JP6948014B2 - Microstrip antenna and array antenna - Google Patents

Description

The present invention relates to a microstrip antenna. Further, the present invention relates to an array antenna in which a plurality of microstrip antennas are arranged.

In the conventional directional control array antenna, a phase shifter is connected in front of a plurality of antenna elements and the excitation phase of each antenna element is changed to form a beam having a desired directivity (Non-Patent Document 1). 4 groups-2 volumes-7 chapters). In this way, the configuration in which the antenna and the phase shifter are individually designed is currently the mainstream.

Further, as a microstrip antenna that radiates circularly polarized waves, a configuration in which a degenerate separation element is provided on a square or circular radiating element is known (Non-Patent Document 1, Group 4, Volume 2, Chapter 5). The degenerate separation element has a difference in the lengths of two orthogonal current paths, and is a protrusion or a notch provided in the radiation element. The position where the contraction separation element is provided is a position formed at 45 ° with respect to the extension direction of the power feeding line connected to the radiation element.

Further, Patent Document 1 discloses a microstrip antenna in which the radiating element has an annular shape, a feeding point is provided at the inner center of the ring, and a feeding line for connecting the feeding point and the radiating element is provided. It is described that the feeding line is formed into two lines in a radial pattern, and the input impedance can be adjusted by adjusting the angle formed by the two lines without using a separate matching means. Further, it is described that a line that divides the angle formed by the two lines into two is used as a reference line, and a degenerate separation element is provided at a position forming 45 ° with respect to the reference line to make an antenna for circularly polarized waves. Has been done.

Japanese Unexamined Patent Publication No. 8-265038

Institute of Electronics, Information and Communication Engineers "Knowledge Forest" Group 4 (Mobile / Wireless)-2 (Antenna / Propagation)-5 (Plane Antenna) and 7 (Array Antenna), http://www.ieice-hbkb.org

However, in the conventional directional control array antenna, the phase cannot be changed by the antenna element alone, and it is necessary to connect a phase shifter in front of the antenna element. Since the conventional phase shifter shifts the phase by a line or a delay line of a predetermined length, the problem is that the larger the phase shift amount, the larger the loss in the phase shifter, the larger the loss of the antenna device, and the larger the device. was there.

Therefore, an object of the present invention is to realize a microstrip antenna capable of changing the phase. Another object is to realize an array antenna having a plurality of microstrip antennas.

The present invention is a substrate made of a dielectric, a ground conductor provided on the back surface of the substrate, an annular radiation conductor provided on the surface of the substrate, and a surface of the substrate surrounded by an inner circumference of the radiation conductor. Select the feeding point provided in the center of the internal region and the exciting part, which is a part of the inner circumference of the radiation conductor and is the area to be fed from the feeding point, and connect the feeding point and the exciting part. A third that controls the on / off conduction between the selection unit and the reduction separation element provided on the outer periphery of the radiation conductor in a direction forming 45 ° with respect to the direction from the feeding point to the excitation unit, and the radiation conductor and the reduction separation element. It has 1 switch and a control circuit, and the selection unit extends radially around the feeding point and controls the conduction between a plurality of feeding lines connected to the inner circumference of the radiation conductor and the conduction of the feeding line on and off. It has a second switch, and the control circuit selects a predetermined power supply line by the second switch, and is formed by the first switch in a direction forming 45 ° with respect to the direction of the selected power supply line. By turning on the conduction between the positioned degenerate separation element and the radiating conductor, it is possible to send and receive circularly polarized waves, and the angle formed by the direction of the selected power supply line with respect to the reference line with the direction of a certain power supply line as the reference line. It is a microstrip antenna characterized in that the phase amount of circularly polarized waves is controlled discretely.

By arranging a plurality of microstrip antennas of the present invention, an array antenna whose directivity can be controlled can be configured.

Further, the shrinkage separation element is provided in each of the direction forming 45 ° clockwise and the direction forming 45 ° counterclockwise with respect to the direction from the feeding point toward the excitation portion, and the first switch feeds. One of the decompression separation elements located in the direction forming 45 ° clockwise with respect to the direction from the point toward the excitation part and the decompression separation element located in the direction forming 45 ° counterclockwise. By turning on the conduction with the radiation conductor and controlling the other to off, it is possible to switch between transmission and reception of right-handed circular polarization and transmission and reception of left-handed circular polarization.

The selection unit has a structure having a plurality of power supply lines arranged radially extending around the power supply point and connected to the inner circumference of the radiation conductor, and a second switch for on / off control of the continuity of the power supply line. can do. As a result, the phase shift function can be realized with a simple structure.

The microstrip antenna of the present invention has a built-in phase shift function. Therefore, the loss can be reduced as compared with the case where a phase shifter is separately provided to control the phase shift amount. In addition, since it is not necessary to separately provide a phase shifter, it is possible to reduce the size, cost, and thickness.

Further, by configuring the array antenna using the microstrip antenna of the present invention, it is possible to reduce the size, cost, and thickness of the antenna device capable of directivity control.

The plan view which showed the structure of the microstrip antenna of Example 1. FIG. The cross-sectional view which showed the structure of the microstrip antenna of Example 1. FIG. The figure which showed the case where the phase shift amount was 60 °. The figure which showed the structure of the microstrip antenna of the modification. The figure which showed the structure of the microstrip antenna of the modification. The figure which showed the modification of the degenerate separation element 15. The figure which showed the modification of the feeding line 13. The figure which showed the modification of the feeding line 13. The figure which showed the structure of the array antenna of Example 2. FIG. A table showing the amount of phase shift for each microstrip antenna. The graph which showed the directivity of the array antenna of Example 2.

Hereinafter, specific examples of the present invention will be described 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 the first embodiment, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIGS. 1 and 2, the microstrip antenna of the first embodiment includes a substrate 10, a ground conductor 11 provided on one surface of the substrate 10, a radiation conductor 12, a feeding line 13, and a feeding point 14. It has a shrinking separation element 15, a first switch 17, and a second switch 16. The power supply line 13 and the second switch 16 correspond to the selection unit of the present invention.

The substrate 10 has a square plate shape made of a dielectric material. A ground conductor 11 is provided on one main surface (hereinafter referred to as a back surface) of the substrate 10 in contact with the back surface thereof. The ground conductor 11 is a metal film, for example, a copper foil.

The radiation conductor 12 is a metal film provided in contact with the other main surface (hereinafter referred to as a surface) of the substrate 10, and is, for example, a copper foil. As shown in FIG. 1, the planar pattern of the radiating conductor 12 is annular. That is, the central portion of the radiating conductor 12 having a disk-shaped pattern is hollowed out concentrically with the outer circumference of the disk. The outer and inner diameters of the radiation conductor 12 are set according to the design frequency f of the microstrip antenna of the first embodiment.

In the first embodiment, the radiating conductor 12 has an annular shape, but it may be a regular polygonal ring such as a square, a regular hexagon, or a regular octagon, or another ring. Further, it is not necessary to match the shape of the inner circumference with the shape of the outer circumference, and it may be an annular shape in which one of the inner circumference and the outer circumference is a circle and the other is a regular polygon. However, it is desirable to make it circular as in Example 1. This is because a pattern with high symmetry improves the characteristics of the antenna and is easy to design.

The feeding point 14 is provided on the surface of the substrate 10 at the center of the inner peripheral region of the annulus of the radiation conductor 12 (the region surrounded by the inner circumference of the annulus).

As shown in FIG. 1, the power feeding line 13 is a linear metal film extending in the diameter direction of the annulus of the radiation conductor 12 with the feeding point 14 as the center on the inner peripheral region of the radiation conductor 12 on the surface of the substrate 10. It consists of, for example, copper foil. Further, six power feeding lines 13 are provided radially at equal angles. One end of the power feeding line 13 on the radiation conductor 12 side is connected to the radiation conductor 12. Further, one end of the feeding line 13 on the feeding point 14 side is separated from the feeding point 14, and a second switch 16 is provided between the one end and the feeding point 14.

In the first embodiment, the number of power supply lines 13 is 6, but the number is not limited to this. The number of power feeding lines 13 can be set according to the amount of phase shift to be controlled, and is arbitrary as long as it is two or more. When the feeding lines 13 are provided at equal angles, the number of feeding lines 13 is n (natural number of 2 or more), and the phase shift in (360 / n) ° units can be realized. In the first embodiment, six feeding lines 13 are provided at equal angles in order to realize phase shift in units of 60 °.

Further, in the first embodiment, the angles formed by the feeding lines 13 are made equal to each other so that the phase shift amount is controlled in units of 60 °. However, when the required phase shift amount is determined, the phase shift amount is controlled. , It is not necessary to provide each power supply line 13 at an equal angle. For example, if only the phase shift amounts of 60 ° and 90 ° are required, only the three feed lines 13 of the reference feed line 13 and the two feed lines 13 forming 60 ° and 90 ° are used. It may be provided. However, when the microstrip antenna of Example 1 is used as the array antenna and the directivity is variable, the amount of phase shift required for each microstrip antenna is not biased. It is desirable to provide them at equal angles.

The degenerate separation element 15 is a rectangular metal film provided on the surface of the substrate 10 and near the outer periphery of the radiation conductor 12, and is, for example, a copper foil. Further, as shown in FIG. 1, six degenerate separation elements 15 are provided radially at equal angles, and are provided at positions forming 45 ° clockwise with respect to the line direction of each feeding line 13. .. Further, the long side of the rectangle of each degenerate separation element 15 and the radial direction of the outer circumference of the radiation conductor 12 are arranged so as to be orthogonal to each other.

The plane pattern of the degenerate separation element 15 does not necessarily have to be rectangular, and may be a triangle, a semicircle, or the like.

The second switch 16 is provided between the feeding point 14 and one end of each feeding line 13 on the feeding point 14 side. Further, the second switch 16 is controlled on and off by a control circuit, and when the second switch 16 is on, the feeding point 14 and the feeding line 13 are connected, and the feeding point 14 and the radiation conductor 12 are electrically connected to each other. On the other hand, when the second switch 16 is off, the feeding point 14 and the feeding line 13 are disconnected, and the feeding point 14 and the feeding line 13 do not conduct electricity.

In this way, the feeding line 13 and the second switch 16 make it possible to select the exciting portion of the radiating conductor 12 (the region of the inner circumference of the radiating conductor 12 to be fed).

In the first embodiment, the feeding line 13 is provided between one end of the feeding line 13 on the feeding point 14 side and the feeding point 14, but the conduction between the feeding point 14 and the radiation conductor 12 can be turned on and off via the feeding line 13. If so, the position of the second switch 16 is arbitrary. For example, the second switch 16 may be provided between one end of the power feeding line 13 on the radiation conductor 12 side and the inner circumference of the radiation conductor 12. Further, the second switch 16 may be provided in the middle of the power feeding line 13.

However, when the position of the second switch 16 is between one end of the feeding line 13 on the radiation conductor 12 side and the inner circumference of the radiation conductor 12, a plurality of radiation conductors 12 are continuous at the feeding point 14, and the impedance And may affect the characteristics of the antenna such as directivity. The same applies to the case where the second switch 16 is provided in the middle of the power supply line 13.

On the other hand, when the position of the second switch 16 is provided between one end of the feeding line 13 on the feeding point 14 side and the feeding point 14, as in the first embodiment, a plurality of radiating conductors are provided on the inner circumference of the radiating conductor 12. 12 is a continuous shape, but the influence on the characteristics of the antenna such as impedance and directivity is small. The radiating conductor 12 is excited in the TM11 mode, the current density is very low in the region near the inner circumference of the annulus, and the influence of the radiating conductor 12 continuous on the inner circumference is also very small. Therefore, it is preferable that the position of the second switch 16 is between one end of the feeding line 13 on the feeding point 14 side and the feeding point 14, as in the first embodiment.

The first switch 17 is provided between the outer circumference of the radiation conductor 12 and each degenerate separation element 15. Further, the first switch 17 is controlled on and off by a control circuit, and when the first switch 17 is on, the outer periphery of the radiation conductor 12 and the degenerate separation element 15 are connected, and between the radiation conductor 12 and the degeneracy separation element 15. Conducts. On the other hand, when the first switch 17 is off, the outer circumference of the radiation conductor 12 and the degenerate separation element 15 are cut off, and the radiation conductor 12 and the degeneracy separation element 15 do not conduct electricity.

The control circuit for on / off control of the first switch 17 and the second switch 16 is a DC circuit. Therefore, it is preferable to insert a capacitor between the second switch 16 and the feeding point 14 and the feeding line 13, and between the first switch 17 and the radiation conductor 12 and the degenerate separation element 15 to cut off the direct current.

A diode switch, an FET switch, a MEMS switch, or the like can be used for the first switch 17 and the second switch 16.

Next, the operation of the microstrip antenna of the first embodiment will be described. The microstrip antenna of the first embodiment is an antenna that transmits and receives circularly polarized waves, and controls the first switch 17 and the second switch 16 to create a state similar to physically rotating the attitude of the antenna. This makes it possible to control the amount of phase shift of circularly polarized waves.

A more specific control method will be described. In the microstrip antenna of the first embodiment, the on / off of the first switch 17 and the second switch 16 is controlled as follows in order to transmit and receive circularly polarized waves.

The second switch 16 is controlled so that the continuity of one predetermined power supply line 13 is turned on, and the continuity of all other power supply lines 13 is turned off. In FIG. 1, among the second switches 16, those that are on are shown in black, and those that are off are shown in white.

Regarding the first switch 17, the connection between the degenerate separation element 15 and the radiation conductor 12 corresponding to the power feeding line 13 in which conduction is turned on is turned on, and the connection between the other degeneration separation element 15 and the radiation conductor 12 is turned off. To control. That is, the degenerate separation element 15 and the radiation conductor located in the direction (R2 direction in FIG. 1) clockwise at 45 ° with respect to the line direction (R1 direction in FIG. 1) of the power supply line 13 in which conduction is turned on. The connection with 12 is turned on, and the connection between the other degenerate separation element 15 and the radiation conductor 12 is controlled to be turned off. In FIG. 1, among the first switches 17, those that are on are shown in black, and those that are off are shown in white. Hereinafter, it will be expressed in the same manner in other figures. The degenerate separation element 15 located in the direction opposite to the direction forming 45 ° (R2 direction) may also be turned on for continuity with the radiation conductor 12. Since the symmetry is further improved, the characteristics as an antenna for transmitting and receiving circularly polarized waves are also further improved.

When the second switch 16 and the first switch 17 are controlled as described above, radiation is emitted in a direction (R2 direction) that forms 45 ° clockwise with respect to the line direction (R1 direction) of the power feeding line 13 in which continuity is turned on. Since the conductor 12 is conducting with the shrinkage separation element 15, the current path is longer than the direction forming 45 ° counterclockwise (R3 direction in FIG. 1). Therefore, the resonance frequency is slightly different between the R2 direction and the R3 direction. Here, if the area of the degenerate separation element 15 and the like are set properly, the phase difference between the mode in the R2 direction and the mode in the R3 direction can be set to π / 2 at the frequency between the two resonance frequencies. As a result, the mode in the R2 direction and the mode in the R3 direction are combined to form circularly polarized waves.

As described above, the radiating conductor 12 can be resonated in the TM11 mode at the design frequency f, is perpendicular to the main surface of the substrate 10, and is substantially hemispherical from the grounding conductor 11 side toward the radiating conductor 12 side. It operates as an antenna that radiates left-handed circularly polarized waves in one direction.

Next, a method of controlling the phase of circularly polarized waves will be described. The phase of circularly polarized light is changed by controlling the on / off position by controlling the second switch 16 and the first switch 17 to create a state similar to the physical rotation of the attitude of the antenna. Is possible. Specifically, the feed line 13 for turning on the conduction may be changed, and the degenerate separation element 15 for conducting the conduction with the radiation conductor 12 may be changed to the degenerate separation element 15 corresponding to the feed line 13. In this case, the angle formed by the line direction of the power supply line 13 with conduction turned on with respect to the line direction of the reference power supply line 13 is the phase shift amount as it is. In the first embodiment, since the feeding lines 13 are provided at equal angles of 60 °, the phase can be controlled in units of 60 ° in the range of 0 to 360 °. That is, in the microstrip antenna of Example 1, the phase shift amount can be controlled at 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °.

As a more specific example, the case of shifting the phase at 60 ° will be described with reference to FIGS. 1 and 3. The reference phase is the phase of circularly polarized waves transmitted and received in the case of FIG. As shown in FIGS. 1 and 3, the continuity of the power supply line 13 at a position 60 ° counterclockwise (position in the R4 direction) with respect to the line direction (R1 direction) of the reference power supply line 13 is transmitted by the second switch 16. Turn it on and turn off the continuity of the other power supply lines 13. Further, the connection between the degenerate separation element 15 (the degenerate separation element 15 in the R5 direction in FIG. 3) corresponding to the power feeding line 13 in which the continuity is turned on and the radiation conductor 12 is turned on, and the other degenerate separation elements 15 are turned off. do. When the on / off of the second switch 16 and the first switch 17 is changed in this way, the attitude of the antenna becomes the same as that of rotating 60 ° counterclockwise around the central axis (FIGS. 1 and 1). See 3 for comparison). As a result, the characteristics such as impedance and directivity do not change, but the transmission / reception phase is delayed by 60 °. In this way, a phase shift amount of 60 ° with respect to the reference phase can be realized.

As described above, according to the microstrip antenna of the first embodiment, it is possible to realize a circularly polarized antenna having a built-in phase shifter. Therefore, the loss can be reduced as compared with the conventional case in which a phase shifter is separately provided to control the phase shift amount. In addition, since it is not necessary to separately provide a phase shifter, it is possible to reduce the size, cost, and thickness.

Although the microstrip antenna of the first embodiment transmits and receives left-handed circularly polarized waves, it can also be configured to transmit and receive right-handed circularly polarized waves. In the first embodiment, the degenerate separation elements 15 are provided at positions (positions in the R2 direction) of 45 ° clockwise with respect to the line direction (R1 direction) of the power feeding line 13, whereby left-handed circularly polarized light can be transmitted and received. However, if the degenerate separation elements 15 are provided at 45 ° counterclockwise positions (positions in the R3 direction), the antenna can be used to transmit and receive right-handed circularly polarized light. .. That is, as shown in FIG. 4, if the configuration of the microstrip antenna of the first embodiment shown in FIG. 1 is horizontally inverted, right-handed circularly polarized waves can be transmitted and received.

The degenerate separation element 15 is provided at both the clockwise 45 ° position (R2 direction position) and the counterclockwise 45 ° position (R3 direction position), and either degenerate separation element is provided by the first switch 17. By selecting whether to conduct the 15 with the radiation conductor 12, it is possible to realize an antenna capable of switching between left-handed circularly polarized light and right-handed circularly polarized light (see FIG. 5).

Further, in the first embodiment, the degenerate separation element 15 is a conductor provided on the substrate 10, but it may be a slit provided near the outer periphery of the radiation conductor 12. FIG. 6 shows a case where the degenerate separation element 15 is a slit. As shown in FIG. 6, a rectangular slit 25 is provided on the outer peripheral portion of the radiation conductor 12, and the conductor 22 is provided inside the slit 25. Then, a first switch 17 is provided between the radiating conductor 12 and the conductor 22, and the connection between the radiating conductor 12 and the conductor 22 can be turned on and off by the first switch 17. With this configuration, circularly polarized waves can be transmitted and received as in the case of the first embodiment, and the phase shift amount can be changed in units of 60 ° by controlling the second switch 16 and the first switch 17. Can be done.

Further, the design frequency f of the microstrip antenna of the first embodiment is not particularly limited, and the design frequency f can be set in the range of, for example, 1 to 100 GHz.

Further, in the first embodiment, the excitation unit (the region to which power is supplied in the inner circumference of the radiation conductor 12) is selected by the power supply line 13 and the second switch 16, but the excitation unit can be selected electrically and mechanically. Any structure may be used as long as it is a structure. The degenerate separation element 15 may be provided in a direction forming 45 ° with respect to the direction from the feeding point 14 to the exciting portion. The exciting portion may be an arbitrary region as long as it is a part of the radiation conductor 12, not the entire inner circumference. Further, it does not have to be a continuous region, and may be divided into a plurality of regions. When the width of the excitation unit is wide, or when the excitation unit is divided into a plurality of regions, the degenerate separation element 15 is provided in a direction forming 45 ° with respect to the direction from the feeding point 14 toward the center of gravity of the excitation unit. It suffices if it is provided.

For example, in the first embodiment, the shape of the power feeding line 13 is a straight line having a constant line width, but the present invention is not limited to this. The line may have any shape as long as it has a shape that connects the feeding point 14 and the inner circumference of the radiation conductor 12. Instead of the feeding line 13, a fan-shaped feeding line 33 in which the line width gradually increases from the feeding point 14 side toward the inner circumference of the radiation conductor 12 may be used (see FIG. 7). If the shape of the feeding line 33 is such a pattern, impedance matching between the feeding point 14 and the radiation conductor 12 can be easily performed.

Further, for example, in the first embodiment, power is supplied from one power supply line 13 to the radiation conductor 12, but power may be supplied from two or more power supply lines 13 to the radiation conductor 12. By feeding power to the radiating conductor 12 from the plurality of exciting portions in this way, impedance matching between the feeding point 14 and the radiating conductor 12 can be easily performed depending on the distance between the excitation portions and the like. When power is supplied from a plurality of excitation units, it is preferable that the plurality of excitation units are arranged so as to be line-symmetric with respect to a certain symmetry line. Impedance matching becomes easier, and antenna element design becomes easier.

FIG. 8 is shown as a specific example. In FIG. 1, the conduction of the feeding line 13 extending in the R1 direction was turned on and the excitation unit was set to one place, but in FIG. 8, the feeding line 13 extending clockwise in the R1 direction and the left The two conductions of the power feeding line 13 extending in the direction of 60 ° are turned on, and the exciting parts are set in two places. Then, the connection between the degenerate separation element 15 located 45 ° clockwise with respect to the direction of the center of gravity (R1 direction) of the two excitation portions from the feeding point 14 and the radiation conductor 12 is turned on. Even when the excitation unit is provided at two locations as shown in FIG. 8, left-handed circularly polarized waves are transmitted and received as in the case of FIG. 1, and the phase shift amount is also the same as in the case of FIG.

FIG. 9 is a diagram showing the configuration of the array antenna of the second embodiment. As shown in FIG. 9, the array antenna of the second embodiment has a configuration in which eight microstrip antennas 100 # 1 to # 8 of the first embodiment are linearly arranged at predetermined intervals. The eight microstrip antennas 100 # 1 to # 8 are formed on the same substrate 10, the ground conductor 11 is also shared, and the other components are separately formed. Further, the lines are evenly distributed in a tree shape up to the feeding points 14 of the microstrip antennas 100 # 1 to # 8, so that the power supply to the microstrip antennas is in phase. Hereinafter, as shown in FIG. 9, the main surface of the substrate 10 is the xy plane, the arrangement direction of the microstrip antennas 100 # 1 to # 8 in the main surface is the y-axis, and the direction orthogonal to the y-axis is the x-axis. The direction perpendicular to the main surface of the substrate 10 is defined as the z-axis. Further, the microstrip antennas 100 # 1 to # 8 are in the order of # 1, # 2, ... In the positive direction of the y-axis.

Each of the microstrip antennas 100 # 1 to # 8 is set to have a predetermined phase shift amount by the control of the second switch 16 and the first switch 17, whereby the array antenna of the second embodiment is in the yz plane. Is set to form a directional beam in a predetermined direction. In the second embodiment, the phase shift amount is set so as to be a directional beam in the direction of 30 ° with respect to the z-axis in the yz plane.

In order to form a directional beam in a predetermined direction, theoretically, the phase shift amount is set so that the phase difference between adjacent microstrip antennas is Δφ = (2πd / λ) × sinθ. Just do it. Here, d is the arrangement interval of the microstrip antennas 100 # 1 to # 8, λ is the free space wavelength of the radiated wave, and θ is the direction of the directional beam (θ = 30 ° in Example 2). However, the phase shift amount of each microstrip antenna 100 # 1 to # 8 cannot be continuously controlled, and is a discrete value in 6 stages of 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °. Since it can be controlled with, select the phase shift amount closest to the theoretical value from them.

FIG. 10 is a table showing the correspondence between the theoretical value and the actual phase shift amount of each microstrip antenna 100 # 1 to # 8 for the phase shift amount of each microstrip antenna 100 # 1 to # 8. ..

FIG. 11 is a graph showing the result of calculating the directivity pattern in the yz plane of the array antenna when the theoretical value is taken and the result of calculating the directivity pattern in the yz plane of the array antenna of Example 2. be. In the case of the theoretical value, it can be seen that the power peak is formed in the direction of 30 ° with respect to the z-axis, and a directional beam of 30 ° is formed. On the other hand, the array antenna of the second embodiment also has a directivity beam of 30 ° formed, and it can be seen that the directivity is substantially the same as the directivity in the case of the theoretical value. In this way, the phase shift control of each microstrip antenna 100 # 1 to # 8 is not continuous control but discrete control, but even in that case, a directional beam close to the theoretical value is obtained. It turns out that it can be formed.

As described above, the array antenna of the second embodiment uses the microstrip antennas 100 # 1 to # 8 of the first embodiment as each antenna element. Therefore, the directivity of the array antenna of the second embodiment can be easily controlled by controlling the phase shift amount of each of the microstrip antennas 100 # 1 to # 8 by controlling the second switch 16 and the first switch 17. It is possible to form a directional beam in a predetermined direction. Further, since the array antenna of the second embodiment uses the microstrip antennas 100 # 1 to # 8 of the first embodiment as each antenna element, the loss can be reduced, the size can be reduced, the cost can be reduced, and the thickness can be reduced. Can be done.

The array antenna of Example 2 was one in which the microstrip antennas 100 of Example 1 were linearly arranged one-dimensionally, but the present invention naturally applies to the two-dimensionally arranged array antenna. Can be applied to.

The present invention can be used as an array antenna whose directivity can be controlled.

10: Substrate 11: Ground conductor 12: Radiant conductor 13: Feed line 14: Feed point 15: Degenerate separation element 16: Second switch 17: First switch 100 # 1 to # 8: Microstrip antenna

Claims (3)

A substrate made of a dielectric and
The ground conductor provided on the back surface of the substrate and
A radiation conductor annular provided on a surface of the substrate,
A feeding point provided in the center of an internal region surrounded by the inner circumference of the radiation conductor on the surface of the substrate.
An excitation unit that is a part of the inner circumference of the radiation conductor and is a region to be fed from the feeding point is selected, and a selection unit that connects the feeding point and the excitation unit is used.
A degenerate separation element provided on the outer periphery of the radiation conductor in a direction forming 45 ° with respect to the direction from the feeding point to the excitation portion.
A first switch that controls on / off of conduction between the radiation conductor and the degenerate separation element, and
Control circuit and
Have,
The selection unit includes a plurality of feeding lines extending radially around the feeding point and connected to the inner circumference of the radiation conductor, and a second switch for on / off control of continuity of the feeding line. ,
The control circuit selects a predetermined power supply line by the second switch, and the regression separation element located in a direction forming 45 ° with respect to the direction of the selected power supply line by the first switch. By turning on the conduction between the and the radiation conductor, it is possible to send and receive circularly polarized light, and the direction of the feeding line is set as the reference line, and the angle formed by the direction of the selected feeding line with respect to the reference line is determined. The phase amount of circularly polarized waves is controlled discretely,
A microstrip antenna that features that. The degenerate separation element is provided in each of a direction forming 45 ° clockwise and a direction forming 45 ° counterclockwise with respect to the direction from the feeding point toward the exciting portion.
The first switch is located in a direction forming 45 ° clockwise with respect to the direction from the feeding point toward the exciting portion, and the decompression separation element located in a direction forming 45 ° counterclockwise. Of the regression separation elements, one of the reduction separation elements and the radiation conductor is controlled to be turned on and the other is controlled to be off.
The microstrip antenna according to claim 1, wherein the transmission / reception of right-handed circularly polarized waves and the transmission / reception of left-handed circularly polarized waves can be switched by this. The array antenna according to claim 1 or 2 , wherein a plurality of microstrip antennas are arranged, and the directivity can be controlled by controlling the phase shift amount of each of the microstrip antennas.

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