Antenna device

Abstract

This antenna device is characterized by comprising an antenna array in which a plurality of active antennas, each including an antenna and a semiconductor structure and generating or detecting electromagnetic waves, are arranged, and is further characterized in that: in the antenna array, a plurality of columns in which one or more active antennas are arranged in a first direction are arranged in a second direction that intersects the first direction; and each of the plurality of columns is arranged with an offset length in the first direction with respect to the adjacent columns.

Description

Antenna device

[0001] The present disclosure relates to an antenna device.

[0002] As a current injection type light source that generates electromagnetic waves in the frequency range of 30 GHz to 30 THz (hereinafter referred to as "terahertz waves"), oscillators that integrate a semiconductor element having electromagnetic wave gain for terahertz waves and a resonator are known. Among these, oscillators that integrate a resonant tunneling diode (RTD) and an antenna are expected to operate at room temperature in the frequency range around 1 THz.

[0003] Patent Document 1 discloses an antenna array for terahertz waves in which a plurality of oscillators, each of which integrates an RTD and an antenna, are arranged on the same substrate.

[0004] Japanese Patent Application Laid-Open No. 2021-32685

[0005] Jpn. J. Appl. Phys. , Vol. 47, No. 6 (2008), pp. 4375-4384J. Appl. Phys. , Vol. 103, 124514 (2008)

[0006] In the antenna array disclosed in Patent Document 1, each antenna element is arranged in a square so that the adjacent antenna elements are spaced apart at a pitch equal to or less than the wavelength of the terahertz waves to be detected or generated, or at an integer multiple of that wavelength. While a square arrangement allows for a high-density arrangement by narrowing the spacing between antenna elements, there is a possibility that the gain will be significantly reduced due to mutual coupling between the antennas. Conversely, widening the spacing between antenna elements can narrow the beam width, but this may increase the side lobes. There is a need to devise antenna element spacing and arrangement to achieve efficient generation or detection of electromagnetic waves.

[0007] In view of the above, an object of the present disclosure is to efficiently arrange an antenna array to achieve efficient generation or detection of electromagnetic waves.

[0008] An antenna device according to a first aspect of the present disclosure comprises an antenna array in which a plurality of active antennas, each including an antenna and a semiconductor structure, are arranged to generate or detect electromagnetic waves, wherein the antenna array is characterized in that a plurality of rows in which one or more of the active antennas are arranged in a first direction are arranged in a second direction intersecting the first direction, and each of the plurality of rows is arranged with an offset length in the first direction relative to adjacent rows.

[0009] According to the present disclosure, an antenna array can be efficiently arranged to achieve efficient generation or detection of electromagnetic waves.

[0010] FIGS. 1A and 1B are schematic diagrams of an antenna array according to embodiment 1. FIG. 2 is a top view of the antenna array according to embodiment 1. FIGS. 3A and 3B are cross-sectional views of the antenna array according to embodiment 1. FIGS. 4A and 4B are schematic diagrams of an antenna array according to embodiment 2. FIG. 5 is a top view of the antenna array according to embodiment 2. FIGS. 6A and 6B are cross-sectional views of the antenna array according to embodiment 2. FIG. 7 is a schematic diagram of an antenna array according to embodiment 3. FIG. 8 is a top view of an antenna array according to embodiment 4. FIG. 9 is a top view of the antenna array according to embodiment 4. FIG. 10 is a graph showing the effect of the antenna array according to embodiment 1. FIG. 11 is a schematic diagram of an antenna array according to embodiment 5. FIG. 12 is a schematic diagram of an antenna array according to embodiment 5.

[0011] [Embodiment 1] The configuration of an antenna device 10 according to this embodiment that can be applied to electromagnetic waves (particularly terahertz waves) will be described with reference to Figures 1A, 1B, 2, 3A, and 3B. Note that, although the following description will be given particularly of a case where the antenna device 10 is used as a transmitter, the antenna device 10 can also be used as a receiver. Here, terahertz waves refer to electromagnetic waves within a frequency range of 10 GHz to 100 THz, and in one example, refer to electromagnetic waves within a frequency range of 30 GHz to 30 THz.

[0012] 1A shows a block diagram illustrating an example system configuration of an antenna device 10, and FIG. 1B shows a schematic top view of the antenna device 10 in one example. The antenna device 10 includes an antenna array 11 consisting of multiple (n) active antennas AA1 to AAn arranged in an array, and a bias control unit 12. Note that the bias control unit 12 may be provided outside the antenna array 11.

[0013] The active antenna AA1 integrates at least one antenna AN1 and a semiconductor RTD1 serving as an oscillation source, and is configured to emit terahertz waves TW with an oscillation frequency of fTHz. In this case, the active antenna AA1 may be configured to excite circularly polarized waves. Note that the components of the active antenna AA1 other than the semiconductor RTD1 serving as the oscillation member may be considered to be the antenna AN1, or, for example, only the antenna conductor or a combination of the antenna conductor and a ground (GND) conductor may be considered to be the antenna AN1. The same applies to the other active antennas AA2 to AAn.

[0014] 1B, a square patch antenna can be used as an example of the antenna AN. However, this is just one example, and antennas of shapes other than a square patch antenna may be used as long as they can output electromagnetic waves in a predetermined frequency band, such as frequencies in the terahertz band (10 GHz or more and 100 THz or less).

[0015] Each of the semiconductor RTD1 to RTDn of the active antenna includes a semiconductor structure for generating or detecting terahertz waves. In this embodiment, an example will be described in which a resonant tunneling diode (RTD) is used as this semiconductor structure. Note that the semiconductor structure here is not limited to an RTD, and any semiconductor having electromagnetic wave gain or carrier nonlinearity (nonlinearity of current associated with voltage change in current-voltage characteristics) for terahertz waves will suffice.

[0016] Therefore, in the following description, the semiconductor RTD1 to RTDn may be described as the semiconductor layer 100. In addition to the semiconductor structure described above, the semiconductor layer 100 may also include electrodes for forming ohmic junctions with the semiconductor structure and electrode layers for connecting to upper and lower wiring layers. The bias control unit 12 is a power supply for controlling bias signals applied to the semiconductor RTD1 to RTDn, and is electrically connected to the semiconductor RTD1 to RTDn.

[0017] FIG. 1B shows an example of the arrangement of nine active antennas. In the antenna array according to this embodiment, three active antennas are arranged in each row in a first direction, such as AA1 to AA3, AA4 to AA6, and AA7 to AA9, and each row is arranged in a second direction intersecting the first direction, for a total of three rows. The second direction is, for example, a direction substantially perpendicular to the first direction. Each row is arranged with an offset length in the first direction relative to adjacent rows. For example, each row is arranged with a substantially uniform offset length in the first direction relative to adjacent rows. In FIG. 1B, the active antennas in the even-numbered rows are periodically arranged with an offset of ½ the wavelength of the terahertz waves to be detected or generated relative to the active antennas in the odd-numbered rows.

[0018] In antenna arrays, the spacing between antenna elements is an important parameter. Narrowing the spacing between antenna elements allows for a higher-density antenna array in a smaller area. However, this increases mutual coupling between antenna elements, reducing gain, and the high density places constraints on circuit configurations such as phase shifters. On the other hand, widening the spacing between antenna elements allows for a narrower main lobe beamwidth. This is advantageous in terms of mutual coupling between antenna elements, and also makes it easier to reduce the number of elements and configure circuits. However, widening the spacing between elements can generate radiation in unwanted directions, known as side lobes, which can cause problems with radio wave transmission and reception and reduce gain. For this reason, it is important to appropriately determine the spacing between antenna elements based on each design concept, such as whether to prioritize the desired radiation directivity or physical constraints such as board size.

[0019] A staggered arrangement, such as that shown in Figure 1A, increases the degree of freedom in placement while maintaining antenna characteristics, allowing for a more efficient placement of the antenna array. For example, the spacing between antenna elements can be increased to narrow the beamwidth of the main lobe or due to circuit configuration constraints such as phase shifters and wiring. In this case, compared to the previously mentioned square arrangement, where the pitch is an integer multiple of the wavelength, side lobes can be reduced while maintaining the main lobe characteristics. Furthermore, even when constructing a higher-density antenna array, antenna elements can be placed more flexibly, and depending on the placement method, mutual coupling between each antenna element can be suppressed.

[0020] Note that the active antennas AA1 to AA9 each have the same configuration. Therefore, hereinafter, when there is no need to distinguish between the active antennas AA1 to AA9, the term "active antenna AA" will be used as a general term. In other words, the configuration of the "active antenna AA" described below applies to each of the active antennas AA1 to AA9 that make up the antenna array 11.

[0021] Figure 10 shows the radiation patterns of a square arrangement (dashed line) and a staggered arrangement (solid line) using nine active antennas at an oscillation frequency of 450 GHz. As shown in Figure 10, the main lobe gain near 0 degrees, which is the front direction of the antenna, is equivalent for both arrangements. On the other hand, the side lobe gain near -30 to -120 degrees is approximately -5 to -10 dB lower for the staggered arrangement. As such, the antenna array of this embodiment can reduce the side lobes while maintaining the main lobe characteristics, confirming the superiority of the staggered arrangement over the square arrangement.

[0022] (Regarding the Active Antenna Array Configuration) Next, the structure and configuration of the antenna device 10 as described above will be described with reference to FIGS. 2, 3A, and 3B. FIG. 2 shows a top view of an example configuration of the antenna array 11, and FIG. 3 shows a cross-sectional view thereof. As shown in FIGS. 3A and 3B, the active antenna AA includes a substrate 110, a conductor layer 109, a conductor layer 101, and dielectric layers 104 to 106. As shown in FIG. 3, the substrate 110, the conductor layer 109, and the conductor layer 101 are stacked in this order, and the dielectric layers 104 to 106 are located between the two conductor layers (wiring layers), the conductor layer 109 and the conductor layer 101. The dielectric layers 104 to 106 are arranged in the following order from the conductor layer 109 side: dielectric layer 106, dielectric layer 105, and dielectric layer 104.

[0023] Antenna configurations such as those shown in Figures 2, 3A, and 3B are called microstrip antennas that use microstrip lines of finite length. Here, we will explain an example using a patch antenna, which is a microstrip resonator. Conductor layer 101 is a patch conductor (upper conductor of the patch antenna) of active antenna AA, and is arranged so as to face conductor layer 109 via dielectric layers 104 to 106. Conductor layer 109 is a ground conductor (ground conductor, GND conductor) that is electrically grounded, and also serves as a reflector layer.

[0024] The active antenna AA has a width L of λ in the AA' direction (resonance direction) of the conductor layer 101. ＴＨｚ It is set to operate as a λ / 2 resonator. ＴＨｚ is the effective wavelength in the dielectric layers 104 to 106 of the terahertz wave that resonates in the active antenna AA. ０ Let the effective relative dielectric constant of the dielectric layer 104 be ε ｒ Then, λ ＴＨｚ = λ ０ ×ε ｒ －１／２ It is expressed as:

[0025] The active antenna AA has a semiconductor structure that is a semiconductor layer 100. The semiconductor layer 100 corresponds to RTD1 to RTD9 in FIG. 1 and, as described above, is a resonant tunneling diode (RTD) in this embodiment. An RTD is a typical semiconductor structure that has electromagnetic wave gain in the terahertz wave frequency band, and is also called an active layer. For this reason, hereinafter, the semiconductor layer 100 may be referred to as an "RTD."

[0026] The RTD has a resonant tunneling structure layer including a plurality of tunnel barrier layers, a quantum well layer provided between the plurality of tunnel barriers, and a multiple quantum well structure that generates terahertz waves by intersubband transition of carriers. The RTD has electromagnetic wave gain in the frequency range of terahertz waves based on the photon-assisted tunneling phenomenon in the negative differential resistance region of the current-voltage characteristics, and exhibits self-sustained oscillation in the negative differential resistance region.

[0027] The semiconductor layer 100 is electrically connected to the conductor layer 101. The semiconductor structure is, for example, a mesa-type structure, and the semiconductor layer 100 includes an electrode (ohmic or Schottky) that contacts the semiconductor structure and an electrode layer for connecting to upper and lower wiring layers. The semiconductor layer 100 is located inside the active antenna AA and is configured to oscillate or detect terahertz waves. The semiconductor layer 100 is composed of a semiconductor layer that has electromagnetic wave gain or nonlinearity for terahertz waves.

[0028] The active antenna AA is an active antenna in which a semiconductor layer 100 and a patch antenna (antenna AN) are integrated. The frequency fTHz of the terahertz waves oscillated from the active antenna AA alone is determined by the resonant frequency of a total parallel resonant circuit that combines the reactance of the patch antenna and the semiconductor layer 100.

[0029] Specifically, from the equivalent circuit of the oscillator described in Non-Patent Document 1, for a resonant circuit combining the RTD and the antenna admittance (YRTD and Yaa), the frequency that satisfies the amplitude condition of equation (1) and the phase condition of equation (2) is determined as the oscillation frequency fTHz. Re[YRTD]+Re[Y11]≦0 (1) Im[YRTD]+Im[Y11]=0 (2)

[0030] Here, YRTD is the admittance of the semiconductor layer 100, Re is the real part, and Im is the imaginary part. Since the semiconductor layer 100 includes an RTD, which is a negative resistance element, Re[YRTD] has a negative value. Furthermore, Y11 represents the admittance of the entire structure of the active antenna AA1 as viewed from the semiconductor layer 100.

[0031] Note that a quantum cascade laser (QCL) structure having a multilayer structure of several hundred to several thousand semiconductor layers may be used as the semiconductor layer 100. In this case, the semiconductor layer 100 is a semiconductor layer including a QCL structure.

[0032] Furthermore, the semiconductor layer 100 may be a negative resistance element such as a Gunn diode or an IMPATT diode, which are often used in the millimeter wave band.

[0033] Furthermore, a high-frequency element such as a transistor with one terminal terminated may be used as the semiconductor layer 100, and a heterojunction bipolar transistor (HBT), a compound semiconductor layer-based FET, a high electron mobility transistor (HEMT), or the like may be used as the transistor.

[0034] Furthermore, a negative differential resistance of a Josephson device using a superconductor layer may be used as the semiconductor layer 100. In other words, the semiconductor layer 100 does not have to be an RTD, and any structure having similar characteristics may be used as long as it is a semiconductor structure for generating or detecting electromagnetic waves in a predetermined frequency band.

[0035] Although an RTD is used here as a configuration suitable for terahertz waves, an antenna array compatible with electromagnetic waves of any frequency band may be realized with the configuration described in this embodiment. That is, the semiconductor layer 100 in this embodiment is not limited to an RTD that outputs terahertz waves, but may be formed using a semiconductor that can output electromagnetic waves of any frequency band.

[0036] In microstrip resonators such as patch antennas, a thick dielectric layer reduces conductor loss and improves radiation efficiency. The dielectric layers 104-106 are required to be thick enough to be formed (typically 3 μm or thicker), have low loss and a low dielectric constant in the terahertz band, and be easily microfabricated (planarized or etched). The thicker the dielectric layer, the higher the radiation efficiency, but if it is too thick, multi-mode resonance may occur. Therefore, the upper limit of the dielectric layer thickness can be designed to be no more than 1 / 10 of the oscillation wavelength.

[0037] On the other hand, since miniaturization of diodes and high current density are necessary to increase the frequency and output of oscillators, the dielectric layer is also required to suppress leakage current and prevent migration as an insulating structure of the diode. To satisfy the above two requirements, dielectric layers 104 to 106 may be made of different materials.

[0038] The dielectric layer 104 may be made of an organic dielectric material such as BCB (benzocyclobutene, manufactured by Dow Chemical Company, εr1=2), polytetrafluoroethylene, or polyimide, where εr1 is the relative dielectric constant of the first dielectric layer 104. Alternatively, the first dielectric layer 104 may be made of an inorganic dielectric material such as a TEOS oxide film or spin-on glass, which can be formed into a relatively thick film and has a low dielectric constant.

[0039] Furthermore, the dielectric layers 105 and 106 are required to have insulating properties (the ability to act as an insulator or a high-resistance material that does not conduct electricity when subjected to DC voltage), barrier properties (the ability to prevent the diffusion of metal materials used in the electrodes), and processability (the ability to be processed with submicron precision). Materials that satisfy these requirements include inorganic insulating materials such as silicon oxide (εr2=4), silicon nitride (εr2=7), aluminum oxide, and aluminum nitride. εr2 is the relative dielectric constant of the dielectric layers 105 and 106.

[0040] Here, when the dielectric layers 104 to 106 have a multilayer structure as in this embodiment, the relative dielectric constant εr of the dielectric layers 104 to 106 is an effective relative dielectric constant determined from the thickness and relative dielectric constant εr1 of the dielectric layer 104 and the thickness and relative dielectric constant εr2 of the dielectric layers 105 to 106.

[0041] Furthermore, from the viewpoint of impedance matching between the antenna and space, in order to reduce the difference in dielectric constant between the antenna and air, the dielectric layer 104 may be made of a material different from that of the dielectric layers 105 and 106, and may be made of a material with a low relative dielectric constant (εr1<εr2). Note that in the antenna device 10, the dielectric layer does not need to have a multi-layer structure, and may have a structure formed of only one layer of the above-mentioned materials.

[0042] The semiconductor layer 100 is disposed on a conductor layer 109 formed on a substrate 110. The semiconductor layer 100 and the conductor layer 109 are electrically connected. Note that, in order to reduce ohmic loss, the semiconductor layer 100 and the conductor layer 109 can be connected with low resistance.

[0043] A via 103 is disposed on the semiconductor layer 100 on the side opposite to the side on which the conductor layer 109 is disposed, and the via 103 is electrically connected to the semiconductor layer 100. The semiconductor layer 100 is embedded in a dielectric layer 106, and is covered on its periphery by the dielectric layer 106.

[0044] The semiconductor layer 100 includes an ohmic electrode, which is a conductor that forms an ohmic connection with the semiconductor, to reduce ohmic loss and RC delay due to series resistance. Examples of materials that can be used for the ohmic electrode include Ti / Au, Ti / Pd / Au, Ti / Pt / Au, AuGe / Ni / Au, TiW, Mo, and ErAs. Note that the materials are represented by element symbols, and the substances represented by each symbol will not be described in detail here. This also applies to the following description.

[0045] Furthermore, by using a semiconductor in which the region where the semiconductor and ohmic electrode are in contact is heavily doped with impurities, the contact resistance can be further reduced, thereby achieving higher output and higher frequencies. The absolute value of the negative resistance, which indicates the magnitude of the gain of an RTD used in the terahertz wave band, is generally on the order of 1 to 100 Ω, so the semiconductor layer 100 can be configured to suppress electromagnetic wave loss to 1% or less of that. Therefore, the contact resistance of the ohmic electrode can be suppressed to 1 Ω or less as a guideline.

[0046] In order to operate in the terahertz wave band, the semiconductor layer 100 is formed so that its width is typically about 0.1 to 5 μm. Therefore, the contact resistance is set to a resistivity of 10 Ω·μm. ２ The resistance is controlled to a range of 0.001 to several Ω.

[0047] The semiconductor layer 100 may also be configured to include a metal (Schottky electrode) that forms a Schottky contact rather than an ohmic contact. In this case, the contact interface between the Schottky electrode and the semiconductor exhibits rectification, and the active antenna AA can be used as a terahertz wave detector. The following describes a configuration using an ohmic electrode.

[0048] 3A, the inside of the active antenna AA is stacked in the following order: substrate 110, conductor layer 109, semiconductor layer 100, via 103, and conductor layer 101. Via 103 is formed inside dielectric layers 104 to 106, and conductor layer 101 and semiconductor layer 100 are electrically connected via via 103.

[0049] Here, if the width of the via 103 is too large, the resonance characteristics of the patch antenna will deteriorate and the radiation efficiency will decrease due to an increase in parasitic capacitance. Therefore, the width of the via 103 can be configured to be a dimension that does not interfere with the resonant electric field, typically, 1 / 10 or less of the effective wavelength λ of the terahertz wave of the standing oscillation frequency fTHz of the active antenna AA.

[0050] Furthermore, the width of the via 103 may be small enough not to increase the series resistance, and can be reduced to approximately twice the skin depth as a guideline. To reduce the series resistance to a level not exceeding 1 Ω, the width of the via 103 is typically in the range of 0.1 μm to 20 μm.

[0051] 3B, the conductor layer 101 is electrically connected to the wiring layer 108 through a via, and the wiring layer 108 is electrically connected to the bias control unit 12 through a bias wiring layer 102, which is a common wiring formed within the chip. The bias control unit 12 may also be called a power supply circuit. The wiring layer 102 is disposed between the dielectric layer 104 and the dielectric layer 105. The wiring layer 108 is drawn out from each of the antennas.

[0052] The bias control unit 12 is a power supply for supplying a bias signal to the semiconductor layer 100 of the active antenna AA. Therefore, by connecting the wiring layer 102 and the wiring layer 108 drawn out from each adjacent antenna, a bias signal is supplied to the semiconductor layer 100 of each antenna. Since the bias wiring layer 102 is common, a sufficient wiring width can be ensured, thereby reducing operating voltage variations between antennas due to variations in wiring resistance, and stabilizing synchronization even when the number of arrays increases. In addition, it is possible to make the structure around the antenna symmetrical, preventing the radiation pattern from being distorted.

[0053] The vias 107 connecting the conductor layer 101 and the wiring layer 108 are connection portions for electrically and mechanically connecting the wiring layer 108 to the conductor layer 101. In this way, a structure electrically connecting upper and lower layers is called a via. In addition to serving as members constituting the patch antenna, the conductor layers 109 and 101 also serve as electrodes for injecting current into the RTD, which is the semiconductor layer 100, by being connected to these vias. In this embodiment, the vias are formed of a material having a resistivity of 1×10 －６ Materials with a resistance of Ω·m or less can be used, specifically metals and metal compounds such as Ag, Au, Cu, W, Ni, Cr, Ti, Al, AuIn alloy, and TiN.

[0054] The width of the via 107 connecting the conductor layer 101 and the wiring layer 108 is smaller than the width of the conductor layer 101. Here, the width of the conductor layer 101 refers to the width in the electromagnetic wave resonance direction (i.e., the A-A' direction) within the active antenna AA. The width of the portion (connection portion) of the wiring layer 108 connected to the via 107 is smaller (thinner) than the width of the conductor layer 101 (active antenna AA). These widths can be set to 1 / 10 or less (λ / 10 or less) of the effective wavelength λ of the terahertz waves with an oscillation frequency fTHz present in the active antenna AA. By arranging the via 107 and the wiring layer 108 in dimensions and positions that do not interfere with the resonant electric field within the active antenna AA, radiation efficiency can be improved.

[0055] Furthermore, the via 107 can be positioned at a node of the electric field of the terahertz wave with an oscillation frequency of fTHz standing in the active antenna AA. In this case, the via 107 and the wiring layer 108 are configured to have impedances sufficiently higher than the absolute value of the negative differential resistance of the RTD, which is the semiconductor layer 100, in a frequency band near the oscillation frequency fTHz. In other words, the via 107 and the wiring layer 108 are connected to the active antenna AA so as to present a high impedance to the RTD at the oscillation frequency fTHz. In this case, the active antenna AA is isolated (separated) at the frequency fTHz through the path via the bias wiring layer 102. This prevents the current with the oscillation frequency fTHz induced in each active antenna via the wiring layer 102 and the bias control unit 12 from affecting adjacent antennas. Furthermore, interference between the electric field with the oscillation frequency fTHz standing in the active antenna AA and these power supply members is suppressed.

[0056] The bias wiring layer 102 is a bias wiring common to multiple active antennas AA. The bias control unit 12 is arranged outside the chip to supply a bias signal to the semiconductor layer 100 of each antenna. The bias control unit 12 includes a stabilization circuit for suppressing low-frequency parasitic oscillation.

[0057] The stabilization circuit is set to have an impedance lower than the absolute value of the negative resistance corresponding to the gain of the semiconductor layer 100 in the frequency band from DC to 10 GHz. To stabilize the relatively high frequencies of 0.1 to 10 GHz, an AC short circuit is provided for each active antenna, in which a TiW resistive layer 116 and an MIM (Metal-Insulator-Metal) capacitor 115 are connected in series, as shown in FIG. 3B . In this case, the MIM capacitor 115 has a large capacitance within the above-mentioned frequency range, and in one example, a capacitance of approximately several pF. The MIM capacitor 115 of this embodiment uses a structure in which a portion of the dielectric layer 106 is sandwiched between the conductor layer 113 and the conductor layer 109, which is GND.

[0058] (Specific Materials and Structural Dimensions) A specific example of the antenna array 11 will be described. The antenna array 11 is a semiconductor device capable of single-mode oscillation in the frequency band of 0.45 to 0.50 THz. The substrate 110 is a semi-insulating InP substrate. The semiconductor layer 100 is composed of a multiple quantum well structure made of InGaAs / AlAs lattice-matched to the substrate 110, and in this embodiment, an RTD with a double-barrier structure is used. This is also called an RTD semiconductor heterostructure.

[0059] The current-voltage characteristics of the RTD used in this embodiment are measured such that the peak current density is 9 mA / μm ２ and the differential negative conductance per unit area is 10 mS / μm ２ The semiconductor layer 100 is formed in a mesa structure, and is composed of a semiconductor structure including an RTD and an ohmic electrode for electrical connection with the semiconductor structure. The mesa structure is circular with a diameter of 2 μm, and the magnitude of the negative differential resistance of the RTD in this case is approximately -30 Ω per diode. In this case, the negative differential conductance of the semiconductor layer 100 including the RTD is estimated to be approximately 30 mS, and the diode capacitance is estimated to be approximately 10 fF.

[0060] The active antenna AA is a patch antenna having a structure in which dielectric layers 104 to 106 are sandwiched between a conductor layer 101, which is a patch conductor, and a conductor layer 109, which is a ground conductor. The conductor layer 101 is a square patch antenna with one side measuring 150 μm, and the resonator length (L) of the antenna is 150 μm. A semiconductor layer 100 including an RTD is integrated inside the antenna.

[0061] The conductor layer 101, which is a patch conductor, is composed of a metal layer (Ti / Au) mainly composed of a thin Au film with low resistivity. The conductor layer 109, which is a ground conductor, is composed of a Ti / Au layer and a semiconductor layer made of an n+-InGaAs layer, and the metal and semiconductor layers are connected by low-resistance ohmic contact. The dielectric layer 104 is composed of BCB (benzocyclobutene, manufactured by Dow Chemical Company). The dielectric layers 105 and 106 are made of 1 μm-thick SiO ２ Each is composed of:

[0062] 3A, around the semiconductor layer 100, the conductor layer 109, the semiconductor layer 100, the via 103 made of a conductor containing Cu, and the conductor layer 101 are laminated in this order from the substrate 110 side and electrically connected. The RTD, which is the semiconductor layer 100, is disposed at a position shifted by 40% (60 μm) of one side of the conductor layer 101 from the center of gravity of the conductor layer 101 in the resonance direction (i.e., the A-A' direction). Here, the input impedance when feeding high frequency power from the RTD to the patch antenna is determined by the position of the RTD within the antenna.

[0063] 3B , the conductor layer 101 is connected to a wiring layer 108, which is located at the same level as the bias wiring layer 102 arranged on the dielectric layer 105, via a via 107 formed of Cu. The wiring layer 102 and the wiring layer 108 are formed of metal layers containing Ti / Au stacked on the dielectric layer 105.

[0064] The wiring layer 108 is connected to the bias control unit 12 via a bias wiring layer 102, which is a common wiring formed within the chip. The active antenna AA is designed to obtain oscillation with a power of 0.2 mW at a frequency fTHz=0.5 THz by setting a bias in the negative resistance region of the RTD included in the semiconductor layer 100.

[0065] Vias such as vias 103 and 107 have a cylindrical structure with a diameter of 10 μm. The wiring layer 108 is configured with a pattern formed of a metal layer containing Ti / Au, with a width of 10 μm and a length of 75 μm in the resonance direction (i.e., the A-A' direction). The via 107 is connected to the conductor layer 101 at the center in the resonance direction (i.e., the A-A' direction) and at the end of the conductor layer 101 in the B-B' direction. This connection position corresponds to a node of the electric field of the terahertz wave with a frequency of f THz standing in the active antenna AA1.

[0066] [Embodiment 2] In this embodiment, an antenna device 20 in which active antennas are coupled by coupling lines will be described. Figures 4A and 4B show the configuration of the antenna device 20. Figure 4A is a block diagram illustrating the system configuration of the antenna device 20, and Figure 4B is a schematic top view of the antenna device 20 as viewed from above.

[0067] 4A, the antenna device 20 of this embodiment has a configuration in which coupled lines CL1 to CLn-1 are added between the active antennas compared to the antenna device 10 of embodiment 1. The coupled lines CL are transmission lines for mutual injection locking at the frequency fosc, and the active antennas are electrically connected by these coupled lines CL.

[0068] In one example, in order to synchronize the active antennas AA1-AA4 in the horizontal direction, a coupling line CL14 is connected between these active antennas. The same applies to the other active antennas. Here, the coupling line is implemented as, for example, a microstrip line. However, this is not limiting, and the coupling line may also be realized by a slot line. Connecting each active antenna with a coupling line can improve the accuracy of frequency and phase.

[0069] Next, the structure and configuration of the antenna device 20 described above will be described with reference to Figures 5, 6A, and 6B. Figure 5 is a schematic top view of the antenna array 21, and Figures 6A and 6B are its cross-sectional views. Note that detailed description of the same configuration as the antenna device 10 of the first embodiment will be omitted below.

[0070] 5, 6A, and 6B, adjacent antennas are coupled to each other by a coupling line CL and are synchronized with each other at the terahertz wave oscillation frequency fTHz due to the mutual injection locking phenomenon, which is a phenomenon in which multiple self-excited oscillators oscillate in synchronization with each other due to interaction.

[0071] For example, active antennas AA1 and AA4 are coupled to each other by a coupling line CL14, and are further coupled to each other via a conductor layer 111, as shown in Fig. 6A. The conductor layer 111 is made of, for example, Ti / Au. The same applies to other adjacent active antennas.

[0072] Note that "mutually coupled" refers to a relationship in which a current induced in one active antenna acts on another adjacent active antenna due to the coupling, thereby changing the transmission and reception characteristics of the other.

[0073] When mutually coupled active antennas are synchronized in phase or in opposite phase, mutual injection locking occurs, causing the electromagnetic fields between the active antennas to strengthen or weaken each other, which allows the antenna gain to be adjusted.

[0074] The length of the path of the coupling wire that couples the active antennas together is preferably set based on the wavelength of the electromagnetic wave, and in particular, is preferably set to be approximately equal to n wavelengths (n is an integer) of the electromagnetic wave.

[0075] In this embodiment, the entire coupling line coupling the active antennas is referred to as coupling line CL. The coupling lines coupling each antenna constituting the coupling line CL are represented by numbers and letters corresponding to each active antenna. For example, the coupling line coupling active antennas AA1 and AA4 is represented as coupling line CL14.

[0076] The oscillation conditions of the antenna array 11 are determined by the conditions of mutual injection locking in a configuration in which two or more individual RTD oscillators are coupled, as described in Non-Patent Document 2. Specifically, consider the oscillation conditions of an antenna array in which active antennas AA1 and AA2 are coupled by a coupling line CL12. In this case, two oscillation modes occur: positive-phase mutual injection locking and anti-phase mutual injection locking. The oscillation conditions for the positive-phase mutual injection locking oscillation mode (even mode) are expressed by equations (3) and (4), and the oscillation conditions for the anti-phase mutual injection locking oscillation mode (odd mode) are expressed by equations (5) and (6).

[0077] Positive phase (even mode): Frequency f = feven Yeven = Y11 + Y12 + YRTD Re(Yeven) ≦ 0 (3) Im(Yeven) = 0 (4) Opposite phase (odd mode): Frequency f = fodd Yodd = Y11 + Y12 - YRTD Re(Yodd) ≦ 0 (5) Im(Yodd) = 0 (6)

[0078] Here, Y12 is the mutual admittance between active antenna AA1 and active antenna AA2. Y12 is proportional to the coupling constant that represents the strength of coupling between the antennas, and ideally, the real part of -Y12 is large and the imaginary part is zero. The antenna array 11 of this embodiment is coupled under the condition of mutual injection locking in positive phase, and the oscillation frequency fTHz≈feven. Similarly, the other antennas are coupled to each other along the coupling line CL so as to satisfy the above-mentioned condition of mutual injection locking in positive phase.

[0079] The bonded line CL is a microstrip line in which the dielectric layers 104 to 106 are sandwiched between the conductor layer 111 and the conductor layer 109 or the wiring layer 102. For example, as shown in FIG. 6A , the bonded line CL45 has a structure in which the dielectric layers 104 to 106 are sandwiched between the conductor layer 111 (CL45) and the conductor layer 109 or the wiring layer 102. Similarly, the bonded line CL56 has a structure in which the dielectric layers 104 to 106 are sandwiched between the conductor layer 111 (CL56) and the conductor layer 109 or the wiring layer 102.

[0080] The antenna array 21 is an antenna array configured such that the antennas are coupled to each other by AC coupling (alternating current coupling, capacitive coupling). For example, in plan view, the conductor layer 111, which is the upper conductor layer of the coupling line CL45, overlaps with the conductor layers 101, which are the patch conductors of the active antennas AA4 and AA5, with the dielectric layer 112 sandwiched between them, and is connected by capacitive coupling. More specifically, in plan view, the conductor layer 111 of the coupling line CL45 overlaps with the conductor layer 101 by 5 μm, with the dielectric layer 112 sandwiched between them, near the radiation ends of the active antennas AA4 and AA5, forming capacitive structures C1 and C2.

[0081] In this configuration, the capacitance structures C1 and C2 function as high-pass filters, shorting the terahertz band and opening the low-frequency band, thereby contributing to the suppression of multimode oscillation. However, this configuration is not a mandatory requirement, and a DC-coupling configuration may be used in which the conductor layer 111 of the coupling line CL45 is directly coupled (connected) to the conductor layers 101 of the active antennas AA4 and AA5. An antenna array synchronized by DC coupling can synchronize adjacent antennas with strong coupling, making synchronization through pull-in easier and more resistant to variations in frequency and phase between the antennas. While the coupling between active antennas AA4 and AA5 has been described as an example here, the same applies to the coupling between the other active antennas AA1 to AA9.

[0082] In the antenna array 21, the conductor layer 101 of the active antenna AA, the conductor layer 111 of the coupled wire CL, and the bias wiring layer 102 are arranged on different layers. In this way, the conductor layer 101 of the active antenna AA and the conductor layer 111 of the coupled wire CL, which transmit high frequencies (fTHz), are arranged on different layers from the bias wiring layer, which transmits low frequencies (DC to several tens of GHz).

[0083] This allows the layout of the transmission lines, such as their width, length, and routing, to be freely set within each layer. Furthermore, as shown in FIG. 5, when viewed from above (in a plan view), the bond line CL and the bias wiring layer 102 intersect with each other, resulting in a more compact layout. This allows for a larger number of antennas to be placed. Furthermore, this configuration allows for independent control of the impedance of the bond line CL and bias control of the semiconductor layer 100.

[0084] In the terahertz band, resistance increases due to the skin effect, so conductor loss associated with high-frequency transmission between antennas cannot be ignored. As the current density between conductor layers increases, conductor loss per unit length (dB / mm) increases. In the case of a microstrip line, conductor loss per unit length (dB / mm) is inversely proportional to the square of the dielectric thickness. Therefore, to increase the radiation efficiency of an antenna array, conductor loss can be reduced by thickening not only the antenna but also the dielectric constituting the coupling line CL.

[0085] In contrast, the antenna array 21 of this embodiment has a configuration in which a bias wiring layer 102 is disposed on a dielectric layer 105, and a conductor layer 101 of the antenna through which a high frequency wave of a frequency f THz is transmitted and a conductor layer 111 of the coupling line CL are disposed on the upper layer of the dielectric layer 104. This configuration makes it possible to suppress a decrease in the radiation efficiency of the antenna array due to conductor loss in the terahertz band.

[0086] From the viewpoint of conductor loss, the thickness of the dielectric constituting the bond line CL is preferably 1 μm or more, and in one example, by setting the dielectric thickness to 2 μm or more, the loss due to conductor loss in the terahertz band can be suppressed to about 20%. Similarly, from the viewpoint of conductor loss, a wide distance can be ensured in the thickness direction between the conductor layer 111 constituting the bond line CL and the wiring layer 102 and the conductor layer 109.

[0087] The bias wiring layer 102 can function as a low-impedance line up to the gigahertz band by setting the dielectric to 2 μm or less, for example, 1 μm or less. Even if the dielectric is set to a thickness of 2 μm or more, connecting a shunt component consisting of a resistive layer 116 and an MIM capacitor 115 to the bias wiring layer 102 as shown in FIG. 6B allows the bias wiring layer 102 to function as a low-impedance line and suppress low-frequency oscillation.

[0088] It is also conceivable that radiation from the coupled line CL may affect radiation from the antenna array 21. For this reason, it is desirable to have a structure that suppresses radiation from the coupled line CL, such as by arranging the coupled line CL symmetrically in the antenna array or by making the bent portion a curve with a large radius of curvature.

[0089] 7 is a schematic top view of the antenna device 30, showing the configuration of the antenna device 30 arranged in a diamond (rhombus) shape. Active antennas AA1, AA2-AA3, AA4-AA6, AA7-AA8, and AA9 are arranged in rows, one at a time, two at a time, three at a time, two at a time, and one at a time, in a first direction, and five rows are arranged in a second direction substantially perpendicular to the first direction. Each row is arranged with a substantially uniform offset length from adjacent rows in the first direction.

[0090] As in the second embodiment described above, the coupling line CL is a transmission line for mutual injection locking at the frequency fosc, and the active antennas are electrically connected by this coupling line CL. In one example, a coupling line CL24 is connected between the active antennas AA2 and AA4 to synchronize these antennas in the horizontal direction. The same applies to the other active antennas.

[0091] Here, the coupling lines are implemented as, for example, microstrip lines. However, this is not limiting and the coupling lines may be realized as slot lines. Connecting the active antennas with coupling lines can improve the accuracy of frequency and phase. Note that a description of the same configuration as the antenna array 21 of the second embodiment will be omitted here.

[0092] According to this configuration, it is possible to change the arrangement while maintaining the same gain in the front direction as in the first or second embodiment, while keeping the antenna area the same, and this increases the degree of freedom in designing the routing and arrangement of circuits such as the coupling line CL and the phase shifter.

[0093] In this embodiment, the number of active antennas arranged in the center row is greater than the other rows, and the number of active antennas arranged in the rows between the center row and the end rows is a value between the number of active antennas arranged in the center row and the number of active antennas arranged in the end rows.

[0094] Fourth Embodiment In this embodiment, an example of an antenna array arrangement configuration having nine active antennas will be described. Note that, in the following, detailed description of the same configuration as the antenna device 10 of the first embodiment will be omitted.

[0095] Fig. 8 shows a top view of an antenna array 41, which is an example of an antenna array according to this embodiment. Fig. 9 shows a top view of an antenna array 51, which is another example of an antenna array according to this embodiment. In the antenna array 41 of this embodiment, the active antenna AA4 of the antenna array 21 of embodiment 2 has been removed, and active antennas AA4-1 and AA4-2 have been newly added.

[0096] In the antenna array 21 of the second embodiment, the active antennas AA are arranged in an array such that each row has a substantially uniform offset in the first direction relative to adjacent rows. When arranged in this manner, a portion of the active antenna AA4 protrudes into the active antennas in the adjacent row. By halving the physical dimensions of this protruding active antenna AA4 and locating one half below the active antenna AA6, a higher-density antenna array can be realized. Furthermore, the arrangement of the active antennas and the coupling lines is more symmetrical, further reducing side lobes.

[0097] The other configurations of the antenna array 41 according to this embodiment are the same as those of the antenna array 21, and therefore detailed description thereof will be omitted here. Furthermore, the physical dimensions of the active antennas AA4-1 and AA4-2 are half the physical dimensions of the active antenna AAn. However, since two active antennas AA4-1 and AA4-2 are disposed in this embodiment, the effective aperture area is equivalent to the aperture area of ​​the antenna array 21 according to the second embodiment.

[0098] Furthermore, in the antenna array 51 shown in FIG. 9, the active antennas AA are arranged in an array with each of multiple rows being offset from adjacent rows by a substantially uniform length in the second direction. When the active antennas AA are arranged with such substantially uniform offset lengths, some of the active antennas AA protrude. Therefore, in the antenna array 51, similar to the antenna array 41, the active antenna AA2 of the antenna array 21 of embodiment 2 is removed, and active antennas AA2-1 and AA2-2 are newly added. In the antenna array 51, the active antenna AA2 is divided into active antennas AA2-1 and AA2-2. One of the active antennas, AA2-2, is then positioned to the right of the active antenna AA8. As a result, according to this embodiment, a higher density antenna array than the antenna array 21 is realized.

[0099] In this embodiment, the shapes of the active antennas AA4-1, AA4-2, AA2-1, and AA2-2 are half the shapes of the active antenna AAn. That is, in the antenna arrays 41 and 51, the dimensions of at least one of the multiple active antennas are different from the dimensions of the remaining active antennas. This reduces the fluctuations in the resonant frequency and radiation pattern of the active antennas AA4-1, AA4-2, AA2-1, and AA2-2, as well as their physical dimensions. This results in changes in antenna characteristics, such as reduced gain and radiation efficiency. Therefore, these antenna characteristics must be adjusted for the antenna array by changing the position of the feed point and the conductor layer. Therefore, in the active antennas AA4-1, AA4-2, AA2-1, and AA2-2 of this embodiment, only the surface conductor layer 101 of the active antenna AAn is halved. As a result, the radiation pattern is improved when the active antennas of this embodiment are used compared to when a shape is adopted in which all components of the active antenna AAn are halved. Therefore, the antenna arrays 41 and 51 of this embodiment have further reduced side lobes compared to the antenna array 21, and the characteristics of the antenna array are improved.

[0100] In this embodiment, in order to realize an antenna array with higher density than the antenna array 21 and reduce side lobes, active antennas AA4-1, AA4-2, AA2-1, and AA2-2 are used, in which only the conductor layer 101 of the active antenna AAn is halved. For example, as described above, with the antenna arrays 41 and 51 of this embodiment, further improvement in antenna array characteristics can be expected by changing the position of the feed point and the conductor layer. Note that the shapes of the antenna arrays 41 and 51 of this embodiment are not limited to the shapes shown in Figures 8 and 9. Any shape may be adopted for the antenna arrays 41 and 51 as long as it satisfies the respective design concepts and constraints, such as whether to prioritize the desired radiation directivity, physical constraints such as board size, or structural constraints of the active antenna.

[0101] [Embodiment 5] In this embodiment, an example of an antenna array arrangement that is adopted when the above-mentioned active antenna is rotated 45 degrees in a plan view will be described. Note that, hereinafter, detailed description of the same configuration as the antenna device 10 of embodiment 1 will be omitted.

[0102] 11 and 12 show antenna arrays 61 and 71 according to the present embodiment, respectively. In the antenna arrays 61 and 71 according to the present embodiment, each active antenna AA is rotated by approximately 45 degrees in a plan view relative to the active antenna AA of the antenna array 21 according to the second embodiment. That is, in the antenna arrays 61 and 71, the active antennas AA are arranged so that the first direction is rotated by approximately 45 degrees with respect to the electric field direction or the magnetic field direction of the active antenna.

[0103] In the antenna arrays 61 and 71, various beams can be formed by adjusting the phase input to each active antenna AA. In the antenna array 21 of the second embodiment, the active antennas AA are arranged in an array such that each row has a substantially uniform offset length in a first direction relative to adjacent rows. When arranged in this manner, a portion of the active antenna AA 4 protrudes into the active antennas in the adjacent rows. In contrast, in the antenna arrays 61 and 71 of the present embodiment, the active antennas AA are arranged symmetrically with respect to an axis passing through the center of the antenna array in a planar view. Furthermore, in the antenna arrays 61 and 71, the active antennas AA are arranged to extend in multiple directions in a planar view. The other configurations of the antenna arrays 61 and 71 are similar to those of the antenna array 21, and therefore detailed description thereof will be omitted here.

[0104] The antenna arrays 61 and 71 of the present embodiment, which employ such an arrangement, offer advantages in terms of beamforming optimization. Specifically, in the antenna arrays 61 and 71, the active antennas AA are arranged to spread in multiple directions, enabling more precise directional resolution and improved beamforming flexibility. Furthermore, the antenna arrays 61 and 71 make it easier to adjust the width and shape of the beam for a specific direction, enabling the formation of a beam that covers a wider area or a beam that is more narrowly focused, as needed.

[0105] The antenna array 61 shown in Figure 11 is an example of an antenna array using 13 active antennas. The antenna array 71 shown in Figure 12 is an example of an antenna array using 37 active antennas. In both antenna arrays, the active antennas AA are arranged in multiple rows with a substantially uniform offset length in the second direction relative to adjacent rows. Therefore, by adopting a staggered active antenna arrangement in the antenna arrays 61 and 71, the deterioration of side lobes that accompanies an increase in the number of active antennas is reduced, and not only can beam flexibility be improved but also main lobe gain can be improved.

[0106] In this embodiment, it is assumed that the shape of the substrate 110 in a plan view is square, but further miniaturization and improved characteristics of the antenna array can be achieved by, for example, making the shape of the substrate 110 octagonal, similar to the external shape of the antenna array. Furthermore, any shape may be adopted for the antenna arrays 61 and 71 as long as it satisfies the respective design concepts and constraints, such as whether to prioritize the desired radiation directivity, whether to prioritize physical constraints such as substrate size, or whether to prioritize structural constraints of the active antenna.

[0107] In other embodiments, the bias wiring from the bias control unit 12 is connected to each active antenna AA individually. On the other hand, in this embodiment, multiple active antennas AA arranged along directions offset by approximately 45 degrees from the first direction are connected by a common bias wiring. This configuration can improve the degree of freedom in wiring layout.

[0108] Other Embodiments Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist thereof.

[0109] For example, in the above-described embodiment, the carriers are assumed to be electrons, but the present invention is not limited to this and may be implemented using holes. Furthermore, the materials for the substrate and dielectric may be selected according to the intended use, and semiconductor layers such as silicon, gallium arsenide, indium arsenide, and gallium phosphide, and resins such as glass, ceramic, polytetrafluoroethylene, and polyethylene terephthalate may be used.

[0110] Although the above-described embodiment uses a square patch antenna as a terahertz wave resonator, the shape of the resonator is not limited to this. For example, a resonator having a structure using a patch conductor of a polygonal shape such as a rectangle or a triangle, a circle, an ellipse, or the like may be used.

[0111] Furthermore, the number of negative differential resistance elements integrated in the element is not limited to one, and a resonator including multiple negative differential resistance elements may be used. The number of lines is also not limited to one, and a configuration having multiple lines may be used. By using the antenna device described in the above embodiments, it is possible to oscillate and detect terahertz waves.

[0112] In addition, in each of the above-described embodiments, a double-barrier RTD made of InGaAs / AlAs grown on an InP substrate has been described as the RTD. However, the present disclosure is not limited to these structures and material systems, and elements can be provided using other structures and material combinations. For example, an RTD with a triple-barrier quantum well structure or an RTD with four or more multiple-barrier quantum wells may also be used.

[0113] In addition, for example, in some of the above-described embodiments, examples have been shown in which the antennas AN included in two active antennas that are arranged adjacent to each other in an array configuration among multiple active antennas are coupled, but this is not limited to this. If wiring is possible, two antennas AN included in two active antennas that are not adjacent to each other may also be coupled.

[0114] In the above-described embodiment, in the array arrangement of the active antennas AA, each of the multiple rows is arranged with a substantially uniform offset length relative to the adjacent rows in a first direction. The offset length can be substantially equal to, but is not limited to, half the wavelength of the electromagnetic wave (e.g., terahertz wave) to be detected or generated. For example, the beam direction can be changed by appropriately setting the offset length, i.e., the antenna element spacing, to obtain a desired directivity. Furthermore, the spacing between the multiple rows can be substantially equal to, but is not limited to, half the wavelength of the electromagnetic wave.

[0115] In the above-described embodiment, the horizontal direction, which is the electric field direction of the patch antenna, is defined as the second direction in the array arrangement of the active antennas AA. However, this is not limited to this. The vertical direction, which is the magnetic field direction of the patch antenna, may also be defined as the second direction. In this case, in the array arrangement of the active antennas AA, multiple rows in which the active antennas are arranged in the second direction may be arranged in the first direction, and each of the multiple rows may be arranged with a substantially uniform offset length in the second direction relative to adjacent rows. The definitions of the first direction and the second direction may be changed depending on the antenna elements used.

[0116] In the above embodiment, the antenna array is rotated approximately 45 degrees relative to the first direction, but the rotation angle is not limited to this and can be selected appropriately. Also, the number of active antennas AA arranged in each row can be changed.

[0117] Furthermore, the connection between the bias wiring from the bias control unit 12 and the active antenna is not limited to that shown in each embodiment, and can be changed as appropriate.

[0118] The embodiments described above can be modified as appropriate without departing from the spirit and scope of the present invention. The disclosure of this specification includes not only what is described in this specification, but also all matters that can be understood from this specification and the drawings attached hereto.

[0119] The technology of the present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the technology of the present disclosure. Therefore, the following claims are appended to disclose the scope of the technology of the present disclosure.

[0120] This application claims priority based on Japanese Patent Application No. 2024-114459 filed on July 18, 2024 and Japanese Patent Application No. 2025-083387 filed on May 19, 2025, the entire contents of which are incorporated herein by reference.

[0121] AA: Active antenna AN: Antenna RTD, 100: Semiconductor 10, 20, 30: Antenna device, 11, 21: Antenna array

Claims

1. An antenna device comprising an antenna array in which a plurality of active antennas, each including an antenna and a semiconductor structure, are arranged to generate or detect electromagnetic waves, wherein the antenna array is configured such that a plurality of rows, each row having one or more of the active antennas arranged in a first direction, are arranged in a second direction intersecting the first direction, and each of the plurality of rows is arranged with an offset length in the first direction relative to adjacent rows.

2. The antenna device according to claim 1, further comprising a coupling wire for coupling at least two of said plurality of active antennas to each other.

3. The antenna device according to claim 2, wherein the path length of the coupled line is based on the wavelength of the electromagnetic wave.

4. The antenna device according to claim 3, wherein the path length of the coupled line is approximately equal to n wavelengths (n is an integer) of the electromagnetic wave.

5. The antenna device according to any one of claims 1 to 4, characterized in that the electromagnetic waves are electromagnetic waves in the terahertz band.

6. The antenna device according to any one of claims 1 to 5, wherein the offset length is approximately equal to half the wavelength of the electromagnetic wave.

7. The antenna device according to any one of claims 1 to 6, wherein the spacing between the plurality of rows is approximately equal to half the wavelength of the electromagnetic wave.

8. The antenna device according to any one of claims 1 to 7, wherein the first direction of the active antenna is substantially the same as the electric field direction of the antenna.

9. The antenna device according to any one of claims 1 to 7, wherein the first direction of the active antenna is substantially the same as the magnetic field direction of the antenna.

10. The antenna device according to any one of claims 1 to 9, wherein the active antenna excites a circularly polarized wave.

11. The antenna device according to any one of claims 1 to 10, wherein the plurality of active antennas are arranged in a staggered pattern.

12. The antenna device according to any one of claims 1 to 11, wherein the dimensions of at least one of the plurality of active antennas are different from the dimensions of the other active antennas.

13. An antenna device according to any one of claims 1 to 11, wherein at least one of the plurality of active antennas has physical dimensions that are half the physical dimensions of the other active antennas.

14. The antenna device according to claim 8, wherein the active antenna is arranged so that the first direction is rotated by approximately 45 degrees with respect to the electric field direction of the antenna.

15. The antenna device according to claim 9, wherein the active antenna is arranged so that the first direction is rotated by approximately 45 degrees with respect to the direction of the magnetic field of the antenna.

Images