Plane wave generation mechanism

Abstract

To provide a plane wave generation mechanism capable of generating a plane wave in a short transmission line.SOLUTION: A plane wave generation mechanism 2 comprises: a ground conductor plate 231; a parallel flat plate 233 forming a parallel flat plate line between the ground conductor plate 231 and itself; and a plurality of probes 235 disposed while being arranged side by side at equal intervals in a row in a direction orthogonal with a propagation direction of electromagnetic waves at a position closer to one end of the parallel flat plate line in the propagation direction of the electromagnetic waves and supplying the electromagnetic waves to the parallel flat plate line.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a plane wave generating mechanism, and relates to a technique suitable for use as a power feeder for satellite communication antennas mounted on various mobile objects, for example. [Background technology]

[0002] A known conventional plane wave generating mechanism is one that uses a pillbox (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-505229 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the pillbox system requires a sufficiently long transmission line (for example, a transmission line longer than 10λ, where λ is the free-space wavelength), which results in problems such as increased transmission loss and a larger device.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a plane wave generating mechanism that is capable of generating a plane wave using a short transmission line. [Means for solving the problem]

[0006] In order to solve the above problems, the plane wave generating mechanism according to the present invention comprises a ground conductor plate, a parallel plate arranged parallel to the ground conductor plate, a dielectric substrate arranged between the ground conductor plate and the parallel plate to form a parallel plate line for propagating an electromagnetic wave, a power feeding dielectric substrate arranged on the side of the ground conductor plate opposite to the dielectric substrate, and a pair of parallel plate lines arranged at equal intervals in a row along a direction perpendicular to the propagation direction of the electromagnetic wave, the parallel plate lines being disposed near one end of the power feeding dielectric substrate in the propagation direction of the electromagnetic wave.d a plurality of probes arranged side by side in a line, penetrating the dielectric substrate and supplying electromagnetic waves to the parallel plate line; death , the distance d is adjusted to satisfy λ / 2≦d<λ, where λ is the free space wavelength of an electromagnetic wave, and the probe penetrates a blind hole formed in the dielectric substrate. It is characterized by:

[0007] The plane wave generating mechanism according to the present invention may have a plurality of phase shifters provided corresponding to each of the plurality of probes, and may tilt the wavefront of the electromagnetic wave propagating through the parallel plate line by controlling the phase of the electromagnetic wave supplied to each of the plurality of probes using the plurality of phase shifters.

[0008] The plane wave generating mechanism according to the present invention comprises: On the surface of the power supply dielectric substrate opposite to the ground conductor plate, The antenna may have a power divider formed by patterning a microstrip line to branch wiring from a vertex electrically connected to an antenna port toward each of the plurality of probes, and the power divider may be used to supply electromagnetic waves to each of the plurality of probes. [Effects of the Invention]

[0009] According to the plane wave generating mechanism of the present invention, power is supplied via multiple probes, which makes it possible to generate a plane wave using a short transmission line (specifically, about 1λ (where λ is the free space wavelength)), which in turn makes it possible to avoid an increase in transmission loss and to configure, for example, the power supply section of an antenna in a compact manner.

[0010] Furthermore, the plane wave generating mechanism according to the present invention is adapted to feed power via a plurality of probes, making it possible to generate plane waves over a wide frequency band.

[0011] When the phase of the electromagnetic wave supplied to each of the multiple probes is controlled by multiple phase shifters, the plane wave generating mechanism of the present invention can tilt the wavefront of the electromagnetic wave propagating through the parallel plate line, making it possible to output an electromagnetic wave with an arbitrarily tilted wavefront.

[0012] The plane wave generating mechanism of the present invention supplies electromagnetic waves to each probe using a power divider circuit formed by branching wiring from the apex of the power divider toward each probe by patterning a microstrip line, and when this is used, it becomes possible to easily incorporate a phase shifter without complicating the circuit configuration. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a circuit diagram showing a schematic configuration of a phased array antenna according to a first embodiment including a plane wave generating mechanism in accordance with an embodiment of the present invention. FIG. [Figure 2] 1A and 1B are diagrams showing a schematic configuration of a plane wave generating mechanism according to an embodiment (i.e., the plane wave generating mechanism of the phased array antenna in FIG. 1), in which (A) is a perspective view and (B) is an exploded perspective view. [Figure 3] 3A and 3B are diagrams showing a schematic configuration of the plane wave generating mechanism of Fig. 2, in which (A) is a plan view showing the state in which the light has passed through a parallel plate, and (B) is a bottom view. [Figure 4] 3 is a diagram showing an example of a plane wave (electric field distribution) generated by the plane wave generating mechanism of FIG. 2. FIG. [Figure 5] 3 is a graph showing an S parameter S11 (return loss) in the plane wave generating mechanism of FIG. 2. [Figure 6] FIG. 2 is a perspective view showing a schematic configuration of a feed array of the phased array antenna of FIG. 1. [Figure 7] 3A and 3B are diagrams showing examples of electric field distribution in the plane wave generating mechanism of Fig. 2. (A) shows the electric field distribution in the case of in-phase excitation, and (B) shows the electric field distribution in the case of out-of-phase excitation. [Figure 8] This figure explains the directivity in the xy plane of the phased array antenna in Figure 1. (A) is a diagram showing the case where the radiating stubs are excited in phase, and (B) is a diagram showing the case where the radiating stubs are excited with a phase difference. [Figure 9] FIG. 7 shows an example of the directivity of the feed array of FIG. 6. [Figure 10] FIG. 10 is a circuit diagram showing a schematic configuration of a phased array antenna according to a second embodiment of the present invention, including a plane wave generating mechanism. [Figure 11] FIG. 11 is a partially enlarged perspective view showing a schematic configuration of a radiation stub of a feed array in the phased array antenna of FIG. 10. [Figure 12] 12 is a graph showing the S-parameter S11 (return loss) of the feed array of FIG. 11. [Figure 13] 11A and 11B are diagrams illustrating the directivity in the xz plane of the phased array antenna in Fig. 10. (A) is a diagram illustrating the case where multiple radiating stubs are excited in the same phase, and (B) is a diagram illustrating the case where multiple radiating stubs are excited with a phase difference. [Figure 14] FIG. 1 is a diagram illustrating an equivalent circuit model of a transmission line. [Figure 15] 10 is a graph showing an example of the characteristics of a voltage-variable dielectric. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described below based on the illustrated embodiments.

[0015] <First Embodiment> 1 is a circuit diagram showing a schematic configuration of a phased array antenna 11 according to a first embodiment of the present invention, including a plane wave generating mechanism 2. The phased array antenna 11 according to the first embodiment has the plane wave generating mechanism 2, an antenna unit 3, a rotating unit 4, and a control unit 5.

[0016] The plane wave generating mechanism 2 according to the embodiment comprises a ground conductor plate 231, a parallel plate 233 which forms a parallel plate line between itself and the ground conductor plate 231, a plurality of probes 235 which are arranged at equal intervals in a row along a direction perpendicular to the propagation direction of the electromagnetic wave at a position near one end of the parallel plate line in the propagation direction of the electromagnetic wave and which supply the electromagnetic wave to the parallel plate line, and a plurality of phase shifters 22 which are provided corresponding to each of the plurality of probes 235, and which are configured to tilt the wavefront of the electromagnetic wave propagating along the parallel plate line by controlling the phase of the electromagnetic wave supplied to each of the plurality of probes 235 using the plurality of phase shifters 22.

[0017] In addition, in the phased array antenna 11 of this embodiment, the antenna section 3 has a feed array 31 including a plate-shaped base 311 and a plurality of radiating stubs 312 formed as convex portions protruding in a row from one plate surface of the base 311, the radiating stubs 312 being spaced apart at equal intervals from each other in the propagation direction of the electromagnetic waves output from the plane wave generating mechanism 2 and incident on the base 311, and arranged parallel to each other along a direction perpendicular to the propagation direction of the electromagnetic waves. Beam scanning in the azimuth angle direction is performed by rotating the feed array 31 with the rotating section 4, and beam scanning in the elevation angle direction is performed by tilting the wavefront of the electromagnetic waves propagating through the parallel plate line of the plane wave generating mechanism 2, thereby tilting the wavefront of the electromagnetic waves output from the plane wave generating mechanism 2 and incident on the base 311 of the antenna section 3.

[0018] (Plane wave generation mechanism) The plane wave generating mechanism 2 is a mechanism that functions as a power feed section of the antenna, and mainly includes a power divider 21, a plurality of phase shifters 22, and a plane wave generating section 23. In the explanation here, the structure of the plane wave generating mechanism 2 corresponds to the x-axis, y-axis, and z-axis directions of a three-dimensional Cartesian coordinate system defined by mutually orthogonal x-axis, y-axis, and z-axis, as shown in FIG.

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

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

[0021] A dielectric substrate 232 is disposed between the ground conductor plate 231 and the parallel plate 233, and a dielectric image line (here, a parallel plate line) is formed within the dielectric substrate 232, which propagates electromagnetic waves in a direction (in the figure, the z-axis direction) perpendicular to the thickness direction of the dielectric substrate 232 (in the figure, the x-axis direction).

[0022] Electromagnetic waves are fed to the parallel plate line formed between the ground conductor plate 231 and the parallel plate 233 via multiple probes 235, and as electromagnetic waves are fed from each of the multiple probes 235, the electromagnetic waves propagate along the z-axis direction between the ground conductor plate 231 and the parallel plate 233.

[0023] A power feeding dielectric substrate 234 is arranged on the side of the ground conductor plate 231 opposite 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 this power feeding dielectric substrate 234 in the z axis direction (in the figure, the end opposite to the side in the direction of the z axis arrow).

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

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

[0026] The power divider 21 is realized by a dividing circuit formed by branching wiring by patterning a microstrip line from a vertex 211 at the center position (or a position near the center) in a plan view of the power feeding 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 divider 21 from the vertex 211, the number of branching stages, and the number of divisions at each stage.

[0027] The vertex 211 of the power divider 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 of the coaxial connector is not limited to a specific structure / configuration in this invention, so a detailed explanation will be omitted, but the coaxial connector can have, for example, an inner conductor that is electrically connected to each probe 235 via power divider 21 and receives a signal (SIG) from the inner conductor of the coaxial cable (not shown), and an outer conductor that is electrically connected to ground conductor plate 231 and receives a signal (e.g., GND) from the outer conductor of the coaxial cable, and can have a structure / configuration that supplies an RF signal (in other words, a wireless communication wave) to power divider 21 and, ultimately, to each probe 235.

[0029] The phase shifter 22 is specifically configured by a digital phase shifter, controls the phase of the RF signal divided by the power divider 21 , and supplies the phase-controlled RF signal to the probe 235 .

[0030] The phase shifters 22 are provided for each of the branched lines in the dividing circuit serving as the power divider 21 , that is, for 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 211 of the power divider 21 is divided by a predetermined amount by the power divider 21 (in other words, the amplitude is controlled) and the phase is controlled by the phase shifter 22, and then the signal is fed between the ground conductor plate 231 and the parallel plate 233 via each probe 235.

[0033] According to the plane wave generating mechanism 2 having the above-described configuration, a plane wave is generated on 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 plane wave generating mechanism 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 an area corresponding to five probes 235).

[0034] 5 shows the S parameter S11 (i.e., return loss) of the plane wave generating mechanism 2. From FIG. 5, it is confirmed that the return loss is maintained at a good level over a wide frequency band, and good reflection characteristics can be provided.

[0035] (antenna part) The antenna unit 3 has, as its main component, a feed array 31. In this explanation, the structure of the feed array 31 corresponds to the x-axis, y-axis, and z-axis directions of a three-dimensional Cartesian coordinate system defined by mutually orthogonal x-axis, y-axis, and z-axis, as shown in FIG.

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

[0037] The multiple radiating stubs 312 are each formed as a row of protrusions protruding from one plate surface (the surface on the side in the direction of the x-axis arrow in the drawing) of the base 311. The multiple radiating stubs 312 are spaced apart from one another at equal intervals D in the direction (z-axis direction in the drawing) in which the plane wave / electromagnetic wave (RF signal) output from the plane wave generating mechanism 2 and incident on the feed array 31 (specifically, the base 311) propagates, and are arranged parallel to one another with their longitudinal directions aligned in a direction (y-axis direction in the drawing) perpendicular to the z-axis direction.

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

[0039] The feed array 31 comprises a conductive back plate 314 which forms the other plate surface of the base 311 (the surface opposite to the side in the direction of the x-axis arrow in the figure), and a conductive front plate 315 (made up of multiple components) which is arranged at a distance from the back plate 314 and is bent along the y-axis direction to form radiating stubs 312, and is formed so that a dielectric 313 fills the space between the back plate 314 and the front plate 315 (including the inside of each radiating stub 312).

[0040] The side surfaces of each radiating stub 312 (surfaces along the xy plane in the drawing) are covered with a curved, conductive surface plate 315. On the other hand, the tip surfaces of the convex structures of each radiating stub 312 having a protruding structure (surfaces on the side in the direction of the x-axis arrow in the drawing) do not have a conductive shield and allow electromagnetic energy to propagate through the tip surfaces of the radiating stubs 312, thereby defining the antenna radiation pattern.

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

[0042] The feed array 31 having the above configuration corresponds to part of a structure also known as a continuous transverse stub (CTS) antenna, and the function of the feed array 31 is explained, for example, in "The Continuous Transverse (CTS) Array: Basic Theory, Experiment, and Application" (Milroy, WW, "Proceedings of the Antenna Applications Symposium Held on September 25-27, 1991, Volume 1," AD-A253 682, pp. 253-283), as well as in JP-T-2006-522561, U.S. Patent Nos. 6,281,838, 5,757,379, 5,483,248, 5,379,007, and 5,266,961.

[0043] (Rotating part) The rotating unit 4 rotates the plane wave generating mechanism 2 and the antenna unit 3. Specifically, the rotating unit 4 is configured as a mechanism including, for example, a rotary joint and a motor, and rotates 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 unit 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 in the elevation (EL) direction. The azimuth (AZ) angle is an angle defined with north or south as 0° and clockwise as positive. The elevation (EL) angle is an angle defined with the horizon as 0° and pointing toward the zenith.

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

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

[0048] Specifically, by controlling each phase shifter 22 of the plane wave generating mechanism 2, a tilt is imparted 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 plane wave generating mechanism 2, and a tilt is imparted to the wavefront of the electromagnetic wave output from the plane wave generating mechanism 2 and incident on the feed array 31 (specifically, the base 311) of the antenna unit 3, thereby performing beam scanning in the elevation angle (EL) direction.

[0049] That is, by using oblique incidence of the guided wave mode propagating to the feed array 31, the phase plane of the electromagnetic wave entering the radiating stub 312 is changed in the longitudinal direction of the radiating stub 312 (in the y-axis direction in the coordinate system shown in FIG. 6), thereby performing beam scanning in the H-plane in the transverse direction (in the y-axis direction in the same coordinate system).

[0050] An example of the electric field distribution in the plane wave generating mechanism 2 is shown in Fig. 7 (A) which 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 further to each probe 235) is controlled by each phase shifter 22 so that the difference Δφ in the amount of phase shift between adjacent phase shifters 22 is 0 (zero), and the RF signal after phase control is supplied to each probe 235, thereby realizing the electric field distribution as shown in Fig. 7 (A).

[0051] 10(B) shows the electric field distribution in the case of phase-difference excitation by multiple 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 so that the difference Δφ in the amount of phase shift between adjacent phase shifters 22 is a certain value (however, not 0) and is constant, and the phase-controlled RF signal is supplied to each probe 235, thereby realizing the electric field distribution shown in FIG.

[0052] Here, the antenna section 3 uses oblique incidence of the guided mode propagating to the feed array 31 to change the phase front of the electromagnetic wave entering the radiating stub 312 in the longitudinal direction of the radiating stub 312, thereby making the radiating stub 312 function as a mechanism in which a plurality of element antennas are lined up in a row at a mutual interval d along the longitudinal direction of the radiating stub 312 (where d is the mutual interval between the probes 235). The (imaginary) element antennas considered to constitute the radiating stub 312 are called "virtual element antennas 312a."

[0053] 8(A) shows the relationship between the arrangement of the multiple virtual element antennas 312a and the directivity when the radiating stubs 312 are excited in phase, that is, when each of the multiple virtual element antennas 312a considered to constitute the radiating stub 312 is excited in phase. This case can be considered as a case where adjacent virtual element antennas 312a are excited in phase, in other words, a case where each phase shifter 22 is controlled and excited so that the difference Δφ in the amount of phase shift between adjacent phase shifters 22 is 0 (zero).

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

[0055] 8(B) shows the relationship between the arrangement of the multiple virtual element antennas 312a and the directivity when the radiating stub 312 is excited with a phase difference, that is, when each of the multiple virtual element antennas 312a considered to constitute the radiating stub 312 is excited with a phase difference. This case can be considered as a case where adjacent virtual element antennas 312a are excited with a phase difference of Δφ (≠0), in other words, a case where each phase shifter 22 is controlled and excited so that the difference Δφ in the amount of phase shift between adjacent phase shifters 22 is constant at a certain value (however, not 0).

[0056] When the radiating stub 312 is excited with a phase difference, the wavefront of the electromagnetic wave is tilted with respect to the arrangement of the multiple 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 perpendicular to the arrangement of the multiple virtual element antennas 312a (in the x-axis direction in the figure), where Δθ=d·sin(Δφ) (where d is the distance between the probes 235).

[0057] By applying the phase shift control that realizes the relationship between the arrangement of the multiple virtual element antennas 312a, which are considered to constitute the radiating stub 312, and the directivity as described above to each phase shifter 22 of the plane wave generating mechanism 2, it is possible to scan the directivity within the xy plane (in the coordinate system shown in FIG. 6).

[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) using each phase shifter 22 of the plane wave generating mechanism 2 and thereby controlling the phase that excites the radiation stub 312, the directivity of the feed array 31 can be controlled as shown in Fig. 9, and ultimately beam scanning in the elevation angle (EL) direction can be performed electronically.

[0059] According to the plane wave generating mechanism 2 of embodiment 1, power is supplied via multiple probes 235, which makes it possible to generate a plane wave using a short transmission line (specifically, about 1λ (where λ is the free space wavelength)), which in turn makes it possible to avoid an increase in transmission loss, makes it possible to configure the antenna power supply section compact, and makes it possible to generate a plane wave over a wide frequency band.

[0060] According to the plane wave generating mechanism 2 of the first embodiment, the phase of the electromagnetic wave supplied to each of the plurality of probes 235 is controlled by the plurality of phase shifters 22, so that the wavefront of the electromagnetic wave propagating through the parallel plate line can be tilted, and it becomes possible to output an electromagnetic wave with an arbitrarily tilted wavefront.

[0061] According to the plane wave generating mechanism 2 of embodiment 1, electromagnetic waves (RF signals, wireless communication waves) are supplied to each probe 235 using a distribution circuit as the power divider 21 formed by branching wiring from the vertex 211 of the power divider 21 toward each probe 235 by patterning a microstrip line, so that the phase shifter 22 (specifically, a digital phase shifter) can be easily incorporated without complicating the circuit configuration.

[0062] Furthermore, according to the phased array antenna 11 of the first embodiment, beam scanning in the elevation angle direction is performed by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the plane wave generating mechanism 2, thereby tilting the wavefront of the electromagnetic wave output from the plane wave generating mechanism 2 and incident on the base 311 of the antenna unit 3. This makes it possible to improve the scanning speed of the beam scanning, achieve high aperture efficiency, and realize a low-profile antenna.

[0063] <Embodiment 2> 10 is a circuit diagram showing a schematic configuration of a phased array antenna 12 according to a second embodiment of the present invention, including a plane wave generating mechanism 2. The phased array antenna 12 according to the second embodiment has the plane wave generating mechanism 2, an antenna unit 3, and a control unit 5.

[0064] The phased array antenna 12 in this embodiment has an antenna section 3 having a feed array 31 including a plate-like base 311, a plurality of radiating stubs 312 formed as convex portions projecting in a row from one plate surface of the base 311, the radiating stubs 312 being spaced apart at equal intervals from one another in a direction in which an electromagnetic wave output from a plane wave generating mechanism 2 and incident on the base 311 propagates, and arranged parallel to one another along a direction perpendicular to the direction in which the electromagnetic wave propagates, and a VVD phase shifter 32 arranged at a tip end portion of each of the plurality of radiating stubs 312 along the longitudinal direction of the radiating stub 312, By changing the voltage applied to each of the VVD phase shifters 32 of the multiple radiation stubs 312 and changing the relative dielectric constant of each of the VVD phase shifters 32 of the multiple radiation stubs 312, the wavefront of the electromagnetic wave passing through each of the multiple radiation stubs 312 is tilted, thereby performing beam scanning in the azimuth angle direction, and by tilting the wavefront of the electromagnetic wave propagating through the parallel plate line of the plane wave generating mechanism 2, the wavefront of the electromagnetic wave output from the plane wave generating mechanism 2 and incident on the base 311 of the antenna unit 3 is tilted, thereby performing beam scanning in the altitude angle direction.

[0065] This embodiment differs from the first embodiment in that it does not have a rotating section 4 but does have a VVD phase shifter 32 and a phase shifter power supply 36. However, other configurations are the same as those of the first embodiment, and therefore, the same symbols are used for the same components as those of the first embodiment, and their description will be omitted.

[0066] The VVD (short 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 radiating stub 312 of the feed array 31 and is radiated into free space.

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

[0068] In the example shown in FIG. 11, a pair of VVD phase shifters 32, 32 are disposed so as to be spaced apart in the x-axis direction in the drawing and to face each other with an insulating portion 33 interposed therebetween (in other words, sandwiched between them).

[0069] 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 multi-layer structure (specifically, a pair as shown in FIG. 11) is shown in FIG. 12. It can be seen from FIG. 12 that by using a multi-layer VVD phase shifter 32, the return loss can be maintained at a good level over a wide frequency band, making it possible to realize an antenna with good reflection characteristics.

[0070] However, it is not essential for the present invention that the VVD phase shifters 32 be arranged in a multi-layer structure, and the VVD phase shifters 32 may be arranged in a single-layer structure. When the VVD phase shifters 32 have a single-layer structure, specifically, only the VVD phase shifters 32 on the side indicated by the arrow on the x-axis in FIG. 11 are arranged.

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

[0072] The phase shifter power supply 36 supplies power to the electrodes 34 of the feed array 31. This allows the VVD phase shifter 32 to receive power and operate by controlling the voltage applied to the VVD phase shifter 32. Note that the power supply (e.g., a low-voltage power supply of about 12 to 24 V; not shown) of the phase shifter 22 (specifically, a digital phase shifter) and the phase shifter power supply 36 (e.g., a high-voltage power supply of about several hundred to several thousand V) of the VVD phase shifter 32 are configured as separate power supplies. In addition, the back plate 314 functions as a common ground for the power supply (low-voltage power supply) of the phase shifter 22 and the phase shifter power supply 36 (high-voltage power supply).

[0073] The phase shifter power supplies 36 are provided corresponding to the plurality of radiating stubs 312, respectively.

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

[0075] The phased array antenna 12 electronically scans the beam in the elevation angle (EL) direction by controlling the phase of the electromagnetic wave (RF signal) using each phase shifter 22 of the plane wave generating mechanism 2. The electronic beam scanning in the elevation angle (EL) direction is the same as in the first embodiment.

[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) through a combination of each phase shifter 22 in the plane wave generating mechanism 2 and each VVD phase shifter 32 in the antenna unit 3.

[0077] The phased array antenna 12 scans the directivity in the xz plane (in the coordinate system shown in FIG. 6) by applying the relationship between the arrangement and directivity of the multiple virtual element antennas 312a explained in relation to the first embodiment above, also using FIG. 7 and FIG. 8, to the arrangement of the multiple radiating stubs 312.

[0078] Specifically, by controlling the VVD phase shifter 32 arranged in each radiating stub 312 of the feed array 31 of the antenna section 3, a tilt is given to the wavefront of the electromagnetic wave passing through the radiating stub 312, and beam scanning is performed in the azimuth angle (AZ) direction.

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

[0080] 13(A) shows the relationship between the arrangement of the multiple radiating stubs 312 and the directivity when the multiple radiating stubs 312 are excited in phase, in other words, when the same voltage is applied to each of the multiple VVD phase shifters 32, that is, when the VVD phase shifters 32 of each radiating stub 312 have the same relative dielectric constant εr0. This case can be considered as when the adjacent radiating stubs 312 are excited in phase, in other words, when each VVD phase shifter 32 is controlled and excited so that the difference Δφ in the amount of phase shift between the adjacent radiating stubs 312 is 0 (zero).

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

[0082] 13(B) shows the relationship between the arrangement of the multiple radiating stubs 312 and directivity when the multiple radiating stubs 312 are excited with a phase difference, in other words, when different voltages are applied to each of the multiple VVD phase shifters 32, that is, when the relative permittivity of the VVD phase shifters 32 of each radiating stub 312 is different, εr0, εr1, εr2, .... This case can be considered as a case where the adjacent radiating stubs 312 are excited with a phase difference of Δφ (≠0), in other words, a case where each VVD phase shifter 32 is controlled and excited so that the difference Δφ in the amount of phase shift between adjacent VVD phase shifters 32 is a constant value (but not 0).

[0083] Here, an equivalent circuit model of a general transmission line using a dielectric with a relative dielectric constant εr is shown in Figure 14. The transmission phase φ of this transmission line is given by the following equation 1. 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) / λ0 Here, φ is the transmission phase of the transmission line L: thickness of dielectric εr: relative permittivity λ0: wavelength in free space

[0084] The material used for voltage-variable dielectrics is a ferroelectric such as barium titanate (BaTiO3), and is fabricated as a bulk ceramic or a thin film formed on a semiconductor substrate. Figure 15 shows an example of the relationship between the applied voltage and the effective dielectric constant, which is a characteristic of a voltage-variable dielectric.

[0085] According to the above formula 1, voltages with a difference of ΔE (≠0) are applied to each VVD phase shifter 32 for each adjacent radiating stub 312 so that the relative permittivities εr0, εr1, εr2, ... of the VVD phase shifters 32 of each radiating stub 312 are realized such that a phase difference of Δφ (≠0) occurs for each adjacent radiating stub 312 (see Figure 13 (B)).

[0086] When a voltage difference ΔE adjusted so that the relative permittivities εr0, εr1, εr2, . . . produce a phase difference of Δφ (≠ 0) is used and a voltage with this difference ΔE is applied to each of the multiple VVD phase shifters 32, the wavefront of the electromagnetic wave is tilted with respect to the arrangement of the multiple radiating stubs 312 (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 perpendicular to the arrangement of the multiple radiating stubs 312 (the x-axis direction in the figure), where Δθ = D sin(Δφ) (where D is the distance between the radiating stubs 312).

[0087] In addition, the difference Δφ in the amount of phase shift for adjacent phase shifters 22 when each of the multiple virtual element antennas 312a considered to constitute the radiating stub 312 is excited with a phase difference, and the difference Δφ in the amount of phase shift for the VVD phase shifters 32 of adjacent radiating stubs 312 when differential voltages are applied to each of the multiple VVD phase shifters 32 may be the same value or different values.

[0088] According to the plane wave generating mechanism 2 of the second embodiment, power is supplied via a plurality of probes 235, which makes it possible to generate a plane wave with a short transmission line (specifically, about 1λ (where λ is the free space wavelength)), which in turn makes it possible to avoid an increase in transmission loss, to configure the antenna power supply section compactly, and to generate a plane wave over a wide frequency band.

[0089] According to the plane wave generating mechanism 2 of the second embodiment, the phase of the electromagnetic wave supplied to each of the plurality of probes 235 is controlled by the plurality of phase shifters 22, so that the wavefront of the electromagnetic wave propagating through the parallel plate line can be tilted, and it becomes possible to output an electromagnetic wave with an arbitrarily tilted wavefront.

[0090] According to the plane wave generating mechanism 2 of the second embodiment, electromagnetic waves (RF signals, wireless communication waves) are supplied to each probe 235 using a distribution circuit as the power divider 21 formed by branching the wiring from the vertex 211 of the power divider 21 toward each probe 235 by patterning a microstrip line, so that the phase shifter 22 (specifically, a digital phase shifter) can be easily incorporated without complicating the circuit configuration.

[0091] Furthermore, according to the phased array antenna 12 of the second embodiment, the voltage applied to each of the VVD phase shifters 32 of the plurality of radiation stubs 312 is changed to change the relative dielectric constant of each of the VVD phase shifters 32 of the plurality of radiation stubs 312, thereby tilting the wavefront of the electromagnetic wave passing through each of the plurality of radiation stubs 312, thereby performing beam scanning in the azimuth angle direction, and also the wavefront of the electromagnetic wave propagating through the parallel plate line of the plane wave generating mechanism 2 is tilted to tilt the wavefront of the electromagnetic wave output from the plane wave generating mechanism 2 and incident on the base 311 of the antenna unit 3, thereby performing beam scanning in the elevation angle direction. Therefore, it is possible to improve the scanning speed of beam scanning, realize high aperture efficiency, and realize a low-profile antenna.

[0092] According to the phased array antenna 12 of the second embodiment, the VVD phase shifter 32 is arranged at the tip of the convex structure of each radiation stub 312 having a protruding structure, so that it is possible to reduce loss in the feeder line.

[0093] According to the phased array antenna 12 of the second embodiment, a multi-layered VVD phase shifter 32 is arranged for each radiating stub 312, so that it is possible to realize an antenna with good reflection characteristics in which the return loss is maintained at a good level over a wide frequency band.

[0094] The above describes an embodiment of the present invention, but the specific configuration is not limited to the above embodiment, and even if there are design changes or the like within the scope of the gist of the present invention, they are included in the present invention.

[0095] Specifically, in the above embodiment, the plane wave generating mechanism 2 functions as a power feed section of the antenna, and the plane waves generated by the plane wave generating mechanism 2 are incident on the phased array antennas 11 and 12. However, the use of the plane wave generating mechanism 2 is not limited to the power feed section of the antenna, and it may be incorporated into another device or used in combination with another device. [Explanation of symbols]

[0096] 11 Phased array antenna (first embodiment) 12 Phased array antenna (embodiment 2) 2. Plane wave generation mechanism 21 Power divider 211 Apex 22 Phase shifter 23 Plane wave generator 231 Ground conductor plate 232 Dielectric Substrate 233 parallel plate 234 Power supply dielectric substrate 235 Probe 3 Antenna section 31 Feed Array 311 Base 312 Radiation Stub 312a Virtual Element Antenna 313 Dielectric 314 Back Plate 315 Surface Plate 32 VVD phase shifter 33 Insulation section 34 electrodes 35 Insulation sheet 36 Phase shifter power supply 4 Rotating part 5. Control section

Claims

1. A ground conductor plate; a parallel plate disposed parallel to the ground conductor plate; a dielectric substrate disposed between the ground conductor plate and the parallel plate, forming a parallel plate line for propagating electromagnetic waves; a power supply dielectric substrate disposed on the opposite side of the ground conductor plate from the dielectric substrate; a plurality of probes arranged in a line at equal intervals d along a direction perpendicular to the propagation direction of the electromagnetic wave at a position near one end of the feeding dielectric substrate in the propagation direction of the electromagnetic wave, the probes penetrating through to the dielectric substrate and supplying the electromagnetic wave to the parallel plate line; The distance d is adjusted to satisfy λ / 2≦d<λ, where λ is the free space wavelength of the electromagnetic wave, The probe penetrates a blind hole formed in the dielectric substrate. A plane wave generating mechanism characterized by:

2. a plurality of phase shifters provided corresponding to the plurality of probes, a phase of the electromagnetic wave supplied to each of the plurality of probes is controlled by the plurality of phase shifters, thereby tilting the wavefront of the electromagnetic wave propagating through the parallel plate line; 2. The plane wave generating mechanism according to claim 1 .

3. a power divider formed by patterning a microstrip line to branch wiring from a vertex electrically connected to the antenna port toward each of the plurality of probes, on a surface of the feeding dielectric substrate opposite to the ground conductor plate; supplying electromagnetic waves to each of the plurality of probes using the power divider; 3. The plane wave generating mechanism according to claim 1 or 2.

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