JP2005229381A - Multiple resonance type antenna device with reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide-band slot antenna with a small reflector having a good voltage standing wave ratio without changing the external dimensions of the slot antenna.
In an antenna having a slot radiating element 11 and a reflecting plate 12, a groove-shaped metal plate 13 is provided between the slot radiating element 11 and the reflecting plate 12, and the trough side of the metal plate 13 is disposed on the slot radiating element 11. And an antenna device 1 with a multi-resonant reflection plate in which the longitudinal direction of the metal plate 13 is parallel to the slot radiating element 11.
[Selection] Figure 1

Description

  The present invention relates to a communication antenna.

  A conventional slot antenna is formed of a double-sided copper-clad printed circuit board, and has a structure in which a slot hole is formed on one side of the board and a feed line is formed on the other side. Such a slot antenna is widely used as a transmission / reception antenna for wireless communication in the form of a multi-element array antenna.

  The slot length of the slot antenna is determined by a length of ½ of the wavelength of the desired frequency in consideration of the dielectric constant of the dielectric. The slot antenna has the property that the impedance of the entire antenna changes depending on the position of the feeder line in the slot and the distance from the reflector. Therefore, in order to increase the bandwidth of the desired frequency without changing the size of the antenna, the parasitic element 14 of the slot antenna 31 is provided just above the opening of the slot radiating element 11 as shown in FIG. A method of causing resonance between the slot radiating element 11 and the parasitic element 14 is known.

  The prior art document information related to the invention of this application includes the following.

JP 2002-33619 A

  However, since the opening length of the slot radiating element 11 provided on the antenna element substrate 19 is determined by ½ of the wavelength of the operating frequency, when the desired frequency is to be widened, there is no parasitic power just above the slot opening. The element 14 is overlapped in two and three stages to cause multiple resonance. For this reason, there was a problem that the shape of the whole antenna becomes large.

  When parasitic elements are stacked in multiple stages, there is a problem that they cannot be accommodated in a conventional cover having a predetermined shape.

  Accordingly, an object of the present invention is to provide a wide-band slot antenna with a small reflector having a good voltage standing wave ratio without changing the external dimensions of the slot antenna.

  The present invention has been devised to achieve the above object, and the first invention is an antenna having a slot radiating element and a reflecting plate, and a groove type is provided between the slot radiating element and the reflecting plate. The antenna device with a multiple resonance type reflector is provided with a metal plate, the trough side of the metal plate faces the slot radiating element, and the longitudinal direction of the metal plate is parallel to the slot radiating element.

  In the second invention, the peak side of the metal plate is in contact with the reflecting plate.

  According to a third aspect of the present invention, the metal plate has a groove shape having a substantially U-shaped or U-shaped cross section perpendicular to the longitudinal direction.

  In a fourth aspect of the invention, the metal plate has a groove shape with a substantially V-shaped cross section orthogonal to the longitudinal direction.

  According to the present invention, it is possible to obtain an excellent effect of obtaining a broadband small slot antenna with a reflector having a good voltage standing wave ratio without changing the external dimensions of the slot antenna.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an antenna device with a multiple resonance type reflector according to a preferred embodiment of the present invention. FIG. 1A is a front view of an antenna device with a multiple resonance type reflector. FIG. 1B is a perspective view of an antenna device with a multiple resonance type reflector.

  The antenna device 1 with a multiple resonance type reflector includes an antenna element substrate 19 provided with a slot radiating element 11, a reflector 12 that reflects electromagnetic waves radiated from the slot radiating element 11, and a longitudinal direction of the metal plate. A groove-shaped metal plate 13 having a substantially U-shaped cross section (or a substantially U-shaped or V-shaped alphabet), and a power feeding section 15 for feeding electromagnetic waves to the antenna element substrate 19 It is configured with.

  The antenna device 1 with a multiple resonance type reflector includes a U-shaped grooved metal plate 13 between the slot radiating element 11 and the reflector 12. The trough side of the metal plate 13 faces the slot radiating element 11. The longitudinal direction of the metal plate 13 is parallel to the slot radiating element 11. Further, the peak side of the metal plate 13 is in contact with the reflecting plate 12.

  The reflection plate 12 is made of a conductor material, and is formed in a rectangular parallelepiped shape having one surface opened, that is, a box shape. The slot radiation element 11 is formed on a conductor material surface (hereinafter referred to as a back surface) 12b facing the opening surface 12a. It has a function of reflecting electromagnetic waves radiated from.

  The reflecting plate 12 is not limited to the rectangular parallelepiped shape shown in the figure, and may be formed in a cylindrical shape with a part of the side surface opened. By providing the antenna element substrate 19 in the opening, the antenna function and effect are not impaired. .

  On the opening surface 12a of the reflecting plate 12, the antenna element substrate 19 is provided so as to cross the reflecting plate side surface 12c, and both ends of the antenna element substrate 19 are fixedly attached to the edges of the reflecting plate side surfaces 12c.

  The antenna element substrate 19 is formed of a printed board in which a conductor material is provided on both surfaces of a dielectric plate (for example, copper-clad). The antenna element substrate 19 is formed with a slot radiating element 11 in which a copper hole is formed by etching or the like on one surface of a printed circuit board. The antenna element substrate 19 has a structure in which copper provided on the other surface of the printed circuit board is processed by etching or the like, and a feeder line 16 is formed so as to be orthogonal to the slot radiating element 11.

  The antenna element substrate 19 has a surface on which the feeder line 16 is formed facing the back surface 12b of the reflecting plate 12, and a surface on which the slot radiating element 11 is formed facing the front surface of the opening surface 12a of the reflecting plate 12.

  The slot radiating element 11 has a length in the longitudinal direction of the slot that is ½ of the wavelength of the electromagnetic wave used.

  The antenna element substrate 19 is not limited to the form described so far, and a structure in which a slot is provided in a plate-like metal conductor has a function as a slot antenna element similar to the antenna element substrate 19.

  The feed line 16 is an elongated microstrip line, and is provided so as to cross the slot radiating element 11 at right angles. The feeder line 16 is a line provided for feeding an electromagnetic wave radiated from the slot radiating element 11. Other than the microstrip line, a method using a coaxial cable power supply is similarly applied.

  The power feeding unit 15 is attached to the antenna element substrate 19 or the reflecting plate 12. The core line side of the power feeding unit 15 is connected to one end of the power feeding line 16 formed on the antenna element substrate 19, and the ground side of the power feeding unit 15 is connected to the ground of the antenna element substrate 19 or the reflector 12.

  The metal plate 13 is formed of a groove-shaped (channel shape) conductive metal plate having a substantially U-shaped cross section perpendicular to the longitudinal direction of the metal plate, and the peak side of the metal plate 13 is in contact with the reflecting plate 12. It is fixed to the reflector 12.

  FIG. 2 shows an embodiment of such a metal plate. FIG. 2A is a perspective view of the grooved conductor metal plate 13 having a substantially U-shaped cross section. FIG. 2B is a perspective view of the grooved conductor metal plate 23 having a substantially V-shaped cross section.

  The metal plates 13 and 23 are formed into a groove shape by bending a rectangular metal plate along the longitudinal direction. The side that becomes convex by this bending is called the mountain side, and the side that becomes concave is called the valley side.

  The metal plate 13 may have a substantially U-shaped cross section by smoothing the U-shaped corners.

  The metal plate 23 has a groove shape in which a cross section orthogonal to the longitudinal direction of the metal plate forms a substantially V shape.

  The metal plates 13 and 23 are longer in the longitudinal direction than the slot length of the slot radiating element 11. That is, the length of the metal plates 13 and 23 is set to be longer than ½ of the wavelength of the electromagnetic wave used by the antenna device 1 with a multiple resonance type reflector. Further, the metal plates 13 and 23 are preferably formed to have a groove depth so that the groove depth is 1/8 or more of the wavelength of the electromagnetic wave used. This is a dimensional distance suitable for resonance when generating resonance of electromagnetic waves, which will be described in detail later.

  The shape and quantity of the metal plates 13 and 23 may be determined so that a desired antenna radiation pattern can be obtained.

  When using, for example, a flat metal plate that does not bend instead of the metal plates 13 and 23, a plurality of the metal plates may be provided at regular intervals in parallel with the back surface 12b.

  Next, the function and effect of the antenna device 1 with multiple resonance reflectors will be described.

  The electromagnetic wave having a predetermined frequency fed to the feeding unit 15 is propagated through the feeding line 16 provided on the antenna element substrate 19. The electromagnetic wave propagated through the feeder line 16 is radiated from the slot radiating element 11. Part of the radiated electromagnetic waves is incident on the reflecting plate 12 and the metal plate 13.

  A part of the electromagnetic wave incident on the reflecting plate 12 and the metal plate 13 is reflected from the reflecting plate 12 and the metal plate 13 and returns to the opening surface of the reflecting plate 12 (that is, the antenna element substrate 19) 12a. The electromagnetic wave radiated from the slot radiating element 11 and the electromagnetic wave reflected from the reflector 12 and the metal plate 13 are combined and emitted in the front direction.

  An antenna directivity pattern is formed by the synthesized electromagnetic wave. The directivity direction of this antenna directivity pattern is substantially the direction from the back surface 12b toward the opening surface 12a, and substantially coincides with the vertical direction of the opening surface 12a.

  The multi-resonance type antenna device with a reflector 1 resonates between the slot radiating element 11 and the metal plate 13.

  Specifically, a part of the electromagnetic wave radiated from the slot radiating element 11 is incident on the metal plate 13 and is reflected from the primary resonance in which resonance occurs between the slot radiating element 11 and the metal plate 13 and from the metal plate 13. An electromagnetic wave that has returned to the opening surface 12a is reflected by the antenna element substrate 19 and incident on the metal plate 13 again to resonate and generate secondary resonance.

  As mentioned above, the metal plate 13 forms a conductor metal plate longer than ½ of the wavelength of the electromagnetic wave to be used, and the depth of the groove formed by bending the metal plate 13 is the wavelength of the electromagnetic wave to be used. Since it is formed to be 1/8 or more, it has a dimension and shape in which resonance easily occurs.

  On the other hand, when the distance between the antenna element substrate 19 and the reflecting plate 12 and the metal plate 13 is too short with respect to the wavelength of the electromagnetic wave to be used, it is radiated from the slot radiating element 11 by element resonance and directly enters the free space. The point at which the radiated electromagnetic wave and the electromagnetic wave reflected by the reflecting plate 12 and the metal plate 13 and radiated to the free space by the reflecting plate resonance are combined is extremely limited, and multiple resonance hardly occurs. That is, the phase of the electromagnetic wave radiated from the slot radiating element 11 and the phase of the electromagnetic wave reflected by the reflecting plate 12 and the metal plate 13 are shifted from each other and cancel each other, so that no resonance occurs.

  On the other hand, the phase of the electromagnetic wave radiated from the slot radiating element 11 is obtained by taking about 1/8 or more of the wavelength of the electromagnetic wave using the distance between the slot radiating element 11 and the reflecting plate 12 and the metal plate 13. The phases of the electromagnetic waves reflected by the reflecting plate 12 and the metal plate 13 are matched, and resonance is likely to occur.

  By providing the metal plate 13 between the antenna element substrate 19 and the reflection plate 12, multiple resonance can be generated, so that the bandwidth of the antenna can be increased without substantially changing the shape and size of the antenna.

  This multi-resonance type reflector-equipped antenna device 1 does not require the parasitic elements 14 to be stacked in multiple stages unlike the conventional slot antenna 31 of FIG. 5, so that it can be accommodated in a conventional cover having a predetermined shape. There is also the effect.

  Further, by attaching the metal plate 13 or the metal plate 23, it is effective in improving the voltage standing wave ratio in a wide band as shown below.

  FIGS. 3 and 4 show the state of improvement of the voltage standing wave ratio as a return loss.

  FIG. 3 is a characteristic diagram showing a voltage standing wave ratio when a U-shaped groove-shaped metal plate is attached to the antenna device with a multiple resonance type reflector and when it is not attached. The horizontal axis in FIG. 3 indicates the frequency (unit: GHz), and the vertical axis indicates the return loss (unit: dB).

  A solid line in the characteristic diagram is a characteristic curve when the U-shaped metal plate 13 is attached, and a broken line is a characteristic curve when the U-shaped metal plate 13 is not attached.

  As can be seen from the figure, when the U-shaped metal plate 13 is not attached at a frequency of about 2.6 GHz, the return loss is about −24 dB, whereas when the U-shaped metal plate 13 is attached. Shows that the return loss is about -35.9 dB, which is a significant improvement of about 12 dB.

  FIG. 4 is a characteristic diagram showing a voltage standing wave ratio when a V-shaped grooved metal plate is attached to and not attached to an antenna device with multiple resonance type reflectors. The horizontal axis of FIG. 4 indicates the frequency (unit: GHz), and the vertical axis indicates the return loss (unit: dB).

  A solid line in the characteristic diagram is a characteristic curve when the V-shaped metal plate 23 is attached, and a broken line is a characteristic curve when the V-shaped metal plate 23 is not attached.

  As can be seen from the figure, when the V-shaped metal plate 23 is not attached at a frequency of about 2.6 GHz, the return loss is about −24 dB, whereas when the V-shaped metal plate 23 is attached. It can be seen that the return loss is improved by about 7 dB to about -31 dB.

  In this embodiment, the case where one slot radiating element 11 is provided has been described. However, even in a slot array antenna provided with a plurality of slot radiating elements 11, a number of metal plates corresponding to the plurality of slots 11 are provided. 13 and 23 are provided between the antenna element substrate 19 and the back surface 12b of the reflecting plate 12, so that the broadband resonance and voltage regulation can be achieved as in the antenna device 1 with a multiple resonance type reflecting plate provided with only one slot radiating element 11. It is possible to improve the standing wave ratio.

  As described above, the metal plate 13 is provided between the antenna element substrate 19 and the reflection plate 12, so that multiple resonances can be easily generated, and the small size and shape are almost the same as the conventional size. Can be realized.

  This miniaturized antenna has an excellent effect that the antenna frequency can be widened by providing the metal plate 13 and causing multiple resonance.

  Furthermore, it has an excellent effect that the voltage standing wave ratio of the antenna can be improved over a wide band.

  Further, since the addition of the metal plates 13 and 23 stays between the antenna element substrate 11 and the reflection plate 12, there is a manufacturing cost and an economic effect that the metal plates 13 and 23 can be accommodated in a conventional cover having a predetermined shape.

FIG. 1A is a front view of an antenna device with a multiple resonance type reflector. FIG. 1B is a perspective view of an antenna device with a multiple resonance type reflector. FIG. 2A is a perspective view of a U-shaped grooved metal plate attached to an antenna device with multiple resonance type reflectors. FIG. 2B is a perspective view of a V-shaped grooved metal plate attached to the antenna device with a multiple resonance type reflector. It is a characteristic view which shows the voltage standing wave ratio when not installing it, when a U-shaped groove type metal plate is attached to the antenna apparatus with a multiple resonance type reflector. It is a characteristic view which shows the voltage standing wave ratio when not attaching the V-shaped groove-shaped metal plate to the antenna apparatus with a multiple resonance type reflector. It is a perspective view which shows the slot antenna of background art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna apparatus 11 with a multiple resonance type reflector 11 Slot radiation element 12 Reflector 12a Opening surface 12b Back surface 12c Reflector side surface 13 U-shaped metal plate 15 Feed part 16 Feed line 19 Antenna element substrate

Claims (4)

  In an antenna having a slot radiating element and a reflecting plate, a groove-shaped metal plate is provided between the slot radiating element and the reflecting plate, and a trough side of the metal plate faces the slot radiating element and the metal plate An antenna device with multiple resonance type reflectors, characterized in that the longitudinal direction of the antenna is parallel to the slot radiating element.   The antenna device with a multiple resonance type reflector according to claim 1, wherein the peak side of the metal plate is in contact with the reflector.   3. The antenna device with a multiple resonance type reflector according to claim 1, wherein the metal plate has a groove shape having a substantially U-shaped or U-shaped cross section perpendicular to the longitudinal direction. 3. The antenna device with a multiple resonance type reflector according to claim 1, wherein the metal plate has a groove shape having a substantially V-shaped cross section orthogonal to the longitudinal direction.

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