JP7283162B2 - Microstrip and array antennas - Google Patents

Description

The present invention relates to microstrip antennas. The present invention also relates to an array antenna in which a plurality of such microstrip antennas are arranged.

Patent Literature 1 describes a microstrip antenna capable of switching the polarization direction of linearly polarized waves. Patent Document 1 describes that a circular radiation conductor is provided with a plurality of feeding points, and by switching the feeding points, the polarization direction is switched in a linear direction connecting the center of the radiation conductor and the feeding points.

Further, Patent Document 2 describes a microstrip antenna capable of switching between right-handed circularly polarized waves and left-handed circularly polarized waves. In Patent Document 2, a feeder line is connected to the outer periphery of a circular patch antenna, four perturbation elements are provided near the outer periphery of the patch antenna in a direction forming 45 degrees with respect to the feeder line, and each perturbation element and A configuration with four switches connecting to the patch antenna is shown. Then, a pair of perturbation elements located in a direction forming an angle of 45 degrees counterclockwise with respect to the feed line is connected to the patch antenna, and the connection between the other pair of perturbation elements and the patch antenna is turned off. can be an antenna that radiates a right-handed circularly polarized wave, and the connection between a pair of perturbation elements located in a direction forming 45 degrees clockwise with respect to the feed line and the patch antenna is turned on, and another pair of perturbation elements It is described that by turning off the connection between and the patch antenna, the antenna can be made to radiate left-handed circularly polarized waves.

JP-A-2003-142940 JP-A-2000-4119

However, in Patent Document 1, since it is necessary to arrange a plurality of feeding points near the center of the radiating element, it is difficult to increase the number of feeding points, and it is only possible to roughly control the polarization direction of linearly polarized waves. could not.

Further, the microstrip antenna of Patent Document 2 can be operated as a linearly polarized antenna by increasing the size of the perturbation element. cannot be controlled.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to realize a microstrip antenna capable of controlling the polarization direction of a linearly polarized wave.

A first aspect of the present invention includes an insulating layer, a first radiation conductor provided on the insulating layer and having a circular pattern, a feed point provided at the center of the first radiation conductor, and a a plurality of second radiation conductors provided in the vicinity of the outer periphery of the first radiation conductor and spaced apart from each other by a predetermined distance; a switch for controlling connection and disconnection between the first radiation conductor and each of the second radiation conductors; and the switch is controlled such that one of the second radiation conductors is connected to the first radiation conductor and the other second radiation conductors are disconnected from the first radiation conductor. A microstrip antenna characterized by:

The pattern of the first radiation conductor is preferably circular. The characteristics of the antenna are improved, and the design is easy.

The second radiation conductor may be an isosceles trapezoid, and may be arranged with two bases aligned in the circumferential direction of the first radiation conductor. Antenna bandwidth can be increased.

A second aspect of the present invention is an array antenna in which the microstrip antennas of the present invention are arranged, wherein the second radiating conductor connected to the first radiating conductor is fed between the adjacent microstrip antennas. The array antenna is characterized in that the directions with respect to the points differ by 180°.

A third aspect of the present invention includes a first microstrip antenna, a second microstrip antenna arranged adjacent to the first microstrip antenna, a 90° phase shifter having a phase shift amount of 90°, The first microstrip antenna and the second microstrip antenna have an insulating layer, a first radiating conductor provided on the insulating layer and having a circular or regular polygonal pattern, and at the center of the first radiating conductor A feeding point provided, a plurality of second radiation conductors provided on an insulating layer and spaced apart from each other by a predetermined distance in the vicinity of the outer periphery of the first radiation conductor, and the first radiation conductor and each of the second radiation conductors. a switch for controlling connection and disconnection between the second radiation conductors, the switch connecting one of the second radiation conductors to the first radiation conductor and disconnecting the other second radiation conductors from the first radiation conductors; and the direction of the second radiating conductor connected to the first radiating conductor in the first microstrip antenna with respect to the feed point and the direction of the second radiating conductor connected to the first radiating conductor in the second microstrip antenna The circularly polarized antenna is characterized in that the direction of the radiation conductor with respect to the feeding point forms 90°, and the 90° phase shifter is connected to the front stage of the first microstrip antenna.

A fourth aspect of the present invention is an array antenna in which the circularly polarized antennas of the third aspect of the present invention are arranged, wherein the phase difference of the circularly polarized waves between the adjacent circularly polarized antennas is a predetermined amount. 2, the direction of the second radiation conductor connected to the first radiation conductor of the first microstrip antenna and the second microstrip antenna with respect to the feeding point is set.

Further, a fifth aspect of the present invention has first to fourth microstrip antennas and a 90° phase shifter having a phase shift amount of 90°, and the first to fourth microstrip antennas include an insulating layer a first radiation conductor provided on the insulating layer and having a circular or regular polygonal pattern; a feed point provided at the center of the first radiation conductor; A plurality of second radiation conductors provided at predetermined intervals near the outer periphery, and switches for controlling connection and disconnection between the first radiation conductors and the second radiation conductors, the switches each One of the second radiation conductors is connected to the first radiation conductor, and controlled to be disconnected from the other second radiation conductor and the first radiation conductor, and the first to fourth microstrip antennas are: The first microstrip antenna and the fourth microstrip antenna are arranged diagonally, and the second microstrip antenna and the third microstrip antenna are arranged diagonally in a 2×2 square lattice. The direction of the second radiation conductor connected to the first radiation conductor in the microstrip antenna and the fourth microstrip antenna with respect to the feed point, and the direction of the second radiation conductor connected to the first radiation conductor in the second microstrip antenna and the third microstrip antenna A circularly polarized wave characterized in that the directions of the two radiation conductors with respect to the feeding point form 90°, and the 90° phase shifter is connected to the front stage of the first microstrip antenna and the fourth microstrip antenna. Antenna.

A sixth aspect of the present invention is an array antenna in which the circularly polarized antennas of the fifth aspect of the present invention are arranged, wherein the phase difference of the circularly polarized waves between the adjacent circularly polarized antennas is a predetermined amount. 2, the direction of the second radiation conductor connected to the first radiation conductor of the first to fourth microstrip antennas with respect to the feed point is set.

ADVANTAGE OF THE INVENTION According to this invention, the microstrip antenna which can control the polarization direction of a linearly-polarized wave simply by switch control is realizable.

2 is a plan view showing the configuration of the microstrip antenna of Example 1. FIG. FIG. 2 is a cross-sectional view showing the configuration of the microstrip antenna of Example 1; FIG. 4 is a diagram showing the correspondence between the position of the second radiation conductor 13 to be connected and the polarization direction. The figure which showed the current path and impedance. FIG. 4 is a diagram showing results of calculation of S11 of the microstrip antenna of Example 1 by simulation; 4 is a diagram showing the directional gain of the microstrip antenna of Example 1. FIG. FIG. 10 is a diagram showing the configuration of a transmission system according to a second embodiment; The figure which showed the structure of the transmission system of Example 3. FIG. The figure which showed the structure of the transmission system of Example 4. FIG. The figure which showed the structure of the transmission system of Example 5. FIG. FIG. 5 is a diagram showing a modification of the microstrip antenna of Example 1;

Specific examples of the present invention will be described below with reference to the drawings, but the present invention is not limited to the examples.

FIG. 1 is a plan view showing the configuration of the microstrip antenna of Example 1, and FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in FIGS. 1 and 2, the microstrip antenna of Example 1 includes a substrate 10, a ground conductor 11, a first radiation conductor 12, a second radiation conductor 13, a feeding point 14, and a switch 15. have.

The substrate 10 is a circular plate made of dielectric material. A ground conductor 11 is provided over the entire surface of one main surface (hereinafter referred to as the back surface) of the substrate 10 in contact with the back surface. The ground conductor 11 is a metal film, such as copper foil. Instead of the substrate 10, a layer of air or vacuum may be used. In other words, any insulating layer that electrically separates the ground conductor 11 from the first radiation conductor 12 and the second radiation conductor 13 may be used.

The first radiation conductor 12 is a metal film, such as a copper foil, provided in contact with the other main surface (hereinafter referred to as the surface) of the substrate 10 . The plane pattern of the first radiation conductor 12 is a circle, as shown in FIG. The diameter of the first radiation conductor 12 is set according to the design frequency f of the microstrip antenna of the first embodiment and the like.

Although the pattern of the first radiation conductor 12 is circular in the first embodiment, it may be a regular polygon such as a square, a regular hexagon, or a regular octagon. However, it is desirable to use a circle as in the first embodiment. This is because a pattern with high symmetry improves antenna characteristics and is easy to design.

A feeding point 14 is provided at the center of the first radiation conductor 12 . Any conventionally known method can be used as the power supply method. For example, the substrate 10 and the ground conductor 11 may be provided with holes to allow the coaxial line to pass therethrough, and the power may be fed by connecting the center of the first radiation conductor 12 to the coaxial line.

The second radiation conductor 13 is a rectangular metal film, such as a copper foil, provided on the surface of the substrate 10 and near the outer circumference of the first radiation conductor 12 at a predetermined distance. Also, as shown in FIG. 1, eight second radiation conductors 13 are provided radially at equal angles (that is, at intervals of 45°). Further, the second radiation conductor 13 is arranged so that its long side direction is aligned with the radial direction of the first radiation conductor 12 . The length and width of the second radiation conductor 13 are set according to the design frequency f and bandwidth of the microstrip antenna of the first embodiment.

The planar pattern of the second radiation conductor 13 does not necessarily have to be rectangular, and may be any shape such as a triangle, a semicircle, a trapezoid, or a sector. Further, if the width of the second radiation conductor 13 (the width of the first radiation conductor 12 in the circumferential direction) increases with increasing distance from the center, the microstrip of the first embodiment can be obtained. Antenna bandwidth can be increased. FIG. 11 shows a modification in which the second radiation conductor 13 is an isosceles trapezoid and two bases are aligned in the circumferential direction of the first radiation conductor 12 .

In addition, in the first embodiment, the number of the second radiation conductors 13 is equal to eight, but the number is not limited to this. As will be described later, since the position of the second radiation conductor 13 corresponds to the polarization direction of the linearly polarized wave, the number and arrangement angle of the second radiation conductor 13 can be changed according to the polarization direction of the linearly polarized wave to be controlled. should be set. For example, if the number of the second radiation conductors 13 is n (n is a natural number of 2 or more) and they are arranged at equal angles, the polarization direction of linearly polarized waves can be switched every (360/n)°.

The switches 15 are provided between the outer circumference of the first radiation conductor 12 and each second radiation conductor 13 . Also, the switch 15 is on/off controlled by a control circuit (not shown). When the switch 15 is on, the outer periphery of the first radiation conductor 12 and the second radiation conductor 13 are connected, and the first radiation conductor 12 and the second radiation conductor 12 are connected. Conduction is established with the radiation conductor 13 . On the other hand, when the switch 15 is off, the outer periphery of the first radiation conductor 12 and the second radiation conductor 13 are disconnected, and the outer periphery of the first radiation conductor 12 and the second radiation conductor 13 are not electrically connected.

A control circuit for on/off control of the switch 15 is a DC circuit. The antenna, on the other hand, operates on alternating current. Therefore, it is preferable to insert an inductor between the switch 15 and the control circuit to cut off the alternating current.

A diode switch, an FET switch, a MEMS switch, or the like can be used as the switch 15 .

Next, the operation of the microstrip antenna of Example 1 will be described. The microstrip antenna of Example 1 is an antenna that transmits and receives linearly polarized waves, and is an antenna that can control the polarization direction by controlling the switch 15 .

When one of the eight second radiation conductors 13 is selected and connected to the first radiation conductor 12 under the control of the switch 15, the first radiation conductor 12 and the second radiation conductor 13 as a whole are electrically centered. , the position of the feeding point 14 is displaced, so that the first radiation conductor 12 and the second radiation conductor 13 can be excited. Also, the polarization direction of the linearly polarized wave is the linear direction connecting the center of the first radiation conductor 12 and the center of the second radiation conductor 13 connected to the first radiation conductor 12 . Therefore, by changing the second radiation conductor 13 connected to the first radiation conductor 12 under the control of the switch 15, the polarization direction of the linearly polarized wave can be switched.

FIG. 3 is an example showing the relationship between the position of the connected second radiation conductor 13 and the polarization direction of the linearly polarized wave. In FIG. 3, the second radiation conductor 13 that is not connected is shown in white. Also, in FIG. 3, the horizontal direction is used as a reference for the polarization direction. As shown in FIG. 3A, when the second radiation conductor 13 on the lateral right side is connected, the linear direction connecting the feed point 14 of the first radiation conductor 12 and the center of the connected second radiation conductor 13 is polarized. A polarization direction of 0° can be realized. Also, as shown in FIG. 3(c), when the second radiation conductor 13 positioned at 45° to the lateral direction is connected, the polarization direction becomes 45°, and as shown in FIG. When the second radiation conductor 13 located in the direction is connected, the polarization direction becomes 90°.

When the second radiation conductor 13 opposite to the second radiation conductor 13 of the desired polarization direction by 180° is connected, the polarization direction is the same, but the phase is different by 180°. For example, when the second radiation conductor 13 on the lateral left side is connected as shown in FIG. 3(d), the polarization direction is the same lateral direction as in FIG. differ by 180°.

Therefore, in the microstrip antenna of Example 1, the polarization direction of the linearly polarized wave can be controlled to 0°, 45°, 90°, and 135° with respect to the horizontal direction, and the phase in each polarization direction can be changed to It can be controlled in two ways, 0° and 180°.

FIG. 4A is a diagram showing current paths of the first radiation conductor 12 and the second radiation conductor 13. FIG. FIG. 4A shows only the second radiation conductors 13 connected to the first radiation conductors 12 among the plurality of second radiation conductors 13 in the microstrip antenna of the first embodiment. Also, the x-axis is taken in the radial direction of the first radiation conductor 12 and in the direction passing through the center of the second radiation conductor 13 . Further, as shown in FIG. 4A, among the end points of the first radiation conductor 12 and the second radiation conductor 13 on the x-axis, the end point on the first radiation conductor 12 side is A, and the end point on the second radiation conductor 13 side is A. be A'. As shown in FIG. 4A, during excitation, the current flows between A and A', and in the first radiation conductor 12, it mainly flows in the vicinity of the circumference.

FIG. 4(b) is a diagram showing the impedance at each point between A and A'. As shown in FIG. 4B, due to the asymmetry due to the second radiation conductor 13 being connected to the first radiation conductor 12, the point where the impedance becomes 0 is the center of the first radiation conductor 12 (feeding point 14). , and the impedance at the feeding point 14 becomes a positive value Zin'. Therefore, by setting the input impedance of the feeding port to Zin', it is possible to match the impedance between the microstrip antenna of the first embodiment and the feeding port.

FIG. 5 is a diagram showing results of calculation of S11 of the microstrip antenna of Example 1 by simulation. As shown in FIG. 5, it was found possible to design an antenna that matches at the center point of S11 (4.87 GHz frequency).

6 is a diagram showing the directional gain of the microstrip antenna of Example 1. FIG. The model is similar to that of FIG. The origin is taken at the center (feeding point 14) of the first radiation conductor 12, the x-axis is taken in the same direction as in FIG. 10, the direction from the rear surface to the front surface of the substrate 10 is taken as positive, and the y-axis is taken in the direction perpendicular to the x-axis and the z-axis. The horizontal axis of FIG. 6 is the angle with respect to the positive direction of the z-axis, and the vertical axis is the directivity gain (dBi). As shown in FIG. 6, in both the yz plane and the xz plane, the gain peaked at about 0°, the maximum gain was about 6.8 dBi, and the directivity of about 92° was obtained for the 3 dB beam width. .

As described above, according to the microstrip antenna of the first embodiment, by selecting the second radiation conductor 13 to be connected to the first radiation conductor 12 by the switch 15, it is possible to easily switch the polarization direction of the linearly polarized wave. A linearly polarized antenna can be realized.

FIG. 7 is a diagram showing the configuration of a transmission system according to the second embodiment. As shown in FIG. 7, the transmission system of the second embodiment includes an array antenna composed of two microstrip antennas 200, two variable phase shifters 201, a high frequency power supply 202, a distributor 203, and a switch control section 204. , is composed of The microstrip antenna 200 has the same configuration as that of the first embodiment.

A high frequency power supply 202 is a power supply that supplies high frequency power to the two microstrip antennas 200 . High-frequency power from a high-frequency power supply 202 is equally divided by a distributor 203 and input to the feed point 14 of the microstrip antenna 200, respectively. Further, the path length from the high frequency power supply 301 to the feed point 14 of each microstrip antenna 200 is set equal.

Two microstrip antennas 200 are arranged at regular intervals. The switch control unit 204 is a device that controls each switch 15 of the microstrip antenna 200 . In the second embodiment, the switch control unit 204 controls each switch 15 so that the polarization directions of the linearly polarized waves of the two microstrip antennas 200 are the same.

Variable phase shifter 201 is inserted between distributor 203 and microstrip antenna 200, respectively. Variable phase shifter 201 is a device that changes the phase of the high frequency supplied to microstrip antenna 200 to a desired value. In the second embodiment, the direction of the directional beam is set to a desired direction by setting the phase difference of the high frequencies supplied to the two microstrip antennas 200 to a desired value using the variable phase shifter 201 .

The transmission system of the second embodiment is an antenna capable of transmitting and receiving linearly polarized waves, and by controlling the amount of phase shift by the variable phase shifter 201, the direction of the directional beam can be controlled. By controlling the polarization direction of the linearly polarized wave of the microstrip antenna 200 by 204, the polarization direction of the directional beam can be controlled.

FIG. 8 is a diagram showing the configuration of a transmission system according to the third embodiment. As shown in FIG. 8, the transmission system of Example 3 is composed of an array antenna consisting of four microstrip antennas 300 and a high-frequency power source 301 . The microstrip antenna 300 has a configuration similar to that of the first embodiment. In FIG. 8, among the second radiation conductors 13 of the microstrip antenna 300, those that are not connected to the first radiation conductor 12 are shown in white.

A high frequency power supply 301 is a power supply that supplies high frequency power to the four microstrip antennas 300 . High-frequency power from a high-frequency power supply 301 is equally divided by a distributor 302 and input to the feed point 14 of the microstrip antenna 300 . The distance from the high frequency power supply 301 to the feed point 14 of each microstrip antenna 300 is set equal. Unlike the second embodiment, no variable phase shifter is provided in front of the microstrip antenna 300 .

The four microstrip antennas 300 are arranged at regular intervals in one direction. Each switch 15 is controlled so that the four microstrip antennas 300 all have the same polarization direction of the linearly polarized waves and the phase difference between the adjacent microstrip antennas 300 is 180°. That is, the positions of the second radiation conductors 13 connected to the first radiation conductors 12 are made to differ by 180° between adjacent microstrip antennas 300 . In FIG. 8, in the first and third microstrip antennas 300 from the left, the first radiating conductor 12 is connected to the top of the two vertical second radiating conductors 13, and the second and fourth from the left. In the microstrip antenna 300 of FIG. 2, the first radiation conductor 12 is connected to the lower one of the two vertical second radiation conductors 13 . Therefore, in the configuration of FIG. 8, the polarization direction is the vertical direction in the figure. Also, the direction of the directional beam is determined by the spacing of each microstrip antenna 300 .

The transmission system of Example 3 is capable of transmitting linearly polarized waves, can direct a directional beam in a predetermined direction without using a variable phase shifter, and can control the polarization direction of linearly polarized waves. can do.

FIG. 9 is a diagram showing the configuration of a transmission system according to the fourth embodiment. As shown in FIG. 9, the transmission system of Example 4 is composed of an array antenna consisting of eight microstrip antennas 400, a high frequency power supply 401, and a 90° phase shifter 402. FIG. The microstrip antenna 400 has the same configuration as that of the first embodiment. In FIG. 9, among the second radiation conductors 13 of the microstrip antenna 400, those that are not connected to the first radiation conductor 12 are shown in white.

A high-frequency power supply 401 is a power supply that supplies high-frequency power to eight microstrip antennas 400 . High-frequency power from a high-frequency power supply 401 is equally divided by a distributor (not shown) and input to feeding points of the microstrip antenna 400 . The distance from the high frequency power source 401 to the feed point 14 of each microstrip antenna 400 is set equal.

The microstrip antennas 400 are arranged in a 2×4 matrix as shown in FIG. The upper microstrip antenna 400 and the lower microstrip antenna 400 constitute one antenna unit, and four antenna units are arranged in one direction at predetermined intervals. Hereinafter, the antenna units are referred to as U1 to U4 from the left side in FIG. For the four microstrip antennas 400 in the lower row, a 90° phase shifter 402 is inserted between the high frequency power supply 401 and the feed point 14 of each microstrip antenna 400 . The 90° phase shifter 402 is a device that advances the phase of the high frequency from the high frequency power supply 401 by 90°.

The switch 15 of the microstrip antenna 400 is controlled so that each of the antenna units U1 to U4 operates as a right-hand circularly polarized antenna. That is, the position of the second radiation conductor 13 connected to the first radiation conductor 12 in the upper microstrip antenna 400 corresponds to the position of the second radiation conductor 13 connected to the first radiation conductor 12 in the lower microstrip antenna 400. 90° clockwise with respect to the position of . Because of this setting, the linearly polarized wave radiated from the lower microstrip antenna 400 has a polarization direction orthogonal to that of the linearly polarized wave radiated from the upper microstrip antenna 400 and has a phase of 90 degrees ahead. Therefore, the composite wave of the electromagnetic wave radiated from the upper microstrip antenna 400 and the electromagnetic wave radiated from the lower microstrip antenna 400 becomes a right-hand circularly polarized wave.

Further, the switch 15 of the microstrip antenna 400 is controlled so that the phase difference between adjacent antenna units is 45° for each of the antenna units U1 to U4. In a circularly polarized antenna, when the circularly polarized antenna is physically rotated, the phase of the circularly polarized wave also changes by the rotation angle. In the microstrip antenna 400, by changing the position of the second radiation conductor 13 connected to the first radiation conductor 12, the same state as physically rotating the antenna can be obtained.

Therefore, in the fourth embodiment, the position of the second radiation conductor 13 connected to the first radiation conductor 12 in a given microstrip antenna 400 is changed to the position of the second radiation conductor 13 connected to the microstrip antenna 400 adjacent to the left. is shifted counterclockwise by 45° with respect to the position of . As a result, the microstrip antenna 400 adjacent to the left side is physically rotated counterclockwise by 45°. As a result, the antenna unit U2 is in the same state as if the antenna unit U1 were physically rotated counterclockwise by 45°, and the circularly polarized waves radiated from the antenna unit U2 are radiated from the antenna unit U1. The phase differs by 45° with respect to circularly polarized waves. The same applies to the circularly polarized waves radiated from the antenna units U3 and U4, and the phases of the circularly polarized waves radiated from the antenna units U1 to U4 are shifted by 45°.

In the fourth embodiment, each of the antenna units U1 to U4 is a right-handed circularly polarized antenna, but may be a left-handed circularly polarized antenna. This is because the position of the second radiation conductor 13 connected to the first radiation conductor 12 in the upper microstrip antenna 400 is the second radiation conductor connected to the first radiation conductor 12 in the lower microstrip antenna 400. It can be realized by making the position 90° counterclockwise with respect to the position of 13 . Therefore, the antenna units U1 to U4 can easily switch between right-handed circularly polarized waves and left-handed circularly polarized waves by controlling the switch 15. FIG.

Further, in the fourth embodiment, the phase difference between each of the antenna units U1 to U4 is set to 45°. The phase difference between each antenna unit U1-U4 can also be set to multiples of 45°.

With the above configuration, the antenna units U1 to U4 operate in the same manner as a linear array antenna in which circularly polarized antennas are arranged at regular intervals in one direction. , the directional beam can be directed in a predetermined direction according to the spacing of the antenna units U1-U4.

The transmission system of Example 4 is an antenna capable of transmitting and receiving circularly polarized waves, and can direct a directional beam in a predetermined direction without using a variable phase shifter.

The transmission system of the fifth embodiment is obtained by changing the configuration of the antenna unit in the transmission system of the fourth embodiment to an antenna unit U5 shown in FIG. The antenna unit U5 has a configuration in which four microstrip antennas 500 are arranged in a 2×2 square lattice. The microstrip antenna 500 has a configuration similar to that of the first embodiment. In FIG. 10, among the second radiation conductors 13 of the microstrip antenna 500, those that are not connected to the first radiation conductor 12 are shown in white. 10, the upper left microstrip antenna is 500a, the upper right microstrip antenna is 500b, the lower left microstrip antenna is 500c, and the lower right microstrip antenna is 500d.

Of the four microstrip antennas 500a to 500d, two diagonal microstrip antennas 500a and 500d are controlled by the switch 15 to change the position of the second radiation conductor 13 connected to the first radiation conductor 12. The polarization directions and phases of the linearly polarized waves are made the same. In addition, for the two microstrip antennas 500b and 500c on different diagonals, the position of the second radiation conductor 13 connected to the first radiation conductor 12 is shifted to the position of the second radiation conductor 13 connected to the microstrip antennas 500a and 500d. 2 The position is 90° clockwise with respect to the position of the radiation conductor 13 . As a result, the directions and phases of the linearly polarized waves of the microstrip antennas 500b and 500c are the same, and are orthogonal to the directions of the linearly polarized waves of the microstrip antennas 500a and 500d. Also, the microstrip antennas 500 a and 500 d are directly connected to the high frequency power supply 401 . Also, the microstrip antennas 500b and 500c are connected to the high frequency power source 401 via the 90° phase shifter 402, and are in a state of leading the phases of the microstrip antennas 500a and 500d by 90°.

The antenna unit U5 in the fifth embodiment thus set operates as a right-handed circularly polarized antenna, like the antenna units U1 to U4 in the fourth embodiment. That is, the composite wave of the electromagnetic waves radiated from each of the microstrip antennas 500a to 500d is a right-hand circularly polarized wave. In the antenna units U1 to U4 of the fourth embodiment, when the direction of the directional beam is greatly tilted in the direction perpendicular to the arrangement direction of the antenna units U1 to U4, the position of the electromagnetic waves from the two microstrip antennas constituting the antenna unit is Although the phase difference becomes large and it does not operate as a circularly polarized wave, the antenna unit in Example 5 can operate as a circularly polarized wave antenna regardless of the direction of the directional beam.

In the fifth embodiment, grating lobes may occur when the intervals between the antenna units become large. However, the grating lobes can be suppressed by a method of making the intervals between the antenna units unequal.

Further, although Examples 2 to 5 are transmission systems having a linear array antenna in which the microstrip antennas of Example 1 are arranged in one direction, planar array antennas in which the microstrip antennas of Example 1 are arranged two-dimensionally are used. Of course, it is also possible to use it as an antenna.

INDUSTRIAL APPLICABILITY The present invention can be used as an array antenna capable of controlling the polarization direction and directivity of linearly polarized waves, and can be used for microwave power transmission and the like.

10: substrate 11: ground conductor 12: first radiation conductor 13: second radiation conductor 14: feeding point 15: switch 200 to 500: microstrip antenna 201: variable phase shifter 202, 301: high frequency power supply 203, 302: distribution Device 204: Switch control unit

Claims (7)

an insulating layer;
a first radiation conductor provided on the insulating layer and having a circular pattern;
a feed point provided at the center of the first radiation conductor;
a plurality of second radiation conductors provided on the insulating layer and spaced apart from each other by a predetermined distance in the vicinity of the outer periphery of the first radiation conductor;
a switch for controlling connection and disconnection between the first radiation conductor and each of the second radiation conductors;
has
The switch is controlled such that one of the second radiation conductors is connected to the first radiation conductor, and the other second radiation conductor and the first radiation conductor are disconnected.
A microstrip antenna characterized by: 2. The microstrip antenna according to claim 1, wherein said second radiation conductor has an isosceles trapezoidal shape, and is arranged with two bases aligned in the circumferential direction of said first radiation conductor. An array antenna in which the microstrip antenna according to claim 1 or claim 2 is arranged,
Between the adjacent microstrip antennas, the direction of the second radiation conductor connected to the first radiation conductor with respect to the feeding point differs by 180°.
An array antenna characterized by: a first microstrip antenna;
a second microstrip antenna positioned adjacent to the first microstrip antenna;
a 90° phase shifter having a phase shift amount of 90°;
The first microstrip antenna and the second microstrip antenna are
an insulating layer;
a first radiation conductor provided on the insulating layer and having a circular or regular polygonal pattern;
a feed point provided at the center of the first radiation conductor;
a plurality of second radiation conductors provided on the insulating layer and spaced apart from each other by a predetermined distance in the vicinity of the outer periphery of the first radiation conductor;
a switch for controlling connection and disconnection between the first radiation conductor and each of the second radiation conductors;
has
the switch is controlled such that one of the second radiation conductors is connected to the first radiation conductor, and the other second radiation conductor and the first radiation conductor are disconnected;
A direction of the second radiation conductor connected to the first radiation conductor in the first microstrip antenna with respect to the feeding point, and a direction of the second radiation conductor connected to the first radiation conductor in the second microstrip antenna. with respect to the feed point forms 90°,
The 90° phase shifter is connected in front of the first microstrip antenna,
A circularly polarized antenna characterized by: An array antenna in which the circularly polarized antenna according to claim 4 is arranged,
The second radiation connected to the first radiation conductors of the first microstrip antenna and the second microstrip antenna such that the phase difference of the circularly polarized waves between the adjacent circularly polarized antennas is a predetermined amount. an orientation of the conductor with respect to the feed point is set;
An array antenna characterized by: first to fourth microstrip antennas;
a 90° phase shifter having a phase shift amount of 90°;
The first to fourth microstrip antennas are
an insulating layer;
a first radiation conductor provided on the insulating layer and having a circular or regular polygonal pattern;
a feed point provided at the center of the first radiation conductor;
a plurality of second radiation conductors provided on the insulating layer and spaced apart from each other by a predetermined distance in the vicinity of the outer periphery of the first radiation conductor;
a switch for controlling connection and disconnection between the first radiation conductor and each of the second radiation conductors;
has
the switch is controlled such that one of the second radiation conductors is connected to the first radiation conductor, and the other second radiation conductor and the first radiation conductor are disconnected;
The first to fourth microstrip antennas are arranged so that the first microstrip antenna and the fourth microstrip antenna are diagonally positioned, and the second microstrip antenna and the third microstrip antenna are diagonally positioned. , arranged in a 2×2 square grid,
The direction of the second radiation conductor connected to the first radiation conductor in the first microstrip antenna and the fourth microstrip antenna with respect to the feeding point, and the direction in the second microstrip antenna and the third microstrip antenna a direction of the second radiation conductor connected to the first radiation conductor with respect to the feeding point forms an angle of 90°;
The 90° phase shifter is connected in front of the first microstrip antenna and the fourth microstrip antenna,
A circularly polarized antenna characterized by: An array antenna in which the circularly polarized antenna according to claim 6 is arranged,
The feeding of the second radiation conductor connected to the first radiation conductor of the first to fourth microstrip antennas so that the phase difference of the circularly polarized waves between the adjacent circularly polarized antennas is a predetermined amount. A direction is set for the point,
An array antenna characterized by:

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