Phase modulator and phased array antenna device

Abstract

This phase modulator includes: an input unit to which an AC signal is input from an oscillator; an output unit that outputs the AC signal input to the input unit to an antenna; and a phase modulation unit that is disposed between the input unit and the output unit, modulates a phase of the AC signal input to the input unit, and transmits the phase-modulated signal to the output unit. The phase modulation unit includes: wiring connected to the input unit and the output unit; a transistor connected between a first portion and a second portion of the wiring; a counter electrode facing the wiring; and a liquid crystal layer provided between the wiring and the counter electrode.

Description

Phase modulator and phased array antenna device

[0001] An embodiment of the present invention relates to a phase modulator using a liquid crystal material, or to a phased array antenna device having a phase modulator using a liquid crystal material.

[0002] A phased array antenna device has the characteristic that, when a radio frequency signal is applied to some or all of a plurality of antenna elements, the amplitude and phase of each radio frequency signal are controlled, thereby enabling the radiation directivity of the antenna to be controlled while keeping the antenna orientation fixed in one direction. In a phased array antenna device, a phase modulator is used to control the phase of the radio frequency signal applied to the antenna elements.

[0003] Various phase modulator methods have been adopted, including a method of physically changing the length of a transmission line to modulate the phase of a high-frequency signal, a method of changing the impedance along the transmission line to modulate the phase of a high-frequency signal through reflection, and a method of generating a signal with a desired phase by controlling the gain of an amplifier that amplifies two signals with different phases and combining the two signals.In addition to these, a method that utilizes the unique property of liquid crystal material, in which the dielectric constant changes depending on the applied voltage, has been disclosed as an example of a phase modulator (see Patent Document 1).

[0004] Japanese Patent Application Publication No. 11-103201

[0005] In a phase modulator using liquid crystal, it is desirable to be able to arbitrarily adjust the phase of a high-frequency signal between its input and output sections within the range of 0° to 360°. However, because there is a limit to the amount of change in the dielectric constant of the liquid crystal material used in the phase modulator, and because the wiring length (path length of the high-frequency signal) used in the phase modulator is fixed, it is difficult to adjust the phase of the radio wave within the range of 0° to 360°.

[0006] An object of one embodiment of the present invention is to make it possible to freely adjust the phase of a high frequency signal between the input and output of a phase modulator.

[0007] A phase modulator according to one embodiment of the present invention has an input section to which an AC signal from an oscillator is input, an output section that outputs the AC signal input to the input section to an antenna, and a phase modulation section arranged between the input section and the output section that modulates the phase of the AC signal input to the input section and transmits it to the output section, wherein the phase modulation section comprises wiring connected to the input section and the output section, transistors connected to first and second portions on the wiring, a counter electrode facing the wiring, and a liquid crystal layer between the wiring and the counter electrode.

[0008] 2 is a plan view showing an overview of a phased array antenna apparatus according to an embodiment of the present invention. FIG. 3 is a plan view showing an overview of a phase modulator according to an embodiment of the present invention. FIG. 4 is a plan view showing wiring of a phase modulator according to an embodiment of the present invention. FIG. 5 is a plan view showing a counter electrode of a phase modulator according to an embodiment of the present invention. FIG. 6 is a cross-sectional view taken along line A1-A2 of FIG. 2. FIG. 7 is a cross-sectional view taken along line B1-B2 of FIG. 2. FIG. 8 is a cross-sectional view taken along line C1-C2 of FIG. 2. FIG. 9 is a circuit configuration diagram of a phased array antenna apparatus according to an embodiment of the present invention. FIG. 10 is a diagram showing phase modulation by a phase modulator according to an embodiment of the present invention. FIG. 11 is a plan view showing wiring of a phase modulator according to an embodiment of the present invention. FIG. 12 is a plan view showing wiring of a phase modulator according to an embodiment of the present invention. FIG. 13 is a plan view showing wiring of a phase modulator according to an embodiment of the present invention. FIG. 14 is a diagram showing input impedance of an open stub in a phase modulator according to an embodiment of the present invention. FIG. 15 is a plan view showing wiring of a phase modulator according to an embodiment of the present invention.

[0009] Each embodiment of the present invention will be described below with reference to the drawings. The following disclosure is merely an example. Configurations that a person skilled in the art can easily arrive at by appropriately modifying the configuration of the embodiment while maintaining the gist of the invention are naturally included within the scope of the present invention. For clarity of explanation, the drawings may show the width, thickness, shape, etc. of each part more schematically than the actual form. However, the illustrated shapes are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, components similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0010] In each embodiment of the present invention, the direction from the substrate toward the liquid crystal layer is referred to as "up" or "upper." Conversely, the direction from the liquid crystal layer toward the substrate is referred to as "down" or "downper." While the terms "up" and "downper" are used for convenience of explanation, the vertical relationship between the substrate and the liquid crystal layer may be different from that illustrated. In the following description, for example, the expression "liquid crystal layer on a substrate" merely describes the vertical relationship between the substrate and the liquid crystal layer as described above, and other components may be disposed between the substrate and the liquid crystal layer. "Above" or "below" refers to the stacking order in a structure in which multiple layers are stacked. When referring to a first component above a transistor, the transistor and the first component may not overlap in a planar view. On the other hand, when referring to a first component vertically above a transistor, the transistor and the first component may overlap in a planar view.

[0011] In this specification, unless otherwise specified, expressions such as "α includes A, B, or C," "α includes any one of A, B, and C," and "α includes one selected from the group consisting of A, B, and C" do not exclude cases where α includes multiple combinations of A to C. Furthermore, these expressions do not exclude cases where α includes other elements.

[0012] The following embodiments can be combined with each other unless a technical contradiction occurs.

[0013] 1. First Embodiment The configuration of a phased array antenna device 10 according to one embodiment of the present invention will be described with reference to Fig. 1. The phased array antenna device 10 is a device that modulates the phase of a high-frequency signal output from an oscillator and radiates the modulated signal from an antenna.

[0014] [1-1. Configuration of Phased Array Antenna Apparatus 10] FIG. 1 is a plan view showing an overview of a phased array antenna apparatus according to one embodiment of the present invention. As shown in FIG. 1, the phased array antenna apparatus 10 includes a phase modulation unit 100, antenna elements 124, a distributor 126, an oscillator 128, signal lines 130, and a power supply 140. A plurality of antenna elements 124 are provided. The plurality of antenna elements 124 are arranged linearly, arc-shaped, or planarly to form an antenna element array. A high-frequency signal output from the oscillator 128 is distributed to the plurality of signal lines 130 by the distributor 126, modulated by the phase modulation unit 100, and emitted to the outside from the antenna elements 124. The power supply 140 is a DC power supply. The high-frequency signal is modulated by supplying a DC voltage from the power supply 140 to the phase modulation unit 100. While FIG. 1 illustrates a configuration in which the antenna elements 124 are arranged in a zigzag pattern, the configuration is not limited to this.

[0015] The phase modulation section 100 includes a feed conductor section 106 (a first feed conductor section 106a and a second feed conductor section 106b), wiring 108, a ground conductor section 110, a spacer 118, a sealant 120, and a liquid crystal layer 122. A phase modulation section 100 is provided for each of the plurality of antenna elements 124. The feed conductor section 106, wiring 108, and spacer 118 are provided individually for each phase modulation section 100. On the other hand, the ground conductor section 110, the sealant 120, and the liquid crystal layer 122 are provided in common to the plurality of phase modulation sections 100.

[0016] As will be described in detail later, the substrate (first substrate 102) on which the power supply conductor 106 and the wiring 108 are provided faces the substrate (second substrate 104) on which the ground conductor 110 is provided (see FIG. 5 ). The power supply conductor 106 and the wiring 108 face the ground conductor 110 via a liquid crystal layer 122 (see FIG. 5 ). The first substrate 102 and the second substrate 104 are separated by spacers 118 (see FIG. 7 ). The spacers 118 may be spherical or columnar. In a plan view, the wiring 108, the spacers 118, the sealant 120, and the liquid crystal layer 122 overlap the substrates. As described above, the ground conductor 110 faces the wiring 108, and therefore the ground conductor 110 can be referred to as a "counter electrode." In this case, the liquid crystal layer 122 can be said to be provided between the wiring 108 and the counter electrode.

[0017] As will be described in detail later, the wiring 108 has a non-linear shape. Specifically, the wiring 108 has a meandering shape. However, the shape of the wiring 108 is not limited to a meandering shape. A first power supply conductor portion 106a is connected to a first end P1 of the wiring 108. A second power supply conductor portion 106b is connected to a second end P2 of the wiring 108. The first power supply conductor portion 106a and the second power supply conductor portion 106b are arranged in an area that does not overlap with the substrates (the first substrate 102 and the second substrate 104) in a plan view. The first power supply conductor portion 106a and the second power supply conductor portion 106b have approximately the same shape.

[0018] A slit 111 is provided between the first power supply conductor 106a and a signal line 130 (e.g., a coaxial cable) that transmits a high-frequency signal. The width of the slit 111 is 1 μm or more and 10 μm or less, which is a distance that allows the high-frequency signal to be transmitted. Therefore, the signal line 130 transmits the high-frequency signal to the first power supply conductor 106a. On the other hand, a DC voltage is not transmitted from the signal line 130 to the first power supply conductor 106a.

[0019] The first power supply conductor portion 106a has a shape that is wider than the wiring 108. The first power supply conductor portion 106a is formed so as to match the input impedance in a circuit that propagates a high-frequency signal. For example, when the first power supply conductor portion 106a is connected to a coaxial cable (50 Ω), the first power supply conductor portion 106a is formed so that the input impedance is 50 Ω.

[0020] A slit 112 is provided between the second feed conductor 106b and the antenna element 124. The width of the slit 112 is 1 μm or more and 10 μm or less, which is a distance that allows high-frequency signals to be transmitted. Therefore, the second feed conductor 106b transmits high-frequency signals to the antenna element 124. On the other hand, a DC voltage is not transmitted from the second feed conductor 106b to the antenna element 124.

[0021] As described above, the slit 111 is provided between the first power supply conductor portion 106 a and the signal line 130, and the slit 112 is provided between the second power supply conductor portion 106 b and the antenna element 124. Therefore, when a DC voltage is supplied from the power source 140 to the first power supply conductor portion 106 a, the potentials of the first power supply conductor portion 106 a, the second power supply conductor portion 106 b, and the wiring 108 are controlled separately from the signal line 130 and the antenna element 124.

[0022] Since a high-frequency signal from the oscillator 128 is input to the first power supply conductor 106a, the first power supply conductor 106a can be referred to as the "input section." A high-frequency signal input to the input section and modulated by the phase modulation section 100 is transmitted to the second power supply conductor 106b. The high-frequency signal is output from the second power supply conductor 106b to the antenna element 124. Therefore, the second power supply conductor 106b can be referred to as the "output section." In this case, the phase modulation section 100 can be said to be disposed between the input section and the output section. Furthermore, the wiring 108 can be said to be connected to the input section and the output section. The phase modulation section 100 modulates the phase of the high-frequency signal and transmits it to the output section.

[0023] [1-2. Configuration of Phase Modulation Unit 100] The configuration of the phase modulation unit 100 will be described using FIGS. 2 to 8. FIG. 2 is a plan view showing an overview of a phase modulator according to one embodiment of the present invention. As shown in FIG. 2, the phase modulation unit 100 includes transistors Tr1 and Tr2 in addition to the above configuration. The transistor Tr1 connects the first portion X1 and the second portion X2 on the wiring 108. The transistor Tr2 connects the third portion X3 and the fourth portion X4 on the wiring 108. With respect to the path of the wiring 108 between the first power supply conductor 106a and the second power supply conductor 106b, the path length passing through the transistor Tr1 (first path length) is shorter than the path length not passing through the transistor Tr1 (second path length). Similarly, the path length passing through the transistor Tr2 is shorter than the path length not passing through the transistor Tr2.

[0024] The transistors Tr1 and Tr2 are turned on and off by supplying a voltage to their respective gate electrodes, and thus the path length of the wiring 108 between the first power supply conductor 106 a and the second power supply conductor 106 b is adjusted by the voltage supplied to each of the gate electrodes of the transistors Tr1 and Tr2.

[0025] The wiring 108 has a meander shape. The transistors Tr1 and Tr2 are provided so as to connect adjacent folded portions in the meander shape. In the embodiment shown in FIG. 2 , the transistors Tr1 and Tr2 are provided only in the folded portion at one end of the folded portions at both ends in the Z1 direction (the lower folded portion of the upper and lower folded portions in FIG. 2 ).

[0026] In other words, the wiring 108 includes line portions (first line portion 1081 and second line portion 1082) extending in the Z1 direction and a short-circuit portion 1083 that short-circuits the first line portion 1081 and the second line portion 1082. The second line portion 1082 is disposed in the Z2 direction relative to the first line portion 1081. In other words, the first line portion 1081 and the second line portion 1082 are elongated in the Z1 direction, and the short-circuit portion 1083 connects the first line portion 1081 and the second line portion 1082 at one end of the first line portion 1081 and the second line portion 1082 in the Z1 direction. In this embodiment, the Z2 direction is perpendicular to the Z1 direction, but this configuration is not limited thereto. The Z2 direction may be any direction that intersects with the Z1 direction.

[0027] The first line portion 1081 and the second line portion 1082 are each longer than the short-circuit portion 1083. The first line portion 1081 and the second line portion 1082 are arranged side by side in the Z2 direction, and the first line portion 1081 and the second line portion 1082 are connected by the short-circuit portion 1083 at first ends (upper ends in FIG. 2 ) of each of the first line portion 1081 and the second line portion 1082 in the Z1 direction. Meanwhile, the first line portion 1081 and the second line portion 1082 are connected by the transistor Tr1 at second ends (ends opposite the first ends) of the first line portion 1081 and the second line portion 1082 in the Z1 direction. However, the transistor Tr1 is not limited to the configuration of FIG. 2 as long as it is provided so as to connect the first line portion 1081 and the second line portion 1082 at a position different from the short-circuit portion 1083 in the Z1 direction.

[0028] In the present embodiment, the configuration in which the transistors Tr1 and Tr2 are provided only at the second end of the first line portion 1081 has been illustrated, but the present invention is not limited to this configuration. For example, the transistors may be provided at the first end of the first line portion 1081 in place of the short-circuit portion 1083.

[0029] FIG. 3 is a plan view showing the wiring of a phase modulator according to one embodiment of the present invention. FIG. 3 shows a plan view of the first substrate 102. The first substrate 102 is a flat substrate having an insulating surface. The first power supply conductor 106a, the second power supply conductor 106b, and the wiring 108 are provided on this insulating surface. This structure is fabricated by forming at least one conductive film on the surface of the first substrate 102 and patterning the conductive film by etching. The first substrate 102 is formed of an insulating material such as glass or ceramic, and the insulating surface may be formed by its own physical properties or by forming an insulating film on the surface. The conductive film is a metal film such as aluminum or copper, and is fabricated by vacuum deposition or sputtering. Metal foil may be used instead of the conductive film.

[0030] Fig. 4 is a plan view showing the counter electrodes of a phase modulator according to one embodiment of the present invention. Fig. 4 also shows a plan view of the second substrate 104. The second substrate 104 is a flat base body having an insulating surface. A ground conductor 110 is provided over substantially the entire surface of one main surface of the second substrate 104. The ground conductor 110 is also formed of a conductive film. The second substrate 104 is made of the same material as the first substrate 102.

[0031] The phase modulation unit 100 has a structure in which a surface of the first substrate 102 on which the wiring 108 is provided and a surface of the second substrate 104 on which the ground conductor 110 is provided are disposed opposite each other with a gap therebetween. As shown in Fig. 2, a spacer 118 is provided in an area surrounded by a sealant 120. The spacer 118 determines the thickness of a liquid crystal layer 122 that exists between the opposing wiring 108 and ground conductor 110. For example, the spacer 118 may be formed of a metal material or an insulating material.

[0032] 2 , a sealant 120 is provided to fix the first substrate 102 and the second substrate 104 in a state in which the substrates are disposed opposite each other, and to seal the liquid crystal layer 122. The sealant 120 is provided along the outer periphery of the second substrate 104. The sealant 120 is provided so as to surround the liquid crystal layer 122, and the liquid crystal layer 122 is sealed between the first substrate 102 and the second substrate 104.

[0033] Fig. 5 is a cross-sectional view taken along the line A1-A2 in Fig. 2. As shown in Fig. 5, the phase modulation unit 100 has a structure in which a first substrate 102 and a second substrate 104 are arranged facing each other with a gap therebetween, and a liquid crystal layer 122 is provided between the wiring 108 and the ground conductor 110. The liquid crystal layer 122 is filled in a space sealed by a sealant 120.

[0034] The liquid crystal layer 122 is made of a liquid crystal material. Examples of liquid crystal materials that can be used include nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, discholesteric liquid crystal, and ferroelectric liquid crystal (e.g., chiral smectic liquid crystal). A change in the orientation state of the liquid crystal layer 122 changes the dielectric constant of the liquid crystal layer 122. The orientation of the liquid crystal molecules contained in the liquid crystal layer 122 is controlled by a DC voltage applied to the wiring 108 from a power source 140. This power source 140 is sometimes referred to as a power supply unit. Meanwhile, the liquid crystal molecules of the liquid crystal layer 122 cannot follow an AC electric field generated by a high-frequency signal propagating through the wiring 108. Therefore, the orientation state of the liquid crystal layer 122 is not changed by the high-frequency signal. The phase modulation unit 100 utilizes this characteristic to control the phase of the high-frequency signal propagating through the wiring 108.

[0035] Although not shown in FIG. 5, an alignment film for controlling the alignment state of the liquid crystal molecules is provided between the wiring 108 and the liquid crystal layer 122 and between the ground conductor 110 and the liquid crystal layer 122 .

[0036] Fig. 6 is a cross-sectional view taken along line B1-B2 in Fig. 2. As shown in Figs. 2 and 6, the first power supply conductor 106a is provided in a region that does not overlap with the second substrate 104 in a plan view. The first power supply conductor 106a is provided on the same surface of the first substrate 102 as the surface on which the wiring 108 is provided (the surface facing the second substrate 104). Although not shown, the second power supply conductor 106b has a similar structure.

[0037] When the phase modulation section 100 is connected to a coaxial cable, the first feed conductor section 106a is connected to the inner conductor (core wire) of the coaxial cable, and the ground conductor section 110 is connected to the outer conductor (shield wire).

[0038] 7, spacers 118 are provided between the first substrate 102 and the second substrate 104 to maintain a constant gap. This gap is the cell gap of the cell that encloses the liquid crystal layer 122. This gap can also be referred to as the thickness of the liquid crystal layer 122. For example, the spacers 118 are provided at positions adjacent to the sealant 120 or at positions near the sealant 120. The number of spacers 118 to be provided is arbitrary.

[0039] A high-frequency signal and a control signal that controls the orientation of the liquid crystal are applied to the wiring 108. The control signal is preferably a DC signal or a polarity inversion signal whose polarity is inverted every certain time. Application of the control signal to the wiring 108 changes the orientation of the liquid crystal molecules in the liquid crystal layer 122. Because liquid crystal molecules are a type of polar molecule, the dielectric constant of the liquid crystal layer 122 changes depending on the orientation state of the liquid crystal molecules. The dielectric constant of the liquid crystal layer 122 can be adjusted by the magnitude of the voltage of the control signal. In other words, the phase modulation unit 100 can change the dielectric constant of the liquid crystal layer 122 by the control signal applied to the wiring 108. In the liquid crystal layer 122, the region where the orientation of the liquid crystal molecules changes is mainly the region where the wiring 108 and the ground conductor 110 face each other.

[0040] [1-3. Circuit Configuration of Phased Array Antenna Apparatus 10] Fig. 8 is a circuit configuration diagram of a phased array antenna apparatus according to one embodiment of the present invention. As shown in Fig. 8, the phase modulation unit 100 is represented by a resistance R, a capacitance C, and an inductance L. A slit 111 is provided between the phase modulation unit 100 and the oscillator 128, and the two are insulated from each other with respect to DC voltage, but a high-frequency signal can be transmitted from the oscillator 128 to the phase modulation unit 100. Similarly, a slit 112 is provided between the phase modulation unit 100 and the antenna element 124, and the two are insulated from each other with respect to DC voltage, but a high-frequency signal can be transmitted from the phase modulation unit 100 to the antenna element 124.

[0041] The capacitance C is the capacitance between the wiring 108, which uses the liquid crystal layer 122 as a dielectric, and the ground conductor 110. As described above, the dielectric constant of the liquid crystal layer 122 is controlled by the voltage applied between the wiring 108 and the ground conductor 110. The wavelength λ in the medium of the high-frequency signal propagating through the wiring 108 of the phase modulation unit 100 is expressed by the following equation (1).

[0042]

[0043] In the above formula (1), C ｐ is the speed of light. f is the frequency of the high frequency signal. λ ０ is the wavelength of the high-frequency signal in vacuum. ｒ is the dielectric constant of the liquid crystal layer 122.

[0044] In this embodiment, ε ｒ varies depending on the voltage applied between the wiring 108 and the ground conductor 110, and is between 2.5 and 3.7. In other words, by controlling the voltage applied between the wiring 108 and the ground conductor 110, it is possible to change the wavelength λ of the high-frequency signal passing through the phase modulation unit 100. This change in wavelength λ causes the phase difference Δφ to change based on the following equation (2).

[0045]

[0046] In the above formula (2), Δφ is the phase difference, and λ is the path length (the length of the wiring 108). ｇ is the propagation wavelength of the high-frequency signal.ｇ is the propagation velocity of the high frequency signal.

[0047] 9 is a diagram showing the state of phase modulation by a phase modulator according to one embodiment of the present invention. In FIG. 9, region R1 is the region before the high-frequency signal enters the phase modulation unit 100, and is, for example, the region where the first power supply conductor 106a is provided. Region R2 is the region that overlaps with the liquid crystal layer 122 in plan view. Region R3 is the region after the high-frequency signal leaves the phase modulation unit 100, and is, for example, the region where the second power supply conductor 106b is provided. The wavelength of the high-frequency signal in region R1 is λ １ The wavelength of the high frequency signal in region R2 is λ ２ The wavelength of the high frequency signal in region R3 is λ ３ is.

[0048] In this embodiment, the regions R1 and R3 are regions that do not overlap with the liquid crystal layer 122 in a plan view. １ is the wavelength λ ３ On the other hand, since the region R2 overlaps with the liquid crystal layer 122 in a plan view, λ ２ As shown in the above formula (1), varies depending on the orientation of the liquid crystal molecules in the liquid crystal layer 122.

[0049] In FIG. 9, the top waveform is when the voltage V applied to the wiring 108 is V ０ This is the waveform when V ０ is, for example, 0 V. The phase difference at this time is 0°. The voltage applied to the ground conductor 110 is 0 V.

[0050] The second waveform from the top shows the voltage V applied to the wiring 108. １ , and the waveform in region R3 when the phase difference is 0° is shown by the dotted line. １ As a result, the wavelength λ in the region R2 becomes smaller, and the phase at the boundary between the region R2 and the region R3 shifts. ０ When the voltage V for the waveform is V １ When the phase difference is 90°, the waveforms are

[0051] The third waveform from the top shows that the voltage V applied to the wiring 108 is V ２ , and the waveform in region R3 when the phase difference is 0° is shown by the dotted line. ２ As a result, the wavelength λ in the region R2 becomes smaller, and the phase at the boundary between the region R2 and the region R3 becomes further shifted. ０ When the voltage V for the waveform is V ２ When the phase difference between the waveforms is 180°.

[0052] The bottom waveform shows the voltage V applied to the wiring 108 when V ３ , and the waveform in region R3 when the phase difference is 0° is shown by the dotted line. ３ As a result, the wavelength λ in the region R2 becomes smaller, and the phase at the boundary between the region R2 and the region R3 becomes further shifted. ０ When the voltage V for the waveform is V ３ When the phase difference between the waveforms is 270°.

[0053] As described above, the phase difference of the high-frequency signal output from the phase modulation unit 100 can be adjusted by the voltage applied to the wiring 108. The adjustable range of the phase difference is preferably 0° to 360°. However, in reality, there is a limit to the amount of change in the dielectric constant of the liquid crystal layer 122, so it is difficult to adjust the phase difference over the entire range of 0° to 360°. Therefore, in the phase modulation unit 100 according to this embodiment, the adjustable range of the phase difference can be expanded by adjusting the length of the wiring 108.

[0054] 1-4. Configuration of the phase modulation unit 100] Figures 10 and 11 are plan views showing the wiring of a phase modulator according to one embodiment of the present invention. Figures 10 and 11 are drawings extracting only the wiring 108 shown in Figure 2. The lower diagrams in Figures 10 and 11 show the circuit configuration of the wiring 108 and the on / off states of the transistors, and the upper diagrams show equivalent circuit diagrams reflecting the on / off states of the transistors.

[0055] 10 illustrates a case where both transistors Tr1 and Tr2 are in the off state. As shown in FIG. 10, transistor Tr1 is in the off state, and the first portion X1 and the second portion X2 are not short-circuited, so the high-frequency signal propagates from the first portion X1 through the fifth portion X5 to the second portion X2. Similarly, transistor Tr2 is in the off state, and the third portion X3 and the fourth portion X4 are not short-circuited, so the high-frequency signal propagates from the third portion X3 through the seventh portion X7 to the fourth portion X4. As a result, the path of the high-frequency signal in wiring 108 is as shown in the equivalent circuit diagram.

[0056] 11 illustrates a case where transistor Tr1 is in an off state and transistor Tr2 is in an on state. As shown in FIG. 11, transistor Tr1 is in an off state and the first portion X1 and the second portion X2 are not short-circuited, so the high-frequency signal propagates from the first portion X1 through the fifth portion X5 to the second portion X2. Meanwhile, transistor Tr2 is in an on state and the third portion X3 and the fourth portion X4 are short-circuited, so the high-frequency signal propagates from the third portion X3 through transistor Tr2 to the fourth portion X4. As a result, the path of the high-frequency signal in wiring 108 is as shown in the equivalent circuit diagram.

[0057] As described above, the wiring 108 includes the transistors Tr1 and Tr2, and the path length of the wiring 108 can be adjusted by controlling the on and off states of these transistors. The adjustable path length allows the phase difference to be further adjusted as shown in the above formula (2). As a result, the phase modulation unit 100 can adjust the phase difference over a wide range.

[0058] In this embodiment, the configuration in which two transistors are provided is exemplified, but the present invention is not limited to this configuration. For example, a configuration in which three or more transistors are provided so that the path length can be adjusted in more stages may be adopted.

[0059] 12 to 14, a phased array antenna apparatus 10 according to a second embodiment will be described. The phased array antenna apparatus 10 according to the second embodiment is similar to the phased array antenna apparatus 10 according to the first embodiment, but differs in the position of the transistor in the path of the wiring 108. In the following description, a description of the same configuration as in the first embodiment will be omitted, and only configurations different from the first embodiment will be described.

[0060] 2-1. Configuration of the Phase Modulation Unit 100 Figures 12 and 13 are plan views showing the wiring of a phase modulator according to one embodiment of the present invention. The lower diagrams in Figures 12 and 13 show the circuit configuration of the wiring 108 and the on / off states of the transistors, and the upper diagrams show equivalent circuit diagrams reflecting the on / off states of the transistors. The phase modulation unit 100 includes transistors Tr3 and Tr4 in addition to transistors Tr1 and Tr2. Transistor Tr3 is provided at a position on the wiring 108 connecting the fifth portion X5 and the sixth portion X6. Transistor Tr4 is provided at a position on the wiring 108 connecting the seventh portion X7 and the eighth portion X8.

[0061] In other words, the wiring 108 includes a first line portion 1081 and a second line portion 1082 extending in the Z1 direction. The second line portion 1082 is disposed in the Z2 direction relative to the first line portion 1081. The transistors Tr1 and Tr3 are provided at different positions in the Z1 direction so as to short-circuit the first line portion 1081 and the second line portion 1082. In this embodiment, the transistors Tr1 and Tr3 are provided at both ends of the first line portion 1081 and the second line portion 1082 in the Z1 direction so as to short-circuit the first line portion 1081 and the second line portion 1082.

[0062] Similar to the transistors Tr1 and Tr2, the transistors Tr3 and Tr4 are turned on and off by supplying a voltage to their gate electrodes, and thus the path length of the wiring 108 between the first power supply conductor 106 a and the second power supply conductor 106 b is adjusted by the voltage supplied to the gate electrodes of the transistors Tr3 and Tr4.

[0063] The transistors Tr1 and Tr3 are connected in parallel to and between the first line portion 1081 and the second line portion 1082. Specifically, the transistor Tr3 is provided at a first end portion (the upper end portion in FIG. 13 ) of the first line portion 1081 and the second line portion 1082 in the Z1 direction, at a position connecting the first line portion 1081 and the second line portion 1082. The transistor Tr1 is provided at a second end portion (the end portion opposite the first end portion) of the first line portion 1081 and the second line portion 1082 in the Z1 direction, at a position connecting the first line portion 1081 and the second line portion 1082.

[0064] 12 illustrates a case in which transistors Tr1 and Tr2 are both off and transistors Tr3 and Tr4 are both on. As shown in FIG. 12, transistor Tr1 is off, the first portion X1 and the second portion X2 are not short-circuited, transistor Tr3 is on, and the fifth portion X5 and the sixth portion X6 are short-circuited. Therefore, the high-frequency signal propagates from the first portion X1 through transistor Tr3 to the second portion X2. Similarly, transistor Tr2 is off, the third portion X3 and the fourth portion X4 are not short-circuited, transistor Tr4 is on, and the seventh portion X7 and the eighth portion X8 are short-circuited. Therefore, the high-frequency signal propagates from the third portion X3 through transistor Tr4 to the fourth portion X4. As a result, the path of the high-frequency signal in wiring 108 is as shown in the equivalent circuit diagram.

[0065] 13 illustrates a case in which transistors Tr1 and Tr4 are off and transistors Tr2 and Tr3 are on. As shown in FIG. 13 , transistor Tr1 is off, the first portion X1 and the second portion X2 are not short-circuited, transistor Tr3 is on, and the fifth portion X5 and the sixth portion X6 are short-circuited. Therefore, the high-frequency signal is propagated from the first portion X1 through transistor Tr3 to the second portion X2. Meanwhile, transistor Tr2 is on, the third portion X3 and the fourth portion X4 are short-circuited, transistor Tr4 is off, and the seventh portion X7 and the eighth portion X8 are not short-circuited. Therefore, the high-frequency signal is propagated from the third portion X3 through transistor Tr2 to the fourth portion X4. As a result, the path of the high-frequency signal in wiring 108 is as shown in the equivalent circuit diagram.

[0066] When transistor Tr2 is on, it appears that the high-frequency signal propagates from the third portion X3 through transistor Tr2 to the fourth portion X4 without deliberately controlling transistor Tr4 to the off state. However, in Figure 11, if the resistance of transistor Tr2 when transistor Tr2 is on is greater than the resistance of the wiring 108 along the path (detour path) from the third portion X3 through the seventh portion X7 along the pattern of wiring 108 to the fourth portion X4, the path length of the high-frequency signal cannot be changed as intended even if transistor Tr2 is on. However, as in this embodiment, by forcibly controlling transistor Tr4 to the off state, the detour path can be cut off, and the path length of the high-frequency signal can be changed as intended.

[0067] 13 shows a transmission line in which the tips of the seventh portion X7 and the eighth portion X8 are open, which is called an open stub circuit. In this state, it is necessary to consider the effects of high-frequency signal reflection at the open tips. The normalized input impedance of the open stub line, taking such effects into account, is expressed by the following equation (3):

[0068]

[0069] In the above formula (3), l is the stub length, which is the distance between the first line portion 1081 and the second line portion 1082. j is the imaginary unit (=√−1), and β is the propagation constant (=2π / λ ｇ ) λ ｇ is the propagation wavelength of the high frequency signal.

[0070] The graph of equation (3) is shown in Fig. 14. Fig. 14 is a diagram showing the input impedance of an open stub in a phase modulator according to one embodiment of the present invention. From the graph in Fig. 14, it can be seen that the impedance is maximum when the phase of the input wavelength is 0, π, or 2π. In other words, in order to suppress the influence of reflections and the like caused by the tips of the first line portion 1081 and the second line portion 1082 that are opened by controlling the transistors to the off state, the lengths in the Z1 direction of the first line portion 1081, the second line portion 1082, and the line portions parallel to them are set to λ ｇ It is preferable to adjust the value to an integral multiple of / 2.

[0071] As described above, in the phase modulation unit 100 according to this embodiment, a plurality of transistors are connected in parallel to two line portions that are long in the Z1 direction and adjacent in the Z2 direction, so that when the path length of a high-frequency signal is changed by turning the transistors on and off, the influence of the resistance of the transistors in the on state can be eliminated. Furthermore, the length of the line portion that is long in the Z1 direction can be set to a value that is equal to the wavelength λ of the high-frequency signal. ｇ For λ ｇ By adjusting the ratio to an integer multiple of / 2, high frequency signals can be efficiently propagated through the wiring 108.

[0072] In the present embodiment, a configuration in which four transistors are provided for four line segments has been exemplified, but the present invention is not limited to this configuration. For example, a configuration in which six or more transistors are provided for six or more line segments, thereby enabling the path length to be adjusted in more stages, may be used.

[0073] 15 , a phased array antenna apparatus 10 according to a third embodiment will be described. The phased array antenna apparatus 10 according to the third embodiment is similar to the phased array antenna apparatus 10 according to the second embodiment, but differs in the configuration of the wiring 108. In the following description, a description of the same configuration as in the second embodiment will be omitted, and only the configuration different from the second embodiment will be described.

[0074] [3-1. Configuration of Phase Modulation Unit 100] Figure 15 is a plan view showing the wiring of a phase modulator according to one embodiment of the present invention. As shown in Figure 15, the wiring 108 has a first wiring unit 210, a second wiring unit 220, and a third wiring unit 230. The first wiring unit 210 has line units 211 to 214 extending longitudinally in the Z1 direction and transistors Tr11 to Tr14. The second wiring unit 220 has line units 221 to 224 extending longitudinally in the Z1 direction and transistors Tr21 to Tr24. The third wiring unit 230 has line units 231 to 234 extending longitudinally in the Z1 direction and transistors Tr31 to Tr34. In the Z1 direction, the line units 211 to 214 are longer than the line units 221 to 224, and the line units 221 to 224 are longer than the line units 231 to 234.

[0075] The transistors Tr11 and Tr13 are provided between the line portions 211 and 212. The transistor Tr11 is provided at a first end (left end in FIG. 15 ) of the line portions 211 and 212 in the Z1 direction, and the transistor Tr13 is provided at a second end (end opposite to the first end) of the line portions 211 and 212 in the Z1 direction. The transistors Tr11 and Tr13 are connected in parallel to the line portions 211 and 212.

[0076] The transistors Tr12 and Tr14 are provided between the line portions 213 and 214. The transistor Tr12 is provided at a first end of the line portions 213 and 214 in the Z1 direction, and the transistor Tr14 is provided at a second end of the line portions 213 and 214 in the Z1 direction. The transistors Tr12 and Tr14 are connected in parallel to the line portions 213 and 214.

[0077] The transistors Tr21 and Tr23 are provided between the line portions 221 and 222. The transistor Tr21 is provided at a first end in the Z1 direction of the line portions 221 and 222, and the transistor Tr23 is provided at a second end in the Z1 direction of the line portions 221 and 222. The transistors Tr21 and Tr23 are connected in parallel to the line portions 221 and 222.

[0078] The transistors Tr22 and Tr24 are provided between the line portions 223 and 224. The transistor Tr22 is provided at a first end of the line portions 223 and 224 in the Z1 direction, and the transistor Tr24 is provided at a second end of the line portions 223 and 224 in the Z1 direction. The transistors Tr22 and Tr24 are connected in parallel to the line portions 223 and 224.

[0079] The transistors Tr31 and Tr33 are provided between the line portions 231 and 232. The transistor Tr31 is provided at a first end of the line portions 231 and 232 in the Z1 direction, and the transistor Tr33 is provided at a second end of the line portions 231 and 232 in the Z1 direction. The transistors Tr31 and Tr33 are connected in parallel to the line portions 231 and 232.

[0080] The transistors Tr32 and Tr34 are provided between the line portions 233 and 234. The transistor Tr32 is provided at a first end of the line portions 233 and 234 in the Z1 direction, and the transistor Tr34 is provided at a second end of the line portions 233 and 234 in the Z1 direction. The transistors Tr32 and Tr34 are connected in parallel to the line portions 233 and 234.

[0081] When high-frequency signals of different frequencies are input to the phase modulation unit 100, the lengths in the Z1 direction of the line portions included in the first wiring portion 210, the second wiring portion 220, and the third wiring portion 230 are determined in accordance with the wavelengths of the high-frequency signals. For example, when the wavelength of the high-frequency signal input to the phase modulation unit 100 is λ ｇ１ , λ ｇ２ , λ ｇ３ If (λ ｇ１ >λ ｇ２ >λ ｇ３ ), the length of the line portions 211 to 214 is λｇ１ / 2, and the length of the line portions 221 to 224 is adjusted to an integer multiple of λ ｇ２ / 2, and the length of the line portions 231 to 234 is adjusted to an integer multiple of λ ｇ３ The value is adjusted to an integer multiple of / 2.

[0082] The phase modulation unit 100 has a wavelength λ ｇ１ When a high-frequency signal having a value of 1 / (1 / 2) is input, the path length is adjusted by the first wiring section 210. That is, the path length is adjusted by turning on / off the transistors Tr11 to Tr14. In this case, as shown in FIG. 15 , the transistors Tr23, Tr24, Tr33, and Tr34 are controlled to be on, and the transistors Tr21, Tr22, Tr31, and Tr32 are controlled to be off. In the example of FIG. 15 , as an example of path length adjustment by the first wiring section 210, the transistors Tr12 and Tr13 are controlled to be on, and the transistors Tr11 and Tr14 are controlled to be off.

[0083] The phase modulation unit 100 has a wavelength λ ｇ２ When a high-frequency signal having a frequency of 100 kHz or less is input, the path length is adjusted by the second wiring portion 220. That is, the path length is adjusted by turning on / off the transistors Tr21 to Tr24. In this case, the transistors Tr13, Tr14, Tr33, and Tr34 are controlled to be in the on state, and the transistors Tr11, Tr12, Tr31, and Tr32 are controlled to be in the off state.

[0084] The phase modulation unit 100 has a wavelength λ ｇ３ When a high-frequency signal having a value of 1 / (1 / 2) is input, the path length is adjusted by the third wiring portion 230. That is, the path length is adjusted by turning on / off the transistors Tr31 to Tr34. In this case, the transistors Tr13, Tr14, Tr23, and Tr24 are controlled to be in the on state, and the transistors Tr11, Tr12, Tr21, and Tr22 are controlled to be in the off state.

[0085] As described above, according to the phase modulation section 100 of this embodiment, even if high-frequency signals of different frequencies are input to the phase modulation section 100, it is possible to obtain the same effects as in the second embodiment for each frequency.

[0086] In the present embodiment, a configuration in which four transistors are provided for four line segments in each of the first wiring section 210, the second wiring section 220, and the third wiring section 230 has been exemplified, but this configuration is not limiting. For example, a configuration in which six or more transistors are provided for six or more line segments may be used, thereby enabling the path length to be adjusted in more stages.

[0087] The above-described embodiments of the present invention can be implemented in any suitable combination as long as they are not mutually contradictory. Configurations in which a person skilled in the art appropriately adds or deletes components or modifies the design, or adds or omits processes or modifies conditions, based on the phased array antenna apparatus and phase modulation unit of each embodiment are also included in the scope of the present invention as long as they include the gist of the present invention.

[0088] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0089] 10: Phased array antenna device, 100: Phase modulation section, 102: First substrate, 104: Second substrate, 106: Power supply conductor section, 106a: First power supply conductor section, 106b: Second power supply conductor section, 108: Wiring, 110: Ground conductor section, 111, 112: Slit, 118: Spacer, 120: Sealing material, 122: Liquid crystal layer, 124: Antenna element, 126: Distributor, 128: Oscillator, 130: Signal line, 140: Power supply, 210: First wiring section, 211 to 214: Wiring section, 220: Second wiring section, 221 to 224: Wiring section, 230: Third wiring section, 231 to 234: Wiring section, 1081: First wiring section, 1082: second line portion, 1083: short circuit portion

Claims

1. A phase modulator comprising: an input section to which an AC signal from an oscillator is input; an output section to output the AC signal input to the input section to an antenna; and a phase modulation section disposed between the input section and the output section to modulate the phase of the AC signal input to the input section and transmit it to the output section, wherein the phase modulation section comprises: wiring connected to the input section and the output section; transistors connected to first and second portions of the wiring; an opposing electrode facing the wiring; and a liquid crystal layer between the wiring and the opposing electrode.

2. A phase modulator according to claim 1, wherein, with respect to the path length of the wiring between the input section and the output section, a first path length passing through the transistor is shorter than a second path length not passing through the transistor.

3. The phase modulator according to claim 2, wherein said phase modulation section further comprises a power supply section for applying a voltage to said wiring to adjust the orientation of liquid crystal molecules contained in said liquid crystal layer.

4. The phase modulator according to claim 1, wherein the wiring is meandering.

5. A phase modulator as described in claim 1, wherein the wiring comprises: a first line portion extending in a first direction; a second line portion extending in the first direction and arranged in a second direction intersecting the first direction relative to the first line portion; and a short-circuit portion short-circuiting the first line portion and the second line portion; and the transistor connects the first line portion and the second line portion at a position different from the short-circuit portion.

6. A phase modulator as described in claim 1, wherein the wiring comprises: a first line portion extending in a first direction; and a second line portion extending in the first direction and arranged in a second direction intersecting the first direction relative to the first line portion; and the transistors include a first transistor and a second transistor that short-circuit the first line portion and the second line portion at different positions in the first direction.

7. A phased array antenna device comprising the phase modulator according to any one of claims 1 to 6 and antenna elements connected to the phase modulator.

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