JP2009033324A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an antenna using a reflector of an EBG (Electromagnetic band-gap) structure to operate in a plurality of frequency bands. <P>SOLUTION: The antenna 1A includes the EBG 1 being a reflector and is configured to arrange an antenna element 15 at a position having height H over the EBG 1. In the EBG 1, square patches 11 smaller than a used wavelength are periodically arranged on the surface of a square device board 10 in a matrix shape, and a ground plane 13 is formed on the rear surface of the device board 10. In the patches 11, in an illustrated example, 25 patches P1-1, P1-2, ..., P5-4 and P5-5 are provided in 5 rows ×5 columns, and a varicap 12 being a variable capacity diode is connected between respective patches. The capacity value of the varicap 12 is changed by controlling the value of voltage +V to be applied to each patch 11, thereby changing the resonance frequency of the EBG 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a low-profile antenna including a reflector having an electromagnetic bandgap structure.

An artificial structure called an electromagnetic band-gap (EBG) is known. The EBG has a structure in which unit structures smaller than the wavelength are periodically arranged. In the unit structure, a metal patch is formed on the surface of the substrate, a ground plane is formed on the back surface of the substrate, and a short-circuit pin that short-circuits the patch and the ground plane is provided through the substrate. An EBG having such a structure resonates at a specific frequency, has a property such that the reflected wave phase becomes +1 (in-phase reflection) at the resonance frequency, and the surface current hardly flows. An antenna using the surface wave propagation blocking characteristics of the ground plane having the EBG structure has been proposed.
JP 2003-304113 A

  A three-dimensional perspective view showing the structure of the conventional EBG 100 is shown in FIG. 28, and a side view showing the structure of the EBG 100 is shown in FIG. The EBG 100 shown in these figures has rectangular patches 111 periodically arranged in a matrix on the surface of a rectangular substrate 110, and a ground plane 113 is formed on the entire back surface of the substrate 110. Yes. The substrate 110 has a predetermined dielectric constant. The EBG 100 has a structure in which unit structures 100-1 smaller than the wavelength are periodically arranged, and one of the unit structures 100-1 is enlarged and shown in FIG. In the unit structure 100-1, a short pin 114 is provided in which a substantially center of a rectangular patch 111 formed on the surface of the substrate 110 is provided through the substrate 110 in a ground plane 113 formed on the back surface of the substrate 110. Is short-circuited. In the EBG 100 in which the unit structures 100-1 are periodically arranged, a capacitance component is generated between the patterns of the patches 111 of the adjacent unit structures 100-1, and an inductor component is generated according to the length of the patch 111. Occurs. Further, a capacitance component is generated between the pattern of the patch 111 and the ground plane 113, and an inductor component is generated by the short-circuit pin 114.

  An equivalent circuit of the unit structure 100-1 in such an EBG 100 is shown in FIG. In the equivalent circuit shown in FIG. 29, capacitors C1, C2, C3, and C4 are capacitance components generated by the gap between the patterns of the patch 111, and are inductors connected in series to the capacitors C1, C2, C3, and C4. L1, L2, L3, and L4 are inductor components generated by the pattern piece length of the patch 111, and the capacitor C5 is a capacitor component between the pattern of the patch 111 and the ground plane 133, and the inductor L5 connected in parallel to the capacitor C5. Is an inductor component of the short-circuit pin 114. In the EBG 100 having a structure in which the unit structures 100-1 of the equivalent circuit shown in FIG. 29 are periodically arranged, the LC resonance circuit by the capacitance component and the inductor component generated in each unit structure 100-1 is continuous. It is conceivable and comes to parallel resonance at a predetermined frequency. At the resonance frequency, the EBG 100 becomes a high-impedance surface, the surface current hardly flows, and it is reflected in the same phase.

  This will be described with reference to FIG. 31. FIG. 31A shows a case where the element 200 is arranged on a reflection plate made of a perfect conductor (PEC: Perfect Electric Conductor) 201 such as a metal plate. In this case, since the reflection coefficient of the PEC 201 is −1 and reflected in the opposite phase, if the element 200 is not installed at the height h of ¼ wavelength from the PEC 201, the phase in the radiation direction is shifted and the radiation characteristic is deteriorated. become. FIG. 31B shows a case where the element 200 is disposed on the reflector made of the EBG 100 described above. In this case, since the reflection coefficient of the EBG 100 is +1 and reflected in the same phase, the height h of the element 200 from the EBG 100 can be made substantially zero. As described above, when the EBG 100 is used as a reflecting plate, an image current having a reverse phase is not generated in the reflecting plate, so that the radiation efficiency does not deteriorate. Further, even if the element 200 is brought into close contact with the reflector, in-phase radiation is generated, so that radiation characteristics are not deteriorated, and the antenna can be lowered.

Next, FIG. 32 shows a three-dimensional perspective view of a configuration example of an antenna using a reflector having an EBG structure, and FIG. 33 shows a side view showing the configuration of this antenna configuration example.
In the antenna 100A shown in FIG. 32, a square spiral element 120 is disposed in close contact with the EBG 100. In the EBG 100, as described above, the rectangular patches 111 are periodically arranged in a matrix on the surface of the rectangular substrate 110 having a predetermined dielectric constant, and the ground plane 113 is formed on the entire back surface. . For example, when the design frequency of the antenna 100A is about 0.6 GHz, the resonance frequency of the EBG 100 is designed to be about 0.6 GHz. Here, when the free space wavelength of the resonance frequency of 0.6 GHz is λ, the patch 111 has a square pattern with one side of about 0.2λ, and the gap between the patches 111 is about 0.02λ. The patch 111 is short-circuited to the ground plane 113 by a short-circuit pin 114, and the substrate 110 is a Teflon substrate having a dielectric constant εr of about 2.2, and the substrate thickness is about 0.04λ. In addition, when the element 120 is arranged on a metal plate at a height of about 0.25 wavelength, it is a square spiral antenna for first mode operation that radiates circularly polarized waves in the axial direction, and the operating frequency is about 0.6 GHz. It is said.

The frequency characteristics of the reflection phase of the EBG 100 are shown in FIG. Referring to FIG. 34, the reflection phase goes from about 180 ° to 0 ° as the frequency becomes higher, and changes to about −180 ° as the frequency becomes higher. At this time, the reflection phase is 0 ° at about 0.6 GHz.
Further, in the antenna 100A provided with the EBG 100, the frequency characteristics of the axial ratio (AR) when the element 120 is arranged at a height of about 0.01λ on the EBG 100 plate, the height characteristic of about 0.25λ on the metal plate. FIG. 35 shows a comparison with the axial ratio when the same element 120 is disposed. Referring to FIG. 35, the circularly polarized radiation band is narrower in the frequency characteristic of the axial ratio of the antenna 100A than in the axial ratio characteristic when the element 120 is arranged on the metal plate indicated by the broken line. I understand. This is because the EBG structure is a resonance structure and exhibits narrow band characteristics. In this case, the EBG structure behaves as a metal plate outside the resonating frequency band. Therefore, the radiation characteristics of the antenna 100 </ b> A deteriorate at a frequency other than the resonating frequency, as in the case where the element 120 is disposed in a low posture on the metal plate.

  Further, in the antenna 100A including the EBG 100, the frequency characteristic of the VSWR (voltage standing wave ratio) when the element 120 is arranged at a height of about 0.01λ on the EBG 100 plate is about 0.25λ on the metal plate. FIG. 36 shows a comparison with the VSWR characteristic in the case where the same element 120 is arranged at the height of. Referring to FIG. 36, in the antenna 100A, a good VSWR is obtained in a band of about 0.54 GHz or more, and a good circularly polarized wave is radiated in this band. Is deteriorated in a lower frequency range than the VSWR characteristic in the case where is arranged. As described above, this is because the EBG structure is a resonance structure and exhibits narrow band characteristics. Furthermore, in the antenna 100A provided with the EBG 100, the directivity characteristics of the XZ plane at the best axial ratio when the element 120 is arranged on the EBG 100 plate at a height of about 0.01λ are shown in FIG. The directivity characteristics are shown in FIG. Referring to FIGS. 37 and 38, good circularly polarized waves are radiated, and at the best point of the axial ratio, the EBG structure is in a resonance state and has the effect of suppressing the propagation of surface waves, so that the backward radiation is suppressed. You can see that

By the way, although antennas built in mobile phones and antennas mounted on vehicles in recent years tend to be miniaturized, they are multifunctional and broadband to operate in bands such as AM, FM, terrestrial digital, and GPS (terrestrial digital TV and FM). May be required for the antenna. In particular, when using multiple radio systems such as software defined radio (cognitive radio), the antenna functions in multiple frequency bands and functions that support polarization (circular polarization, horizontal, vertical) suitable for the radio system. Is required.
However, an antenna using a reflector having an EBG structure has a problem that the operating band becomes narrow, although the attitude can be lowered.
Therefore, an object of the present invention is to provide an antenna that can be lowered in an antenna using a reflector having an EBG structure and can be operated in a plurality of frequency bands.

  In order to achieve the above object, the antenna of the present invention controls the electromagnetic gap structure to be in a substantially resonant state at the operating frequency by varying the capacitance component or the inductor component of the electromagnetic band gap structure in the reflector. This is the main feature.

  According to the present invention, since the electromagnetic gap structure is controlled so as to be substantially in a resonance state at the operating frequency by changing the capacitance component or the inductor component of the electromagnetic band gap structure in the reflector, the reflection of the electromagnetic band gap structure is controlled. The resonance frequency of the plate can be varied, and an antenna that operates well in a plurality of frequency bands can be obtained.

FIG. 1 shows a plan view showing the configuration of the antenna according to the first embodiment of the present invention and a perspective view showing the configuration of the unit structure in three dimensions, and FIG. 2 shows a side view showing the configuration of the first embodiment.
The antenna 1A shown in these drawings includes an EBG1 that is a reflector having an electromagnetic bandgap (EBG) structure, and an antenna element 15 is disposed at a height h above the EBG1. In the EBG 1, square patches 11, which are smaller than the used wavelength, are periodically arranged in a matrix on the surface of the square substrate 10, and a ground plane 13 is formed on the back surface of the substrate 10. Yes. In the illustrated example, the patch 11 includes 25 patches P1-1, P1-2,..., P5-4, P5-5 of 5 rows × 5 columns, and a variable capacitance is provided between the patches. A varicap 12 as a diode is connected with the polarity shown in the figure. Nearly the center of each patch 11 is short-circuited to the ground plane 13 by a short-circuit pin 14 provided through the substrate 10. The EBG 1 has a structure in which unit structures 1-1 smaller than the wavelength are periodically arranged, and one of the unit structures 1-1 is enlarged and shown in FIG. The unit structure 1-1 includes a short-circuit pin 14 in which a substantially center of a square patch 11 formed on the surface of the substrate 10 is provided through the substrate 10 in a ground plane 13 formed on the back surface of the substrate 10. Is short-circuited.

  In the EBG 1 in which such unit structures 1-1 are periodically arranged, a capacitance component is generated between the patterns of the patches 11 of the adjacent unit structures 1-1, and an inductor component according to the length of the patch 11. Occurs. Further, a capacitance component is generated between the pattern of the patch 11 and the ground plane 13, and an inductor component is generated by the short-circuit pin 14. The equivalent circuit of the unit structure 1-1 in the EBG 1 is the same as the equivalent circuit shown in FIG. The substrate 10 is a Teflon substrate having good high frequency characteristics, and has a predetermined dielectric constant. The antenna element 15 is a square spiral antenna of a first mode operation that radiates circularly polarized waves in the axial direction when arranged at a height of about 0.25 wavelength of the used wavelength on a metal plate that is a perfect conductor (PEC). It is said that.

  In the EBG1 shown in FIG. 1, a patch P1-1 in which a black circle is added to the center among 25 patches P1-1, P1-2,..., P5-4, P5-5 of 5 rows × 5 columns. , P1-3, P1-5, P2-2, P2-4, P3-1, P3-3, P3-5, P4-2, P4-4, P5-1, P5-3, P5-5 A positive control voltage + V is applied to the 13 patches 11, and the remaining P1-2, P1-4, P2-1, P2-3, P2-5, P3-2, P3-4, P4-1. , P4-3, P4-5, P5-2, and P5-4, a total of 12 patches 11 have the same potential as the ground. Since the cathode of the varicap 12 connected between the patches 11 is connected to the patch 11 to which the control voltage + V is applied and the anode is set to the same potential as the ground, a reverse voltage is applied to each varicap 12. Is applied. Since the capacity of the varicap 12 becomes smaller as the reverse voltage increases, the capacity value of each varicap 12 can be controlled by changing the voltage value of the control voltage + V. Since each patch 11 is short-circuited to the ground plane 13 by a short-circuit pin 14, although not shown, the ground plane 13a to which the patch 11 to which the control voltage + V is applied is short-circuited is set to the same potential as the ground. The patch 11 is galvanically separated from the ground plane 13b to be short-circuited, and the ground plane 13a and the ground plane 13b are connected in high frequency with a capacitor having a low impedance at the operating frequency.

  Here, for example, it is assumed that the design frequency of the antenna 1A is about 0.6 GHz and the resonance frequency of the EBG 1 is designed to be about 0.6 GHz. In this case, if the free space wavelength of the resonance frequency of 0.6 GHz is λ, one side of the patch 11 having a square pattern is about 0.2λ, and the gap between the patches 11 is about 0.02λ. For example, a Teflon substrate having a dielectric constant εr of about 2.2 is used as the substrate 10 and the thickness of the substrate 10 is set to about 0.04λ. The operating frequency of the antenna element 15 that is a square spiral antenna is about 0.6 GHz, and the height h on the EBG 1 is about 0.01λ. In the antenna 1A under these conditions, the X-direction polarization and Y-direction polarization of the antenna 1A when the voltage value of the control voltage + V is changed to set the capacitance of each varicap 12 to about 1 pF, about 2 pF, and about 3 pF. FIG. 3 shows the frequency characteristic of the reflection phase of FIG. 3, FIG. 4 shows the frequency characteristic of the axial ratio (AR) of the antenna 1A, FIG. 5 shows the frequency characteristic of the gain of the antenna 1A, and FIG. Show. Referring to the reflection phase characteristics shown in FIG. 3, the reflection phase changes from about 180 ° to 0 ° as the frequency increases, and further changes toward about −180 ° as the frequency increases. When the capacitance value of the varicap 12 is about 1 pF, the resonance frequency is about 0.58 GHz. When the capacitance value of the varicap 12 is about 2 pF, the resonance frequency is about 0.505 GHz. Is about 3 pF, the resonance frequency is about 0.445 GHz. Thus, if the voltage value of the control voltage + V is lowered to increase the capacity of the varicap 12, the resonance point can be shifted to the low frequency side, and the voltage value of the control voltage + V is increased to reduce the capacity of the varicap 12. The resonance point can be shifted to the high frequency side. The reason why the resonance frequency changes in accordance with the capacitance value of the varicap 12 is that the equivalent circuit of the unit structure 1-1 constituting the EBG 1 is represented by the equivalent circuit shown in FIG. Further, the reflection phase does not change between the X-direction polarization and the Y-direction polarization. This is because each patch 11 has a square shape and the electrical characteristics in the X and Y directions are the same.

Further, referring to the frequency characteristic of the axial ratio (AR) of the antenna 1A shown in FIG. 4, when the capacitance value of the varicap 12 is about 1 pF, the best axial ratio is about 0.58 GHz. Is about 2505, the best axial ratio is about 0.505 GHz. When the capacitance of the varicap 12 is about 3 pF, the best axial ratio is about 0.445 GHz. Thus, the best axial ratio point moves according to the voltage value of the control voltage + V.
Further, referring to the frequency characteristics of the gain of the antenna 1A shown in FIG. 5, when the capacitance value of the varicap 12 is about 1 pF, the peak point of the gain is about 0.58 GHz, and the capacitance value of the varicap 12 is about 2 pF. At that time, the gain peak point is about 0.5 GHz, and when the capacitance value of the varicap 12 is about 3 pF, the gain peak point is about 0.44 GHz. Thus, the peak point of the gain of the antenna 1A can be varied according to the voltage value of the control voltage + V.
Furthermore, referring to the frequency characteristics of the VSWR of the antenna 1A shown in FIG. 6, the frequency at which the VSWR is about 3 or less is about 0.535 GHz when the capacitance value of the varicap 12 is about 1 pF. When the capacitance value is about 2 pF, it becomes about 0.465 GHz, and when the capacitance value of the varicap 12 is about 3 pF, it becomes about 0.42 GHz. In this way, the impedance used as an index indicating the operating frequency of the antenna 1A can be varied according to the voltage value of the control voltage + V.

  As described above, in the antenna 1A including the EBG 1 as a reflector, the operating frequency of the antenna 1A can be continuously changed by continuously changing the voltage applied to the varicap 12. In this case, the voltage induced in the EBG 1 that is the reflector is a value tens of dB lower than the voltage induced in the antenna element 15. Therefore, for example, in a conventional variable antenna in which a varicap is mounted on the antenna and the operating frequency is varied, the induced voltage may be increased by several tens of dB, and the varicap may be distorted and may not operate. The antenna 1A according to the embodiment operates reliably. Further, when the varicap 12 is connected between the patches 11, the capacity of the EBG1 increases, and the resonance frequency of the EBG1 shifts to a low band. Therefore, the resonance frequency can be corrected by reducing the length of the side of the unit structure 1-1 in the EBG 1 or reducing the height to reduce the inductor component. In this way, the EBG 1 can be reduced in size and the antenna 1A can be reduced in size.

By the way, the circularly polarized wave is a state in which the vertically polarized wave and the horizontally polarized wave have the same amplitude and the phase is shifted by 90 °. Further, since the structure of the EBG1 is rotationally symmetric with respect to the Z axis in the X direction and the Y direction, the structure of the EBG1 has no polarization dependency like the reflection phase characteristic shown in FIG. For this reason, in the resonance state of the EBG 1, the EBG 1 is reflected in the same phase without disturbing the amplitude and phase of the circularly polarized wave radiated from the antenna element 15, thereby realizing a low attitude of the antenna 1 A.
Next, FIG. 7 shows a configuration of the unit structure 2-1 in which the polarization dependence occurs in the frequency characteristic of the reflection phase. The antenna of the second embodiment (not shown) according to the present invention includes an electromagnetic band gap structure (EBG) (not shown) having a configuration in which a plurality of unit structures 2-1 shown in FIG. In the unit structure 2-1, a rectangular patch 21 whose length in the X direction is longer than the length in the Y direction is formed on the surface of the substrate 20 such as a Teflon substrate, and the ground plane 23 is formed on the back surface of the substrate 20. Is formed. Nearly the center of the patch 21 is short-circuited to the ground plane 23 by a short-circuit pin 24 provided through the substrate 20.

  As described above, the reflection phase in the antenna of the second embodiment using the EBG in which the plurality of unit structures 2-1 shown in FIG. 7 having an asymmetric shape in the X direction and the Y direction are periodically arranged as reflectors. The frequency characteristics are shown in FIG. Referring to FIG. 8, the resonance frequency in the X direction where the length of the patch 21 is long is lower than the resonance frequency in the Y direction. This is because the inductor component in the X direction has increased. That is, the reflection phase of the X direction polarization is about 0 ° (resonates) in the vicinity of about 0.5 GHz, whereas the reflection phase of the Y direction polarization is about 150 in the vicinity of 0.5 GHz. The EBG composed of the unit structure 2-1 behaves almost the same as the metal plate. Therefore, when an antenna element is installed in the vicinity of the EBG composed of the unit structure 2-1, an X direction component is radiated at a frequency of about 0.5 GHz, but a Y direction component is not radiated. The linearly polarized wave is emitted. The reflection phase of the Y-direction polarization is about 0 ° (resonates) in the vicinity of about 0.68 GHz, whereas the reflection phase of the X-direction polarization is about −8 in the vicinity of 0.68 GHz. It is 150 °. Therefore, when the antenna element is installed in the vicinity of the EBG composed of the unit structure 2-1, the Y direction component is radiated at the frequency of about 0.68 GHz, but the X direction component is not radiated. The linearly polarized wave is emitted. As described above, in the antenna of the second embodiment in which the EBG composed of the unit structure 2-1 having an asymmetric shape in the X direction and the Y direction is used as a reflector, polarization dependency occurs.

Next, FIG. 9 is a plan view showing the configuration of the antenna of the third embodiment that utilizes the principle of polarization dependence in the antenna of the second embodiment.
The antenna 3A of the third embodiment according to the present invention shown in FIG. 9 has the same configuration as that of the antenna 1A of the first embodiment, and the polarity of the voltage applied to each patch is changed. That is, the antenna 3A of the third embodiment includes an EBG3 that is a reflector having an electromagnetic band gap (EBG) structure, and an antenna element 35 that is a square spiral antenna is disposed at a height h above the EBG3. It is configured. In the EBG 3, square patches 31 that are smaller than the wavelength used are periodically arranged in a matrix on the surface of the square substrate 30, and a ground plane (not shown) is formed on the back surface of the substrate 30. ing. In the illustrated example, the patch 31 is provided with 25 patches P1-1, P1-2,..., P5-4, P5-5 of 5 rows × 5 columns, and a variable capacitance is provided between the patches. A varicap 32 as a diode is connected with the polarity shown in the figure. Nearly the center of each patch 31 is short-circuited to the ground plane by a short-circuit pin provided through the substrate 30. In this way, the EBG 3 is configured by periodically arranging unit structures similar to the unit structure 1-1 shown in FIG. The substrate 30 is a Teflon substrate or the like having good high frequency characteristics, and has a predetermined dielectric constant.

  In the antenna 3A of the third embodiment shown in FIG. 9, a black circle is attached to the center of 25 patches P1-1, P1-2,..., P5-4, P5-5 of 5 rows × 5 columns. A positive control voltage + V is applied to a total of 15 patches 31 of the patches P1-1 to P1-5, P3-1 to P3-5, and P5-1 to P5-5, and the remaining P2-1 A total of ten patches 31 to P2-5, P4-1 to P4-5 are set to the same potential as the ground. Thereby, since the five patches 31 of the patches P1-1 to P1-5 have the same potential, the varicaps 32 connecting the patches 31 are short-circuited in terms of high frequency and electrically short-circuited. Can be considered. Further, the five patches 31 of the patches P3-1 to P3-5 and the five patches 31 of the patches P5-1 to P5-5 are the same, and can be regarded as being electrically short-circuited.

Here, the X direction polarization of the antenna 3A when the condition of the antenna 3A of the third embodiment is the same as the condition of the antenna 1A of the first embodiment except for the condition of the polarity of the voltage applied to each patch 31. FIG. 10 shows frequency characteristics of the reflection phase of the Y-direction polarization. In this case, the height of the antenna element 35 on the EBG 3 is about 0.01λ.
Referring to the reflection phase characteristics shown in FIG. 10, for the Y-direction polarization, the reflection phase only changes from about 180 ° to about 150 ° even if the frequency changes from 0.2 GHz to 1 GHz. Is not resonant. Thus, it can be seen that the EBG 3 behaves almost the same as the metal plate with respect to the Y-direction polarization. As for the X-direction polarization, the reflection phase changes from about 180 ° to 0 ° as the frequency increases, and changes toward about −180 ° as the frequency increases. When the positive voltage + V voltage value is controlled and the capacitance value of the varicap 32 is about 1 pF, the resonance frequency is about 0.58 GHz, and the capacitance value of the varicap 32 is about 2 pF. The resonance frequency is about 0.49 GHz, and when the capacitance value of the varicap 32 is about 3 pF, the resonance frequency is about 0.43 GHz. As described above, when the voltage value of the control voltage + V is lowered to increase the capacitance of the varicap 32, the resonance point can be shifted to the low frequency side, similarly to the antenna 1A of the first embodiment.

Further, in the antenna 3A of the third embodiment, the directional characteristics of the XZ plane when the capacitance value of the varicap 32 is about 1 pF and the frequency is 0.6 GHz are shown in FIG. The directivity characteristics are shown in FIG. Referring to FIG. 11, it can be seen that X-direction polarization is radiated well. Then, referring to FIG. 12, it can be seen that the Y-direction polarization is not radiated. Further, FIG. 13 shows the frequency characteristics of the VSWR when the capacitance value of the varicap 32 is about 1 pF in the antenna 3A of the third embodiment, and the capacitance value of the varicap 12 in the antenna 1A of the first embodiment is about. It is shown in comparison with the frequency characteristic of VSWR when it is 1 pF. Referring to FIG. 13, it can be seen that the input impedance is disturbed in the low band due to the effect that the Y-direction polarization is not radiated, but the influence in the vicinity of the resonance frequency of the EBG 3 is small. As described above, in the antenna 3A of the third embodiment, by setting the polarity of the voltage applied to each patch 31 to the polarity shown in the figure, only the X-direction linearly polarized wave is radiated without radiating the Y-direction polarized wave. The polarization-dependent antenna 3A can be obtained.
Since each patch 31 is short-circuited to the ground plane by a short-circuit pin, although not shown, the ground plane to which the patch 31 to which the control voltage + V is applied is short-circuited, and the patch 31 having the same potential as the ground. Are separated in a direct current manner from a ground plane to be short-circuited, and both ground planes are connected in high frequency by a capacitor having a low impedance at the operating frequency.

Next, FIG. 14 is a plan view showing the configuration of the antenna of the fourth embodiment that utilizes the principle of polarization dependence in the antenna of the second embodiment.
The antenna 4A of the fourth embodiment according to the present invention shown in FIG. 14 has the same configuration as the antenna 3A of the third embodiment, and changes the polarity of the voltage applied to the patch. That is, the antenna 4A of the fourth embodiment includes an EBG4 that is a reflector having an electromagnetic band gap (EBG) structure, and an antenna element 45 that is a square spiral antenna is disposed at a height h above the EBG4. It is configured. In the EBG 4, square patches 41, which are smaller than the wavelength used, are periodically arranged in a matrix on the surface of the square substrate 40, and a ground plane (not shown) is formed on the back surface of the substrate 40. ing. In the illustrated example, the patch 41 includes 25 patches P1-1, P1-2,..., P5-4, P5-5 of 5 rows × 5 columns, and a variable capacitance is provided between the patches. A varicap 42 as a diode is connected with the polarity shown in the figure. The approximate center of each patch 41 is short-circuited to the ground plane by a short-circuit pin provided through the substrate 40. As described above, the EBG 4 is configured by periodically arranging unit structures similar to the unit structure 1-1 shown in FIG. The substrate 40 is a Teflon substrate or the like having good high-frequency characteristics and has a predetermined dielectric constant.

  In the antenna 4A of the fourth embodiment shown in FIG. 14, a black circle is attached to the center of 25 patches P1-1, P1-2,..., P5-4, P5-5 of 5 rows × 5 columns. Patches P1-1, P1-3, P1-5, P2-1, P2-3, P2-5, P3-1, P3-3, P3-5, P4-1, P4-3, P4-5 , P5-1, P5-3, and P5-5, a positive control voltage + V is applied to a total of 15 patches 41, and the remaining P1-2, P1-4, P2-2, P2-4, P3 A total of ten patches 41 of -2, P3-4, P4-2, P4-4, P5-2, and P5-4 are at the same potential as the ground. Thereby, since the five patches 41 of the patches P1-1, P2-1,..., P5-1 in the first row have the same potential, the varicap 42 connecting these patches 41 has a high frequency. Therefore, it can be regarded as a short circuit. The same applies to the five patches 41 in the third and fifth rows, and can be regarded as being electrically short-circuited.

Here, the X-direction polarization of the antenna 4A when the conditions of the antenna 4A of the fourth embodiment are the same as the conditions of the antenna 1A of the first embodiment except for the condition of the polarity of the voltage applied to each patch 41. FIG. 15 shows the frequency characteristics of the reflection phase of the Y-direction polarization. In this case, the height of the antenna element 45 on the EBG 4 is about 0.01λ.
Referring to the reflection phase characteristics shown in FIG. 15, for the X-direction polarization, the reflection phase changes only from about 180 ° to about 150 ° even if the frequency changes from 0.2 GHz to 1 GHz. Is not resonant. Thus, it can be seen that the EBG 4 behaves almost the same as the metal plate with respect to the X-direction polarization. As for the Y-direction polarized wave, the reflection phase changes from about 180 ° to 0 ° as the frequency increases, and further changes toward about −180 ° as the frequency increases. When the positive voltage + V voltage value is controlled and the capacitance value of the varicap 42 is about 1 pF, the resonance frequency is about 0.58 GHz, and the capacitance value of the varicap 42 is about 2 pF. Has a resonance frequency of about 0.49 GHz, and when the capacitance value of the varicap 42 is about 3 pF, the resonance frequency is about 0.43 GHz. As described above, when the voltage value of the control voltage + V is lowered to increase the capacitance of the varicap 42, the resonance point can be shifted to the low frequency side, similarly to the antenna 1A of the first embodiment.

Further, in the antenna 4A of the fourth embodiment, the varicap 42 has a capacitance value of about 1 pF and the directivity characteristics of the XZ plane when the frequency is 0.6 GHz are shown in FIG. The directivity characteristics are shown in FIG. Referring to FIG. 16, it can be seen that X-direction polarization is not radiated, and FIG. 17 is that Y-direction polarization is well radiated. Thus, in the antenna 4A of the fourth embodiment, by setting the polarity of the voltage applied to each patch 41 to the polarity shown in the figure, only the linearly polarized wave in the Y direction is radiated without radiating the X direction polarized wave. The polarization-dependent antenna 4A can be obtained.
Since each patch 41 is short-circuited to the ground plane by a short-circuit pin, although not shown, the ground plane to which the patch 41 to which the control voltage + V is applied is short-circuited, and the patch 41 having the same potential as the ground. Are separated in a direct current manner from a ground plane to be short-circuited, and both ground planes are connected in high frequency by a capacitor having a low impedance at the operating frequency.
By the way, in the antenna 3A of the first embodiment, when the polarity of the voltage that can be applied to each patch can be switched as in the antenna 3A of the third embodiment and the antenna 4A of the fourth embodiment, X The antenna can be switched from directional polarization to Y-direction polarization. In this case, the antenna element 15 needs an antenna that can radiate circularly polarized waves.

Although the patches 11 to 41 in the antennas 1A to 4A according to the first to fourth embodiments of the present invention described above have a rectangular patch shape having a short-circuit pin, the present invention is not limited to this. FIG. 18 shows various shapes of patches formed on the surface of the EBG.
The patch 10a shown in FIG. 18A has a hexagonal shape, and a short-circuit pin 14a that is short-circuited to the ground plane is connected to the center. The patch 10b shown in FIG. 18B has a circular shape, and a short-circuit pin 14b that is short-circuited to the ground plane is connected to the center. The patch 10c shown in FIG. 18C has a cross shape, and a short-circuit pin 14c that is short-circuited to the ground plane is connected to the center. The patch 10d shown in FIG. 18 (d) has a shape in which four corners and a central portion are combined into a cross shape with a small square shape, and a short-circuit pin 14d that is short-circuited to the ground plane is connected to the center. The patch 10e shown in FIG. 18 (e) has a triangular shape, and a short-circuit pin 14e that is short-circuited to the ground plane is connected substantially at the center.
The shape of the EBG patch in the antenna according to the present invention can be any one of FIGS. 18A to 18E instead of the quadrangle. In this case, the shorting pin may be eliminated. The same operation can be obtained even if the unit structure in the EBG is replaced by a lumped constant circuit such as a chip inductor or a capacitor. Further, the antenna element arranged on the EBG reflector may have any shape as long as it emits a necessary polarized wave. That is, a circularly polarized antenna is used when circularly polarized radiation is required or when polarized waves are switched, and a linearly polarized antenna is used when only linearly polarized radiation is required.

Further, the resonance frequency and polarization characteristics may be mechanically controlled. FIG. 19 is a plan view showing the configuration of the antenna 5A of the fifth embodiment according to the present invention that can mechanically control the resonance frequency and polarization characteristics, and FIG. 20 is a side view showing the configuration.
The antenna 5A of the fifth embodiment shown in these drawings includes an EBG 5 that is a reflector having an electromagnetic bandgap (EBG) structure, and an antenna element 56 that is a square spiral antenna at a height h above the EBG 5 is provided. Arranged and configured. In the EBG 5, square patches 51, which are made smaller than the wavelength used, are periodically arranged in a matrix on the surface of a rectangular substrate 50, and the gaps between the patches 51 are arranged on the substrate 50. The first control board 52 having the conductive first small pieces 54 formed periodically in the column direction is disposed below the board 50 and corresponds to the position of the gap between the patches 51. A second control board 53 on which conductive second small pieces 55 are periodically formed in the row direction is arranged. Further, a ground plane 57 is disposed under the second control board 53. The substrate 50, the first control substrate 52, and the second control substrate 53 are Teflon substrates having good high-frequency characteristics, and have a predetermined dielectric constant.

The first control board 52 can move mechanically up and down with respect to the board 50. When the first control board 52 is brought close to the board 50, the gap between the two becomes narrow and the action of the first small piece 54 causes the Y direction. The resonance frequency in the Y direction can be lowered by increasing the capacitance of the first control board 52. When the first control board 52 is moved away from the board 50, the gap between the two becomes wider and the first small piece 54 reduces the Y-direction capacity. Thus, the resonance frequency in the Y direction can be increased. Also, the second control board 53 can be moved mechanically up and down with respect to the board 50, and when the second control board 53 is brought close to the board 50, the gap between the two becomes narrow and the second small piece 55 acts. The X-direction capacitance can be increased by lowering the resonance frequency in the X-direction, and when the second control substrate 53 is moved away from the substrate 50, the gap between the two becomes wider and the second small piece 55 acts to reduce the capacitance in the X-direction. The resonance frequency in the X direction can be increased by decreasing the frequency. As a result, the polarization in the X direction and the polarization in the Y direction can be controlled independently. Thus, in the antenna 5A of the fifth embodiment, the resonance frequencies in the X direction and the Y direction can be controlled independently, and the polarization-dependent antenna 5A can be obtained.
In the case where only the operation frequency control of circular polarization is performed, the first small piece 54 and the second small piece 55 can be formed on one control board.

Further, FIG. 21 shows a configuration of another example in which the resonance frequency is mechanically controlled in the antenna of the present invention. The side view shown in FIG. 21 shows the configuration of an EBG 6 having an electromagnetic band gap (EBG) structure in which an antenna element is omitted and used as a reflector.
A dielectric substrate 62 is provided on the EBG 6 shown in FIG. 21 so as to move up and down so as to cover the front surface. An antenna element that radiates circularly polarized wave or linearly polarized wave (not shown) is disposed at a position of height h on the dielectric substrate 62. In the EBG 6, square patches 61, which are made smaller than the used wavelength, are periodically arranged in a matrix on the surface of a square substrate 60, and a ground plane 63 is formed on the back surface of the substrate 60. Yes. Almost the center of each patch 61 is short-circuited to the ground plane 63 by a short-circuit pin 64 provided through the substrate 60. The substrate 60 is a Teflon substrate or the like having good high frequency characteristics, and has a predetermined dielectric constant.
The dielectric substrate 62 can move mechanically up and down with respect to the substrate 60. When the dielectric substrate 62 is brought close to the substrate 60, the gap between the two becomes narrow and the inductor component increases, so that the EBG 6 The resonance frequency can be lowered, and when the dielectric substrate 62 is moved away from the substrate 60, the gap between the two becomes wider and the inductor component decreases, so that the resonance frequency of the EBG 6 can be raised.

Next, FIG. 22 shows a configuration for controlling the resonance frequency by switching in the antenna of the present invention. The plan view shown in FIG. 22 shows the configuration of an EBG 7 having an electromagnetic band gap (EBG) structure in which an antenna element is omitted and used as a reflector.
An antenna element that can radiate circularly polarized waves (not shown) is arranged at a height h on the EBG 7 shown in FIG. In the EBG 7, square patches 71, which are smaller than the used wavelength, are periodically arranged in a matrix on the surface of the square substrate 70, and a ground plane (not shown) is formed on the back surface of the substrate 70. ing. In the illustrated example, the patch 71 is provided with 16 patches P1-1, P1-2,..., P4-3, and P4-4 of 4 rows × 4 columns. 71 are grouped into groups G1, G2, G3, and G4. A PIN diode 72, which is a switching diode, is connected between the patches 71 belonging to the groups G1 to G4 with the polarity shown in the figure, but the PIN diode 72 is not connected between the patches 71 in different groups. Nearly the center of each patch 71 is short-circuited to the ground plane by a short-circuit pin provided through the substrate 70. Thus, the EBG 7 is configured by periodically arranging unit structures similar to the unit structure 1-1 shown in FIG. The substrate 70 is a Teflon substrate or the like having good high frequency characteristics, and has a predetermined dielectric constant.

  In the EBG7 shown in FIG. 22, in the 16 patches P1-1, P1-2,..., P4-3, P4-4 of 4 rows × 4 columns, a patch with a black circle at the center belonging to the group G1 P1-1, P2-2, patches P1-3, P2-4 with a black circle at the center belonging to group G2, patches P3-1, P4-2, group G4 with a black circle at the center belonging to group G3 A positive voltage + V or a voltage of 0V is applied to the patch 71 of the patches P3-3 and P4-4 with a black circle at the center belonging to A, and the remaining patch 71 is set to 0V, which is the same potential as the ground. Here, when a positive voltage + V is applied to a patch with a black circle in the center, the PIN diode 72 becomes conductive, and the four patches belonging to each of the groups G1 to G4 are electrically connected and equivalently It will work as one patch. As a result, the capacitance component and the inductor component of the EBG 7 increase and the resonance frequency is lowered. When 0V is applied to a patch with a black circle in the center, the PIN diode 72 is disabled and each patch 71 operates as a unit structure of the EBG 7, so that the resonance frequency of the EBG 7 becomes the original resonance frequency. .

FIG. 23 shows the frequency characteristics of the reflection phase of EBG7. In this case, the resonance frequency of the EBG 7 is designed to be about 0.6 GHz. When the free space wavelength of the resonance frequency of 0.6 GHz is λ, one side of the patch 71 is about 0.2λ, and between the patches 71 The gap is about 0.02λ. For example, the dielectric constant εr of the substrate 70, which is a Teflon substrate, is about 2.2, and the thickness of the substrate 70 is about 0.04λ.
Referring to FIG. 23, when 0V is applied to the PIN diode 72 and the PIN diode 72 is turned off, the resonance frequency is about 0.6 GHz, and a positive voltage + V is applied to the patch 71 with a black circle in the center. It can be seen that the resonance frequency when the PIN diode 72 is passed is about 0.4 GHz.

Next, another configuration for controlling the resonance frequency by switching in the antenna of the present invention is shown in FIG. The plan view shown in FIG. 24 shows the configuration of an EBG 8 having an electromagnetic band gap (EBG) structure in which an antenna element is omitted and used as a reflector.
An antenna element that can radiate circularly polarized waves (not shown) is arranged at a height h on the EBG 8 shown in FIG. In the EBG 8, square patches 81 that are smaller than the used wavelength are periodically arranged in a matrix on the surface of the square substrate 80, and a ground plane (not shown) is formed on the back surface of the substrate 80. ing. In the illustrated example, the patch 81 is provided with 36 patches P1-1, P1-2,..., P6-5, and P6-6 in 6 rows × 6 columns. 81 are grouped into groups G1, G2, G3, and G4. A PIN diode 82, which is a switching diode, is connected between the patches 81 belonging to the groups G1 to G4 with the polarity shown in the figure, but the PIN diode 82 is not connected between the patches 81 in different groups. The approximate center of each patch 81 is short-circuited to the ground plane by a short-circuit pin provided through the substrate 80. In this way, the EBG 8 is configured by periodically arranging unit structures similar to the unit structure 1-1 shown in FIG. The substrate 80 is a Teflon substrate or the like having good high frequency characteristics, and has a predetermined dielectric constant.

  24. In the EBG8 shown in FIG. 24, in the 36 patches P1-1, P1-2,..., P6-5, P6-6 of 6 rows × 6 columns, a patch with a black circle at the center belonging to the group G1 P1-2, P2-1, P2-3, P3-2, patches P1-5, P2-4, P2-6, P3-5 with a black circle at the center belonging to the group G2, and the center belonging to the group G3 Patches P4-2, P5-1, P5-3 and P6-2 with black circles, patches P4-5, P5-4, P5-6 and P6-5 with a black circle at the center belonging to group G4 A positive voltage + V or a voltage of 0V is applied to the patch 71, and the remaining patch 81 with a white circle in the center is set to 0V having the same potential as the ground. Here, when a positive voltage + V is applied to a patch with a black circle in the center, the PIN diode 82 becomes conductive, and nine patches belonging to each of the groups G1 to G4 are electrically connected and equivalently It will work as one patch. As a result, the capacitance component and the inductor component of the EBG 8 increase, and the resonance frequency can be shifted to the low frequency side. When 0V is applied to a patch with a black circle in the center, the PIN diode 82 is disabled and each patch 81 operates as a unit structure of the EBG 8. Therefore, the resonance frequency of the EBG 8 is the original resonance. It becomes frequency.

In the configuration in which the resonance frequency is controlled by switching in the antenna of the present invention described above, it consists of 1 × 1 patch resonance in which each patch is operated as an EBG unit structure, or N × N patch to which a PIN diode is connected in advance. Only two types of group resonances can be obtained. Therefore, FIG. 25 shows a configuration in which all resonances of a group of 1 × 1, 2 × 2,..., N × N patches can be obtained. The plan view shown in FIG. 25 shows the configuration of an EBG 9 having an electromagnetic bandgap (EBG) structure in which an antenna element is omitted and is used as a reflector.
An antenna element (not shown) that can radiate circularly polarized waves is arranged at a height h on the EBG 9 shown in FIG. In the EBG 9, square patches 91 that are smaller than the used wavelength are periodically arranged in a matrix on the surface of the square substrate 90, and a ground plane (not shown) is formed on the back surface of the substrate 90. ing. In the illustrated example, the patch 91 is provided with 36 patches P1-1, P1-2,..., P6-5, P6-6 of 6 rows × 6 columns. Two PIN diodes 92 having opposite polarities are connected in parallel. Nearly the center of each patch 91 is short-circuited to the ground plane by a short-circuit pin provided through the substrate 90. In this way, the EBG 9 is configured by periodically arranging unit structures similar to the unit structure 1-1 shown in FIG. The substrate 90 is a Teflon substrate or the like having good high-frequency characteristics, and has a predetermined dielectric constant.

  In the configuration of the EBG 9 shown in FIG. 25, a positive voltage + V or 0 V is applied to the patch 91 with a black circle at the center, and the remaining patch 91 with a white circle at the center is set to 0 V, which has the same potential as the ground. ing. In this case, when 0 V is applied to a patch with a black circle in the center, the potential difference between adjacent patches 91 becomes 0 V, and the two PIN diodes 92 connected in parallel between them are not conductive, so Since the matching patch 91 is in an open state, the resonance frequency of the EBG 9 becomes the original resonance frequency. Further, when a positive voltage + V is applied to the patch 91 with a black circle in the center, the potential difference between adjacent patches 91 becomes equal to or higher than the operating voltage of the PIN diode 92, and the PIN diodes connected in parallel are connected therebetween. Of the 92, the PIN diodes 92 connected in the forward direction become conductive, and the adjacent patches 91 are short-circuited. Therefore, all of the patches P1-1, P1-2,..., P6-5, and P6-6 are short-circuited to form a unit structure including 36 6 × 6 patches 91, and the resonance frequency of the EBG 9 is set. It becomes possible to shift to the lowest frequency side.

  Next, in the configuration of the EBG 9 shown in FIG. 25, a configuration in which the application mode of the voltage applied to each patch 91 is changed is shown in FIG. In the EBG9 shown in FIG. 26, a positive voltage + V or 0V is applied to the patch 91 with a black circle at the center, and the remaining patch 91 with a white circle at the center is set to 0V, which is the same potential as the ground. Yes. Here, when 0 V is applied to a patch with a black circle in the center, the potential difference between adjacent patches 91 becomes 0 V, and the two PIN diodes 92 connected in parallel between them are not conductive, so that Since the matching patch 91 is in an open state, the resonance frequency of the EBG 9 becomes the original resonance frequency. In addition, when a positive voltage + V is applied to the patch 91 with a black circle in the center, the patch 91 in which the potential difference between adjacent patches 91 is equal to or higher than the operating voltage of the PIN diode 92 is connected in parallel. Among the PIN diodes 92, the PIN diodes 92 connected in the forward direction become conductive, and the adjacent patches 91 are short-circuited.

  That is, in the configuration shown in FIG. 26, the patch P1-1 and the adjacent patches P1-2 and P2-1 are short-circuited, and the patch P2-2 and the adjacent patches P1-2 and P2-1 are short-circuited. As a result, the four patches P1-1, P1-2, P2-1, and P2-2 are short-circuited, and a group G1 composed of four 2 × 2 patches 91 has a unit structure. In this case, the patch P1-2 and the patch P1-3, the patch P2-2 and the patch P2-3, the patch P2-1 and the patch P3-1, and the patch P2-2 and the patch P3-2 have the same potential. Both of the two PIN diodes 92 connected in parallel between them are disconnected, and the patches are opened. Since the same applies to the other patches 91, the EBG 9 operates as nine groups of groups G1 to G9 shown in the figure each consisting of four patches, and the resonance frequency of the EBG 9 is shifted to the low frequency side. Will be able to.

  Furthermore, in the configuration of the EBG 9 shown in FIG. 25, another configuration in which the application mode of the voltage applied to each patch 91 is changed is shown in FIG. In the EBG 9 shown in FIG. 27, a positive voltage + V or 0V is applied to the patch 91 with a black circle at the center, and the remaining patch 91 with a white circle at the center is set to 0 V, which has the same potential as the ground. Yes. Here, when 0 V is applied to a patch with a black circle in the center, the potential difference between adjacent patches 91 becomes 0 V, and the two PIN diodes 92 connected in parallel between them are not conductive, so that Since the matching patch 91 is in an open state, the resonance frequency of the EBG 9 becomes the original resonance frequency. In addition, when a positive voltage + V is applied to the patch 91 with a black circle in the center, the patch 91 in which the potential difference between adjacent patches 91 is equal to or higher than the operating voltage of the PIN diode 92 is connected in parallel. Among the PIN diodes 92, the PIN diodes 92 connected in the forward direction become conductive, and the adjacent patches 91 are short-circuited.

That is, in the configuration shown in FIG. 27, the patch P1-1 and the adjacent patches P1-2 and P2-1 are short-circuited, and the patch P2-2 and the adjacent patches P1-2, P2-1, and P2- 3, P3-2 are short-circuited. Furthermore, patches P1-2 and P2-3 adjacent to the patch P1-3, patches P2-1 and P3-2 adjacent to the patch P3-1, patches P2-3 and P3-2 adjacent to the patch P3-3, and 9 are short-circuited, and therefore, nine patches 91 of patches P1-1 to P1-3, P2-1 to P2-3, and P3-1 to P3-3 are short-circuited to form 3 × 3 nine patches 91. Group G1 has a unit structure. In this case, patch P1-3 and patch P1-4, patch P2-3 and patch P2-4, patch P3-1 and patch P4-1, patch P3-2 and patch P4-2, patch P3-3 and patch P4 Since −3 has the same potential, both of the two PIN diodes 92 connected in parallel between them are disconnected, and the patches are in an open state. Since the same applies to the other patches 91, the EBG 9 operates as four groups G1 to G4 shown in the figure each including nine patches, and the resonance frequency of the EBG9 is shifted to the low frequency side. Will be able to.
As described above, in the configuration of the EBG 9 shown in FIG. 25, the resonance frequency of the EBG 9 can be controlled by switching the application mode of the voltage applied to each patch 91. By expanding the application mode of the voltage applied to each patch 91, the EBG unit structure can be freely switched and the resonance frequency can be controlled by switching the voltage application mode from 1 × 1 to N × N. become able to.

In the antenna according to the present invention described above, the EBG has been described as 5 rows × 5 columns. However, the EBG is not limited thereto, and an EBG having patches arranged in an arbitrary number of rows and columns can be used.
Further, in the antenna of each embodiment according to the present invention, when the wavelength of the use frequency is λ, the length of one side of the square patch can be set to about 0.04λ to about 0.3λ. The gap may be about 0.001λ to about 0.04λ. Further, the thickness of the EBG can be about 0.001λ to about 0.06λ, and the height h of the antenna element disposed on the EBG can be about 0.1λ to about 0.20λ. Theoretically, the height h can be made as low as possible. Furthermore, although the antenna according to the present invention operates if the number of patches of the EBG is 2 × 2 or more, it is practically required to be 6 × 6 or more. Characteristics are stable. The length of the side of the EBG needs to be longer than the length of the side of the antenna element. In the above description, the antenna element is a rectangular spiral antenna. However, when an antenna element that radiates circularly polarized waves is required, a circular spiral antenna, a loop antenna, or a cross dipole antenna can be used. When the antenna element only needs to radiate linearly polarized waves, a dipole antenna or the like can be used.

It is the top view which shows the structure of the antenna of 1st Example of this invention, and the perspective view which shows the structure of a unit structure in three dimensions. It is a side view which shows the structure of the antenna of 1st Example of this invention. It is a figure which shows the frequency characteristic of the reflection phase of X direction polarization | polarized-light and Y direction polarization | polarized-light in the antenna of 1st Example of this invention. It is a figure which shows the frequency characteristic of the axial ratio (AR) in the antenna of 1st Example of this invention. It is a figure which shows the frequency characteristic of the gain in the antenna of 1st Example of this invention. It is a figure which shows the frequency characteristic of VSWR in the antenna of 1st Example of this invention. It is a perspective view which shows the structure of the unit structure of the antenna of 2nd Example of this invention in three dimensions. It is a figure which shows the frequency characteristic of the reflection phase of X direction polarization | polarized-light and Y direction polarization | polarized-light in the antenna of 2nd Example of this invention. It is a top view which shows the structure of the antenna of 3rd Example of this invention. It is a figure which shows the frequency characteristic of the reflection phase of X direction polarization | polarized-light and Y direction polarization | polarized-light in the antenna of 3rd Example of this invention. It is a figure which shows the directional characteristic of the XZ plane in the antenna of 3rd Example of this invention. It is a figure which shows the directional characteristic of the YZ surface in the antenna of 3rd Example of this invention. It is a figure which shows the frequency characteristic of VSWR in the antenna of 3rd Example of this invention. It is a top view which shows the structure of the antenna of 4th Example of this invention. It is a figure which shows the frequency characteristic of the reflection phase of X direction polarization | polarized-light and Y direction polarization | polarized-light in the antenna of 4th Example of this invention. It is a figure which shows the directional characteristic of the XZ plane in the antenna of 4th Example of this invention. It is a figure which shows the directional characteristic of the YZ surface in the antenna of 4th Example of this invention. It is a figure which shows the shape of the various patches in the antenna of each Example of this invention. It is a top view which shows the structure of the antenna of 5th Example concerning this invention which can control a resonant frequency and a polarization characteristic mechanically. It is a side view which shows the structure of the antenna of 5th Example concerning this invention. It is a figure which shows the structure of the other example which mechanically controls the resonant frequency in the antenna of this invention. It is a top view which shows the structure which controls the resonant frequency by switching in the antenna of this invention. It is a figure which shows the frequency characteristic of the reflection phase in the structure shown in FIG. It is a top view which shows the other structure which controls a resonant frequency by switching in the antenna of this invention. It is a top view which shows the further another structure which controls the resonant frequency by switching in the antenna of this invention. In the antenna of this invention, it is a top view which shows the structure which varied the application aspect of the voltage applied to each patch in the further another structure which controls a resonant frequency by switching. In the antenna of this invention, it is a top view which shows the structure which varied the application aspect of the voltage applied to each patch in the further another structure which controls a resonant frequency by switching. It is a three-dimensional perspective view which shows the structure of the conventional EBG. It is a figure which shows the equivalent circuit of the unit structure which comprises the conventional EBG. It is a side view which shows the structure of the conventional EBG. It is a figure for demonstrating the reflection by a perfect conductor, and the reflection by EBG. It is a three-dimensional perspective view which shows the structure of the conventional antenna which uses EBG. It is a side view which shows the structure of the conventional antenna which uses EBG. It is a figure which shows the frequency characteristic of the reflection phase in the conventional antenna. It is a figure which shows the frequency characteristic of the axial ratio in the conventional antenna. It is a figure which shows the frequency characteristic of VSWR in the conventional antenna. It is a figure which shows the directional characteristic of the XZ surface in the conventional antenna. It is a figure which shows the directional characteristic of the YZ surface in the conventional antenna.

Explanation of symbols

1 EBG, 1-1 unit structure, 1A antenna, 2-1 unit structure, 3 EBG, 3A antenna, 4 EBG, 4A antenna, 5 EBG, 5A antenna, 6 EBG, 7 EBG, 8 EBG, 9 EBG, 10 substrate 10a patch, 10b patch, 10c patch, 10d patch, 10e patch, 11 patch, 12 varicap, 13 ground plane, 14 shorting pin, 14a shorting pin, 14b shorting pin, 14c shorting pin, 14d shorting pin, 14e shorting pin 15 antenna elements, 20 substrates, 21 patches, 23 ground planes, 24 short pins, 30 substrates, 31 patches, 32 varicaps, 35 antenna elements, 40 substrates, 41 patches, 42 varicaps, 45 antenna elements, 50 substrates, 51 patches, 52 First Control Board, 53 Second Control Board, 54 First Small Piece, 55 Second Small Piece, 56 Antenna Element, 57 Ground Plane, 60 Substrate, 61 Patch, 62 Dielectric Substrate, 63 Ground Plane, 64 Shorting Pin, 70 Substrate, 71 patch, 72 PIN diode, 80 substrate, 81 patch, 82 PIN diode, 90 substrate, 91 patch, 92 PIN diode, 100 EBG, 100-1 unit structure, 100A antenna, 110 substrate, 111 patch, 113 ground plane 114 short circuit pins, 120 elements, 133 ground planes, 200 elements

Claims (6)

An antenna comprising a reflector having an electromagnetic bandgap structure and an antenna element that can be disposed close to the reflector until it is in close contact with the reflector,
An antenna comprising: control means for controlling the electromagnetic gap structure to be in a substantially resonant state at a use frequency by changing a capacitance component or an inductor component of the electromagnetic band gap structure in the reflection plate. The electromagnetic bandgap structure includes a plurality of patches that are periodically arranged on the surface of a substrate that is a dielectric, and a ground plane that is formed on substantially the entire back surface of the substrate.
The control means connects the plurality of patches with a variable capacitance diode, and controls the magnitude of the voltage applied to the variable capacitance diode, thereby changing the capacitance component in the electromagnetic band gap structure. The antenna according to claim 1. The electromagnetic bandgap structure includes a plurality of patches that are periodically arranged on the surface of a substrate that is a dielectric, and a ground plane that is formed on substantially the entire back surface of the substrate.
The control means divides the plurality of patches into a plurality of groups including the same number of the patches, connects the patches belonging to the group with a switching diode, and applies a voltage to each patch. By controlling the above, the plurality of patches can be operated as individual patches or patches in which the patches in the group are electrically connected, thereby changing the capacitance component and the inductor component in the electromagnetic band gap structure. The antenna according to claim 1, wherein the antenna is configured as described above. The electromagnetic bandgap structure includes a plurality of patches that are periodically arranged on the surface of a substrate that is a dielectric, and a ground plane that is formed on substantially the entire back surface of the substrate.
The control means connects the plurality of patches in parallel with forward and reverse switching diodes, and controls the polarity of the voltage supplied to each patch and whether or not to apply the plurality of patches. The capacitive component and the inductor component in the electromagnetic band gap structure are made variable by operating the patch as an individual patch or a patch in which an arbitrary number of the patches are electrically connected. Item 1. The antenna according to Item 1. The electromagnetic bandgap structure includes a plurality of patches that are periodically arranged on the surface of a substrate that is a dielectric, and a ground plane that is formed on substantially the entire back surface of the substrate.
The control means has a control board disposed on the board and formed with conductive small pieces located on the gaps between the patches, and the interval between the control board and the board is variable. The antenna according to claim 1, wherein a capacitance component in the electromagnetic band gap structure is made variable. The electromagnetic band gap structure includes a plurality of patches that are periodically arranged in a matrix on the surface of a rectangular substrate that is a dielectric, and a ground that is spaced apart from the back side of the substrate. With a plane,
The control means constitutes each column of the matrix, and a first control board on which the conductive small pieces located on the gaps between the patches constituting each row of the matrix are formed and disposed on the board. A conductive control piece located on a gap between the patches and a second control board disposed between the board and the ground plane; and the first control board and the board. The capacitance component in the electromagnetic band gap structure is made variable by changing the interval or by changing the interval between the second control substrate and the substrate. antenna.

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