JP2018198349A - Antenna element and array antenna - Google Patents

Abstract

To provide, on an integrated circuit board, a broadband array antenna for use in a wireless communication system using microwave, millimeter wave, terahertz wave and the like.SOLUTION: A broadband slot array antenna uses four broadband slot antenna elements 10a having different center frequencies and eight antenna element 10b and is comprised of a configuration in which the four antenna elements 10a and the eight antenna element 10b are disposed in 2-4-4-2 rows by a combination with coupling of the antenna elements taken into consideration.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a broadband antenna element used in a wireless communication system such as a microwave, a millimeter wave, and a terahertz wave.

  A terahertz wave is an electromagnetic wave located in a frequency range from 300 GHz (0.3 THz) to 3 THz. Although ultra-high-speed communication in the frequency band of 300 GHz or higher is being studied, there is no legal system regarding the frequency used. However, if large-capacity data of 100 Gbps or more comparable to optical fiber communication can be realized by terahertz wave radio, high-definition television reception and high-quality video non-reception will be possible on remote islands and the sea where optical fiber installation is difficult. It is possible to exchange with compression or low compression. In addition, it can be applied as an alternative when the optical fiber network is cut due to an earthquake or volcanic eruption.

  In order to transmit 100 Gbps data wirelessly, a band of at least 100 GHz or more is required. Moreover, in order to reduce the conversion loss of the optical signal to the THz signal, an optical-terahertz-wave converter (Uni-traveling-carrier Photodiode, UTC-PD) is created on the integrated circuit substrate, and the same integrated circuit substrate It is necessary to create an antenna on top. So far, an element using the bow tie antenna described in Non-Patent Document 1 has been disclosed. However, since the bow tie antenna has radiation directivity on both sides, electromagnetic waves are absorbed into the conversion element substrate and good radiation characteristics are obtained. Was not obtained. Therefore, an antenna that does not emit radiation into the conversion element substrate (inside the integrated circuit substrate) is required.

  In addition, for long-distance communication, it is necessary to form a sharp radiation beam (high directivity gain). Usually, a plurality of antenna elements having the same operating frequency are arrayed to obtain a high directivity gain. In this case, the operating frequency of the antenna is one frequency, and a signal over a wide band cannot be transmitted.

  The inventors have proposed a unidirectional slot array antenna that operates in the 300 GHz band on an integrated circuit substrate. The antenna described in Non-Patent Document 2 is configured on an indium phosphide substrate, a part of the indium phosphide substrate 103 is dug, and a floating metal layer 102 that is not electrically connected to other circuits is stacked thereon, The structure is such that polyimide 104 is laminated thereon, and further, a metal layer 101 serving as an antenna surface is laminated. The floating metal layer 102 blocks radiation into the integrated circuit board. 4 × 4 = 16 antenna elements 10 are arranged on the metal layer 101 on the antenna surface, and a high directivity gain is obtained by feeding a 300 GHz signal in the same phase. The shape of the antenna element 10 is described in Patent Document 1.

  7A and 7B are a plan view and a cross-sectional view in the case where the antenna element described in Non-Patent Document 2 is designed so that the operating frequency is 600 GHz. The antenna is laid out on the metal layer 101. The floating metal layer 102 is not connected to the metal layer 101 and other wirings. Since the signal input section of the array antenna has a coplanar structure in which both the signal line and the ground plane exist on the antenna plane 101, the signal line of the optical-terahertz wave conversion element is the signal line of the coplanar line, and the ground conductor is the coplanar line. The same metal layer 101 is connected to the ground plane.

  FIG. 8 is a plan view when twelve antenna elements 10 of FIG. 7 are used and arranged in a 2-4-2-2 row. Usually, since a semiconductor wafer is circular, antenna elements cannot be arranged at four corners. In this case, the maximum gain = 12.07 dBi and the band (3 dB band: a band in which the gain is halved) = 30 GHz.

Patent No. 4811807

R. Yano, H .; Gotoh, Y .; Hirayama, “Terahertz wave detection performance of photoconductive antennas: Role of antenna structure and gate pulse intensity”, J. Am. Applied Physics, 97, 103103 (2005). 4x4 planar array antenna on indium phosphide substrate for 0.3-THZ band application, H.C. KANAYA, M.M. KOGA, K.K. TSUGAMI, G.M. CHAI EU, K.E. KATO, Proc. SPIE Photonics West 2017, 101031N, 2017.

  However, although the techniques shown in FIG. 7 and FIG. 8 can perform the operation frequency with a terahertz wave, the band is insufficient and the practicality is poor.

  The present invention realizes a wide band of terahertz waves by arranging a relatively high frequency antenna element and a low frequency antenna element while realizing a plurality of resonance conditions with a single antenna element. An antenna element and an array antenna are provided.

  An antenna element according to the present invention has a curved open end of a unidirectional slot antenna, and is arranged so as to face a planar first metal plate with an insulating material facing the plane of the first metal plate. A second metal plate provided; and a power feeding unit that feeds power to the first metal plate. The first metal plate has a linear first slot extending in the first direction and is opposite to the first direction. The first metal plate has a straight second slot extending in the second direction, the edge of the first metal plate facing the straight line of the first slot is curved, and the first metal facing the straight line of the second slot The edge of the plate is curved.

  Thus, in the antenna element according to the present invention, by bending the open end of the unidirectional slot antenna, there is an effect that a plurality of resonance conditions can be realized and a wide band can be achieved.

  An array antenna according to the present invention is an array antenna using the above-described antenna element, which connects a plurality of antennas having different frequencies in the same phase, and is curved from the first slot and the second slot. A plurality of first antenna elements having a relatively long distance to the edge of the first metal plate and a plurality of relatively short second antenna elements are arranged in a lattice pattern.

  As described above, in the array antenna according to the present invention, a plurality of different frequencies and a relatively high frequency antenna element and a relatively low frequency antenna element are connected in the same phase, so that a wide band and There is an effect that an array antenna having a high directivity gain can be realized.

It is a top view of the antenna element which concerns on 1st Embodiment. It is a top view of each antenna element used for the array antenna concerning a 1st embodiment. It is a top view of the array antenna which concerns on 1st Embodiment. It is a figure which shows the frequency characteristic of the gain in the two antenna elements of FIG. It is a figure which shows the frequency characteristic of the gain in the array antenna of FIG. It is a figure which shows the radiation pattern in the array antenna of FIG. It is the top view and sectional drawing of an antenna element which operate | move by 600 GHz by the conventional design method. FIG. 8 is a plan view of an array antenna in which the antenna elements of FIG. 7 are arranged in 2-4-4-2 rows.

  Embodiments of the present invention will be described below. Also, the same reference numerals are given to the same elements throughout the present embodiment.

  An antenna element and an array antenna according to the present embodiment will be described with reference to FIGS. FIG. 1 is a plan view of an antenna element according to the present embodiment. The cross-sectional shape of the antenna element 10 in FIG. 1 is the same as that shown in FIG. 7, and is configured on the indium phosphide substrate 103. A part of the indium phosphide substrate 103 is dug, and other circuits are electrically connected thereto. A structure in which a floating metal layer 102 having no connection is laminated, a metal layer (back surface) 101b is laminated thereon, polyimide 104 is laminated thereon, and a metal layer (front surface) 101a serving as an antenna surface is laminated. It has become. The floating metal layer 102 blocks radiation into the integrated circuit board.

  Further, as shown in FIG. 1, the planar shape of the antenna element 10 according to the present embodiment is such that the front open end is curved with respect to the antenna shape of FIG. A plurality of resonance conditions are realized in the antenna element 10 itself. More specifically, the planar metal layer (back surface) 101b (not shown in FIG. 1) and the plane of the metal layer (back surface) 101b are arranged to face each other through polyimide 104 which is an insulating material. A metal layer (front surface) 101a and a power supply electrode 105 for supplying power to the metal layer (front surface) 101a.

  The metal layer (surface) 101a has a linear first slot 106 extending in the first direction a and a linear second slot extending in the second direction b opposite to the first direction a. 107, the edge 108 of the metal layer (surface) 101a facing the straight line of the first slot 106 is curved, and the edge 109 of the metal layer (surface) 101a facing the straight line of the second slot 107 is curved. Is curved.

  That is, since the first slot 106 has a shape having a plurality of different distances from the edge 108 and the second slot 107 has a shape having a plurality of different distances, a plurality of resonances. It is possible to realize a broad band by realizing conditions and emitting signals at a plurality of frequencies.

  Next, antenna elements that operate in different frequency bands are designed using the antenna element 10 described above. FIG. 2 is a plan view of each antenna element used in the array antenna according to the present embodiment. The array antenna according to the present embodiment is realized by arranging antenna elements 10 operating in different frequency bands shown in FIG. 2 in parallel on the array. 2A shows a low frequency antenna element 10a having a relatively low frequency, and FIG. 2B shows a high frequency antenna element 10b having a relatively high frequency. The difference between the antenna elements 10a and 10b is that the distances from the first slot 106 and the second slot 107 to the opposing edges 108 and 109 are different. That is, as shown in FIG. 2, the relatively high frequency antenna element 10 b has the opposite edges from the first slot 106 and the second slot 107 as compared to the relatively low frequency antenna element 10 a. The distance to the parts 108 and 109 is shortened. That is, the frequency to be transmitted and received is a different band.

  FIG. 3 is a plan view of a broadband array antenna using the antenna element of FIG. The array antenna 20 uses 12 elements of relatively low frequency antenna elements 10a and 8 elements of relatively high frequency antenna elements 10b, thereby forming an array of 12 elements in total in a 2-4-2-2 row. The antenna 20 is realized.

  In addition, since each antenna element couple | bonds together, the combination method of an antenna element needs optimization. For example, the number of antenna elements 10 in the array antenna 20 is not limited to 12 elements, and may be any number. The antenna element 10a and the antenna element 10b are preferably arranged so that the antenna elements 10a are adjacent to each other and the antenna elements 10b are adjacent to each other. Furthermore, the ratio of the number of elements of the antenna element 10a and the antenna element 10b may be 1: 1 or may cause a bias (asymmetrical).

  FIG. 4 shows frequency characteristics of the gain of the antenna element according to this embodiment. The maximum gains of the antenna element 10a and the antenna element 10b are 2.23 dBi and 3.28 dBi, respectively, and the bands are both 100 GHz.

  FIG. 5 shows frequency characteristics of gain in the array antenna according to the present embodiment. The maximum gain is 12.73 dBi and the band is 120 GHz.

  FIG. 6 is a diagram showing a radiation pattern at 600 GHz in the array antenna according to the present embodiment. As shown in FIG. 6, good directivity is obtained in the 0 degree direction (the direction opposite to the inside of the integrated circuit board).

  From the above, it has been clarified that the antenna element and the array antenna according to the present embodiment can achieve a wide band by realizing a plurality of resonance conditions and have a high directivity gain.

  In the above description, the case of 600 GHz is shown, but the parameters used for the design are determined by the ratio to the wavelength, so that the performance is particularly exhibited in other microwave frequencies, millimeter wave frequencies, and terahertz wave frequency bands. Can do.

  Further, although the front open ends of the antenna elements 10a and 10b are curved, for example, a triangular taper structure or a wavy line structure may be used.

  Further, although the number of antenna elements is 12, when the area of the integrated circuit board is large, the number of elements can be increased by a combination that takes into account the coupling between the antenna elements.

  Furthermore, the antenna element 10 has two types, a relatively low frequency antenna element 10a and a relatively high frequency antenna element 10b. For example, in addition to the above, “center frequency antenna element” or antenna element By adding an antenna element on the lower frequency side than 10b and an antenna element on the higher frequency side than the antenna element 10a, the bandwidth can be increased.

10 (10a, 10b) Antenna element 20 Array antenna 102 Floating metal layer 103 Indium phosphide substrate 104 Polyimide 105 Feed electrode 106 First slot 107 Second slot 108, 109 Edge

Claims (4)

  An antenna element having a curved open end of a unidirectional slot antenna. The antenna element according to claim 1, wherein
A planar first metal plate;
A second metal plate disposed opposite to the plane of the first metal plate via an insulating material;
A power feeding unit for feeding power to the first metal plate,
The first metal plate has a linear first slot extending in a first direction and a linear second slot extending in a second direction opposite to the first direction, An antenna element in which the edge of the first metal plate facing the straight line of the slot is curved and the edge of the first metal plate facing the straight line of the second slot is curved. An array antenna using the antenna element according to claim 1 or 2,
An array antenna that connects multiple antennas with different frequencies in the same phase. The multi-antenna according to claim 3,
A plurality of first antenna elements having relatively long distances from the first slot and the second slot to the edge of the curved first metal plate and a plurality of relatively short second antenna elements are latticed. Array antennas arranged in multiple shapes.