Radio wave lens

Abstract

In a radio wave lens (10), unit cells (11) are two-dimensionally arranged on a plane of a substrate (12) that intersects incident radio waves. In each unit cell (11), a conductor section having a shape that bends in a crank shape in the plane of the substrate (12) is formed, or a conductor removal region having a shape that bends in a crank shape in the plane of the substrate (12) is formed in a conductor layer on the substrate (12). Unit cells (11) in which the directions of bending of the conductor sections or the directions of bending of the conductor removal regions differ from one another are two-dimensionally arranged according to a desired phase distribution for radio waves passing through the unit cells (11).

Description

[Technical Field]

[0001] The present invention relates to a radio wave lens that controls the transmission phase distribution of radio waves. [Background technology]

[0002] The millimeter wave and terahertz wave bands used in fifth-generation (5G) and sixth-generation (6G) mobile communication systems have a problem in that they tend to travel in a very straight line, resulting in a significant degradation in communication quality in areas outside the line of sight of the base station. This degradation in communication quality also becomes a problem when an outdoor base station extends its coverage area to indoors through a building's window.

[0003] Therefore, in recent years, attention has been drawn to a technology that uses metasurface technology, which can design the scattering characteristics of incoming waves, to guide radio waves to indoor repeaters by attaching a film with lens functionality to window glass (see, for example, Non-Patent Document 1). In Non-Patent Document 1, a film with a metal metasurface pattern is attached to the window glass, and a distribution of radio wave transmission and reflection is formed on the window glass surface, thereby realizing a desired planar transmission intensity distribution (a binary distribution of 1 (transmission) and 0 (reflection)) and realizing a radio wave lens function.

[0004] However, when forming a distribution of transmitted and reflected radio waves as in Non-Patent Document 1, there is a problem in that only a portion of the radio waves arriving at the window can be used for indoor propagation. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Daisuke Kitayama,et al.,“Transparent dynamic metasurface for a visually unaffected reconfigurable intelligent surface:controlling transmission / reflection and making a window into an RF lens”,Optics Express,vol.29,No.18,pp. 29292-29307,2021 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a radio wave lens that can utilize almost all of the incoming radio waves as transmitted waves. [Means for solving the problem]

[0007] The radio wave lens of the present invention has a first unit cell and a second unit cell on a surface of a substrate that intersects with an incident radio wave. , according to the desired phase distribution of the radio waves passing through these cells. are arranged in two dimensions, The first unit cell is composed of an annular first conductor portion formed on the substrate, a second conductor portion formed on the substrate so as to connect two points on the first conductor portion and divide an area in the first conductor portion where no conductor pattern is present in two equal parts, a first gap dividing the second conductor portion so as to connect the two areas equally divided by the second conductor portion, a comb-teeth-shaped third conductor portion formed at one end of the second conductor portion facing across the first gap, and a comb-teeth-shaped fourth conductor portion disposed at the other end of the second conductor portion facing across the first gap so as to face the third conductor portion in an alternating manner, and the second unit cell is composed of an annular fifth conductor portion formed on the substrate. a sixth conductor formed on the substrate so as to connect two points of the fifth conductor and divide an area in the fifth conductor where there is no conductor pattern into two equal parts; a second gap dividing the sixth conductor so as to connect the two equal parts divided by the sixth conductor; a comb-tooth-shaped seventh conductor formed at one end of the sixth conductor opposite to the second gap; and a comb-tooth-shaped eighth conductor disposed at the other end of the sixth conductor opposite to the second gap so as to be alternately opposed to the seventh conductor, wherein the second conductor and the sixth conductor are shaped to be bent in a crank shape within the plane of the substrate and bent in different directions. It is characterized by the following. [Effects of the Invention]

[0008] According to the present invention, by forming a conductor portion that is bent in a crank shape within the plane of the substrate in each of the first unit cell and the second unit cell, or by forming a conductor removal area that is bent in a crank shape within the plane of the substrate, and by making the bending directions of the conductor portion or the conductor removal area different from each other, and by arranging the first unit cell and the second unit cell two-dimensionally according to the desired phase distribution of the transmitted radio waves, it is possible to utilize almost all of the incoming radio waves as transmitted waves, and to improve the efficiency of the radio wave lens. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a diagram illustrating the difference between the prior art and the present invention. [Figure 2A-2B] 2A and 2B are plan views showing the structure of a unit cell of a radio wave lens according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a graph showing the transmitted scattered wave intensity of the unit cell according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the phase of a transmitted scattered wave of the unit cell according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a plan view showing the structure of a radio wave lens according to a first embodiment of the present invention. [Figure 6] FIG. 6 is a diagram for explaining a method for determining the placement of unit cells according to a second embodiment of the present invention. [Figures 7A-7B] 7A and 7B are plan views showing the structures of unit cells according to first, second and third embodiments of the present invention. [Figure 8] FIG. 8 is a graph showing the transmitted scattered wave intensity of the unit cells according to the first, second, and third embodiments of the present invention. [Figure 9A-9B] 9A and 9B are plan views showing the structure of a unit cell according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a graph showing the transmitted scattered wave intensity of the unit cell according to the third embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing the phase of a transmitted scattered wave of a unit cell according to the third embodiment of the present invention. [Figure 12] FIG. 12 is a plan view showing the structure of a radio wave lens according to a third embodiment of the present invention. [Figures 13A-13B] 13A and 13B are perspective views showing the structure of a unit cell according to a third embodiment of the present invention. [Figure 14] FIG. 14 is a diagram showing the results of an electromagnetic field analysis of the scattered wave phase difference for the unit cells of FIGS. 13A and 13B. [Figure 15] FIG. 15 is an exploded perspective view showing the structure of a unit cell according to a fourth embodiment of the present invention. [Figures 16A-16C]16A to 16C are plan views showing the structures of the polarizing layer and the conductor layer of a unit cell according to a fourth embodiment of the present invention. [Figure 17] FIG. 17 is a graph showing the transmitted scattered wave intensity of the unit cells according to the third and fourth examples of the present invention. [Figures 18A-18B] 18A and 18B are perspective views showing the structures of unit cells according to third and fourth embodiments of the present invention. [Figure 19] FIG. 19 is a diagram showing the results of an electromagnetic field analysis of the transmitted and scattered wave intensity for the unit cells of FIGS. 18A and 18B. [Figures 20A-20B] 20A and 20B are plan views showing the structure of a unit cell according to a fifth embodiment of the present invention. [Figures 21A-21B] 21A and 21B are plan views showing another structure of a unit cell according to the fifth embodiment of the present invention. [Figures 22A-22B] 22A and 22B are plan views showing the structure of a unit cell according to a sixth embodiment of the present invention. [Figures 23A-23B] 23A and 23B are plan views showing another structure of a unit cell according to the sixth embodiment of the present invention. [Figures 24A-24B] 24A and 24B are plan views showing the structure of a unit cell according to a seventh embodiment of the present invention. [Figures 25A-25B] 25A and 25B are plan views showing another structure of a unit cell according to the seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Principle of the Invention] Figure 1 is a diagram illustrating the difference between the conventional technology disclosed in Non-Patent Document 1 and the present invention. In the conventional technology, a binary transmission intensity distribution 101 of 1 (transmission) and 0 (reflection) is formed by a metal metasurface pattern 100. On the other hand, in the present invention, a binary transmission phase distribution 102 of 0 and π [rad] is formed. In this way, the present invention forms a distribution of transmission phase rather than transmission intensity of radio waves using a single-layer metasurface pattern, and utilizes almost all of the radio waves arriving at the metasurface as transmitted waves.

[0011] [First Example] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figures 2A and 2B are plan views showing the unit cell structure of a radio wave lens according to a first embodiment of the present invention. Unit cell 11A is composed of a conductor portion 1A made of a ring-shaped metal and formed on a substrate; a conductor portion 2A made of a metal and formed on the substrate so as to connect two points on conductor portion 1A and divide an area within conductor portion 1A where no conductor pattern is present in half; and a gap 3A that divides conductor portion 2A so as to connect two areas 4A divided equally by conductor portion 2A. Conductor portion 2A has two 90-degree bends, with gap 3A located midway between the two bends.

[0012] Unit cell 11B is composed of conductor portion 1B made of a ring-shaped metal formed on a substrate, conductor portion 2B made of a metal formed on the substrate so as to connect two points on conductor portion 1B and divide the area without a conductor pattern in conductor portion 1B into two equal parts, and gap 3B dividing conductor portion 2B so as to connect the two areas 4B divided equally by conductor portion 2B. Conductor portion 2B has two 90-degree bends, and gap 3B is located midway between these two bends.

[0013] In the present invention, radio waves are incident from a direction perpendicular to a plane including conductors 1A and 2A and gap 3A of unit cell 11A and conductors 1B and 2B and gap 3B of unit cell 11B (the plane of the paper in FIGS. 2A and 2B). In FIGS. 2A and 2B, x, y, and z represent coordinate axes, Hin represents the direction of the magnetic field component of the incident radio wave (arriving wave), Ein represents the direction of the electric field component of the arriving wave, HsA represents the direction of the magnetic field component of the scattered wave radiated from gap 3A of unit cell 11A, EsA represents the direction of the electric field component of the scattered wave radiated from gap 3A, HsB represents the direction of the magnetic field component of the scattered wave radiated from gap 3B of unit cell 11B, and EsB represents the direction of the electric field component of the scattered wave radiated from gap 3B.

[0014] In this embodiment, the conductor 2A of the unit cell 11A is bent in a crank-like shape within a plane including the conductors 1A and 2A and the gap 3A. The direction in which the gap 3A crosses the conductor 2A (the vertical direction in FIGS. 2A and 2B) is parallel to the direction of the electric field component Ein of the incident wave. This allows the scattered wave radiated from the gap 3A to have an electric field component EsA perpendicular to the direction of the electric field component Ein of the incident wave. Furthermore, the conductor 2B of the unit cell 11B is bent in a crank-like shape within a plane including the conductors 1B and 2B and the gap 3B. This allows the direction in which the gap 3B crosses the conductor 2B to be parallel to the direction of the electric field component Ein of the incident wave. This allows the scattered wave radiated from the gap 3B to have an electric field component EsB perpendicular to the direction of the electric field component Ein of the incident wave. In this embodiment, the scattered wave, whose polarization is rotated 90 degrees relative to the incident wave, is utilized as a transmitted wave.

[0015] In both unit cells 11A and 11B, conductors 2A and 2B are bent in a crank shape, but the bending directions of conductors 2A and 2B are opposite to each other. In other words, unit cells 11A and 11B are mirror-symmetrical.

[0016] The intensity of the scattered wave, whose polarization is rotated 90 degrees relative to the incident wave, is maximum near the resonant frequency of unit cells 11A and 11B. The resonant frequency of unit cell 11A is determined by the capacitive and inductive components derived from conductors 1A and 2A and gap 3A. Similarly, the resonant frequency of unit cell 11B is determined by the capacitive and inductive components derived from conductors 1B and 2B and gap 3B. The resonant frequencies of unit cells 11A and 11B are designed according to the frequency to be used.

[0017] The phase of the scattered wave relative to the phase of the incoming wave differs by π [rad] between unit cells 11A and 11B, where the bending directions of conductor portions 2A and 2B are opposite. Figure 3 shows the intensity of the transmitted scattered wave for unit cells 11A and 11B, and Figure 4 shows the phase of the transmitted scattered wave for unit cells 11A and 11B. In Figure 3, 30 and 31 indicate the intensity of the scattered wave for unit cells 11A and 11B, respectively. In Figure 4, 40 and 41 indicate the phase of the scattered wave for unit cells 11A and 11B, respectively.

[0018] In this embodiment, a phase-distribution type radio wave lens 10 can be realized with only one layer of metal metasurface pattern by arranging unit cells 11A and 11B two-dimensionally on a substrate 12 made of a dielectric material such as glass, as shown in Figure 5, according to the desired binary phase distribution of 0 and π [rad]. 11 in Figure 5 represents either unit cell 11A or unit cell 11B. In this embodiment, almost all of the radio waves arriving at the metasurface can be used as transmitted waves, improving the efficiency of the radio wave lens 10 compared to conventional technology.

[0019] [Second Example] Next, a second embodiment of the present invention will be described. In this embodiment, the structure of the unit cell of the radio wave lens is the same as in the first embodiment, so the description will be made using the symbols in Figs. 2A and 2B. In this embodiment, when a radio wave is guided from the source of the incoming wave to a desired receiving point through the radio wave lens, a phase difference G due to the difference in optical path length for each unit cell is generated. n The unit cells 11A and 11B are arranged so as to correct this.

[0020] 6 is a diagram for explaining a method for determining the arrangement of unit cells 11A and 11B in this embodiment. Let N be the total number of unit cells 11A and 11B that make up the radio wave lens 10, P1 be the wave source of the incoming wave that enters the radio wave lens 10, P2 be the receiving point where energy is to be guided via the radio wave lens 10, and p be the position of the n-th unit cell 11 (11A or 11B). n (n is an integer from 1 to N), the distance from P1 to an arbitrary reference point on the substrate 12 (the center point of the substrate 12 in the example of FIG. 4) is D1, the distance from P2 to the reference point is D2, and the distance from P1 to pn Distance to d 1n , P2 to p n Distance to d 2n The phase difference G of the radio wave caused by the optical path length difference for each unit cell at the receiving point P2 n is expressed as follows: G n =2π((d 1n -D1)+(d 2n -D2)) / λ (1)

[0021] λ is the wavelength of the incoming wave. Phase difference G of the radio wave per unit cell n By correcting the above and arranging the unit cells so that the phases of the radio waves arriving at the reception point P2 from each unit cell are matched, it is possible to determine the unit cell arrangement that induces scattered waves to the reception point P2.

[0022] For example, the phase difference G n Unit cell 11A may be placed at a position on substrate 12 where the remainder when divided by 2π is in the range of 0 to π, and unit cell 11B may be placed at a position where the remainder is in the range of π to 2π. Note that the same function can be achieved even if the positions of unit cell 11A and unit cell 11B are interchanged.

[0023] Furthermore, if the distance D1 is calculated to be sufficiently longer than the size of the radio wave lens 10, it is possible to determine a unit cell arrangement that assumes a plane wave arriving from the direction of the reception point P1. Furthermore, if the distance D2 is calculated to be sufficiently longer than the size of the radio wave lens 10, it is possible to achieve the function of deflecting the transmitted wave in the direction of the reception point P2.

[0024] [Third Example] When a unit cell in which the presence or absence of the conductor pattern of the unit cell of the first embodiment is reversed is used and the polarization of the incoming wave is rotated 90 degrees relative to that of the first embodiment, the intensity of the transmitted wave, whose polarization is rotated 90 degrees relative to the incoming wave, becomes maximum near the resonant frequency of the unit cell, and scattered waves are radiated in the transmitted direction even in areas with frequencies higher than the resonant frequency.

[0025] 7A and 7B are plan views showing the structure of a unit cell of the first embodiment and this embodiment. The unit cell 11Aa is composed of a conductor layer 5A made of metal and rectangular in plan view formed on a substrate. The conductor layer 5A includes a ring-shaped conductor removal region 6A, a conductor removal region 7A formed to connect two points in the conductor removal region 6A and divide the conductor pattern in the conductor removal region 6A into two equal parts, two conductor patterns 8A equally divided by the conductor removal region 7A, and a conductor remaining portion 9A dividing the conductor removal region 7A to connect the two conductor patterns 8A. In this embodiment, the conductor removal region 7A is bent in a crank-like shape within the plane of the conductor layer 5A. The conductor removal region 7A has two 90-degree bends, with the conductor remaining portion 9A positioned midway between the two bends. Thus, the unit cell 11Aa has a shape that is the inverse of the unit cell 11A, with or without the conductor patterns.

[0026] As in the first and second embodiments, in this embodiment, the incident wave is incident from a direction perpendicular to the plane of the unit cell 11Aa including the conductor layer 5A (the plane of the paper in FIGS. 7A and 7B). In FIGS. 7A and 7B, HsAa represents the direction of the magnetic field component of the scattered wave radiated from the unit cell 11Aa, and EsAa represents the direction of the electric field component of the scattered wave radiated from the unit cell 11Aa.

[0027] In the first and second embodiments, the direction in which the gaps 3A and 3B cross the conductor portions 2A and 2B (the vertical direction in Figures 2A, 2B, 7A, and 7B) is parallel to the direction of the electric field component Ein of the arriving wave. On the other hand, in this embodiment, the direction in which the conductor remaining portion 9A crosses the conductor removed area 7A (the vertical direction in FIGS. 7A and 7B) is perpendicular to the direction of the electric field component Ein of the incoming wave.

[0028] The transmitted and scattered wave intensities of the unit cell 11A of the first and second embodiments and the unit cell 11Aa of this embodiment are shown in Fig. 8. 80 and 81 denote the scattered wave intensities of the unit cells 11A and 11Aa, respectively. Fig. 8 shows that near the resonant frequency of the unit cell 11Aa, the intensity of the transmitted wave, whose polarization is rotated 90 degrees with respect to the incident wave, is at its maximum, and that the scattered wave is radiated in the transmitted direction even in a frequency range higher than the resonant frequency.

[0029] As with the first and second embodiments, this embodiment also allows for the formation of a unit cell in which the bending direction of the conductor removal region is reversed. The unit cell 11Ba shown in FIGS. 9A and 9B is composed of a conductor layer 5B made of metal and rectangular in plan view formed on a substrate. The conductor layer 5B includes a ring-shaped conductor removal region 6B, a conductor removal region 7B formed to connect two points in the conductor removal region 6B and divide the conductor pattern in the conductor removal region 6B into two equal parts, two conductor patterns 8B equally divided by the conductor removal region 7B, and a conductor remaining portion 9B dividing the conductor removal region 7B so as to connect the two conductor patterns 8B. In this embodiment, the conductor removal region 7B is bent in a crank-like shape within the plane of the conductor layer 5B. The conductor removal region 7B has two 90-degree bends, with the conductor remaining portion 9B positioned midway between the two bends. Thus, the unit cell 11Ba has a shape that reverses the presence or absence of the conductor patterns of the unit cell 11B.

[0030] In both unit cells 11Aa and 11Ba, conductor removal regions 7A and 7B are curved in a crank shape, but the curved directions of conductor removal regions 7A and 7B are opposite to each other. In other words, unit cells 11Aa and 11Ba are mirror-symmetrical. 9A and 9B, HsBa represents the direction of the magnetic field component of the scattered wave radiated from the unit cell 11Ba, and EsBa represents the direction of the electric field component of the scattered wave radiated from the unit cell 11Ba.

[0031] The phase of the scattered wave relative to the phase of the incoming wave differs by π [rad] between unit cells 11Aa and 11Ba. Figure 10 shows the intensity of the transmitted scattered wave for unit cells 11Aa and 11Ba, and Figure 11 shows the phase of the transmitted scattered wave for unit cells 11Aa and 11Ba. In Figure 10, 110 and 111 indicate the intensity of the scattered wave for unit cells 11Aa and 11Ba, respectively. In Figure 11, 112 and 113 indicate the phase of the scattered wave for unit cells 11Aa and 11Ba, respectively.

[0032] In this way, the relationship that the phase of the transmitted scattered wave differs by π [rad] between the unit cell 11Aa and the unit cell 11Ba is the same as in the first and second embodiments. n By arranging unit cell 11Aa at a position on substrate 12 where the remainder when dividing π by 2π is in the range of 0 to π, and unit cell 11Ba at a position where the remainder is in the range of π to 2π, it is possible to realize a radio wave lens that functions over a wider bandwidth than the first and second embodiments, which can utilize scattered waves in the transmission direction only near the resonant frequency. FIG. 12 shows the structure of radio wave lens 10a, in which unit cells 11Aa and 11Ba are arranged two-dimensionally on substrate 12. In FIG. 12, 11a represents either unit cell 11Aa or unit cell 11Ba. As with the second embodiment, the same function can be achieved even if the positions of unit cell 11Aa and unit cell 11Ba are interchanged.

[0033] For example, Fig. 14 shows the results of an electromagnetic field analysis of the scattered wave phase difference for the structures of unit cell 11Aa and unit cell 11Ba in Figs. 13A and 13B. In Figs. 13A and 13B, k represents the wave number direction. The dimensions of rectangular conductor layers 5A and 5B in the x and y directions are 800 µm in plan view. Fig. 14 confirms that the phase difference between the transmitted scattered wave of unit cell 11Aa and the transmitted scattered wave of unit cell 11Ba is π [rad] across the entire analyzed frequency range.

[0034] [Fourth Example] Next, a fourth embodiment of the present invention will be described. Fig. 15 is an exploded perspective view showing the structure of a unit cell according to the fourth embodiment of the present invention. In the unit cell 11Ab of this embodiment, polarizing layers 13 and 14 are arranged on the incident side of the conductor layer 5A described in the third embodiment where the incoming wave is incident and on the outgoing side where the transmitted wave is emitted. In Fig. 15, HsAb represents the direction of the magnetic field component of the scattered wave radiated from the unit cell 11Ab, and EsAb represents the direction of the electric field component of the scattered wave radiated from the unit cell 11Ab.

[0035] 16A, 16B, and 16C are plan views showing the structures of the polarizing layers 13 and 14 and the conductor layer 5A of this embodiment. The structure of the conductor layer 5A is as described in the third embodiment. The deflection layer 13 on the side where the incoming wave is incident on the conductor layer 5A has a conductor pattern 15 made of metal formed thereon so as to transmit polarized waves in the direction in which the conductor remaining portion 9A crosses the conductor removal area 7A (the vertical direction in FIGS. 16A, 16B, and 16C). On the other hand, the polarizing layer 14 on the side where the transmitted wave is emitted from the conductor layer 5A has a conductor pattern 16 made of metal formed thereon so as to transmit polarized waves in the direction orthogonal to the direction in which the conductor remaining portion 9A crosses the conductor removal area 7A (the horizontal direction in FIGS. 16A, 16B, and 16C). In other words, the conductor pattern 16 is formed so that the transmitted polarized wave rotates 90 degrees relative to the polarizing layer 13 on the incident side.

[0036] Fig. 17 is a diagram showing the transmitted scattered wave intensity of the unit cell 11Aa of the third embodiment and the unit cell 11Ab of this embodiment. 170 and 171 in Fig. 17 indicate the scattered wave intensity of the unit cells 11Aa and 11Ab, respectively. In this embodiment, the transmitted scattered wave intensity can be increased compared to the third embodiment. It is to be noted that both the polarizing layers 13 and 14 may be provided, or only one of them may be provided.

[0037] FIG. 19 shows the results of an electromagnetic field analysis of the transmitted scattered wave intensity for a unit cell 11Aa of the third embodiment shown in FIG. 18A and a unit cell 11Ab of an infinite periodic structure shown in FIG. 18B, in which a conductor layer 5A is formed on one surface of a substrate 12 and a polarizing layer 13 is formed on the other surface of the substrate 12. The dimensions of the conductor layer 5A in the x and y directions of the unit cells 11Aa and 11Ab are 800 μm. In FIG. 19, 190 indicates the transmitted scattered wave intensity of the unit cell 11Aa, and 191 indicates the transmitted scattered wave intensity of the unit cell 11Ab. In this embodiment, by providing a deflection layer 13 on the side where the incoming wave is incident, the transmitted scattered wave intensity is improved by 5 dB or more, the loss is reduced to 2 dB or less, and low-loss, wide-band characteristics are obtained.

[0038] In this embodiment, the case where the conductor layer 5A of the unit cell 11Aa of the third embodiment is used has been described, but it is also possible to similarly form the unit cell 11Ba by arranging a polarizing layer on at least one of the side of the conductor layer 5B where the incoming wave is incident and the side where the transmitted wave is emitted, thereby forming the unit cell.

[0039] 15, 16A, 16B, and 16C, if a unit cell in which the conductor layer 5B is arranged instead of the conductor layer 5A is designated as 11Bb, the phase difference of the transmitted scattered wave between the unit cell 11Ab and the unit cell 11Bb is π [rad], which is the same as in the first and second embodiments. n By arranging unit cell 11Ab at a position on substrate 12 where the remainder when dividing by 2π is in the range of 0 to π, and by arranging unit cell 11Bb at a position where the remainder is in the range of π to 2π, it is possible to realize a radio wave lens that functions over a wider bandwidth than the first and second embodiments, which can utilize scattered waves in the transmission direction only near the resonant frequency. As with the second embodiment, it is possible to achieve the same function by swapping the positions of unit cell 11Ab and unit cell 11Bb.

[0040] [Fifth Example] When arranging the unit cells according to the second embodiment, if the distance D1 from the wave source P1 of the incoming wave to the reference point on the substrate 12 or the distance D2 from the reference point to the receiving point P2 becomes short, the phase difference G of the radio wave due to the difference in the optical path length for each unit cell decreases. n changes significantly depending on the position of the unit cell on the substrate. Therefore, when the distances D1 and D2 are short, it is desirable to have a smaller unit cell size.

[0041] Therefore, by introducing a comb-tooth structure into the gap separating the conductors 2A and 2B of the unit cell as shown in Figures 20A and 20B, it is possible to achieve a unit cell size that is smaller than the wavelength of the frequency being used. In Figures 20A and 20B, the same components as in Figures 2A and 2B are denoted by the same reference numerals.

[0042] The unit cell 11Ac is composed of a conductor portion 1A made of a ring-shaped metal and formed on a substrate, a conductor portion 2A made of a metal and formed on the substrate so as to connect two points on the conductor portion 1A and divide an area without a conductor pattern in halves in the conductor portion 1A, and a gap 3Ac that divides the conductor portion 2A so as to connect the two areas 4A equally divided by the conductor portion 2A. A conductor portion 2Ac-1 that is comb-like in plan view is formed at one end of the conductor portion 2A that faces across the gap 3Ac. A conductor portion 2Ac-2 that is comb-like in plan view and arranged alternately with the conductor portion 2Ac-1 is formed at the other end of the conductor portion 2A that faces across the gap 3Ac.

[0043] The unit cell 11Bc is composed of a conductor portion 1B made of a ring-shaped metal and formed on a substrate, a conductor portion 2B made of a metal and formed on the substrate so as to connect two points on the conductor portion 1B and divide the area without a conductor pattern in halves in two, and a gap 3Bc that divides the conductor portion 2B so as to connect the two areas 4B equally divided by the conductor portion 2B. A conductor portion 2Bc-1 that is comb-like in plan view is formed at one end of the conductor portion 2B that faces each other across the gap 3Bc. A conductor portion 2Bc-2 that is comb-like in plan view is formed at the other end of the conductor portion 2B that faces each other across the gap 3Bc and is arranged opposite the conductor portion 2Bc-1 so as to be staggered.

[0044] In both unit cells 11Ac and 11Bc, conductor portions 2A and 2B are bent in a crank shape, but the bending directions of conductor portion 2A and conductor portion 2B are opposite to each other. Unit cell 11Ac and unit cell 11Bc are in a mirror symmetric relationship.

[0045] When a radio wave lens is constructed using unit cells 11Ac and 11Bc, the phase difference G n The unit cell 11Ac is placed at a position on the substrate 12 where the remainder when divided by 2π is in the range of 0 to π, and the unit cell 11Bc is placed at a position where the remainder is in the range of π to 2π. The same function can be achieved even if the positions of the unit cells 11Ac and 11Bc are interchanged.

[0046] The example in Figures 20A and 20B shows the case where the comb-tooth structure is applied to the first embodiment, but the comb-tooth structure may also be applied to the third and fourth embodiments as shown in Figures 21A and 21B. In Figures 21A and 21B, the same components as in Figures 9A and 9B are assigned the same reference numerals.

[0047] The unit cell 11Ad is composed of a conductor layer 5Ad made of metal and rectangular in plan view formed on a substrate. The conductor layer 5Ad is formed with a ring-shaped conductor removal region 6A, a conductor removal region 7A formed to connect two points in the conductor removal region 6A and divide the conductor pattern in the conductor removal region 6A into two equal parts, two conductor patterns 8A equally divided by the conductor removal region 7A, and a conductor remaining portion 9Ad dividing the conductor removal region 7A to connect the two conductor patterns 8A. A conductor removal region 7Ad-1 having a comb-like shape in plan view is formed at one end of the conductor removal region 7A facing each other across the conductor remaining portion 9Ad. A conductor removal region 7Ad-2 having a comb-like shape in plan view is formed at the other end of the conductor removal region 7A facing each other across the conductor remaining portion 9Ad, and is arranged opposite the conductor removal region 7Ad-1 so as to be staggered. The unit cell 11Ad has a shape that is the inverse of the unit cell 11Ac in terms of the presence or absence of a conductor pattern.

[0048] The unit cell 11Bd is composed of a conductor layer 5Bd made of metal and rectangular in plan view formed on a substrate. The conductor layer 5Bd is formed with a ring-shaped conductor removal region 6B, a conductor removal region 7B formed to connect two points in the conductor removal region 6B and divide the conductor pattern in the conductor removal region 6B in half, two conductor patterns 8B equally divided by the conductor removal region 7B, and a conductor remaining portion 9Bd that divides the conductor removal region 7B to connect the two conductor patterns 8B. A conductor removal region 7Bd-1 having a comb-like shape in plan view is formed at one end of the conductor removal region 7B facing each other across the conductor remaining portion 9Bd. A conductor removal region 7Bd-2 having a comb-like shape in plan view is formed at the other end of the conductor removal region 7B facing each other across the conductor remaining portion 9Bd. The unit cell 11Bd has a shape that is the inverse of the unit cell 11Bc, with respect to the presence or absence of the conductor pattern.

[0049] When a radio wave lens is constructed using the unit cells 11Ad and 11Bd, the phase difference G n The unit cell 11Ad is arranged at a position on the substrate 12 where the remainder when divided by 2π is in the range of 0 to π, and the unit cell 11Bd is arranged at a position where the remainder is in the range of π to 2π. The same function can be achieved even if the positions of the unit cells 11Ad and 11Bd are interchanged.

[0050] As explained in the fourth embodiment, a polarizing layer may be disposed on at least one of the sides of the conductor layers 5Ad and 5Bd where the incoming wave is incident and the sides where the transmitted wave is emitted. In this embodiment, the unit cell can be made smaller, so that the receiving point where the radio waves are guided by the radio wave lens can be designed to be close, and the deflection angle of the radio waves by the radio wave lens can be designed to be large.

[0051] [Sixth Example] In this embodiment, by introducing a meander line structure into the annular conductor portion of the unit cell as shown in Figures 22A and 22B, it is possible to realize a unit cell size that is smaller than the wavelength at the frequency used, as in Example 5. In Figures 22A and 22B, the same components as in Figures 2A and 2B are assigned the same reference numerals.

[0052] The unit cell 11Ae is composed of a conductor portion 1Ae made of a ring-shaped metal and formed on a substrate, a conductor portion 2A made of a metal and formed on the substrate so as to connect two points on the conductor portion 1Ae and divide an area in the conductor portion 1Ae where no conductor pattern is present in half, and a gap 3A that divides the conductor portion 2A. The conductor portion 1Ae is formed in a meander line shape.

[0053] The unit cell 11Be is composed of a conductor portion 1Be made of a ring-shaped metal and formed on a substrate, a conductor portion 2B made of a metal and formed on the substrate so as to connect two points on the conductor portion 1Be and divide an area in the conductor portion 1Be where there is no conductor pattern into two equal parts, and a gap 3B that divides the conductor portion 2B. The conductor portion 1Be is formed in a meander line shape.

[0054] In both unit cells 11Ae and 11Be, conductors 2A and 2B are bent in a crank shape, but conductors 2A and 2B are bent in opposite directions. Unit cells 11Ae and 11Be are mirror-symmetric.

[0055] When a radio wave lens is constructed using unit cells 11Ae and 11Be, the phase difference G n The unit cell 11Ae is arranged at a position on the substrate 12 where the remainder when divided by 2π is in the range of 0 to π, and the unit cell 11Be is arranged at a position where the remainder is in the range of π to 2π. The same function can be achieved even if the positions of the unit cells 11Ae and 11Be are interchanged.

[0056] The example in Figures 22A and 22B shows the case where the meander line structure is applied to the first embodiment, but the meander line structure may also be applied to the third and fourth embodiments as shown in Figures 23A and 23B. In Figures 23A and 23B, the same components as in Figures 9A and 9B are assigned the same reference numerals.

[0057] The unit cell 11Af is composed of a conductor layer 5Af made of metal and rectangular in plan view formed on a substrate. The conductor layer 5Af is formed with a ring-shaped conductor removal region 6Af, a conductor removal region 7A formed to connect two points in the conductor removal region 6Af and divide the conductor pattern in the conductor removal region 6Af into two equal parts, two conductor patterns 8A equally divided by the conductor removal region 7A, and a conductor remaining portion 9A dividing the conductor removal region 7A. The conductor removal region 6Af is formed in a meander line shape. The unit cell 11Af has a shape that is the inverse of the unit cell 11Ae, with or without the conductor pattern.

[0058] The unit cell 11Bf is composed of a conductor layer 5Bf made of metal and having a rectangular shape in a plan view formed on a substrate. The conductor layer 5Bf is formed with a ring-shaped conductor removal region 6Bf, a conductor removal region 7B formed to connect two points in the conductor removal region 6Bf and divide the conductor pattern in the conductor removal region 6Bf into two equal parts, two conductor patterns 8B equally divided by the conductor removal region 7B, and a conductor remaining portion 9B dividing the conductor removal region 7B. The conductor removal region 6Bf is formed in a meander line shape. The unit cell 11Bf has a shape that is the inverse of the unit cell 11Be in terms of the presence or absence of the conductor pattern.

[0059] When the unit cells 11Af and 11Bf are used to form a radio wave lens, the phase difference G n The unit cell 11Af is placed at a position on the substrate 12 where the remainder when divided by 2π is in the range of 0 to π, and the unit cell 11Bf is placed at a position where the remainder is in the range of π to 2π. The same function can be achieved even if the positions of the unit cells 11Af and 11Bf are interchanged.

[0060] As explained in the fourth embodiment, a polarizing layer may be disposed on at least one of the sides of the conductor layers 5Af and 5Bf where the incoming wave is incident and the side where the transmitted wave is emitted.

[0061] [Seventh Example] As shown in Figures 24A, 24B, 25A, and 25B, the fifth and sixth embodiments can be combined. In Figures 24A and 24B, the same components as those in Figures 2A, 2B, 20A, 20B, 22A, and 22B are designated by the same reference numerals. A unit cell 11Ag includes a conductor portion 1Ae made of a ring-shaped metal and formed on a substrate; a conductor portion 2A made of a metal and formed on the substrate so as to connect two points on the conductor portion 1Ae and divide an area of ​​the conductor portion 1Ae where no conductor pattern is present in half; and a gap 3Ac that divides the conductor portion 2A. Conductor portions 2Ac-1 and 2Ac-2 that are comb-shaped in a planar view are formed on the conductor portion 2A. The conductor portion 1Ae is formed in a meander-line shape.

[0062] The unit cell 11Bg is composed of a conductor portion 1Be made of a ring-shaped metal and formed on a substrate, a conductor portion 2B made of a metal and formed on the substrate so as to connect two points on the conductor portion 1Be and divide the area without a conductor pattern in the conductor portion 1Be into two equal parts, and a gap 3Bc that divides the conductor portion 2B. The conductor portion 2B is formed with conductor portions 2Bc-1 and 2Bc-2 that are comb-shaped in a plan view. The conductor portion 1Be is formed in a meander line shape.

[0063] When a radio wave lens is constructed using unit cells 11Ag and 11Bg, the phase difference G n The unit cell 11Ag is placed at a position on the substrate 12 where the remainder when divided by 2π is in the range of 0 to π, and the unit cell 11Bg is placed at a position where the remainder is in the range of π to 2π. The same function can be achieved even if the positions of the unit cells 11Ag and 11Bg are interchanged.

[0064] In Figures 25A and 25B, the same components as those in Figures 9A, 9B, 21A, 21B, 23A, and 23B are designated by the same reference numerals. The unit cell 11Ah is composed of a conductor layer 5Ah made of metal and rectangular in plan view formed on a substrate. The conductor layer 5Ah is formed with a ring-shaped conductor removal region 6Af, a conductor removal region 7A formed to connect two points in the conductor removal region 6Af and divide the conductor pattern in the conductor removal region 6Af into two equal parts, two conductor patterns 8A equally divided by the conductor removal region 7A, and a conductor remaining portion 9Ad dividing the conductor removal region 7A so as to connect the two conductor patterns 8A. The conductor removal region 7A is formed with conductor removal regions 7Ad-1 and 7Ad-2 that are comb-like in plan view. The conductor removal region 6Af is formed in a meander-line shape. The unit cell 11Ah has a shape that is the inverse of the unit cell 11Ag, with or without conductor patterns.

[0065] The unit cell 11Bh is composed of a conductor layer 5Bh made of metal and rectangular in plan view formed on a substrate. The conductor layer 5Bh is formed with a ring-shaped conductor removal region 6Bf, a conductor removal region 7B formed to connect two points in the conductor removal region 6Bf and divide the conductor pattern in the conductor removal region 6Bf into two equal parts, two conductor patterns 8B equally divided by the conductor removal region 7B, and a conductor remaining portion 9Bd that divides the conductor removal region 7B to connect the two conductor patterns 8B. The conductor removal region 7B is formed with conductor removal regions 7Bd-1 and 7Bd-2 that are comb-like in plan view. The conductor removal region 6Bf is formed in a meander line shape. The unit cell 11Bh has a shape that is the inverse of the unit cell 11Bg, with or without conductor patterns.

[0066] When the unit cells 11Ah and 11Bh are used to form a radio wave lens, the phase difference G n The unit cell 11Ah is placed at a position on the substrate 12 where the remainder when divided by 2π is in the range of 0 to π, and the unit cell 11Bh is placed at a position where the remainder is in the range of π to 2π. The same function can be achieved even if the positions of the unit cells 11Ah and 11Bh are interchanged.

[0067] As explained in the fourth embodiment, a polarizing layer may be disposed on at least one of the sides of the conductor layers 5Ah and 5Bh where the incoming wave is incident and the sides where the transmitted wave is emitted.

[0068] Some or all of the above embodiments may be described as, but are not limited to, the following supplementary notes.

[0069] (Supplementary Note 1) In the radio wave lens of the present invention, a first unit cell and a second unit cell are arranged two-dimensionally on a surface of a substrate that intersects with the incident radio waves, and the first unit cell and the second unit cell each have a conductor portion formed thereon that is crank-shaped within the surface of the substrate, or a conductor removal region formed in a conductor layer on the substrate that is crank-shaped within the surface of the substrate, the bending directions of the conductor portion or the bending directions of the conductor removal region differ from each other, and the first unit cell and the second unit cell are arranged two-dimensionally in accordance with a desired phase distribution of the radio waves that pass through them.

[0070] (Supplementary Note 2) In the radio wave lens described in Supplementary Note 1, the first unit cell is composed of an annular first conductor portion formed on the substrate, a second conductor portion formed on the substrate so as to connect two points on the first conductor portion and divide an area in the first conductor portion where no conductor pattern is present in two equal parts, and a first gap dividing the second conductor portion so as to connect the two equal parts divided by the second conductor portion; the second unit cell is composed of an annular third conductor portion formed on the substrate, a fourth conductor portion formed on the substrate so as to connect two points on the third conductor portion and divide an area in the third conductor portion where no conductor pattern is present in two equal parts, and a second gap dividing the fourth conductor portion so as to connect the two equal parts divided by the fourth conductor portion; the second conductor portion and the fourth conductor portion are crank-shaped and bent in different directions within the plane of the substrate.

[0071] (Supplementary Note 3) In the radio wave lens described in Supplementary Note 2, a comb-tooth-shaped fifth conductor is formed at one end of the second conductor facing across the first gap, a comb-tooth-shaped sixth conductor is formed at the other end of the second conductor facing across the first gap and arranged opposite the fifth conductor so as to alternate with the fifth conductor, a comb-tooth-shaped seventh conductor is formed at one end of the fourth conductor facing across the second gap, and an comb-tooth-shaped eighth conductor is formed at the other end of the fourth conductor facing across the second gap and arranged opposite the seventh conductor so as to alternate with the seventh conductor.

[0072] (Supplementary Note 4) In the radio wave lens according to Supplementary Note 2, the first conductor portion and the third conductor portion are each formed in a meander line shape.

[0073] (Supplementary Note 5) In the radio wave lens described in Supplementary Note 1, the first unit cell is made up of a first conductor layer formed on the substrate, and the second unit cell is made up of a second conductor layer formed on the substrate, and the first conductor layer has a ring-shaped first conductor removal area, a second conductor removal area formed so as to connect two points of the first conductor removal area and divide the conductor pattern in the first conductor removal area into two equal parts, and a second conductor removal area dividing the second conductor removal area so as to connect the two equally divided conductor patterns by the second conductor removal area. The second conductor layer is formed with a first conductor remaining portion, and the second conductor layer is formed with a third annular conductor removal region, a fourth conductor removal region formed to connect two points of the third conductor removal region and divide the conductor pattern in the third conductor removal region into two equal parts, and a second conductor remaining portion dividing the fourth conductor removal region so as to connect the two conductor patterns equally divided by the fourth conductor removal region, and the second conductor removal region and the fourth conductor removal region are crank-shaped and bent in different directions within the plane of the substrate.

[0074] (Appendix 6) In the radio wave lens described in Appendix 5, a comb-tooth-shaped fifth conductor removal region is formed at one end of the second conductor removal region facing across the first conductor remaining portion, a comb-tooth-shaped sixth conductor removal region is formed at the other end of the second conductor removal region facing across the first conductor remaining portion and arranged opposite the fifth conductor removal region so as to alternate with it, a comb-tooth-shaped seventh conductor removal region is formed at one end of the fourth conductor removal region facing across the second conductor remaining portion, and an comb-tooth-shaped eighth conductor removal region is formed at the other end of the fourth conductor removal region facing across the second conductor remaining portion and arranged opposite the seventh conductor removal region so as to alternate with it.

[0075] (Supplementary Note 7) In the radio wave lens according to Supplementary Note 5, the first conductor removal area and the third conductor removal area are each formed in a meander line shape.

[0076] (Supplementary Note 8) In the radio wave lens described in any one of Supplementary Notes 5 to 7, each of the first unit cell and the second unit cell includes a polarizing layer on at least one of the radio wave incident side and radio wave emitting side, the polarizing layer being arranged parallel to the first and second conductor layers and transmitting only desired polarized waves. [Industrial Applicability]

[0077] The present invention can be applied to a technique for controlling the transmission phase distribution of radio waves. [Explanation of symbols]

[0078] 1A, 1Ae, 1B, 1Be, 2A, 2Ac-1, 2Ac-2, 2B, 2Bc-1, 2Bc-2...conductor portion, 3A, 3B...gap, 5A, 5Ad, 5Af, 5Ah, 5B, 5Bd, 5Bf, 5Bh...conductor layer, 8A, 8B...conductor pattern, 6A, 6Af, 6B, 6Bf, 7A, 7Ad-1, 7Ad-2, 7B, 7Bd-1, 7Bd-2...conductor removal area, 9A, 9Ad, 9B...conductor remaining portion, 10, 10a...radio wave lens, 11A, 11Aa to 11Ah, 11B, 11Ba to 11Bh...unit cell, 12...substrate, 13, 14...polarizing layer, 15, 16...conductor pattern.

Claims

1. a first unit cell and a second unit cell are two-dimensionally arranged on a surface of the substrate that intersects with the incident radio wave in accordance with a desired phase distribution of the radio wave that passes through these cells; The first unit cell comprises: a first annular conductor portion formed on the substrate; a second conductor formed on the substrate so as to connect two points of the first conductor and divide an area of ​​the first conductor where no conductor pattern is present into two equal parts; a first gap that divides the second conductor portion so as to connect two equal regions divided by the second conductor portion; a comb-shaped third conductor portion formed at one end of the second conductor portion facing the first gap; a comb-like fourth conductor portion disposed at the other end of the second conductor portion opposed to the third conductor portion so as to be alternately opposed to the third conductor portion across the first gap, The second unit cell comprises: a ring-shaped fifth conductor portion formed on the substrate; a sixth conductor formed on the substrate so as to connect two points of the fifth conductor and divide an area in the fifth conductor where no conductor pattern is present into two equal parts; a second gap dividing the sixth conductor portion so as to connect two equal regions divided by the sixth conductor portion; a comb-shaped seventh conductor portion formed at one end of the sixth conductor portion facing the second gap; and a comb-tooth-shaped eighth conductor portion disposed at the other end of the sixth conductor portion opposed to the seventh conductor portion so as to be alternately opposed to the seventh conductor portion across the second gap, The radio wave lens is characterized in that the second conductor portion and the sixth conductor portion are bent in a crank shape within the plane of the substrate, and the bending directions are different from each other.

2. A first unit cell and a second unit cell are two-dimensionally arranged on a surface of a substrate that intersects with an incident radio wave according to a desired phase distribution of the radio wave passing through these cells; The first unit cell comprises: a first annular conductor portion formed on the substrate; a second conductor formed on the substrate so as to connect two points of the first conductor and divide an area of ​​the first conductor where no conductor pattern is present into two equal parts; a first gap that divides the second conductor portion so as to connect two equal regions divided by the second conductor portion; The second unit cell comprises: a third annular conductor portion formed on the substrate; a fourth conductor formed on the substrate so as to connect two points of the third conductor and divide an area of ​​the third conductor where no conductor pattern is present into two equal parts; a second gap that divides the fourth conductor portion so as to connect two equal regions divided by the fourth conductor portion; the second conductor portion and the fourth conductor portion are bent in a crank shape within the plane of the substrate, and are bent in different directions; The radio wave lens, wherein the first conductor portion and the third conductor portion are each formed in a meander line shape.

3. A first unit cell and a second unit cell are two-dimensionally arranged on a surface of a substrate that intersects with an incident radio wave according to a desired phase distribution of the radio wave passing through these cells; the first unit cell is composed of a first conductor layer formed on the substrate; the second unit cell is formed from a second conductor layer formed on the substrate; The first conductor layer includes: an annular first conductor removal region; a second conductor removal area formed so as to connect two points of the first conductor removal area and divide the conductor pattern in the first conductor removal area into two equal parts; a first conductor remaining portion that divides the second conductor removal area so as to connect two conductor patterns equally divided by the second conductor removal area; a comb-like third conductor removal region formed at one end of the second conductor removal region opposite to the first conductor remaining portion, with the third conductor removal region being spaced apart; a comb-like fourth conductor removal region is formed at the other end of the second conductor removal region that faces the first conductor remaining portion and is arranged to face the third conductor removal region in an alternating manner, The second conductor layer includes: an annular fifth conductor removal region; a sixth conductor removal area formed so as to connect two points of the fifth conductor removal area and divide the conductor pattern in the fifth conductor removal area into two equal parts; a second conductor remaining portion that divides the sixth conductor removal region so as to connect two conductor patterns equally divided by the sixth conductor removal region; a comb-like seventh conductor removal region formed at one end of the sixth conductor removal region opposite to the sixth conductor removal region across the second conductor remaining portion; an eighth conductor removal region having a comb-like shape and arranged to face the seventh conductor removal region so as to be alternately interposed between the sixth conductor removal region and the seventh conductor removal region, the eighth conductor removal region being formed at the other end of the sixth conductor removal region opposite the second conductor remaining portion; The radio wave lens is characterized in that the second conductor removal area and the sixth conductor removal area are bent in a crank shape within the plane of the substrate, and the bending directions are different from each other.

4. A first unit cell and a second unit cell are two-dimensionally arranged on a surface of a substrate that intersects with an incident radio wave according to a desired phase distribution of the radio wave passing through these cells; the first unit cell is composed of a first conductor layer formed on the substrate; the second unit cell is formed from a second conductor layer formed on the substrate; The first conductor layer includes: an annular first conductor removal region; a second conductor removal area formed so as to connect two points of the first conductor removal area and divide the conductor pattern in the first conductor removal area into two equal parts; a first conductor remaining portion is formed that divides the second conductor removal area so as to connect two conductor patterns equally divided by the second conductor removal area; The second conductor layer includes: an annular third conductor removal region; a fourth conductor removal area formed so as to connect two points of the third conductor removal area and divide the conductor pattern in the third conductor removal area into two equal parts; a second conductor remaining portion is formed that divides the fourth conductor removal region so as to connect two conductor patterns equally divided by the fourth conductor removal region; the second conductor removal region and the fourth conductor removal region are bent in a crank shape within the plane of the substrate, and the bending directions are different from each other; The radio wave lens is characterized in that the first conductor removal area and the third conductor removal area are each formed in a meander line shape.

5. 5. The radio wave lens according to claim 3, a first unit cell and a second unit cell each including a polarizing layer disposed parallel to the first and second conductor layers on at least one of an incident side and an outgoing side of the radio wave, the polarizing layer transmitting only desired polarized waves;

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