Phased Array Antenna

Abstract

To provide a phased-array antenna which allows improvement in scan speed of beam scanning.SOLUTION: In a phased-array antenna, a power supply part 2 changes relative permittivity of a VVD phase shifter 32 of each of a plurality of radiating stubs 312 by changing a voltage applied to the VVD phase shifter 32 of each of the plurality of radiating stubs 312. In this way, beam scanning in an azimuth angle direction is performed by tilting a wavefront of an electromagnetic wave which passes each of the plurality of radiating stubs 312. At the same time, a wavefront of the electromagnetic wave propagating in a parallel plate line of the power supply part is tilted so as to tilt a wavefront of the electromagnetic wave outputted from the power supply part to be incident on a base part 311 of an antenna part, thereby performing beam scanning in an altitude angle direction.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a phased array antenna, and more particularly to a technology suitable for application to satellite communication antennas mounted on various mobile bodies, for example.

Background Art

[0002] As a conventional antenna that performs radio wave scanning of a plurality of channels, a mechanical scanning array antenna device that mechanically rotates or tilts the antenna itself is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when changing the azimuth angle by rotating the antenna itself and changing the elevation angle by tilting it by a mechanical mechanism including a rotary joint, a motor, etc., there is a problem that the scanning speed is slow.

[0005] Therefore, an object of the present invention is to provide a phased array antenna capable of improving the scanning speed of beam scanning.

Means for Solving the Problems

[0006] In order to solve the above problems, the phased array antenna according to the present invention has a power feeding unit and an antenna unit. The power feeding unit has a ground conductor plate and parallel plates that form a parallel plate line between the ground conductor plates. The antenna unit has a plate-shaped base and convex portions formed to project in a row from one plate surface of the base, and the convex portions are arranged at equal intervals in the direction in which the electromagnetic waves output from the power feeding unit and incident on the base propagate, and are arranged parallel to each other along a direction orthogonal to the direction in which the electromagnetic waves propagate. A plurality of radiation stubs, and are arranged along the longitudinal direction of the radiation stub at the tip portion of each of the plurality of radiation stubs 、It is composed of a dielectric that can variably control the relative permittivity with the applied voltage, and controls the phase of the electromagnetic wave VVD (Abbreviation of Voltage Variable Dielectric) A feed array including a phase shifter, and by changing the voltage applied to each of the VVD phase shifters of the plurality of radiation stubs to change the relative permittivity of each of the VVD phase shifters of the plurality of radiation stubs, the wavefront of the electromagnetic wave passing through each of the plurality of radiation stubs is tilted to perform beam scanning in the azimuth direction, and at the same time, by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the power feeding unit, the wavefront of the electromagnetic wave output from the power feeding unit and incident on the base of the antenna unit is tilted, thereby performing beam scanning in the elevation angle direction.

[0007] In the phased array antenna according to the present invention, the power feeding unit may be provided with a plurality of probes arranged at equal intervals in a row along a direction orthogonal to the propagation direction of the electromagnetic wave at a position near one end in the propagation direction of the electromagnetic wave in the parallel plate line and supplying the electromagnetic wave to the parallel plate line, and a plurality of phase shifters provided corresponding to each of the plurality of probes. By controlling the phase of the electromagnetic wave supplied to each of the plurality of probes by the plurality of phase shifters, the wavefront of the electromagnetic wave propagating through the parallel plate line may be tilted.

[0008] The phased array antenna according to the present invention has a power distributor formed by branching wiring by patterning a microstrip line from a vertex portion electrically connected to an antenna port toward each of the plurality of probes. The electromagnetic wave is distributed to the plurality of phase shifters by the power distributor, and after the phase is controlled by the plurality of phase shifters, it is supplied to each of the plurality of probes , it may be like this.

Advantages of the Invention

[0009] According to the phased array antenna of the present invention, by changing the voltage applied to each of the VVD phase shifters of the plurality of radiation stubs to change the relative permittivity of each of the VVD phase shifters of the plurality of radiation stubs, the wavefront of the electromagnetic wave passing through each of the plurality of radiation stubs is tilted, thereby performing beam scanning in the azimuth direction. At the same time, by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the feeding unit, the wavefront of the electromagnetic wave output from the feeding unit and incident on the base of the antenna unit is tilted, thereby performing beam scanning in the elevation angle direction. Therefore, it is possible to improve the scanning speed of the beam scanning.

[0010] According to the phased array antenna of the present invention, also, by changing the voltage applied to each of the VVD phase shifters of the plurality of radiation stubs to change the relative permittivity of each of the VVD phase shifters of the plurality of radiation stubs, the wavefront of the electromagnetic wave passing through each of the plurality of radiation stubs is tilted, thereby performing beam scanning in the azimuth direction. At the same time, by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the feeding unit, the wavefront of the electromagnetic wave output from the feeding unit and incident on the base of the antenna unit is tilted, thereby performing beam scanning in the elevation angle direction. Therefore, it is possible to achieve a high aperture efficiency and to realize a low-profile antenna.

[0011] When the phased array antenna according to the present invention is fed through a plurality of probes, it is possible to generate a plane wave over a wide frequency band with a short transmission line (specifically, about 1λ (where λ is the free space wavelength)), thereby avoiding an increase in transmission loss and making it possible to compactly configure the feeding section of the antenna.

[0012] When the phased array antenna according to the present invention supplies electromagnetic waves to each probe using a distribution circuit as a power divider formed by branching the wiring by patterning a microstrip line from the apex of the power divider to each probe, it is possible to easily incorporate a phase shifter without complicating the circuit configuration.

Brief Description of the Drawings

[0013]

Figure 1

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Figure 11

Figure 12

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Figure 15

Embodiments for Carrying Out the Invention

[0014] Hereinafter, this invention will be described based on the illustrated embodiments.

[0015] <Embodiment 1> FIG. 1 is a circuit configuration diagram showing the schematic configuration of a phased array antenna 11 according to Embodiment 1 of this invention. The phased array antenna 11 according to Embodiment 1 includes a power supply unit 2, an antenna unit 3, a rotation unit 4, and a control unit 5.

[0016] The phased array antenna 11 according to this embodiment has a power supply unit 2 including a ground conductor plate 231 and a parallel plate 233 that forms a parallel plate line between the ground conductor plates 231. The antenna unit 3 has a plate-shaped base 311 and a plurality of radiation stubs 312 that are formed as convex portions protruding in a row from one plate surface of the base 311 and are arranged parallel to each other along a direction orthogonal to the direction in which the electromagnetic wave propagates while being spaced apart from each other at equal intervals in the direction in which the electromagnetic wave propagates, which is output from the power supply unit 2 and incident on the base 311. The feed array 31 is provided with a rotation unit 4 that rotates the feed array 31 to perform beam scanning in the azimuth direction, and the wavefront of the electromagnetic wave propagating through the parallel plate line of the power supply unit 2 is inclined to incline the wavefront of the electromagnetic wave output from the power supply unit 2 and incident on the base 311 of the antenna unit 3, thereby performing beam scanning in the elevation angle direction.

[0017] The phased array antenna 11 according to this embodiment further has a plurality of probes 235 that are arranged in a row at equal intervals along a direction orthogonal to the propagation direction of the electromagnetic wave at a position near one end in the propagation direction of the electromagnetic wave in the parallel plate line and supply the electromagnetic wave to the parallel plate line, and a plurality of phase shifters 22 provided corresponding to each of the plurality of probes 235. The phase of the electromagnetic wave supplied to each of the plurality of probes 235 is controlled by the plurality of phase shifters 22 to incline the wavefront of the electromagnetic wave propagating through the parallel plate line.

[0018] (Power supply unit) The power supply unit 2 functions as a plane wave generation mechanism and mainly includes a power distributor 21, a plurality of phase shifters 22, and a plane wave generation unit 23. In the description here, the x-axis direction, y-axis direction, and z-axis direction of the three-dimensional orthogonal coordinate system defined by the x-axis, y-axis, and z-axis that are orthogonal to each other are corresponded as shown in FIG. 2 and the like with respect to the structure of the power supply unit 2.

[0019] The plane wave generation unit 23 includes a ground conductor plate 231, a dielectric substrate 232, a parallel plate 233, a power supply dielectric substrate 234, and a plurality (specifically, the same number as the phase shifters 22) of probes 235 (see FIG. 2).

[0020] The ground conductor plate 231 and the parallel plate 233 are arranged parallel to each other to form a parallel plate line for propagating electromagnetic waves therebetween.

[0021] The dielectric substrate 232 is disposed so as to be interposed between the ground conductor plate 231 and the parallel plate 233, and a dielectric image line (here, a parallel plate line) for propagating electromagnetic waves in a direction (in the figure, the z-axis direction) orthogonal to the thickness direction of the dielectric substrate 232 (in the figure, the x-axis direction) is formed within the dielectric substrate 232.

[0022] Power feeding of electromagnetic waves to the parallel plate line formed between the ground conductor plate 231 and the parallel plate 233 is performed via a plurality of probes 235, and electromagnetic waves are propagated along the z-axis direction between the ground conductor plate 231 and the parallel plate 233 by power feeding of electromagnetic waves from each of the plurality of probes 235.

[0023] The power supply dielectric substrate 234 is disposed on the side of the ground conductor plate 231 opposite to the side of the dielectric substrate 232, and a plurality of probes 235 are arranged in a row at equal intervals along the y-axis direction at a position near one end of the power supply dielectric substrate 234 in the z-axis direction (the end opposite to the side of the arrow of the z-axis in the figure).

[0024] The mutual interval d in the y-axis direction between the probes 235 (see FIG. 3(A)) is adjusted so as to satisfy λ / 2 ≦ d < λ, where λ is the free space wavelength of the electromagnetic wave (in other words, the RF (Radio Frequency) signal).

[0025] The power distributor 21 is disposed on the surface of the power supply dielectric substrate 234 opposite to the side of the ground conductor plate 231 (see FIGS. 2 and 3).

[0026] The power distributor 21 is realized by a distribution circuit formed by branching wiring by means of a microstrip line pattern from the vertex portion 211 at the central position (or a position near the center) in the plan view of the power supply dielectric substrate 234 toward each probe 235. The amplitude of the electromagnetic wave (RF signal) is controlled by the magnitude of the input to the power distributor 21 from the vertex portion 211, the number of branching stages, and the number of divisions at each stage.

[0027] The vertex portion 211 of the power distributor 21 is electrically connected to, for example, a coaxial connector (not shown) that functions as an antenna port (in other words, an input / output port).

[0028] The structure / configuration related to the coaxial connector is not limited to a specific structure / configuration in this invention, so a detailed description is omitted. However, the coaxial connector is, for example, electrically connected to each probe 235 via the power distributor 21, and has an inner conductor to which a signal (SIG) is input from the inner conductor of a coaxial cable (not shown), and an outer conductor that is electrically connected to the ground conductor plate 231 and to which a signal (for example, GND) is input from the outer conductor of the coaxial cable, and can be configured to supply an RF signal (in other words, a wireless communication wave) to the power distributor 21, and by extension, to each probe 235.

[0029] The phase shifter 22 is specifically constituted by a digital phase shifter, controls the phase of the RF signal distributed by the power distributor 21, and supplies the RF signal after phase control to the probe 235.

[0030] The phase shifter 22 is disposed for each of the branched lines in the distribution circuit as the power distributor 21, that is, provided corresponding to each of the plurality of probes 235.

[0031] Each phase shifter 22 (specifically, a digital phase shifter) is controlled by the control unit 5.

[0032] The electromagnetic wave (RF signal) supplied to the apex portion 211 of the power divider 21 is distributed by the power divider 21 in predetermined amounts (in other words, the amplitude is controlled), and after the phase is controlled by the phase shifter 22, it is fed between the ground conductor plate 231 and the parallel plate 233 via each probe 235.

[0033] According to the feeding unit 2 having the above configuration, a plane wave is generated in the parallel plate line formed between the ground conductor plate 231 and the parallel plate 233. As an example of the plane wave generated by the feeding unit 2, an example of the electric field distribution between the ground conductor plate 231 and the parallel plate 233 is shown in FIG. 4 (note that FIG. 4 shows the range corresponding to the five probes 235).

[0034] Also, the S parameter S11 (that is, return loss) in the feeding unit 2 is shown in FIG. 5. It is confirmed from FIG. 5 that the return loss can be maintained at a good level over a wide frequency band and the feeding unit 2 can have good reflection characteristics.

[0035] (Antenna unit) The antenna unit 3 mainly has a feed array 31. In the description here, with respect to the structure of the feed array 31, the x-axis direction, y-axis direction, and z-axis direction of the three-dimensional orthogonal coordinate system defined by the mutually orthogonal x-axis, y-axis, and z-axis are made to correspond as shown in FIG. 6 and the like.

[0036] The feed array 31 includes a plate-shaped base 311, a plurality of radiation stubs 312, and a dielectric 313 that fills the inside (in other words, is filled inside) (see FIG. 6).

[0037] The plurality of radiating stubs 312 are each formed as convex portions that project in a row from one plate surface of the base 311 (the surface on the side of the arrow in the x-axis direction in the figure). The plurality of radiating stubs 312 are spaced apart from each other at equal intervals D in the direction in which a plane wave / electromagnetic wave (RF signal) output from the feeding unit 2 and incident on the feed array 31 (specifically, the base 311) propagates (the z-axis direction in the figure), and are arranged parallel to each other with their longitudinal directions along the direction orthogonal to the z-axis direction (the y-axis direction in the figure).

[0038] The mutual interval D in the z-axis direction between the radiating stubs 312 provided continuously in the z-axis direction (see FIG. 6) is adjusted so as to satisfy λ / 2 ≦ D < λ, where λ is the free space wavelength of the electromagnetic wave (RF signal). Note that the mutual interval d in the y-axis direction between the probes 235 and the mutual interval D in the z-axis direction between the radiating stubs 312 may be the same value or different values.

[0039] The feed array 31 includes a conductive back plate 314 that constitutes the other plate surface of the base 311 (the surface on the side opposite to the side of the arrow in the x-axis direction in the figure), and a conductive front plate 315 (which is composed of a plurality of members) that is arranged spaced apart from the back plate 314 and is bent along the y-axis direction so as to constitute the radiating stubs 312. The dielectric 313 is formed so as to fill the space between the back plate 314 and the front plate 315 (including the inside of each of the radiating stubs 312).

[0040] Note that the side surface of each radiating stub 312 (the surface along the xy plane in the figure) is covered by the conductive front plate 315 that is bent to be formed. On the other hand, the tip surface of the convex structure of each radiating stub 312 having a protruding structure (the surface on the side of the arrow in the x-axis direction in the figure) has no conductive shielding, enables the propagation of electromagnetic energy through the tip surface of the radiating stub 312, and defines the antenna radiation pattern.

[0041] A plane wave / electromagnetic wave (RF signal) generated by the power supply unit 2 is incident on the feed array 31 (specifically, the base 311), and the plane wave / electromagnetic wave (RF signal) excites a z-axis displacement current in the direction in which the plane wave / electromagnetic wave (RF signal) propagates. Then, the z-axis displacement current excites an equivalent electromagnetic wave that travels in the x-axis direction toward the radiation stub 312 at the base 311 and is radiated into free space. Then, the RF signal is radiated in the form of a plane wave through the radiation stub 312 of the feed array 31.

[0042] The feed array 31 having the above configuration corresponds to a part of a structure also called a continuous transverse stub (CTS) antenna. For the function of the feed array 31, see, for example, "The Continuous Transverse (CTS) Array: Basic Theory, Experiment, and Application" (Milroy, W.W. "Proceedings of the Antenna Applications Symposium Held on 25-27 September 1991. Volume 1" AD-A253 682, p253-283) and Japanese Patent Application Laid-Open No. 2006-522561, U.S. Patent No. 6,281,838, U.S. Patent No. 5,757,379, U.S. Patent 5,483,248, U.S. Patent No. 5,379,007, and U.S. Patent No. 5,266,961.

[0043] (Rotating part) The rotating part 4 rotationally drives the power supply unit 2 and the antenna unit 3. Specifically, the rotating part 4 is configured as a mechanism including, for example, a rotary joint or a motor, and rotationally drives the feed array 31 along the yz plane (in the coordinate system shown in FIG. 6).

[0044] The driving of the motor of the rotating part 4 is controlled by the control unit 5, that is, the degree of rotation of the feed array 31 is controlled by the control unit 5.

[0045] (Beam Scanning) The phased array antenna 11 performs beam scanning in the azimuth (AZ) direction and also performs beam scanning in the elevation (EL) direction. Note that the azimuth (AZ) is an angle defined with the north or south direction being 0° and clockwise being positive. Also, the elevation (EL) is an angle defined with the horizon being 0° and directed towards the zenith direction.

[0046] The phased array antenna 11 mechanically performs beam scanning in the azimuth (AZ) direction by rotating the feed array 31 by the rotating part 4.

[0047] The phased array antenna 11 also electronically performs beam scanning in the elevation (EL) direction by controlling the phase of the electromagnetic wave (RF signal) by each phase shifter 22 of the power feeding unit 2.

[0048] Specifically, when each phase shifter 22 of the power feeding unit 2 is controlled, an inclination is given to the wavefront of the electromagnetic wave propagating through the parallel plate line formed between the ground conductor plate 231 and the parallel plate 233 of the power feeding unit 2, and an inclination is given to the wavefront of the electromagnetic wave output from the power feeding unit 2 and incident on the feed array 31 (specifically, the base 311) of the antenna unit 3, thereby performing beam scanning in the elevation (EL) direction.

[0049] That is, by using the inclined incidence of the waveguide mode propagating to the feed array 31 and changing the phase plane of the electromagnetic wave entering the radiation stub 312 in the longitudinal direction of the radiation stub 312 (in the y-axis direction in the coordinate system shown in FIG. 6), beam scanning is performed in the H plane in the transverse direction (the same, y-axis direction).

[0050] An example of the electric field distribution in the power supply unit 2 is shown in FIG. 7. FIG. 7(A) shows the electric field distribution in the case of in-phase excitation by a plurality of probes 235. The phases of the RF signals distributed by the power divider 21 to each phase shifter 22 (and ultimately to each probe 235) are controlled by each phase shifter 22 such that the difference Δφ in the phase shift amounts for adjacent phase shifters 22 is 0 (zero). By supplying the RF signal after phase control to each probe 235, the electric field distribution as shown in FIG. 7(A) is realized.

[0051] FIG. 7(B) shows the electric field distribution in the case of phase difference excitation by a plurality of probes 235. The phases of the RF signals distributed by the power divider 21 to each phase shifter 22 (and ultimately to each probe 235) are controlled by each phase shifter 22 such that the difference Δφ in the phase shift amounts for adjacent phase shifters 22 is a certain value (not 0) and constant. By supplying the RF signal after phase control to each probe 235, the electric field distribution as shown in FIG. 7(B) is realized.

[0052] Here, in the present invention, by using the oblique incidence of the waveguide mode propagating to the feed array 31 to change the phase front of the electromagnetic wave entering the radiation stub 312 in the longitudinal direction of the radiation stub 312, the radiation stub 312 is made to function as a mechanism in which a plurality of element antennas are arranged in a row at an interval d along the longitudinal direction of the radiation stub 312 (where d is the interval between the probes 235). The (assumed) element antenna that constitutes the radiation stub 312 is called the "virtual element antenna 312a".

[0053] FIG. 8(A) shows the relationship between the array and directivity of a plurality of virtual element antennas 312a when the radiation stub 312 is excited in-phase, that is, when each of the plurality of virtual element antennas 312a that are considered to constitute the radiation stub 312 is excited in-phase. In this case, when adjacent virtual element antennas 312a are excited in-phase, in other words, it can be regarded as the case where each phase shifter 22 is controlled and excited such that the difference Δφ in the phase shift amounts for adjacent phase shifters 22 is 0 (zero).

[0054] When the radiation stubs 312 are excited in the same phase, a wavefront of the electromagnetic wave is formed parallel to the array of the plurality of virtual element antennas 312a (in the y-axis direction in the figure), and a main lobe is formed in the direction orthogonal to the array of the plurality of virtual element antennas 312a (in the x-axis direction in the figure).

[0055] Fig. 8(B) shows the relationship between the array of the plurality of virtual element antennas 312a and the directivity when the radiation stubs 312 are excited with a phase difference, that is, when each of the plurality of virtual element antennas 312a regarded as constituting the radiation stubs 312 is excited with a phase difference. In this case, when excited with a phase difference of Δφ (≠0) for each adjacent virtual element antenna 312a, in other words, when each phase shifter 22 is controlled and excited such that the difference Δφ in the phase shift amount for adjacent phase shifters 22 is constant at a certain value (however, not zero).

[0056] When the radiation stubs 312 are excited with a phase difference, the wavefront of the electromagnetic wave is inclined with respect to the array of the plurality of virtual element antennas 312a (in the y-axis direction in the figure), and as a result, the direction of the main lobe rotates by Δθ with respect to the direction orthogonal to the array of the plurality of virtual element antennas 312a (in the x-axis direction in the figure). Note that Δθ = d·sin(Δφ) (where d: the mutual interval between the probes 235).

[0057] By applying the phase shift control that realizes the relationship between the array of the plurality of virtual element antennas 312a regarded as constituting the radiation stubs 312 and the directivity as described above to each phase shifter 22 of the power feeding unit 2, the directivity in the xy plane (in the coordinate system shown in Fig. 6) can be scanned.

[0058] An example of the directivity of the feed array 31 is shown in FIG. 9. By controlling the phase of the electromagnetic wave (RF signal) by each phase shifter 22 of the feeding unit 2, the phase for exciting the radiation stub 312 is controlled, so that, as shown in FIG. 9, the directivity of the feed array 31 can be controlled, and thus beam scanning in the elevation angle (EL) direction can be electronically performed.

[0059] According to the phased array antenna 11 according to Embodiment 1, by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the feeding unit 2, the wavefront of the electromagnetic wave output from the feeding unit 2 and incident on the base 311 of the antenna unit 3 is tilted, so that beam scanning in the elevation angle direction is performed, and thus it is possible to improve the scanning speed of the beam scanning.

[0060] According to the phased array antenna 11 according to Embodiment 1, also, by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the feeding unit 2, the wavefront of the electromagnetic wave output from the feeding unit 2 and incident on the base 311 of the antenna unit 3 is tilted, so that beam scanning in the elevation angle direction is performed, and thus it is possible to realize a high aperture efficiency and to realize a low-profile antenna.

[0061] Further, according to the phased array antenna 11 according to Embodiment 1, since the feeding unit 2 feeds power through a plurality of probes 235, it is possible to generate a plane wave over a wide frequency band and with a short transmission line (specifically, about 1λ (where λ is the free space wavelength)), and thus it is possible to avoid an increase in transmission loss and to configure the feeding unit of the antenna compactly.

[0062] Also, according to the phased array antenna 11 according to Embodiment 1, the power supply unit 2 uses a distribution circuit as the power distributor 21 formed by branching the wiring by the patterning of the microstrip line from the apex portion 211 of the power distributor 21 to each probe 235, so that electromagnetic waves (RF signals, wireless communication waves) are supplied to each probe 235. Therefore, the incorporation of the phase shifter 22 (specifically, a digital phase shifter) can be easily performed without complicating the circuit configuration.

[0063] <Embodiment 2> FIG. 10 is a circuit configuration diagram showing a schematic configuration of a phased array antenna 12 according to Embodiment 2 of the present invention. The phased array antenna 12 according to Embodiment 2 includes a power supply unit 2, an antenna unit 3, and a control unit 5.

[0064] The phased array antenna 12 according to this embodiment has a power supply unit 2 including a ground conductor plate 231 and a parallel plate 233 that forms a parallel plate line between the ground conductor plates 231, and an antenna unit 3 includes a plate-shaped base 311 and a convex portion formed to project in a row from one plate surface of the base 311. A plurality of radiation stubs 312 are arranged parallel to each other along a direction orthogonal to the direction in which the electromagnetic waves output from the power supply unit 2 and incident on the base 311 propagate while being spaced apart from each other at equal intervals in the direction in which the electromagnetic waves propagate. A feed array 31 including a VVD phase shifter 32 disposed along the longitudinal direction of the radiation stub 312 at the tip portion of each of the plurality of radiation stubs 312. By changing the voltage applied to each of the VVD phase shifters 32 of the plurality of radiation stubs 312 to change the relative permittivity of each of the VVD phase shifters 32 of the plurality of radiation stubs 312, the wavefront of the electromagnetic wave passing through each of the plurality of radiation stubs 312 is tilted to perform beam scanning in the azimuth direction, and the wavefront of the electromagnetic wave propagating through the parallel plate line of the power supply unit 2 is tilted to output from the power supply unit 2 and incident on the base 311 of the antenna unit 3. Beam scanning in the elevation angle direction is performed by tilting the wavefront of the electromagnetic wave.

[0065] Although this embodiment is different from the above-described Embodiment 1 in that it does not have the rotating part 4 but has the VVD phase shifter 32 and the power supply 36 for the phase shifter, since other configurations are equivalent to those of the above-described Embodiment 1, the same reference numerals are given to the equivalent configurations as those of Embodiment 1, and the description thereof is omitted.

[0066] The VVD (abbreviation for Voltage Variable Dielectric) phase shifter 32 is specifically composed of a dielectric whose relative permittivity can be variably controlled by the applied voltage, and controls the phase of the electromagnetic wave that travels in the x-axis direction toward the radiation stub 312 of the feed array 31 and is radiated into free space.

[0067] As shown in FIG. 11, the VVD phase shifter 32 is disposed along the longitudinal direction (in the y-axis direction in the figure) of the radiation stub 312 at the tip portion of the convex structure of each radiation stub 312 having a protruding structure of the feed array 31 (the end on the side of the arrow in the x-axis direction in the figure).

[0068] In the example shown in FIG. 11, a pair of VVD phase shifters 32, 32 that are separated in the x-axis direction in the figure and opposed to each other with the insulating portion 33 interposed therebetween (in other words, sandwiched) are disposed.

[0069] FIG. 12 shows a comparison of the S parameter S11 (that is, return loss) in the feed array 31 between the case where the VVD phase shifter 32 has a single-layer structure and the case where it has a multilayer structure (specifically, a pair as shown in FIG. 11). From FIG. 12, it is confirmed that by making the VVD phase shifter 32 have a multilayer structure, an antenna with good reflection characteristics can be realized in which the return loss is maintained at a good level over a wide frequency band.

[0070] However, the arrangement of the VVD phase shifter 32 in a multilayer structure is not an essential configuration in this invention, and the VVD phase shifter 32 may be arranged in a single-layer structure. Specifically, when the VVD phase shifter 32 has a single-layer structure, only the VVD phase shifter 32 on the side of the arrow in the x-axis direction in FIG. 11 is arranged.

[0071] Along the xy plane, between a pair of VVD phase shifters 32, 32, an insulating portion 33 disposed therebetween, and a surface plate 315 that forms a convex structure of each radiation stub 312 having a protruding structure, an electrode 34 is disposed on the side of the pair of VVD phase shifters 32, 32 and the insulating portion 33, and an insulating sheet 35 is disposed on the side of the surface plate 315.

[0072] A phase shifter power supply 36 supplies power to the electrode 34 of the feed array 31. Thereby, the VVD phase shifter 32 receives the power supply, and the voltage applied to the VVD phase shifter 32 is controlled to operate. Note that the power supply of the phase shifter 22 (specifically, a digital phase shifter) (for example, a low-voltage power supply of about 12 to 24 V; not shown) and the phase shifter power supply 36 of the VVD phase shifter 32 (for example, a high-voltage power supply of about several hundred to several thousand V) are configured as separate power supply systems. Further, the back plate 314 functions as a common ground for the power supply of the phase shifter 22 (low-voltage power supply) and the phase shifter power supply 36 (high-voltage power supply).

[0073] The phase shifter power supply 36 is provided corresponding to each of the plurality of radiation stubs 312.

[0074] (Beam Scanning) The phased array antenna 12 performs beam scanning in the azimuth (AZ) direction and also performs beam scanning in the elevation (EL) direction.

[0075] The phased array antenna 12 electronically performs beam scanning in the elevation (EL) direction by controlling the phase of an electromagnetic wave (RF signal) by each phase shifter 22 of the feeding unit 2. The electronic beam scanning in the elevation (EL) direction is the same as in the above-described Embodiment 1.

[0076] The phased array antenna 12 also electronically performs beam scanning in the azimuth (AZ) direction by controlling the phase of an electromagnetic wave (RF signal) by a combination of each phase shifter 22 of the feeding unit 2 and each VVD phase shifter 32 of the antenna unit 3.

[0077] The phased array antenna 12 applies the relationship between the array and directivity of the plurality of virtual element antennas 312a, which was also described with reference to FIGS. 7 and 8 in relation to the above-described Embodiment 1, to the array of the plurality of radiation stubs 312, thereby scanning the directivity in the xz plane (in the coordinate system shown in FIG. 6).

[0078] Specifically, by controlling the VVD phase shifters 32 disposed in each radiation stub 312 of the feed array 31 of the antenna unit 3, an inclination is given to the wavefront of the electromagnetic wave passing through the radiation stub 312, and beam scanning in the azimuth angle (AZ) direction is performed.

[0079] That is, by controlling the relative permittivity εr of each VVD phase shifter 32 (and thus the relative permittivity εr in each radiation stub 312) by controlling the voltage applied to the VVD phase shifter 32 of each radiation stub 312, the phase plane of the electromagnetic wave radiated from the radiation stub 312 is changed in the direction of the arrangement of the plurality of radiation stubs 312 (in the z-axis direction in the coordinate system shown in FIG. 6), thereby performing beam scanning in the longitudinal direction (the same, z-axis direction).

[0080] FIG. 13(A) shows the relationship between the array and directivity of the plurality of radiation stubs 312 when they are excited in the same phase, in other words, when the same voltage is applied to each of the plurality of VVD phase shifters 32, that is, when the relative permittivity of the VVD phase shifter 32 of each radiation stub 312 is εr 0 in the same case. This case can be regarded as a case where adjacent radiation stubs 312 are excited in the same phase, in other words, a case where each VVD phase shifter 32 is controlled and excited such that the difference Δφ in the phase shift amount between adjacent radiation stubs 312 is 0 (zero).

[0081] When the same voltage is applied to each of the plurality of VVD phase shifters 32, a wavefront of the electromagnetic wave is formed parallel to the array of the plurality of radiation stubs 312 (in the z-axis direction in the figure), and a main lobe is formed in the direction orthogonal to the array of the plurality of radiation stubs 312 (in the x-axis direction in the figure).

[0082] Fig. 13(B) shows the relationship between the array and directivity of a plurality of radiating stubs 312 when they are excited with a phase difference, that is, when voltages with differences are applied to each of the plurality of VVD phase shifters 32, that is, when the relative permittivity of the VVD phase shifter 32 of each radiating stub 312 is εr 0 , εr 1 , εr 2 , ··· are different. In this case, when each adjacent radiating stub 312 is excited with a phase difference of Δφ (≠0), that is, when each VVD phase shifter 32 is controlled and excited such that the difference Δφ in the phase shift amount for adjacent VVD phase shifters 32 is constant at a certain value (but not 0).

[0083] Here, an equivalent circuit model of a general transmission line using a dielectric with a relative permittivity εr is shown in Fig. 14. The propagation phase φ of this transmission line is as shown in Equation (1) below. Therefore, by using a voltage-variable dielectric as the medium of the transmission line, it operates as a phase shifter. (Equation 1) φ = 2πL√(εr) / λ 0 Here, φ: Propagation phase of the transmission line L: Thickness of the dielectric εr: Relative permittivity λ 0 : Wavelength in free space

[0084] Note that as the material of the voltage-variable dielectric, ferroelectrics such as barium titanate (BaTiO 3 ) are used and are fabricated as bulk ceramics or thin films formed on a semiconductor substrate. An example of the relationship between the applied voltage and the effective relative permittivity as a characteristic of the voltage-variable dielectric is shown in Fig. 15.

[0085] According to the above Equation (1), the relative permittivity εr of the VVD phase shifter 32 of each radiating stub 312 where a phase difference of Δφ (≠0) occurs for each adjacent radiating stub 312 0 , εr 1 , εr 2, as shown in Fig. 13(B), a voltage with a difference of ΔE (≠0) is applied to each VVD phase shifter 32 for each adjacent pair of radiating stubs 312.

[0086] The relative permittivity εr that causes a phase difference of Δφ (≠0) 0 , εr 1 , εr 2 , when a voltage with the difference ΔE is used and applied to each of the plurality of VVD phase shifters 32 such that the voltage difference ΔE is adjusted to be ΔE, ΔE, ··· for each adjacent pair of radiating stubs 312, the wavefront of the electromagnetic wave is inclined with respect to the arrangement of the plurality of radiating stubs 312 (in the z-axis direction in the figure). As a result, the direction of the main lobe rotates by Δθ with respect to the direction orthogonal to the arrangement of the plurality of radiating stubs 312 (in the x-axis direction in the figure). Note that Δθ = D·sin(Δφ) (where D: the mutual interval between the radiating stubs 312).

[0087] Note that the difference Δφ in the phase shift amount for adjacent phase shifters 22 when each of the plurality of virtual element antennas 312a regarded as constituting the radiating stub 312 is excited with a phase difference, and the difference Δφ in the phase shift amount for the VVD phase shifters 32 of adjacent radiating stubs 312 when a voltage with a difference is applied to each of the plurality of VVD phase shifters 32 may be the same value or different values.

[0088] According to the phased array antenna 12 according to the second embodiment, by changing the voltage applied to each VVD phase shifter 32 of each of the plurality of radiating stubs 312 to change the relative permittivity of each VVD phase shifter 32 of each of the plurality of radiating stubs 312, the wavefront of the electromagnetic wave passing through each of the plurality of radiating stubs 312 is inclined to perform beam scanning in the azimuth direction, and by inclining the wavefront of the electromagnetic wave propagating through the parallel plate line of the power feeding unit 2, the wavefront of the electromagnetic wave output from the power feeding unit 2 and incident on the base 311 of the antenna unit 3 is inclined to perform beam scanning in the elevation angle direction. Therefore, it is possible to improve the scanning speed of the beam scanning.

[0089] According to the phased array antenna 12 according to Embodiment 2, further, by changing the voltage applied to each of the VVD phase shifters 32 of the plurality of radiation stubs 312 to change the relative permittivity of each of the VVD phase shifters 32 of the plurality of radiation stubs 312, the wavefront of the electromagnetic wave passing through each of the plurality of radiation stubs 312 is tilted to perform beam scanning in the azimuth direction, and by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the feeding unit 2, the wavefront of the electromagnetic wave output from the feeding unit 2 and incident on the base 311 of the antenna unit 3 is tilted to perform beam scanning in the elevation angle direction. Therefore, it is possible to achieve high aperture efficiency and to realize a low-profile antenna.

[0090] According to the phased array antenna 12 according to Embodiment 2, further, since the VVD phase shifter 32 is disposed at the tip portion of the convex structure of each radiation stub 312 having a protruding structure, it is possible to reduce the loss of the feeding line.

[0091] According to the phased array antenna 12 according to Embodiment 2, further, since the VVD phase shifter 32 having a multilayer structure is disposed for each radiation stub 312, it is possible to realize an antenna having good reflection characteristics with the return loss maintained at a good level over a wide frequency band.

[0092] Further, according to the phased array antenna 12 according to Embodiment 2, since the feeding unit 2 feeds power through a plurality of probes 235, it is possible to generate a plane wave over a wide frequency band and with a short transmission line (specifically, about 1λ (where λ is the free space wavelength)), and thus it is possible to avoid an increase in transmission loss and to configure the feeding unit of the antenna compactly.

[0093] Also, according to the phased array antenna 12 according to Embodiment 2, the power supply unit 2 uses a distribution circuit as the power distributor 21 formed by branching the wiring by the patterning of the microstrip line from the apex portion 211 of the power distributor 21 to each probe 235, so that electromagnetic waves (RF signals, wireless communication waves) are supplied to each probe 235. Therefore, the incorporation of the phase shifter 22 (specifically, a digital phase shifter) can be easily performed without complicating the circuit configuration.

[0094] As described above, the embodiments of the present invention have been described. However, the specific configuration is not limited to the above-described embodiments, and even if there are design changes or the like within the scope that does not depart from the gist of the present invention, they are included in the present invention.

[0095] Specifically, in the above-described embodiment, the plane wave generated by the power supply unit 2 is made to be incident on the feed array 31 (specifically, the base portion 311) of the antenna unit 3. However, the mechanism for generating the plane wave incident on the feed array 31 is not limited to the power supply unit 2 in the above-described embodiment, and the plane wave generated by another plane wave generation mechanism may be made to be incident on the feed array 31.

Explanation of Reference Numerals

[0096] 11 Phased array antenna (Embodiment 1) 12 Phased array antenna (Embodiment 2) 2 Power supply unit 21 Power distributor 211 Apex portion 22 Phase shifter 23 Plane wave generation unit 231 Ground conductor plate 232 Dielectric substrate 233 Parallel plate 234 Power supply dielectric substrate 235 Probe 3 Antenna unit 31 Feed array 311 Base portion 312 Radiation stub 312a Virtual Element Antenna 313 Dielectric 314 Back Plate 315 Front Plate 32 VVD Phase Shifter 33 Insulating Part 34 Electrode 35 Insulating Sheet 36 Power Supply for Phase Shifter 4 Rotating Part 5 Control Unit

Claims

1. having a power supply unit and an antenna unit, wherein the power supply unit has a ground conductor plate, and a parallel plate that forms a parallel plate line with the ground conductor plate, wherein the antenna unit has a plate-shaped base, and a plurality of radiation stubs formed as convex portions that project in a row from one plate surface of the base and are spaced apart from each other at equal intervals in the direction in which the electromagnetic wave output from the power supply unit and incident on the base propagates, and are arranged parallel to each other along a direction orthogonal to the direction in which the electromagnetic wave propagates, and a VVD (abbreviation for Voltage Variable Dielectric) phase shifter that is disposed along the longitudinal direction of the radiation stub at the tip portion of each of the plurality of radiation stubs and is configured by a dielectric whose relative permittivity can be variably controlled by an applied voltage to control the phase of the electromagnetic wave, and having a feed array, performing beam scanning in the azimuth direction by changing the voltage applied to each of the VVD phase shifters of the plurality of radiation stubs to change the relative permittivity of each of the VVD phase shifters of the plurality of radiation stubs, thereby tilting the wavefront of the electromagnetic wave passing through each of the plurality of radiation stubs, and performing beam scanning in the elevation angle direction by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the power supply unit, thereby tilting the wavefront of the electromagnetic wave output from the power supply unit and incident on the base of the antenna unit, a phased array antenna characterized by the above.

2. wherein the power supply unit has a plurality of probes that are arranged in a row at equal intervals along a direction orthogonal to the propagation direction of the electromagnetic wave at a position near one end in the propagation direction of the electromagnetic wave in the parallel plate line and supply electromagnetic waves to the parallel plate line, and a plurality of phase shifters provided corresponding to each of the plurality of probes, and the wavefront of the electromagnetic wave propagating through the parallel plate line is tilted by controlling the phase of the electromagnetic wave supplied to each of the plurality of probes by the plurality of phase shifters, a phased array antenna according to claim 1, characterized by the above.

3. wherein the power supply unit has a power divider formed by branching wiring by patterning a microstrip line from a vertex portion electrically connected to an antenna port toward each of the plurality of probes, The electromagnetic wave is distributed to the plurality of phase shifters by the power distributor, and after the phases are controlled by the plurality of phase shifters, it is supplied to each of the plurality of probes. The phased array antenna according to claim 2, characterized in that.

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