Reflective metasurface

Abstract

This reflective metasurface comprises: a first metal patch disposed on a first surface, which is the outermost surface of a substrate; a second metal patch disposed on a second surface, which is an inner layer of the substrate; first sub-patches and second sub-patches disposed on a third surface, which is an inner layer of the substrate; a ground region disposed on a fourth surface, which is the outermost surface opposite to the first surface of the substrate; and a switching element formed in a non-conductor region that is formed in the ground region of the fourth surface.

Description

reflective metasurfaces

[0001] The present disclosure relates to a reflective metasurface, and more particularly, to a reflective metasurface based on a switching element implemented in a multilayer substrate package.

[0002] With the rapid development of 5th and 6th generation mobile communications, communication module design technology to support ultra-high-speed, high-capacity communications is rapidly evolving. In 6G communications, coverage expansion methods are being researched to expand the communication area due to the short radio wave range.

[0003] Reconfigurable Intelligent Surfaces (RIS) can expand communication coverage at a lower cost than repeater installations. Radio waves in high-frequency bands above 3 GHz tend to travel in a straight line rather than diffracting. Consequently, communication coverage is reduced. Therefore, RIS can be used to reflect these straight-line radio waves and redirect them in the desired direction, thereby increasing coverage. For 6G communications, the use of frequencies above 7 GHz is being discussed, with 7-20 GHz being a strong candidate.

[0004] Meanwhile, phased array antennas can adjust beam steering direction by electronically controlling the phase of radio waves on a per-element basis. This element-by-element phase control is typically implemented in phase shifters at the radio frequency (RF) level. These phase shifters increase the weight, size, and cost of the phased array antenna.

[0005] Meanwhile, the RIS module can be configured to vary the phase of the reflected signal by changing the on / off state of a switching element, such as a PIN diode. Therefore, an RIS module using a switching element can be implemented as a reflective metasurface. Reflective metasurfaces that operate as reflectors in a specific frequency band have a problem in that their reflection performance deteriorates due to the current formed between the metal patches. In addition, reflective metasurfaces have a problem in that their reflection performance varies greatly depending on the on / off state of the switching element.

[0006] This specification is intended to prevent the reflection performance from being deteriorated depending on the polarization direction of the radio wave incident on the reflective metasurface.

[0007] The purpose of this specification is to minimize the deviation in the reflection performance of a reflective metasurface depending on the on / off state of a switching element.

[0008] The present specification is intended to improve the reflection performance of a reflective metasurface and thereby enhance wireless communication coverage using a reflective metasurface.

[0009] The present specification aims to minimize performance attenuation through a reflective metasurface of a multilayer substrate structure.

[0010] A reflective metasurface according to the present invention includes a first metal patch disposed on a first surface, which is an outermost surface of a substrate; a second metal patch disposed on a second surface, which is an inner layer of the substrate; first sub-patches and second sub-patches disposed on a third surface, which is an inner layer of the substrate; a ground region disposed on a fourth surface, which is an outermost surface opposite the first surface of the substrate; and a switching element formed in a non-conductive region formed in the ground region of the fourth surface.

[0011] According to an embodiment, a first portion of the switching element may be connected by the first metal patch and first vias, and a second portion of the switching element may be connected by the second metal patch and second vias. The first sub-patches may be connected by the ground region and third vias, and the second sub-patches may be connected by the ground region and fourth vias.

[0012] According to an embodiment, the first metal patch may be formed as a polygonal patch having a shape of pentagon or more or a circular patch. The reflective meta surface may further include a fifth via vertically connecting a center point of the first metal patch and the ground region.

[0013] A reflective metasurface according to the present invention comprises: a first metal patch disposed on a first surface, which is an outermost surface of a substrate; a second metal patch disposed on the first surface of the substrate; first sub-patches and second sub-patches disposed spaced apart from one end and the other end of the second metal patch; a ground region disposed on a second surface, which is an outermost surface opposite the first surface of the substrate; and a switching element formed in a non-conductive region formed in the ground region of the fourth surface.

[0014] According to an embodiment, the first sub-patches may be connected to the ground region by first vias, and the second sub-patches may be connected to the ground region by second vias.

[0015] According to an embodiment of the present disclosure, the first metal patch, which is a main patch, is formed as a polygonal or circular structure having a pentagon or larger shape, thereby preventing the reflection performance from being deteriorated depending on the polarization direction of the radio wave incident on the reflective metasurface.

[0016] According to an embodiment of the present disclosure, the switching elements are arranged in mutually perpendicular first and second axis directions of the first metal patch, so that the deviation in the reflection performance of the reflective metasurface depending on the on / off state of the switching elements can be minimized.

[0017] According to an embodiment of the present disclosure, the shape of the first and second metal patch structures and the arrangement structure of the first and second switching elements are optimized to improve the reflection performance of the reflective metasurface, thereby improving the wireless communication coverage using the reflective metasurface.

[0018] According to an embodiment of the present disclosure, the wireless communication coverage using the reflective metasurface can be improved by improving the reflection performance of the reflective metasurface through an overlapping structure between the first and second metal patches.

[0019] According to an embodiment of the present disclosure, performance degradation can be minimized through a reflective meta surface of a multilayer substrate structure so that performance degradation does not occur in a connection structure such as soldering of elements such as switching elements and inductors.

[0020] Further scope of the applicability of this specification will become apparent from the detailed description below. However, since various changes and modifications within the spirit and scope of this specification will be apparent to those skilled in the art, it should be understood that the detailed description and specific examples, such as preferred embodiments, are given by way of example only.

[0021] FIG. 1 illustrates the structure of an array antenna module including a plurality of elements according to the present specification.

[0022] Figure 2 shows a structure implemented with a reflective RIS and a transparent RIS according to the present specification.

[0023] Figure 3 shows the structure of a reflective metasurface on which switching elements are arranged.

[0024] Figure 4 shows the structure of RIS unit cells arranged in a direction matching the angle of incidence of the radio wave or arranged in an inclined direction.

[0025] Fig. 5 is a graph comparing the reflection loss characteristics of the RIS unit cells of Fig. 4.

[0026] FIG. 6 shows a front view of a reflective metasurface according to the first embodiment of the present specification.

[0027] Figure 7 shows a perspective view of the reflective metasurface of Figure 6.

[0028] Fig. 8 shows a second metal patch connected to the first point and the second point of the first metal patch of Fig. 6.

[0029] Figure 9 shows the reflection loss characteristics and phase characteristics according to the on / off state of the switching element in the reflective metasurface of Figure 6.

[0030] Figure 10 shows a front view of a reflective metasurface according to the present specification.

[0031] Figure 11 shows a side view of the reflective metasurface of Figure 10.

[0032] Figure 12 shows the structure of each layer of the reflective metasurface of Figures 10 and 11.

[0033] Fig. 13 shows the current distribution according to the structures of the first and second metal patches according to the embodiments.

[0034] Figure 14 shows the reflection loss characteristics and phase variation characteristics according to the on / off of the switching element in the reflective metasurface of Figures 10 to 12.

[0035] Fig. 15 shows a structure in which a control unit is formed to perform an on / off control operation of a switching element of a reflective metasurface according to the present specification.

[0036] Figure 16 shows the current distribution according to the on / off operation of the first and second switching elements.

[0037] Figures 17 to 19 illustrate reflective metasurfaces with different array structures according to embodiments.

[0038] Hereinafter, specific embodiments of the present invention will be described in detail with drawings.

[0039] Hereinafter, embodiments related to this specification will be described in more detail with reference to the drawings. The suffixes "module" and "part" used in the following description for components are assigned or used interchangeably solely for the convenience of writing the specification, and do not have a distinct meaning or role in themselves.

[0040] Hereinafter, an array antenna module having phase-variable characteristics in relation to the present specification will be described.

[0041] In this regard, a module including a plurality of elements according to the present specification may be referred to as a phase delay array antenna module. The antenna module may be configured to include a plurality of radiators and a phase delay element capable of implementing phase delay. The phase delay element may be implemented as a feed structure of a specific structure without separate electronic components such as a phase shifter.

[0042] The array antenna module can be configured to support 6G wireless communication services. In this regard, the array antenna module can be configured to operate in the millimeter wave band or the 10 GHz band. The array antenna module can be applied to mobile communication antennas, vehicle antennas, or satellite communication antennas.

[0043] 6G wireless communication services aren't limited to electronic devices like mobile terminals or video display devices. They can also be applied to fully autonomous vehicles, artificial intelligence (AI) robots, and electronic devices supporting the augmented and virtual reality (AR / VR)-based metaverse.

[0044] FIG. 1 illustrates the structure of an array antenna module, which is a module including a plurality of elements according to the present specification. Referring to FIG. 1, the array antenna module (1000) may be configured as an array antenna including a plurality of elements (1100-1 to 1100-8). The number of the plurality of elements is not limited to eight and may vary depending on the application.

[0045] The antenna module (1000) may be configured as a one-dimensional array antenna in which a plurality of elements are arranged in one axial direction. As another example, the antenna module (1000) may be configured as a two-dimensional array antenna in which a plurality of elements are arranged in one axial direction and another axial direction perpendicular thereto.

[0046] The spacing (G1) between the plurality of elements (1100-1 to 1100-8) can be implemented as a numerical value related to a wavelength corresponding to an operating frequency. Each of the plurality of elements (1100-1 to 1100-8) can be operably coupled to a phase delay element (1150-1 to 1150-8). The phase delay elements (1150-1 to 1150-8) can be formed as a feed structure having a phase delay. The phase delay elements (1150-1 to 1150-8) can be formed as a feed structure connecting adjacent antenna elements.

[0047] A transmission line (1200) connected to a plurality of elements (1100-1 to 1100-8) may be implemented as a waveguide, a microstrip line, a strip line, or a substrate integrated waveguide (SIW). Each of the plurality of elements (1100-1 to 1100-8) may be independently controlled to be turned on / off. Each of the plurality of elements (1100-1 to 1100-8) may be independently controlled to be turned on / off to adjust the beam forming direction of the antenna module (1000).

[0048] As the plurality of elements (1100-1 to 1100-8) are independently turned on / off, the phase of the signal applied to the plurality of elements (1100-1 to 1100-8) can be varied as illustrated in the transmission line (1200) of FIG. 1. As the interval between the on / off operations among the plurality of elements (1100-1 to 1100-8) decreases, the phase difference between adjacent elements increases. Accordingly, as the interval between the on / off operations among the plurality of elements (1100-1 to 1100-8) decreases, the beamforming angle increases.

[0049] Meanwhile, an antenna module comprising a plurality of antenna elements according to the present specification may be capable of phase adjustment when combined with a reconfigurable intelligent surface (RIS). In this regard, FIG. 2 illustrates a structure implemented with a reflective RIS and a transmissive RIS according to the present specification.

[0050] Referring to FIG. 2(a), the antenna module (1000) may be configured to include a reflective RIS (1000a) and at least one external antenna (1300). A wireless signal radiated from the external antenna (1300) may be configured to be reflected by the reflective RIS (1000a). The beamforming angle of the wireless signal may be varied by independently varying the on / off state of each element constituting the reflective RIS (1000a).

[0051] Referring to FIG. 2(b), the antenna module (1000) may be configured to include a transitive RIS (1000a) and at least one external antenna (1300). A wireless signal radiated from the external antenna (1300) may be configured to pass through the transitive RIS (1000b). The beamforming angle of the wireless signal may be varied by independently varying the on / off state of each element constituting the transitive RIS (1000b).

[0052] Hereinafter, a reflection metasurface according to the present specification will be described. FIG. 3 shows the structure of a reflection metasurface in which a switching element is arranged. Referring to FIG. 3(a), the reflection metasurface (100) can be configured to include a first patch (110), a second patch (120), and a switching element (1200). The switching element (1200) can be arranged between an end of the first patch (110) and an end of the second patch (120). In an area where the first patch (110) and the second patch (120) face each other, the first patch (110) and the second patch (120) can be arranged to be spaced apart from each other by the same interval (Ga).

[0053] Referring to Fig. 3(b), when an incident wave of a specific polarization is applied in the first direction to an RIS surface such as a reflective metasurface (100), the incident wave is reflected and the reflected wave is reflected in the second direction. The magnetic field component of the reflected wave (Hr = H0 - (x)) and electric field component (Er = E0 - The ratio of (x)) can be defined as the surface impedance (wave impedance) (z) as in Equation 1.

[0054]

[0055] Meanwhile, the reflective metasurface according to the present specification may be arranged in a direction matching the angle of incidence of the radio wave or in an inclined direction. In this regard, FIG. 4 shows the structure of RIS unit cells arranged in a direction matching the angle of incidence of the radio wave or in an inclined direction. Referring to FIG. 4, a switching element (1200) may be arranged between an end of a first patch (1110) and an end of a second patch (1120). In an area where the first patch (1110) and the second patch (1120) face each other, the first patch (1110) and the second patch (1120) may be arranged with equal spacing between them. The switching element (1200) may be implemented as a pin diode, but is not limited thereto and may be changed to any switching element depending on the application.

[0056] Figure 4(a) shows the structure of a RIS unit cell (1000) arranged in a direction matching the incident angle of a radio wave. The radio wave can be incident so as to have an H-polarization in the X-axis direction with an incident angle of 0 degrees. The RIS unit cell (1000) can be arranged in a direction matching the incident angle of the radio wave.

[0057] Figure 4(b) shows the structure of a RIS unit cell (1000) arranged in a direction inclined at a predetermined angle (e.g., 10 degrees) with respect to the incident angle of the radio wave. The radio wave may be incident at an incident angle of 0 degrees and have an H-polarization in the X-axis direction. The RIS unit cell (1000) may be arranged in a direction inclined at a predetermined angle with respect to the incident angle of the radio wave.

[0058] As shown in Fig. 4(a), the RIS unit cell (1000) can reflect a radio wave signal having a polarization incident in the direction in which the switching element (1200) is located at a predetermined ratio or higher. However, as shown in Fig. 4(b), if the angle of the polarization incident on the signal is different from the direction in which the switching element (1200) is located, the reflection loss increases significantly, making it unusable as an RIS. To improve this problem, the RIS unit cell can be configured to reflect polarizations in various directions by using multiple switching elements. However, switching elements can be arranged for all polarization directions of 360 degrees.

[0059] Meanwhile, Fig. 5 is a graph comparing the reflection loss characteristics of the RIS unit cells of Fig. 4. Referring to Fig. 4(a) and Fig. 5, (i) when the switching element (1200) is on, the reflection loss is -1.32 dB at 9.8 GHz. Referring to Fig. 4(a) and Fig. 5, (ii) when the switching element (1200) is off, the reflection loss is -0.46 dB at 9.8 GHz. When the switching element (1200) is arranged in a direction matching the polarization direction of the radio wave, the difference in reflection loss depending on whether the switching element is on or off has a limited value of 1 dB or less.

[0060] Referring to Fig. 4(b) and Fig. 5, (iii) when the switching element (1200) is on, the reflection loss is -0.22 dB at 9.8 GHz. Referring to Fig. 4(b) and Fig. 5, (iv) when the switching element (1200) is off, the reflection loss is -5.86 dB at 9.8 GHz. Therefore, as shown in Fig. 4(b), when a radio wave having a polarization in a direction different from the direction in which the RIS unit cell is arranged is incident, the reflection loss performance deteriorates. When the switching element (1200) is arranged in a direction that is about 10 degrees different from the polarization direction of the radio wave, the difference in reflection loss according to the on / off of the switching element significantly increases to more than 5 dB. In this regard, it is almost impossible to expect or predict a polarization direction with 100% purity in a desired direction for a radio wave transmitted in free space.

[0061] A reflective metasurface according to another embodiment of the present disclosure may have metal patches arranged on the same plane of a substrate. In this regard, FIG. 6 illustrates a front view of a reflective metasurface according to a first embodiment of the present disclosure. FIG. 7 illustrates a perspective view of the reflective metasurface of FIG. 6. FIG. 8 illustrates a second metal patch connected to a first point and a second point of the first metal patch of FIG. 6. Referring to FIG. 6 and FIG. 8(a), a second metal patch connected to a first point of the first metal patch (1110) through a first switching element (1210) is illustrated. Referring to FIG. 6 and FIG. 8(b), a second metal patch connected to a second point of the first metal patch (1110) through a second switching element (1220) is illustrated.

[0062] A reflective metasurface (1000a) will be described with reference to FIGS. 6 to 8. The reflective metasurface (1000a) may include a first metal patch (1110), a second metal patch (1120a), first sub-patches (1121) and second sub-patches (1122), a ground region (1100g), and a switching element (1200).

[0063] The first metal patch (1110) may be arranged on the first surface (S1), which is the outermost surface of the substrate. The first metal patch (1110) may be formed as a polygonal patch or a circular patch. The first metal patch (1110) may be formed as a polygonal patch having a shape of 5 or more. For example, the first metal patch (1110) may be formed as a dodecagonal patch, but is not limited thereto and may be changed according to the application. When the switching element (1200) is in the off state, the first metal patch (1110) may operate to resonate at a first frequency within the operating frequency band.

[0064] The second metal patch (1120a) may be placed on the first surface (S1) of the substrate (1010). The first metal patch (1110) and the second metal patch (1120a) may be referred to as a main patch and a sub patch, respectively. The second metal patch (1120) may be placed in the 0 degree direction and the 90 degree direction adjacent to the first point and the second point of the first metal patch (1110).

[0065] Meanwhile, when a first metal patch (1110) having a pentagon or larger shape is used compared to a square shape, the reflection loss performance deviation can be improved for signals having polarization in various directions. However, when a first metal patch (1110) having a pentagon or larger shape is used, the reflection loss performance may be degraded when the switching element is turned off. However, when a first metal patch (1110) having a pentagon or larger shape is used in a structure in which the second metal patches (1120a) are arranged in the 0 degree direction and the 90 degree direction, the reflection loss performance can be improved compared to a square shape.

[0066] In addition, the reflection loss performance can be improved by using the first sub-patches (1121) and the second sub-patches (1122) as a ground pad structure while using the first metal patch (1110) of a pentagon or larger shape. The surface impedance of the first sub-patches (1121) and the second sub-patches (1122) increases through the ground pad structure, thereby improving the reflection loss performance and deviation. Therefore, when the first metal patch (1110) of a pentagon or larger shape is used, the reflection loss performance is improved, and the reflection loss deviation according to the switching element on / off and polarization direction is also improved.

[0067] In this regard, the first sub-patches (1121) and the second sub-patches (1122) may be spaced apart and adjacent to one end and the other end of the second metal patch (1120). The first sub-patches (1121) and the second sub-patches (1122) may be referred to as first ground pads and second ground pads, respectively. The first sub-patches (1121) and the second sub-patches (1122) improve reflection loss and widen the frequency range in which the phase is varied, thereby increasing the operating bandwidth.

[0068] The ground area (1100g) may be placed on the second surface (S2), which is the outermost surface opposite the first surface (S1) of the substrate (1010). The first surface (S1) and the second surface (S2) of the substrate (1010) may correspond to the front surface and the rear surface, respectively.

[0069] The switching element (1200) may be formed in a non-conductive region formed in the ground region (1100g) of the second surface (S2) of the substrate (1010). When the switching element (1200) is in an on state, the first metal patch (1110) and the second metal patch (1120) may operate together to resonate at a second frequency within an operating frequency band. The first frequency may be set to a higher frequency than the second frequency. As the switching element (1200) is turned on / off, the phase may vary by approximately 180 degrees within the operating frequency band.

[0070] The first sub-patches (1121) may be connected to the ground area (1100g) by first vias (V1a, V1b). The second sub-patches (1122) may be connected to the ground area (1100g) by second vias (V2a, V2b).

[0071] The second metal patch (1120a) may be formed to include a plurality of sub-patches. The second metal patch (1120a) may be formed to include a third sub-patch (1123), a fourth sub-patch (1124), and a fifth sub-patch (1125) disposed on the second surface (S2) of the substrate (1010). The second metal patch (1120) may be formed to include a sixth sub-patch (1126), a seventh sub-patch (1127), and an eighth sub-patch (1128) disposed on the second surface (S2) of the substrate (1010). The first and second sub-patches (1121, 1122) of the third side (S3) of the substrate (1010) and the third to eighth sub-patches (1123, 1124, 1125, 1126, 1127, 1128) of the second side (S2) of the substrate (1010) can constitute the second metal patch (1120).

[0072] The third sub-patch (1123) may be formed with a first width (Ws1) and a first length (Ls1). The third sub-patch (1123) may be arranged to be spaced apart from the first point of the first metal patch (1110) by a first interval (Ga1). The fourth sub-patch (1124) may be connected to the third sub-patch (1123) and may be formed to be spaced apart from the first point of the first metal patch (1110) by a second interval (Ga2). The fifth sub-patch (1125) may be connected to the fourth sub-patch (1124) and formed with a third width (Ws3) and a third length (Ls3). The fifth sub-patch (1125) may be arranged to be spaced apart from the first point of the first metal patch (1110) by a third gap (Ga3).

[0073] The second width (Ws2) of the fourth sub-patch (1124) may be formed wider than the first width (Ws1) of the third sub-patch (1123). The third width (Ws3) of the fifth sub-patch (1125) may be formed wider than the second width (Ws2) of the fourth sub-patch (1124).

[0074] The first sub-patches (1121a, 1121b) arranged on the first surface (S1) of the substrate (1010) may be arranged adjacent to one end and the other end of the third sub-patch (1123) and spaced apart from each other in the first axial direction. The first sub-patches (1121a, 1121b) arranged on the first surface (S1) of the substrate (1010) may be arranged to overlap with the fourth sub-patch (1124) in the second axial direction perpendicular to the first axis. The first axial direction may be set to the X-axis direction and the second axial direction may be set to the Y-axis direction.

[0075] The sixth sub-patch (1126) may be formed with a first width (Ws1) and a first length (Ls1). The sixth sub-patch (1126) may be arranged to be spaced apart from the second point of the first metal patch (1110) by a first interval (Ga1). The seventh sub-patch (1127) may be connected to the sixth sub-patch (1126) and may be formed to be spaced apart from the second point of the first metal patch (1110) by a second interval (Ga2). The eighth sub-patch (1128) may be connected to the seventh sub-patch (1127) and formed with a third width (Ws3) and a third length (Ls3). The eighth sub-patch (1128) may be arranged to be spaced apart from a first point of the first metal patch (1110) by a third gap (Ga3). The first point of the first metal patch (1110) may be formed in a second axis direction, and the second point may be formed in a first axis direction perpendicular to the second axis. The first axis direction may be set to the X-axis direction, and the second axis direction may be set to the Y-axis direction.

[0076] The second width (Ws2) of the seventh sub-patch (1127) may be formed wider than the first width (Ws1) of the sixth sub-patch (1126). The third width (Ws3) of the eighth sub-patch (1128) may be formed wider than the second width (Ws2) of the seventh sub-patch (1127).

[0077] The second sub-patches (1122a, 1122b) arranged on the first surface (S1) of the substrate (1010) may be arranged adjacent to one end and the other end of the sixth sub-patch (1126) and spaced apart from each other in the second axial direction. The second sub-patches (1122a, 1122b) arranged on the first surface (S1) of the substrate (1010) may be arranged to overlap the seventh sub-patch (1127) in the first axial direction. The first axial direction may be set to the X-axis direction and the second axial direction may be set to the Y-axis direction.

[0078] The switching element (1200) may be configured to include a first switching element (1210) and a second switching element (1220). The first switching element (1210) may be connected to a first point of the first metal patch (1110) and a third point of the second metal patch (1120). The second switching element (1220) may be connected to a second point of the first metal patch (1110) and a fourth point of the second metal patch (1120b).

[0079] The reflective metasurface (1000) may be configured to further include a bias line (BL) and an inductor (Ind). The second metal patches (1120) may be connected to each other by the bias line (BL). The bias line (BL) may be formed to connect one end of the fifth sub-patch (1125) and the other end of the eighth sub-patch (1128) so that a control voltage is transmitted to the first and second switching elements (1210, 1220). The bias line (BL) is configured to be implemented with a narrow width of a predetermined width (e.g., 0.2 mm) to increase the impedance and block RF signals.

[0080] An inductor (Ind) may be placed at a point on the bias line (BL) and at a point on the second surface (S2) of the substrate (1010) so that the control voltage is transmitted to the switching element (1200) and the RF signal is blocked. The inductor (Ind) placed to block the RF signal may be referred to as an RF choke. When the control voltage is applied to the bias line (BL), the first and second switching elements (1210, 1220) may operate simultaneously. Therefore, the inductor (Ind) may be placed between a point on the bias line (BL) and the ground area (1100g) of the second surface (S2) of the substrate (1010) so that the control voltage is transmitted to the first and second switching elements simultaneously.

[0081] A bias line (BL) may be formed to transmit the first and second control voltages to the first and second switching elements (1210, 1220). The bias line (BL) may be formed to connect one end of the fifth sub-patch (1125) and the other end of the eighth sub-patch (1128).

[0082] The inductor (Ind) may be arranged on the bias line (BL) so that the first control voltage is transmitted to the first switching element (1110) and not transmitted to the second switching element (1120). The inductor (Ind) may be arranged on the bias line (BL) so that the second control voltage is transmitted to the second switching element (1120) and not transmitted to the first switching element (1120). The inductor (Ind) may be arranged between a point on the bias line (BL) and the ground area (1100g) of the fourth surface (S4) of the substrate (1010) so that the first control voltage is transmitted to the first switching element (1110) and the second control voltage is transmitted to the second switching element (1120).

[0083] Meanwhile, Fig. 9 shows the reflection loss characteristics and phase characteristics according to the on / off state of the switching element in the reflective metasurface of Fig. 6. Fig. 9(a) shows the reflection loss characteristics according to the on / off state of the switching element in the reflective metasurface of Fig. 6. Fig. 9(b) shows the phase characteristics according to the on / off state of the switching element in the reflective metasurface of Fig. 6.

[0084] Referring to FIGS. 6 to 9(a), the switching element (1200) exhibits reflection loss performance when turned on / off. The solid line in the graph represents a case where a radio wave is incident in a direction consistent with the polarization direction. The dotted line in the graph represents a case where a radio wave is incident in a direction 45 degrees different from the polarization direction.

[0085] When a radio wave is incident in a manner consistent with the polarization direction, the switching element (1200) exhibits good reflection loss performance, with a reflection loss of -0.5 to -1 dB at 10 GHz depending on the on / off state. In this regard, the first and second sub-patches (1121, 1122) in the form of ground pads located between the first and second metal patches (1110, 1120) increase the surface impedance of the reflective metasurface. This is because the reflection performance of the reflective metasurface improves as the surface impedance increases.

[0086] When a radio wave is incident in a direction different from the polarization direction by 45 degrees, the switching element (1200) exhibits good reflection loss performance with a reflection loss value of -0.5 to -1.2 dB at 10 GHz depending on the on / off state. Therefore, it can be confirmed that the reflection loss performance is not attenuated even when the polarization of the radio wave is incident with a 45 degree deviation. In addition, it can be confirmed that no performance degradation of the reflection loss occurs in the 9.5-10.5 GHz band, which can be included in the operating band centered on 10 GHz.

[0087] Referring to FIGS. 6 to 9(b), the phase change of the reflected radio wave according to the on / off state of the switching element (1200) is shown. The solid line in the graph represents the case where the radio wave is incident in a direction consistent with the polarization direction. The dotted line in the graph represents the case where the radio wave is incident in a direction 45 degrees different from the polarization direction.

[0088] When a radio wave is incident in a manner consistent with the polarization direction, it can be confirmed that the phase of the radio wave changes by approximately 180 degrees at 10 GHz depending on the on / off state of the switching element (1200).

[0089] When a radio wave is incident in a direction 45 degrees different from the polarization direction, it can be confirmed that the phase of the radio wave changes by approximately 180 degrees at 10 GHz depending on the on / off state of the switching element (1200). It can be confirmed that the phase variation characteristics of the reflected signal are not deteriorated even when the radio wave is incident with the polarization shifted by 45 degrees.

[0090] Meanwhile, the reflective metasurface according to the present specification can be implemented as a multilayer substrate. In this regard, FIG. 10 shows a front view of the reflective metasurface according to the present specification. FIG. 11 shows a side view of the reflective metasurface of FIG. 10. FIG. 12 shows the structure of each layer of the reflective metasurfaces of FIGS. 10 and 11.

[0091] Fig. 12(a) shows a first metal patch (1110) of a reflective metasurface disposed on a first surface of a substrate. Fig. 12(b) shows a second metal patch (1120) of a reflective metasurface disposed on a second surface of the substrate. Fig. 12(c) shows first and second sub-patches (1121, 1122) of a reflective metasurface disposed on a third surface of the substrate. Fig. 12(d) shows a ground region (1110g) of a reflective metasurface disposed on a fourth surface of the substrate.

[0092] A reflective metasurface (1000) implemented as a multilayer substrate will be described with reference to FIGS. 10 to 12. The reflective metasurface (1000) may include a first metal patch (1110), a second metal patch (1120), first sub-patches (1121), second sub-patches (1122), a ground region (1100g), and a switching element (1200).

[0093] The first metal patch (1110) may be arranged on the first surface (S1), which is the outermost surface of the substrate (1010). The first metal patch (1110) may be formed as a polygonal patch or a circular patch. The first metal patch (1110) may be formed as a polygonal patch having a shape of 5 or more. For example, the first metal patch (1110) may be formed as a dodecagonal patch, but is not limited thereto and may be changed according to the application. When the switching element (1200) is in the off state, the first metal patch (1110) may operate to resonate at a first frequency within the operating frequency band.

[0094] The second metal patch (1120) may be placed on the second surface (S2), which is an inner layer of the substrate (1010). The first metal patch (1110) and the second metal patch (1120) may be referred to as a main patch and a sub patch, respectively. The second metal patch (1120) may be placed in the 0 degree direction and the 90 degree direction adjacent to the first point and the second point of the first metal patch (1110).

[0095] The first sub-patches (1121) and the second sub-patches (1122) may be arranged on the third surface (S3), which is a layer inside the substrate (1010). The first sub-patches (1121) and the second sub-patches (1122) may be referred to as first ground pads and second ground pads, respectively. The first sub-patches (1121) and the second sub-patches (1122) improve reflection loss and widen the frequency range in which the phase is varied, thereby increasing the operating bandwidth.

[0096] The ground area (1100g) may be placed on the fourth surface (S4), which is the outermost surface opposite the first surface (S1) of the substrate (1010). The first surface (S1) and the fourth surface (S4) of the substrate (1010) may correspond to the front surface and the rear surface, respectively.

[0097] The switching element (1200) may be formed in a non-conductive area formed in the ground area of ​​the fourth surface (S4) of the substrate (1010). When the switching element (1200) is in an on state, the first metal patch (1110) and the second metal patch (1120) may operate together to resonate at a second frequency within the operating frequency band. The first frequency may be set to a higher frequency than the second frequency. As the switching element (1200) is turned on / off, the phase may vary by approximately 180 degrees within the operating frequency band.

[0098] A first part of a switching element (1200) may be connected by a first metal patch (1110) and first vias (V1a, V1b). A change in the second frequency occurs due to a parasitic inductance component of the first vias (V1a, V1b) connected to the first metal patch (1110), which is a main patch, thereby affecting phase shifting. A second part of a switching element (1200) may be connected by a second metal patch (1120) and second vias (V2a, V2b). A change in the second frequency occurs due to a parasitic inductance component of the second vias (V2a, V2b) connected to the second metal patch (1120), which is a sub patch, thereby affecting phase shifting.

[0099] Meanwhile, parasitic capacitance can be generated in the overlapping region of the first metal patch (1110) and the second metal patch (1120), thereby canceling out the parasitic inductance. Accordingly, multiple resonances can be generated by the parasitic inductance and parasitic capacitance, thereby realizing wideband performance. In addition, the occurrence of a second frequency shift due to the parasitic inductance and parasitic capacitance can be minimized.

[0100] In the region where the first metal patch (1110) and the second metal patch (1120) overlap, a stronger electric field is formed than in other regions, thereby increasing coupling between them. Accordingly, the reflection performance of the reflective metasurface (1000) is improved by the first metal patch (1110) and the second metal patch (1120) having overlapping regions.

[0101] The first sub-patches (1121) can be connected to the ground area (1100g) and third vias (V3a, V3b). The second sub-patches (1122) can be connected to the ground area (1100g) and fourth vias (V4a, V4b).

[0102] The reflective metasurface (1000) may be configured to include a plurality of vias connecting a patch disposed within a substrate (1010) and a ground region. The reflective metasurface (1000) may include first vias (V1a, V1b), second vias (V2a, V2b), third vias (V3a, V3b), and fourth vias (V4a, V4b). The reflective metasurface (1000) may further include a fifth via (V5) and a sixth via (V6). The fifth via (V5) may be formed to vertically connect a center point of the first metal patch (1110) and a ground region (1100g). The sixth via (V6) can connect a point on the bias line (BL) of the second side (S2) of the substrate (1010) and a point on the fourth side (S4) where the inductor (Ind) is arranged.

[0103] Three vias are arranged on a first metal patch (1110) of a first surface (S1), which is a first layer of a substrate (1010). The first vias (V1a, V1b) and a fifth via (V5) arranged on the first metal patch (1110) are formed from the first surface (S1), which is a first layer of the substrate (1010), to the fourth surface (S4), which is a fourth layer. The fifth via (V5), which is arranged at the center point of the first metal patch (1110), extends to the fourth surface (S4) of the substrate (1010). The fifth via (V5) and the ground region (1100g) are electrically separated by a dielectric region arranged therebetween, so that a control voltage of a DC bias can be transmitted to the first metal patch (1110). First vias (V1a, V1b) arranged offset in the first and second axis directions from the center point of the first metal patch (1110) are connected to first and second switching elements (1210, 1220) arranged on the fourth surface (S4), which is the fourth layer of the substrate (1010).

[0104] Second vias (V2a, V2b) are arranged on a second metal patch (1120) of a first surface (S2), which is a second layer of a substrate (1010). The second vias (V2a, V2b) arranged on the second metal patch (1120) are formed from the second surface (S2), which is a second layer of the substrate (1010), to the fourth surface (S4), which is a fourth layer. The first and second metal patches (1110, 1120) connected by the first vias (V1a, V1b) are connected to the second metal patch (1120) connected by the second vias (V2a, V2b) and the switching element (1200). As the switching element (1200) is turned on / off, the first and second metal patches (1110, 1120) can be electrically connected or disconnected. A portion of the second metal patch (1120) is positioned to overlap with the first metal patch (1110). To this end, the second vias (V2a, V2b) must be positioned further from the center point of the first metal patch (1110) than the first vias (V1a, V1b).

[0105] A stronger electric field is formed in the overlapping region of the first and second metal patches (1110, 1120) than in other regions, thereby causing normal current flow in the second metal patch (1120). If the first and second metal patches (1110, 1120) are not overlapped in different layers but are spaced apart from each other in the same layer, most of the current flow occurs in the via structure. Accordingly, a stronger magnetic field is generated in the via structure than in other regions, resulting in self-resonance. Therefore, since normal current flow cannot be caused in the second metal patch (1120), the characteristics of the RIS may be deteriorated.

[0106] In this regard, Fig. 13 shows current distributions according to structures of the first and second metal patches according to embodiments. Fig. 13(a) shows the current distribution of the first structure of the first and second metal patches (1110, 1120) formed in a non-overlapping structure. As most of the current is concentrated in the first via (V1), a current having a value higher than a certain level is formed in the overlapping region (Rb) of the first and second metal patches (1110, 1120) as a sub-patch, and a higher electric field than other regions is formed. An electric field distribution having a value higher than a certain level is formed not only in the first and second vias (V1, V2) within the overlapping region (Rb) but also in the second metal patch (1120) as a sub-patch.

[0107] Fig. 13(b) shows the electric field distribution of the second structure of the first and second metal patches (1110, 1120) formed in an overlapping structure. Fig. 13(c) shows the current distribution of the second structure of the first and second metal patches (1110, 1120) formed in an overlapping structure. A higher electric field is formed in the overlapping region (Rb) of the first and second metal patches (1110, 1120) than in other regions. An electric field distribution having a value greater than a certain level is formed not only in the first and second vias (V1, V2) within the overlapping region (Rb) but also in the second metal patch (1120), which is a sub-patch. Accordingly, the current is not concentrated only in the first and second vias (V1, V2), but is transmitted to the region (Rc) where the second metal patch (1120), which is a sub-patch, is arranged.

[0108] Meanwhile, the second metal patch (1120) may be formed to include a plurality of sub-patches. Referring to FIGS. 10 to 12, the second metal patch (1120) may be formed to include a third sub-patch (1123), a fourth sub-patch (1124), and a fifth sub-patch (1125) disposed on the second surface (S2) of the substrate (1010). The second metal patch (1120) may be formed to include a sixth sub-patch (1126), a seventh sub-patch (1127), and an eighth sub-patch (1128) disposed on the second surface (S2) of the substrate (1010). The first and second sub-patches (1121, 1122) of the third side (S3) of the substrate (1010) and the third to eighth sub-patches (1123, 1124, 1125, 1126, 1127, 1128) of the second side (S2) of the substrate (1010) can constitute the second metal patch (1120).

[0109] The third sub-patch (1123) may be formed with a first width (Ws1) and a first length (Ls1). The third sub-patch (1123) may be arranged to overlap the first metal patch (1110). The fourth sub-patch (1124) may be connected to the third sub-patch (1123) and may be formed with a second width (Ws2) and a second length (Ls2). The fourth sub-patch (1124) may be arranged to be spaced apart from a first point, which is a boundary point on one side of the first metal patch (1110), by a first interval (Ga1). The fifth sub-patch (1125) may be connected to the fourth sub-patch (1124) and formed with a third width (Ws3) and a third length (Ls3). The fifth sub-patch (1125) may be positioned spaced apart from a first point, which is a boundary point on one side of the first metal patch (1110), by a second interval (Ga2).

[0110] The second width (Ws2) of the fourth sub-patch (1124) may be formed wider than the first width (Ws1) of the third sub-patch (1123). The third width (Ws3) of the fifth sub-patch (1125) may be formed wider than the second width (Ws2) of the fourth sub-patch (1124).

[0111] The first sub-patches (1121a, 1121b) may be arranged adjacent to one end and the other end of the third sub-patch (1123) and spaced apart from each other in the first axis direction. The first sub-patches (1121a, 1121b) may be arranged to overlap the fourth sub-patch (1124) in a second axis direction perpendicular to the first axis. The first axis direction may be set to the X-axis direction and the second axis direction may be set to the Y-axis direction.

[0112] The sixth sub-patch (1126) may be formed with a first width (Ws1) and a first length (Ls1). The sixth sub-patch (1126) may be arranged to overlap the first metal patch (1110). The seventh sub-patch (1127) may be connected to the sixth sub-patch (1126) and may be formed with a second width (Ws2) and a second length (Ls2). The seventh sub-patch (1127) may be arranged to be spaced apart from a second point that is rotated 90 degrees from a first point that is a boundary point on one side of the first metal patch (1110) by a first interval (Ga2). The eighth sub-patch (1128) may be connected to the seventh sub-patch (1127) and formed with a third width (Ws3) and a third length (Ls3). The eighth sub-patch (1128) may be arranged to be spaced apart from the second point of the first metal patch (1110) by a third interval (Ga3). The first point of the first metal patch (1110) may be formed in the second axis direction, and the second point may be formed in the first axis direction perpendicular to the second axis. The first axis direction may be set to the X-axis direction, and the second axis direction may be set to the Y-axis direction.

[0113] The second width (Ws2) of the seventh sub-patch (1127) may be formed wider than the first width (Ws1) of the sixth sub-patch (1126). The third width (Ws3) of the eighth sub-patch (1128) may be formed wider than the second width (Ws2) of the seventh sub-patch (1127).

[0114] The second sub-patches (1122a, 1122b) may be arranged adjacent to one end and the other end of the sixth sub-patch (1126) and spaced apart from each other in the second axial direction. The second sub-patches (1122a, 1122b) may be arranged to overlap the seventh sub-patch (1127) in the first axial direction. The first axial direction may be set to the X-axis direction and the second axial direction may be set to the Y-axis direction.

[0115] The switching element (1200) may be configured to include a first switching element (1210) and a second switching element (1220). The first switching element (1210) may be connected to a first point of the first metal patch (1110) and a third point of the second metal patch (1120). The second switching element (1220) may be connected to a second point of the first metal patch (1110) and a fourth point of the second metal patch (1120).

[0116] The reflective metasurface (1000) may be configured to further include a bias line (BL) and an inductor (Ind). The bias line (BL) may be formed to transmit first and second control voltages to the first and second switching elements (1210, 1220). The bias line (BL) may be formed to connect one end of the fifth sub-patch (1125) and the other end of the eighth sub-patch (1128).

[0117] An inductor (Ind) may be placed at a point on the bias line (BL) and at a point on the fourth side (S4) of the substrate (1010) so that the control voltage is transmitted to the switching element (1200) and the RF signal is blocked. The inductor (Ind) placed to block the RF signal may be referred to as an RF choke. When the control voltage is applied to the bias line (BL), the first and second switching elements (1210, 1220) may operate simultaneously. Therefore, the inductor (Ind) may be placed between a point on the bias line (BL) and the ground area (1100g) of the fourth side (S4) of the substrate (1010) so that the control voltage is transmitted to the first and second switching elements simultaneously.

[0118] A bias line (BL) may be formed to transmit the first and second control voltages to the first and second switching elements (1210, 1220). The bias line (BL) may be formed to connect one end of the fifth sub-patch (1125) and the other end of the eighth sub-patch (1128).

[0119] The inductor (Ind) may be arranged on the bias line (BL) so that the first control voltage is transmitted to the first switching element (1110) but not to the second switching element (1120). The inductor (Ind) may be arranged on the bias line (BL) so that the second control voltage is transmitted to the second switching element (1120) but not to the first switching element (1120). The inductor (Ind) may be arranged between a point on the bias line (BL) and a ground area (1100g) of the fourth side (S4) of the substrate (1010) so that the first control voltage is transmitted to the first switching element (1110) and the second control voltage is transmitted to the second switching element (1120). The sixth via (V6) on the bias line (BL) of the second side (S2) of the substrate (1010) is connected to the inductor (Ind) of the fourth side (S4). The sixth via (V6) connected to the inductor (Ind) serves to allow the DC bias voltage, which is a control voltage, to flow.

[0120] Meanwhile, the reflection loss characteristics and phase variation characteristics according to the on / off of the switching element in the reflective metasurface of FIGS. 10 to 12 are described. In this regard, FIG. 14 shows the reflection loss characteristics and phase variation characteristics according to the on / off of the switching element in the reflective metasurface of FIGS. 10 to 12.

[0121] Fig. 14(a) shows the reflection loss characteristics according to the on / off of the switching element when radio waves with polarizations of 0, 22.5, 45, 67.5, and 90 degrees are incident on the reflective metasurface. Fig. 14(b) shows the phase variation characteristics according to the on / off of the switching element when radio waves with polarizations of 0, 22.5, 45, 67.5, and 90 degrees are incident on the reflective metasurface.

[0122] Referring to FIGS. 10 to 12 and FIG. 14(a), the switching element (1200) exhibits excellent reflection loss performance of -0.83 to -1.24 dB centered around 9 GHz when turned on and off. It can be seen that there is almost no change in the reflection loss performance even when the polarization of the radio wave is tilted between 0 and 90 degrees. In addition, it can be seen that the frequency bandwidth over which the reflection loss performance is maintained is 8 to 10 GHz, and the performance is stably maintained over a wide frequency range.

[0123] Referring to FIGS. 10 to 12 and 14(b), it can be confirmed that the phase difference changes by about 180 degrees when the switching element (1200) is turned on / off at about 9 GHz. Referring to FIGS. 10 to 12 and 14, it can be confirmed that when the reflective metasurface (1000) according to the present specification is used, there is almost no degradation in reflection loss or phase variation performance even when the polarization of a radio wave is tilted and incident. In this regard, since the reflective metasurface (1000) has a structure that is symmetrical with respect to 0 and 90 degrees, it can be confirmed that it operates with normal RIS for all polarization directions of 0-360 degrees.

[0124] Meanwhile, the switching element (1200) of the reflective metasurface (1000) formed on the substrate (1010) can be turned on / off by a control unit. In this regard, FIG. 15 shows a structure in which a control unit is formed to perform an on / off control operation for the switching element of the reflective metasurface according to the present specification.

[0125] Referring to FIG. 15, the control unit (1400) may be implemented as a wireless communication control unit such as an RFIC. The control unit (1400) may be disposed on a metal pattern (1130) spaced apart from a ground region (1100g) disposed on the back surface of the substrate (1010), but is not limited thereto and may be changed according to the application. The reflective metasurface (1000) composed of a plurality of RIS unit cells may be formed in a 4x4 array structure, but is not limited thereto and may be changed according to the application.

[0126] Referring to FIGS. 6, 10, and 15, a unit cell including a first metal patch (1110) and a second patch (1150) may be arranged as a plurality of unit cells (UC11 to UC14, UC41 to UC44) in the first axial direction and the second axial direction. Bias lines (BL11 to BL14, BL41 to BL44) may be arranged in the spaces between patches of adjacent cells among the plurality of unit cells (UC11 to UC14, UC41 to UC44). The reflective metasurface (1000) composed of the plurality of unit cells (UC11 to UC14, UC41 to UC44) is not limited to a 4x4 array structure and may be formed in any two-dimensional array structure depending on the application. An inductor can be placed at one point of the bias lines (BL11 to BL14, BL41 to BL44) to block the inflow of RF signals.

[0127] A control unit (1400) may be connected to a feed line (1120f) connected to a second metal patch (1120) of one or more cells among the RIS unit cells. The control unit (1400) may be arranged on the second surface of the substrate (1010). The control unit (1400) and the modem may be implemented as an integrated RFIC & Modem Chip (RMC). The unit cell connected to the control unit (1400) may be referred to as a Measurement cell (M-cell). The feed line (1120f) may be coupled in a direct feed method that directly connects the second metal patch (1120) and the control unit (1400) or in a coupling feed method that indirectly connects them.

[0128] The control unit (1400) can analyze the received electromagnetic wave signal to obtain information about the signal. For example, information such as the Received Signal Strength Indicator (RSSI), which is the signal strength, quality, polarization direction, and angle at which the radio wave is incident can be obtained. Based on this information, the MCU (1450) calculates on / off information of each RIS unit cell that can transmit radio waves in a desired reflection direction according to the radio wave incident conditions. The control unit (1400) that is linked to the MCU (1450) applies voltage to each unit cell according to the on / off information of each RIS unit cell.

[0129] The control unit (1400) can be operably coupled to the first and second switching elements (1210, 1220). Meanwhile, the control unit (1400) can control at least one of the first and second switching elements (1210, 1220) to be turned on based on the polarization of the incident radio wave. In this regard, FIG. 16 shows a current distribution diagram according to the on / off operation of the first and second switching elements.

[0130] Referring to FIGS. 6, 10, 15, and 16, the on / off control operation of the first and second switching elements (1210, 122-0) of the control unit (1400) based on the polarization of the incident radio wave will be described.

[0131] Referring to FIGS. 6, 10, 15, and 16(a), a polarization of a radio wave may be incident in the direction of a first axis. The control unit (1400) may control the radio wave to be reflected through the first switching element (1210) in a first state in which the polarization of the incident radio wave is in a first range of -22.5 degrees to 22.5 degrees with respect to the first axis. In the first state, a first current path may be formed with a first length from one side of the first metal patch (1110) to the end of the eighth sub-patch (1125) of the second metal patch (1120). The first current path of the first length may be formed in a predetermined range based on 1 / 2 of a wavelength corresponding to an operating frequency. The operating frequency may correspond to a second frequency of an operating band in which the switching element (1210) is in an on state.

[0132] Referring to FIGS. 6, 10, 15, and 16(b), the polarization of the radio wave may be incident in a direction tilted by 45 degrees with respect to the first axis. The control unit (1400) may control the radio wave to be reflected through the first switching element (1210) and the second switching element (1220) in a second state in which the polarization of the incident radio wave is in a second range of 22.5 degrees to 67.5 degrees with respect to the first axis. In the second state, a second current path may be formed with a second length through the fifth sub-patch (1125) of the second metal patch (1120), one side of the first metal patch (1110), and the eighth sub-patch (1128) of the second metal patch (1120). The second current path of the second length may be formed in a predetermined range based on 1 / 2 of the wavelength corresponding to the operating frequency. The operating frequency may correspond to the second frequency of the operating band in which the switching element (1210) is in the on state.

[0133] Referring to FIGS. 6, 10, 15, and 16(b), a polarization of a radio wave may be incident in the direction of the second axis. The control unit (1400) may control the radio wave to be reflected through the second switching element (1220) in a third state in which the polarization of the incident radio wave is in a third range of -22.5 degrees to 22.5 degrees with respect to the second axis. In the third state, a third current path may be formed with a third length from the other side of the first metal patch (1110) to the end of the fifth sub-patch (1125) of the second metal patch (1120). The third current path with the third length may be formed in a predetermined range based on 1 / 2 of a wavelength corresponding to an operating frequency. The operating frequency may correspond to a second frequency of an operating band in which the switching element (1210) is in an on state.

[0134] Referring to FIGS. 6, 10, 15, and 16, the reflective metasurface (1000a, 1000) can reflect radio waves without causing a degradation in reflection performance regardless of the direction of polarization. When the polarization of the radio wave is not tilted and is incident in the first axis direction, the reflective metasurface (1000a, 1000) resonates at a second frequency. The first current length of the unit cell corresponds to half a wavelength of the resonance frequency. In this regard, the electrical length can be changed depending on the permittivity of the substrate (1010).

[0135] When the polarization of the radio wave is not tilted and is incident in the second axis direction, the reflective metasurface (1000a, 1000) resonates at the second frequency. The third current length of the unit cell corresponds to half a wavelength of the resonant frequency. In this regard, the electrical length can be changed depending on the permittivity of the substrate (1010).

[0136] When the polarization of the radio wave is tilted by 45 degrees in the oblique direction between the first and second axes and is incident, both of the second metal patches (1120) arranged at 0 degrees and 90 degrees are activated. Accordingly, the radio wave having the polarization tilted by 45 degrees in the oblique direction can be reflected without deterioration of the reflection loss performance. Since the first metal patch (1110) has a polygonal shape close to a circle, it is connected to the two second metal patches (1120) without distortion of the current flow and forms a half-wave current path. Therefore, regardless of whether the polarization of the radio wave is incident at 0 degrees or 45 degrees, there is no significant difference in the reflection loss performance.

[0137] Meanwhile, the reflective metasurface according to the present specification can be implemented in an array structure. In this regard, FIGS. 17 to 19 illustrate reflective metasurfaces with different array structures according to embodiments. FIG. 17 illustrates a reflective metasurface (1000) with a rectangular array structure.

[0138] Referring to FIGS. 6, 10, and 12, the reflective metasurface (1000) of the square array structure can be formed as an MXN array structure in the first and second axis directions. For example, it can be formed as unit cells (UC11 to UC14, UC21 to UC24, UC31 to UC34, UC41 to UC44) of a 4X4 array structure in the first and second axis directions. Bias lines (BL11 to BL14, BL21 to BL24, BL31 to BL34, BL41 to BL44) can be arranged to transmit a control voltage to the unit cells of the 4X4 array structure.

[0139] In a reflective metasurface (1000) having a square array structure, the distance between unit cells can be spaced apart by half the wavelength corresponding to the operating frequency. For example, the distance between unit cells can be set to 15 mm, which is half the wavelength, centered at 10 GHz. In this regard, the distance between diagonally positioned cells is formed to be greater than half the wavelength. Therefore, a performance deviation in reflection performance may occur for radio waves incident diagonally on the reflective metasurface (1000) having a square array structure.

[0140] Fig. 18 shows a reflective metasurface (1000b) having a circular array structure. Referring to Figs. 6, 10, and 18, the reflective metasurface (1000b) having a circular array structure may be formed in an array structure spaced apart from a center point by a predetermined angle on a circumference having a predetermined radius. For example, it may be formed of unit cells (UC11 to UC13, UC21 to UC24, UC31 to UC35, UC41 to UC44, UC51 to UC53) having a circular array structure spaced apart from a center point by a predetermined angle on a circumference having a predetermined radius. Bias lines (BL11 to BL13, BL21 to BL24, BL31 to BL35, BL41 to BL44, BL51 to BL53) may be arranged to transmit a control voltage to the unit cells of the circular array structure.

[0141] In the reflective metasurface (1000b) having a circular array structure, the distance between unit cells can be spaced apart by half the wavelength corresponding to the operating frequency. The unit cells can be arranged along a circle having a radius spaced apart by half the wavelength based on the center point of the circular array structure. The unit cells can be arranged regularly along a circle having a radius of r = λ / 2 * n (n=1, 2, 3…). If the ground region of the substrate is also formed in a circular shape, the distance between the unit cells arranged at the outermost edge of the circle and the boundary of the ground region is maintained constant, so that optimal performance can be exhibited. In addition, the reflective metasurface (1000b) having a circular array structure can limit the deviation of the reflection loss performance to a certain level or less for radio waves incident in an oblique direction.

[0142] Fig. 18 shows a reflective metasurface (1000c) having a hexagonal lattice array structure. The hexagonal lattice array structure may be referred to as a honeycomb shape or a zigzag array structure. Referring to Figs. 6, 10, and 18, the reflective metasurface (1000c) having a hexagonal lattice array structure may be formed with a structure in which the unit cells of adjacent rows are shifted by half the distance between them. For example, the unit cells (UC11 to UC13, UC21 to UC24, UC31 to UC35, UC41 to UC44, UC51 to UC53) of the hexagonal lattice array structure may be formed with the unit cells of adjacent rows being shifted by half the distance between them. Bias lines (BL11 to BL13, BL21 to BL24, BL31 to BL35, BL41 to BL44, BL51 to BL53) can be arranged to transmit control voltages to unit cells of a hexagonal lattice structure.

[0143] A reflective metasurface (1000c) having a hexagonal lattice array structure can be formed such that three unit cells adjacent in the row and column directions form an equilateral triangle, and the distance (d) between three unit cells adjacent in the row and column directions can be λ / 2. The distance from the unit cells of the array structure to the boundary of the ground region can be maintained the same, and the unit cells can be arranged as many as possible, regardless of the shape of the boundary of the ground region of the substrate, such as a square, polygon, or circle.

[0144] The above describes a reflective metasurface according to the present specification. Below, the technical effects of the reflective metasurface according to the present specification are described.

[0145] According to an embodiment of the present disclosure, the first metal patch, which is a main patch, is formed as a polygonal or circular structure having a pentagon or larger shape, thereby preventing the reflection performance from being deteriorated depending on the polarization direction of the radio wave incident on the reflective metasurface.

[0146] According to an embodiment of the present disclosure, the switching elements are arranged in mutually perpendicular first and second axis directions of the first metal patch, so that the deviation in the reflection performance of the reflective metasurface depending on the on / off state of the switching elements can be minimized.

[0147] According to an embodiment of the present disclosure, the shape of the first and second metal patch structures and the arrangement structure of the first and second switching elements are optimized to improve the reflection performance of the reflective metasurface, thereby improving the wireless communication coverage using the reflective metasurface.

[0148] According to an embodiment of the present disclosure, the wireless communication coverage using the reflective metasurface can be improved by improving the reflection performance of the reflective metasurface through an overlapping structure between the first and second metal patches.

[0149] According to an embodiment of the present disclosure, performance degradation can be minimized through a reflective meta surface of a multilayer substrate structure so that performance degradation does not occur in a connection structure such as soldering of elements such as switching elements and inductors.

[0150] Further scope of the applicability of this disclosure will become apparent from the detailed description below. However, since various changes and modifications within the spirit and scope of this disclosure will become apparent to those skilled in the art, it should be understood that the detailed description and specific embodiments, such as the preferred embodiments of this disclosure, are given by way of example only. The detailed description should not be construed as limiting in any respect but rather as illustrative. The scope of this disclosure should be determined by a reasonable interpretation of the appended claims, and all changes coming within the scope of equivalents of this disclosure are intended to be embraced therein.

Claims

1. In the reflective metasurface, A first metal patch arranged on a first surface, which is the outermost surface of the substrate; A second metal patch disposed on a second surface which is a layer inside the above substrate; First sub-patches and second sub-patches arranged on the third surface, which is a layer inside the substrate; A ground region arranged on the fourth surface, which is the outermost surface opposite to the first surface of the substrate; and Including a switching element formed in a non-conductive area formed in the ground area of ​​the fourth surface, The first part of the switching element is connected by the first metal patch and the first vias, and the second part of the switching element is connected by the second metal patch and the second vias. A reflective metasurface, wherein the first sub-patches are connected to the ground region by third vias, and the second sub-patches are connected to the ground region by fourth vias.

2. In paragraph 1, The above first metal patch is formed as a polygonal patch or a circular patch having a pentagon or more, A reflective meta surface further comprising a fifth via vertically connecting the center point of the first metal patch and the ground region.

3. In paragraph 1, The above second metal patch, A third sub-patch formed with a first width and a first length and positioned to overlap the first metal patch; A fourth sub-patch connected to the third sub-patch, formed with a second width and a second length, and spaced apart from a first point, which is a boundary point on one side of the first metal patch, by a first interval; and A reflective meta surface comprising a fifth sub-patch connected to the fourth sub-patch, formed with a third width and a third length, and spaced apart from the first point of the first metal patch by a second interval.

4. In paragraph 3, The above first sub-patches are arranged adjacent to one end and the other end of the third sub-patch in the first axial direction, A reflective meta surface, wherein the first sub-patches are arranged to overlap with the fourth sub-patches in a second axis direction perpendicular to the first axis.

5. In paragraph 4, The above second metal patch, A sixth sub-patch formed with a first width and a first length and arranged to overlap the first metal patch; A seventh sub-patch connected to the sixth sub-patch, formed with a second width and a second length, and spaced apart from the first point of the first metal patch by the first interval at a second point rotated by 90 degrees; and An eighth sub-patch is connected to the seventh sub-patch, formed with a third width and a third length, and arranged to be spaced apart from the second point of the first metal patch by the second interval, The first point is formed in the first axis direction and the second point is formed in the second axis direction perpendicular to the first axis, 6. In paragraph 5, The second sub-patches are arranged adjacent to one end and the other end of the sixth sub-patch and spaced apart from each other in the second axial direction, A reflective meta surface, wherein the second sub-patches are arranged to overlap with the seventh sub-patch in the first axial direction.

7. In paragraph 5, The above switching element, a first switching element connected to the first point and the third point of the second metal patch; and A reflective meta surface comprising a second switching element connected to the second point and the fourth point of the second metal patch.

8. In paragraph 7, A bias line formed to connect one end of the fifth sub-patch and the other end of the eighth sub-patch so that a control voltage is transmitted to the first and second switching elements; and A reflective meta surface further comprising an inductor disposed at a point on the bias line and at a point on the fourth surface so as to transmit the control voltage to the switching element and block the RF signal.

9. In paragraph 7, Further comprising a control unit operably coupled with the first and second switching elements, The above control unit, The polarization of the incident radio wave is controlled to be reflected through the first switching element in a first state in a first range of -22.5 degrees to 22.5 degrees with respect to the first axis, The radio wave is controlled to be reflected through the first switching element and the second switching element in a second state in which the polarization of the radio wave is in a second range of 22.5 degrees to 67.5 degrees with respect to the first axis, A reflective meta surface that controls the radio wave to be reflected through the second switching element in a third state in which the polarization of the radio wave is in a third range of -22.5 degrees to 22.5 degrees with respect to the second axis.

10. In paragraph 9, In the first state, a first length from one side of the first metal patch to an end of the fifth sub-patch of the second metal patch is formed in a predetermined range based on 1 / 2 of the wavelength corresponding to the operating frequency, In the second state, a second length passing through the fifth sub-patch of the second metal patch, one side of the first metal patch and the eighth sub-patch of the second metal patch is formed in a predetermined range based on 1 / 2 of the wavelength, A reflective meta surface, wherein a third length from the other side of the first metal patch to the end of the fifth sub-patch of the second metal patch in the third state is formed in a predetermined range based on half of the wavelength.

11. In the reflective metasurface, A first metal patch arranged on a first surface, which is the outermost surface of the substrate; A second metal patch disposed on the first surface of the substrate; First sub-patches and second sub-patches spaced apart and arranged adjacent to one end and the other end of the second metal patch; A ground region arranged on a second surface, which is the outermost surface opposite to the first surface of the substrate; and Including a switching element formed in a non-conductive area formed in the ground area of ​​the fourth surface, A reflective metasurface, wherein the first sub-patches are connected to the ground region by first vias, and the second sub-patches are connected to the ground region by second vias.

12. In paragraph 11, A reflective meta surface, wherein the first metal patch is formed as a polygonal patch having a shape of pentagon or more or a circular patch.

13. In paragraph 11, The above second metal patch, A third sub-patch formed with a first width and a first length and spaced apart from a first point, which is a boundary point on one side of the first metal patch, by a first interval; A fourth sub-patch connected to the third sub-patch, formed with a second width and a second length, and spaced apart from the first point of the first metal patch by the second interval; and A fifth sub-patch is connected to the second sub-patch, formed with a third width and a third length, and arranged to be spaced apart from the first point of the first metal patch by a third interval, The above first sub-patches are arranged adjacent to one end and the other end of the third sub-patch in the first axial direction, A reflective meta surface, wherein the first sub-patches are arranged adjacent to the fourth sub-patch and spaced apart in a second axis direction perpendicular to the first axis.

14. In paragraph 13, The above second metal patch, A sixth sub-patch formed with a first width and a first length and arranged to be spaced apart from a second point of the first metal patch by a first interval; A seventh sub-patch connected to the sixth sub-patch, formed with a second width and a second length, and spaced apart from the second point of the first metal patch by the second interval; and Including an eighth sub-patch connected to the seventh sub-patch, formed with a third width and a third length, and spaced apart from the second point of the first metal patch by a third interval; The first point is formed in the first axis direction and the second point is formed in the second axis direction perpendicular to the first axis, The second sub-patches are arranged adjacent to one end and the other end of the sixth sub-patch and spaced apart from each other in the second axial direction, A reflective meta surface, wherein the second sub-patches are arranged adjacent to the seventh sub-patch and spaced apart from each other in the first axial direction.

15. In paragraph 14, The above switching element, a first switching element connected to the first point and the third point of the second metal patch; and A second switching element is included, which is connected to the second point and the fourth point of the second metal patch. A bias line formed to connect one end of the fifth sub-patch and the other end of the eighth sub-patch so that a control voltage is transmitted to the first and second switching elements; and A reflective meta surface further comprising an inductor disposed at a point on the bias line and at a point on the second surface so that the control voltage is transmitted to the switching element and RF signals are blocked.

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