. The operations so far are the same as those in the second and third embodiments. Next, the plasma setting unit 12 supplies the plasma frequency of the plasma excited in the dielectric tube 1 to a frequency lower than the frequency f based on the frequency f calculated by the data analysis unit 8. The excitation voltage or excitation current to be calculated is calculated and instructed to the plasma excitation power source 4a, the pressure or density of the ionizing gas in the dielectric tube 1a is calculated, and this value is instructed to the ionizing gas adjusting unit 11. The ionizing gas adjusting unit 11 adjusts the ionizing gas in the dielectric tube 1a so that the instructed ionizing gas pressure or density is obtained. Thereby, the plasma excitation power source 4a excites the ionizing gas in the dielectric tube 1a into a plasma state at a frequency lower than the frequency f.

  As in the second embodiment, both the excitation voltage and the excitation current may be controlled. Similarly to the third embodiment, both the pressure and density values of the ionizing gas may be controlled. You may make it control.

  Further, the dielectric tube 1a has been described as having both ends disposed in the vicinity of the moving body surface 2, but a ground conductor is provided on the moving body surface 2, and both ends of the dielectric tube 1 are close to each other on the ground conductor. You may comprise so that it may arrange | position.

Furthermore, an array antenna apparatus including a plurality of antenna elements may be configured using the antenna apparatus of FIG. 5 as an antenna element. When configuring such an array antenna device, at least some of the components of the antenna element may be shared. For example, the radio wave receiver 7, the data analysis unit 8, and the plasma setting unit 12 do not need to be provided in the same number as the plurality of antenna elements, and may be configured to share one set. Each of the plasma excitation power source 4a, the high-frequency signal generator 5, and the ionizing gas adjusting unit 11 may be shared by two or more antenna elements. The cover 6 may also be mounted so as to cover two or more dielectric tubes 1a. As described above, when configuring the array antenna apparatus, it is possible to reduce the circuit scale and cost by sharing at least a part of the components.
A plurality of radio wave receivers 7 may be installed in the reception direction.

  Further, the plasma setting unit 12 controls both the control value of the excitation voltage or the excitation current and the control value of the pressure or density of the ionizing gas so as to set the plasma frequency to a frequency lower than the frequency f of the incoming radio wave. However, it is not always possible to change both the control value of the excitation voltage or excitation current and the control value of the pressure or density of the ionizing gas at the same time. It may be calculated. That is, the conditions for the excitation voltage or the excitation current are not changed, the control is adjusted only by the pressure or density of the ionizing gas, or the conditions for the pressure or density of the ionizing gas are not changed, only the conditions for the excitation voltage or the excitation current. You may perform control which adjusts by. Further, the adjustment may be made sequentially in two stages without changing in parallel.

  As described above, according to the antenna device according to the fourth embodiment of the present invention, the radio wave receiving device that receives the radio wave used by the radar, the data analysis unit that analyzes the frequency of the radio wave received by the radio wave receiving device, An ionizing gas adjusting unit that adjusts at least one of the pressure and density of the ionizing gas inside the dielectric tube, and a pressure and density of the ionizing gas that has a plasma frequency lower than the frequency analyzed by the data analysis unit. Control for instructing the ionizing gas adjusting unit at least one of the values, and control for instructing the plasma excitation power source at least one of the excitation voltage and the excitation current with a plasma frequency lower than the frequency analyzed by the data analysis unit. Among them, a plasma setting unit that controls at least one of them is provided, so that the observability from the radar that receives incoming radio waves can be reduced. Can.

  In each of the above embodiments, the mounting target of the antenna device is a moving body and the moving body is an aircraft. However, the mounting target is not limited to this. For example, the mounting target may be not only an aircraft body, but also a ship hull, a vehicle body, and the like. By equipping the antenna device according to the present invention near the surface of the mounted object and setting the plasma frequency to a frequency lower than the frequency of the incoming radio wave from the radar, observation from the radar can be made difficult.

  In addition, a radar that transmits radio waves for observing a moving object that is an object on which the antenna device is mounted may be mounted on the moving object, or may be disposed on the ground or on the sea. Alternatively, it may be mounted on a satellite.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1, 1a Dielectric tube, 2 Mobile body surface, 3 Electrode terminal, 4, 4a Plasma excitation power supply, 5 High frequency signal generator, 6 Cover, 7 Radio wave receiver, 8 Data analysis part, 9, 10, 12 Plasma setting part , 11 Ionizing gas adjusting unit, 111 accumulating means, 112 control valve.

Claims (10)

A dielectric tube that is bent so that both ends are in the same direction, and an ionizing gas is sealed inside;
A first electrode terminal and a second electrode terminal provided inside the dielectric tube and at both ends of the dielectric tube;
A plasma excitation power source connected to the first electrode terminal and the second electrode terminal and controlling at least one of an excitation voltage and an excitation current to maintain the ionizing gas in a plasma state;
A high-frequency signal generator for supplying a high-frequency signal to at least one of the first electrode terminal and the second electrode terminal and operating the dielectric tube as an antenna;
An antenna apparatus characterized in that a plasma frequency to be in the plasma state is lower than a frequency of a radio wave used by a radar.   The antenna apparatus according to claim 1, wherein a ground conductor is provided on a surface of the moving body, and the dielectric tube is positioned on the ground conductor.   The antenna device according to claim 1, wherein the dielectric tube is located on a surface of the moving body.   4. The antenna apparatus according to claim 2, wherein the moving body is an aircraft.   The antenna device according to any one of claims 1 to 4, wherein the frequency of the radio wave used by the radar is an X-band frequency. A radio wave receiver for receiving radio waves used by the radar;
A data analysis unit for analyzing the frequency of the radio wave received by the radio wave receiver;
The plasma setting unit for instructing the plasma excitation power source to have at least one of an excitation voltage and an excitation current having a plasma frequency lower than the frequency analyzed by the data analysis unit. 6. The antenna device according to any one of items 5. A radio wave receiver for receiving radio waves used by the radar;
A data analysis unit for analyzing the frequency of the radio wave received by the radio wave receiver;
An ionizing gas adjusting unit that adjusts at least one of the pressure and density of the ionizing gas inside the dielectric tube;
And a plasma setting unit for instructing the ionizing gas adjusting unit to set at least one of the pressure and density of the ionizing gas at a plasma frequency lower than the frequency analyzed by the data analysis unit. The antenna device according to any one of claims 1 to 5. A radio wave receiver for receiving radio waves used by the radar;
A data analysis unit for analyzing the frequency of the radio wave received by the radio wave receiver;
An ionizing gas adjusting unit that adjusts at least one of the pressure and density of the ionizing gas inside the dielectric tube;
Control for instructing the ionizing gas adjustment unit to at least one value of the pressure and density of the ionizing gas with a plasma frequency lower than the frequency analyzed by the data analysis unit, and lower than the frequency analyzed by the data analysis unit 2. A plasma setting unit that controls at least one of the control for instructing the plasma excitation power supply to at least one value of an excitation voltage and an excitation current having a plasma frequency. The antenna device according to claim 5.   The antenna apparatus according to claim 1, further comprising a dielectric cover that covers the dielectric tube.   10. An antenna device using the antenna device according to claim 1 as an antenna element, and arranging a plurality of the antenna elements to form an array configuration.

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