Phased Array Antenna

Abstract

To provide a phased-array antenna which allows improvement in scan speed of beam scanning.SOLUTION: A phased-array antenna 11 performs beam scanning in an azimuth angle direction by rotating a feed array 31 with the use of a rotation part 4. At the same time, the phased-array antenna tilts a wavefront of an electromagnetic wave propagating in a parallel plate line of a power supply part 2. In this way, beam scanning in an altitude angle direction is performed by tilting a wavefront of the electromagnetic wave outputted from the power supply part 2 to be incident on a base part of an antenna part 3.SELECTED DRAWING: Figure 1

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. to perform beam scanning, 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] To solve the above problems, the phased array antenna according to the present invention includes a power feeding unit, an antenna unit, and a rotating unit, and the power feeding unit includes a ground conductor plate and the ground conductor plate arranged in parallel with parallel plates, a dielectric substrate disposed so as to be interposed between the ground conductor plate and the parallel plate and forming a parallel plate line for propagating electromagnetic waves, a power supply dielectric substrate disposed on the side of the ground conductor plate opposite to the side of the dielectric substrate, and arranged in a row at equal intervals along a direction orthogonal to the propagation direction of the electromagnetic waves at a position near one end of the power supply dielectric substrate in the propagation direction of the electromagnetic waves, and penetrating through the dielectric substrate to supply electromagnetic waves to the parallel plate line And a plurality of probes,The antenna unit includes a plate-shaped base portion and a plurality of radiation stubs formed as convex portions that extend in a row from one plate surface of the base portion 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. The feed array has a feed array, and the rotation unit rotates the feed array to perform beam scanning in the azimuth direction, and tilts the wavefront of the electromagnetic wave propagating through the parallel plate line of the feed unit to tilt the wavefront of the electromagnetic wave output from the feed unit and incident on the base portion of the antenna unit, thereby performing beam scanning in the elevation angle direction.

[0007] In the phased array antenna according to the present invention, the feeding unit , the A plurality of phase shifters provided corresponding to each of the plurality of probes device And the phase of the electromagnetic wave supplied to each of the plurality of probes is controlled by the plurality of phase shifters to tilt the wavefront of the electromagnetic wave propagating through the parallel plate line.

[0008] In the phased array antenna according to the present invention, the feeding 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 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 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 portion of the antenna unit is tilted, so that beam scanning in the elevation angle direction can be performed, and the scanning speed of beam scanning can be improved.

[0010] According to the phased array antenna of the present invention, 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, so that beam scanning in the elevation angle direction can be performed. As a result, it is possible to achieve high aperture efficiency and to realize a low-profile antenna.

[0011] When the phased array antenna according to the present invention is configured such that the power feeding unit feeds power through a plurality of probes, 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)), thereby avoiding an increase in transmission loss and making it possible to compactly configure the power feeding unit of the antenna.

[0012] When the phased array antenna according to the present invention uses 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 to supply electromagnetic waves 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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Embodiments for Carrying Out the Invention

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

[0015] <Embodiment 1> FIG. 1 is a circuit configuration diagram showing a schematic configuration of a phased array antenna 11 according to Embodiment 1 of the present 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] In the phased array antenna 11 according to this embodiment, the power supply unit 2 includes 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 includes a plate-shaped base 311 and a plurality of radiation stubs 312 that are formed as convex portions that project 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 output from the power supply unit 2 and incident on the base 311 propagates while being spaced apart from each other at equal intervals in the direction in which the electromagnetic wave propagates. The phased array antenna 11 has a feed array 31 including these. By rotating the feed array 31 by the rotation unit 4, beam scanning in the azimuth direction is performed, and by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the power supply unit 2, the wavefront of the electromagnetic wave output from the power supply unit 2 and incident on the base 311 of the antenna unit 3 is tilted, thereby performing beam scanning in the elevation angle direction.

[0017] In the phased array antenna 11 according to this embodiment, the power supply unit 2 also includes 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. By controlling the phase of the electromagnetic wave supplied to each of the plurality of probes 235 by the plurality of phase shifters 22, the wavefront of the electromagnetic wave propagating through the parallel plate line is tilted.

[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, with respect to the structure of the power supply unit 2, 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 mutually orthogonal are corresponded as shown in FIG. 2 and the like.

[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 (in the figure, the x-axis direction) of the dielectric substrate 232 within the dielectric substrate 232 is formed.

[0022] The power supply 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 propagate along the z-axis direction between the ground conductor plate 231 and the parallel plate 233 by the power supply 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 (in the figure, the end opposite to the side of the arrow of the z-axis) in the z-axis direction of the power supply dielectric substrate 234.

[0024] The mutual distance 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 dielectric substrate 234 for power supply, which is 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 the wiring by means of the patterning of the microstrip line from the vertex portion 211 at the central position (or a position near the center) in the plan view of the dielectric substrate 234 for power supply to 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] Since the structure / composition related to the coaxial connector is not limited to a specific structure / composition in this invention, a detailed description is omitted. However, the coaxial connector has, for example, an inner conductor to which a signal (SIG) is input from the inner conductor of a coaxial cable (not shown) and which is electrically connected to each probe 235 via the power distributor 21, 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] Specifically, the phase shifter 22 is 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 vertex portion 211 of the power distributor 21 is distributed by the power distributor 21 by a predetermined amount (in other words, the amplitude is controlled), and the phase is controlled by the phase shifter 22, and then fed between the ground conductor plate 231 and the parallel plate 233 through 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-like 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 extend 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 along their longitudinal directions in a 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 consists 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. A 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 surfaces (the surfaces along the xy plane in the figure) of each radiating stub 312 are covered by the conductive front plate 315 that is bent to be formed. On the other hand, the tip surfaces of the convex structures of each radiating stub 312 having a protruding structure (the surfaces on the side of the arrow in the x-axis direction in the figure) are not shielded conductively, allowing the propagation of electromagnetic energy through the tip surfaces of the radiating stubs 312, and defining the antenna radiation pattern.

[0041] A plane wave / electromagnetic wave (RF signal) generated by the power feeding 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 direction displacement current in the direction in which the plane wave / electromagnetic wave (RF signal) propagates. Then, the z-axis direction 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 transvers stub (CTS) antenna. The functions of the feed array 31 are described, for example, in "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), as well as in 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 feeding unit 2 and the antenna unit 3. Specifically, the rotating part 4 is configured as a mechanism including, for example, a rotary joint and 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 unit 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 phase of the RF signal distributed by the power divider 21 to each phase shifter 22 (and ultimately to each probe 235) is controlled by each phase shifter 22 such that the difference Δφ in the phase shift amount 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 phase of the RF signal distributed by the power divider 21 to each phase shifter 22 (and ultimately to each probe 235) is controlled by each phase shifter 22 such that the difference Δφ in the phase shift amount for adjacent phase shifters 22 is a certain value (non-zero) 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 plane 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 (hypothetical) element antenna that is considered to constitute the radiation stub 312 is called the "virtual element antenna 312a".

[0053] FIG. 8(A) shows the relationship between the array and the 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 amount 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 in parallel with 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 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, and as shown in FIG. 9, the directivity of the feed array 31 can be controlled, and thus it is possible to electronically perform beam scanning in the elevation angle (EL) direction.

[0059] According to the phased array antenna 11 according to the first embodiment, 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 the first embodiment, 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 the first embodiment, 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] Further, according to the phased array antenna 11 according to the first embodiment, 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 ground conductor plate 231 and a parallel plate 233 that forms a parallel plate line between the ground conductor plates 231 in the power supply unit 2. The antenna unit 3 has a plate-shaped base 311 and a plurality of radiation stubs 312 that are formed as convex portions that project 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 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. Each of the plurality of radiation stubs 312 is provided with a VVD phase shifter 32 arranged 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 dielectric constant 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 tilt 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.

[0065] This embodiment differs 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. However, since the other configurations are the same as those of the above-described Embodiment 1, the same reference numerals are given to the configurations equivalent to 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 traveling in the x-axis direction toward the radiation stub 312 of the feed array 31 and 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 portion 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 (i.e., 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 forming the VVD phase shifter 32 in 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, an electrode 34 is disposed on the sides 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 so as to be interposed between the pair of VVD phase shifters 32, 32, the insulating portion 33 disposed therebetween, and the surface plate 315 that forms the convex structure of each radiation stub 312 having a protruding structure.

[0072] The power supply 36 for the phase shifter 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 for 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 power supply 36 for the phase shifter 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 (low-voltage power supply) of the phase shifter 22 and the power supply 36 for the phase shifter (high-voltage power supply).

[0073] The power supply 36 for the phase shifter 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 the 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 that in the first embodiment described above.

[0076] The phased array antenna 12 also electronically performs beam scanning in the azimuth (AZ) direction by controlling the phase of the electromagnetic wave (RF signal) by the 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 of the radiation stubs 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 (AZ) direction is performed.

[0079] That is, by controlling the relative dielectric constant εr of each VVD phase shifter 32 (and thus the relative dielectric constant 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 (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, that is, when the same voltage is applied to each of the plurality of VVD phase shifters 32, that is, when the relative dielectric constant 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, that is, 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 of a plurality of radiating stubs 312 and the directivity when they are excited with a phase difference, that is, when voltages with differences are applied to respective ones of the plurality of VVD phase shifters 32, that is, when the relative dielectric constants of the VVD phase shifters 32 of the respective radiating stubs 312 are 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 (however, not zero).

[0083] Here, an equivalent circuit model of a general transmission line using a dielectric with a relative dielectric constant 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 dielectric constant 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 dielectric constant as characteristics of the voltage-variable dielectric is shown in Fig. 15.

[0085] According to the above Equation 1, the relative dielectric constants εr of the VVD phase shifters 32 of the respective radiating stubs 312 where a phase difference of Δφ (≠0) occurs for each adjacent radiating stub 312 0 , εr 1 , εr 2, so as to achieve (see Fig. 13(B)), a voltage with a difference of ΔE (≠0) is applied to each VVD phase shifter 32 for each adjacent radiation stub 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, the wavefront of the electromagnetic wave is inclined with respect to the arrangement of the plurality of radiation stubs 312 (in the z-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 arrangement of the plurality of radiation stubs 312 (in the x-axis direction in the figure). Note that Δθ = D·sin(Δφ) (where D: the mutual interval between the radiation stubs 312).

[0087] In addition, 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 radiation 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 radiation stubs 312 when voltages with differences are 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 Embodiment 2, by changing the voltage applied to each VVD phase shifter 32 of each of the plurality of radiation stubs 312 to change the relative permittivity of each VVD phase shifter 32 of each of the plurality of radiation stubs 312, the wavefront of the electromagnetic wave passing through each of the plurality of radiation 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 the wavefront of the electromagnetic wave propagating through the parallel plate line of the feeding unit 2 is tilted to tilt the wavefront of the electromagnetic wave output from the feeding unit 2 and incident on the base 311 of the antenna unit 3, so that beam scanning in the elevation angle direction is performed. Therefore, it is possible to realize high aperture efficiency and 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 return loss maintained at a good level over a wide frequency band and having good reflection characteristics.

[0092] Also, 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)). As a result, 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 wiring by microstrip line patterning 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 plane waves generated by other plane wave generation mechanisms 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 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. It has a power supply unit, an antenna unit, and a rotating unit, wherein the power supply unit has a ground conductor plate, a parallel plate arranged parallel to the ground conductor plate, a dielectric substrate disposed so as to be interposed between the ground conductor plate and the parallel plate and forming a parallel plate line for propagating electromagnetic waves, a power supply dielectric substrate disposed on the side of the ground conductor plate opposite to the side of the dielectric substrate, and a plurality of probes arranged at equal intervals in a row along a direction orthogonal to the propagation direction of the electromagnetic waves at a position near one end of the power supply dielectric substrate in the propagation direction of the electromagnetic waves, penetrating through the dielectric substrate and supplying electromagnetic waves to the parallel plate line, wherein the antenna unit has a plate-shaped base, and a feed array including a plurality of radiation stubs formed as convex portions protruding in a row from one plate surface of the base and arranged parallel to each other along a direction orthogonal to the direction in which the electromagnetic waves output from the power supply unit and incident on the base propagate while being spaced apart from each other at equal intervals in the direction in which the electromagnetic waves propagate, performing beam scanning in the azimuth direction by rotating the feed array by the rotating unit, and performing beam scanning in the elevation direction by tilting the wavefront of the electromagnetic waves propagating through the parallel plate line of the power supply unit to thereby tilt the wavefront of the electromagnetic waves output from the power supply unit and incident on the base of the antenna unit, characterized in that it is a phased array antenna.

2. wherein the power supply unit has a plurality of phase shifters provided corresponding to each of the plurality of probes, and tilts the wavefront of the electromagnetic waves propagating through the parallel plate line by controlling the phases of the electromagnetic waves supplied to each of the plurality of probes by the plurality of phase shifters, characterized in that it is the phased array antenna according to Claim 1.

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

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