Electromagnetic band gap structure EBG

Abstract

An electromagnetic band gap (EBG) structure includes an antenna substrate layer, a first conductive region, and a second conductive region. The antenna substrate includes a first planar surface and a second planar surface. The first conductive region is located on the first planar surface of the antenna substrate and is separated from an adjacent first conductive region by a first distance. The second conductive region is located on the first planar surface of the antenna substrate and is separated from the first conductive region by a second distance, and wherein the second conductive region at least partially surrounds the first conductive region.

Description

Technical Field

[0001] This disclosure generally relates to radio frequency (RF) antennas, and more specifically to electromagnetic bandgap structures (EBG) for reducing coupling between adjacent RF antennas. Background Technology

[0002] Electromagnetic bandgap (EBG) structures are used to block electromagnetic waves in certain frequency bands. EBG structures are typically used to prevent coupling between adjacent antennas within a specific frequency band. For antennas manufactured on printed circuit boards, a common EBG structure is a three-dimensional (3D) mushroom-shaped structure, where the board is connected to the ground plane via metal vias. However, the manufacturing of the required number of metal vias significantly increases manufacturing costs. It would be beneficial to design EBG structures that offer good performance in blocking electromagnetic waves within a specific frequency band but at a lower manufacturing cost. Summary of the Invention

[0003] According to one aspect, an electromagnetic bandgap (EBG) structure is provided, the EBG structure including an antenna substrate and at least including a first conductive region and a second conductive region formed on a first planar surface of the antenna substrate. The first conductive region is located on the first planar surface of the antenna substrate and is separated from an adjacent first conductive region by a first distance. The second conductive region is also located on the first planar surface, wherein the second conductive region is separated from the first conductive region by a second distance, and wherein the second conductive region at least partially surrounds the first conductive region.

[0004] According to another aspect, a planar antenna plate is provided, comprising an antenna substrate layer, a top conductive layer, and a bottom conductive layer. The antenna substrate layer has a first planar surface and a second planar surface opposite to the first planar surface. The top conductive layer is located on the first planar surface, and the bottom conductive layer is located on the second planar surface. A first E-band antenna is fabricated in the top conductive layer, wherein the first E-band antenna is configured to receive / transmit radio frequency (RF) signals at E-band frequencies. A second E-band antenna is fabricated in the top conductive layer, wherein the second E-band antenna is configured to receive / transmit RF signals at E-band frequencies, wherein the second E-band antenna is offset relative to the first E-band antenna in the xy plane. A periodic array of two-dimensional electromagnetic bandgap (EBG) structures is also fabricated in the top conductive layer. The periodic array of 2D EBG structures is located between the first E-band antenna and the second E-band antenna, wherein each EBG structure includes a plurality of slots formed in the top conductive layer, wherein the periodic array of 2D EBG structures blocks surface waves in the E-band frequency range. Attached Figure Description

[0005] Figure 1A-1CThese are perspective, top, and side views of an antenna plate with a two-dimensional (2D) electromagnetic bandgap (EBG) structure according to some embodiments.

[0006] Figure 2A This is a top view of a 2D EBG structure according to some embodiments. Figure 2B This is a top view of multiple 2DEBG structures according to some embodiments, and Figure 2C It is along Figure 2A The cross-sectional view taken from line 2B-2B in the diagram.

[0007] Figure 3A This is a top view of a 2D EBG structure according to some embodiments. Figure 3B This is a top view of several 2DEBG structures according to some embodiments, and Figure 3C It is along Figure 3A The cross-sectional view taken from line 3B-3B in the diagram.

[0008] Figure 4 This is a top view of an antenna plate with a 2D electromagnetic bandgap (EBG) structure according to some embodiments.

[0009] Figure 5 This is a diagram illustrating transmit / receive (Tx / Rx) coupling between antennas with EBG structures and between antennas without EBG structures according to some embodiments. Detailed Implementation

[0010] According to one aspect, this disclosure relates to a two-dimensional electromagnetic bandgap structure (EBG) for reducing coupling between adjacent antenna elements. Specifically, the EBG is used on an antenna board (e.g., a printed circuit board) comprising at least a planar antenna substrate layer, a top conductive layer, and a bottom conductive layer. Several methods of manufacturing the antenna can be utilized. For example, in some embodiments, antenna elements (i.e., radiating elements) are manufactured on the antenna board via selective etching of the top conductive layer. In other embodiments, instead of selectively etching the top conductive layer to leave the desired conductive pattern, the desired conductive pattern is selectively plated. In other embodiments, various other known manufacturing techniques (including injection molding) can be used to manufacture the antenna structure. The EBG structure is manufactured in the region between adjacent antennas and includes a repeating or periodic EBG structure pattern. The EBG structure is also manufactured via selective etching of the top conductive layer. The process of etching the top conductive layer to manufacture the EBG structure is the same as the process of etching the top conductive layer to manufacture the antenna, and therefore does not introduce substantial additional costs to the manufacturing process. Specifically, the manufacturing process does not require modification of the underlying antenna substrate layer while still providing the desired decoupling between adjacent antennas.

[0011] Now for reference Figures 1A-1CAn antenna plate 100 having a two-dimensional (2D) electromagnetic bandgap (EBG) structure according to some embodiments is shown. The antenna plate 100 includes at least one receiving antenna 102, at least one transmitting antenna 104, and an EBG region 105 located between the at least one receiving antenna 102 and the at least one transmitting antenna 104. In some embodiments, the antenna plate 100 is fabricated on a substrate having at least a top conductive layer 120, an antenna substrate layer 122, and a bottom conductive layer 124 (e.g., Figure 1C The antenna is mounted on a laminated structure such as a printed circuit board (PCB). Radio frequency (RF) waves propagate within the antenna substrate layer 122 and are constrained in the z-direction by a top conductive layer 120 and a bottom conductive layer 124. A plurality of conductive vias 111 extending between the top conductive layer 120 and the bottom conductive layer 124 constrain the RF waves in the lateral direction (i.e., in the xy plane). Thus, the RF waveguide is defined within the antenna substrate layer 122 by the top conductive layer 120, the bottom conductive layer 124, and the plurality of conductive vias 111. RF signals received by the receiving antenna 102 are transmitted to the output port 106 via the waveguide 110. Similarly, RF signals received at the input port 108 are transmitted to the transmitting antenna 104 via the waveguide 112. Figure 1A and 1B The antenna plate 100 shown is referred to as a slotted antenna, wherein at least one receiving antenna 102 and at least one transmitting antenna 104 are fabricated by forming a plurality of slots 114 within the top conductive layer 120. Each slot exposes the antenna substrate layer 122 adjacent to the top conductive layer 120. The slots 114 can be fabricated using etching (removal) of the top conductive layer 120. In other embodiments, in addition to slotted antennas, other types of antennas (such as microstrip antennas, rod antennas, etc.) can be fabricated on the PCB.

[0012] In some embodiments, the antenna plate 100 can be used as part of a radar sensing system in which a transmitting antenna 104 transmits RF signals and a receiving antenna 102 receives the reflected RF signals, which are used for object detection, ranging, and / or tracking. In other embodiments, the antenna plate 100 can be used in a multiple-input multiple-output (MIMO) communication system that utilizes multiple transmitting antennas and multiple receiving antennas to provide wireless communication between two points. For example, in a MIMO embodiment, instead of transmitting antenna 104 and receiving antenna 102 located on the antenna plate, antennas 102 and 104 can both be receiving antennas and / or both can both be transmitting antennas (or both can both be transceivers capable of transmitting and receiving RF signals). In some embodiments, at least one receiving antenna 102 and at least one transmitting antenna 104 operate in the E-band, extending from approximately 60 gigahertz (GHz) to 90 GHz. Specifically, in some embodiments, at least one receiving antenna 102 and at least one transmitting antenna 104 operate in a frequency range between approximately 72 GHz and 82 GHz, and in some embodiments, in a frequency range between 76 GHz and 78 GHz. The EBG region 105 is designed to create a stopband within the operating frequencies of at least one receiving antenna 102 and at least one transmitting antenna 104 to reduce coupling between the individual antennas. In some embodiments, the stopband operates in the E-band range (e.g., 60 GHz–90 GHz). In other embodiments, the EBG region 105 may be selected to provide a stopband in a frequency range between 72 GHz and 82 GHz, and in some embodiments, in a frequency range between 76 GHz and 78 GHz. Reducing the mutual coupling between the individual antennas can improve the performance of the individual antennas. For example, in embodiments where the antennas are used for radar sensing, the reduced coupling between the respective transmitting antenna 104 and the receiving antenna 102 reduces the noise floor associated with each antenna, thereby increasing the signal-to-noise ratio (SNR) of the radar sensing system and increasing the detection range of the radar sensing system.

[0013] In some embodiments, a plurality of EBG structures located in EBG regions 105 are fabricated by selectively etching (removing) conductive material from the top conductive layer 120. Figures 1A-1COne advantage of the antenna plate 100 shown is that the steps of etching the top conductive layer 120 to create the antenna slot 114 for the receive / transmit antenna can be performed simultaneously with the steps of etching the top conductive layer 120 to create multiple EBG structures. That is, since no additional manufacturing steps are required, the cost of manufacturing multiple EBG structures within the EBG region 105 is extremely low (approximately zero). As mentioned above, in other embodiments, other manufacturing methods, such as electroplating and / or injection molding, can be utilized. However, in general, regardless of the manufacturing technology used, the 2D geometry of the EBG structure (similar to the 2D geometry of the antenna element on the same plane as the EBG structure) means that the manufacturing of the antenna element and the EBG structure will not increase the additional (or much additional) cost of the process.

[0014] The geometry of the EBG structure is chosen to prevent surface waves from propagating along the top conductive layer 120 between at least one receiving antenna 102 and at least one transmitting antenna 104. For example, as referenced... Figures 2A-2C In more detail, in some embodiments, each EBG structure includes multiple trenches etched within a top conductive layer to obtain multiple conductive regions positioned according to a defined pattern, these conductive regions being separated from each other via the etched trenches. Figures 2A-2C In the illustrated embodiment, multiple square conductive regions are positioned inside the EBG structure, and multiple L-shaped conductive regions are positioned to at least partially surround each square conductive region. Figures 3A-3C In another embodiment shown, the EBG structure includes an H-shaped groove etched in the conductive layer.

[0015] refer to Figures 2A-2C The diagram shows an EBG structure 200 according to some embodiments. Figure 2A This is a top view of a single EBG structure 200. Figure 2B It is along Figure 2A The cross-sectional view of EBG structure 200 is shown, taken from line 2B-2B. Figure 2C This is a top view showing multiple EBG structures 200 according to some embodiments.

[0016] exist Figure 2A In the illustrated embodiment, the EBG structure 200 includes a first plurality of conductive regions 202a, 202b, 202c, and 202d, and a second plurality of conductive regions 204a, 204b, 204c, and 204d, each conductive region being separated from each other by etched trenches exposing the underlying antenna substrate 206. As described above, in some embodiments, these trenches are etched into a planar conductive layer, thereby removing the conductive layer to expose the underlying antenna substrate layer. This in Figure 2B The cross-sectional view shown in the figure shows that, Figure 2BIn this process, conductive regions 202a and 202b are separated from each other by etching tanks in which conductive material is removed to expose the underlying antenna substrate layer 206. Figure 2B It is also worth noting that conductive regions 202a and 202b (as well as conductive regions 204a and 204b) are not connected to the bottom conductive layer 207 through vias.

[0017] exist Figure 2A In the illustrated embodiment, the first plurality of conductive regions 202a-202d have a geometry defined by lengths L2 and L5. In some embodiments, lengths L2 and L5 are equal to each other, such that the conductive regions 202a-202d are square. In some embodiments, each conductive region in the first plurality of conductive regions 202a-202d is separated from its adjacent conductive region 202a-202d by a length L6 in the y-direction and by a length L9 in the x-direction. In some embodiments, lengths L6 and L9 are equal to each other, such that each conductive region in the first plurality of conductive regions 202a-202d is equidistant from each other.

[0018] In some embodiments, a second plurality of conductive regions 204a-204d are positioned to at least partially surround a first plurality of conductive regions 202a-202d. In some embodiments, the second plurality of conductive regions 204a-204d are L-shaped. For example, conductive region 204d includes a vertical portion 208 (i.e., extending in the y-direction) and a horizontal portion 210 (i.e., extending in the x-direction). The vertical portion 208 is separated from conductive region 202d by a distance L7, while the horizontal portion 210 is separated from conductive region 202d by a distance L8. In some embodiments, distances L7 and L8 are equal to each other. Furthermore, in some embodiments, each of the second plurality of conductive regions 204a-204d is separated from its adjacent conductive region 204a-204d by a distance L3 in the y-direction and by a distance L4 in the x-direction. In some embodiments, distances L3 and L4 are equal to each other. In some embodiments, the distance L9 between the first conductive regions 202c and 202d is equal to the distance L4 between the second conductive regions 204c and 204d; and the distance L6 between the first conductive regions 202b and 202d is equal to the distance L3 between the second conductive regions 204b and 204d. In some embodiments, distances L3, L4, L6, L7, L8, and L9 are approximately equal.

[0019] The dimensions of the EBG structure 200 are selected, at least in part, based on the desired resistance band. For example, in some embodiments, with Figure 2AThe widths of the etching trenches represented by distances L3, L4, L6, L7, L8, and L9 are less than the distances L2 and L5 between the first plurality of conductive regions 202a, 202b, 202c, and 202d. In some embodiments, the widths of the etching trenches represented by distances L3, L4, L5, L7, L8, and L9 are greater than half the distances L2 and L4 between the first plurality of conductive regions 202a, 202b, 202c, and 202d. In some embodiments, the width of the etching trenches is between 0.1 and 0.2 mm, the width of the first plurality of conductive regions 202a-202d is approximately 0.1 to 0.3 mm, and the length of the EBG structure 200 is approximately 0.9 to 1.1 mm.

[0020] In the embodiment shown in FIG2c, a plurality of EBG structures 200a, 200b, 200c, and 200d are positioned adjacent to each other to provide a repeating or periodic array for use between adjacent antennas. In this embodiment, a second plurality of conductive regions 204 from adjacent EBG structures 200a-200d form a single conductive structure having a width defined by distances L10 and L11. In some embodiments, distances L10 and L11 are equal to each other. In some embodiments, distances L10 and L11 (associated with the combined conductive regions 204) are approximately the same as distance L2 representing the width of conductive region 202. In other embodiments, distances L10 and L11 are approximately half the length of distance L2, such that the width of the combined conductive region 204 is narrower than the width of conductive region 202. In other embodiments, the width of the combined conductive region 204 may be greater than the width of conductive region 202 (e.g., distances L10 and L11 are greater than distance L2).

[0021] exist Figure 1A and 1B In the illustrated embodiment, a periodic pattern is used in the region between the receiver antenna 102 and the transmitter antenna 104, employing a structure such as an EBG (e.g., Figure 2A-2C Multiple EBG structures, such as those shown in the diagram, are utilized. The number of EBG structures 200 used can vary depending on the application. Figure 1A and 1BIn the illustrated embodiment, a total of six rows of EBG structures 200 are utilized in EBG region 105. In other embodiments, more or fewer rows of EBG structures may be used in EBG region 105. In some embodiments, the periodic inclusion of EBG structures 200 in EBG region 105 serves to reduce surface ripple between adjacent antennas 102 and 104. As described above, this reduces coupling between adjacent antennas 102, 104, and thus improves the signal-to-noise ratio (SNR) of the antenna plate. In radar sensing systems, the improved SNR of the antenna plate can increase the detection range of the radar system. In multiple-input multiple-output (MIMO) systems, the reduced surface ripple between adjacent antennas can improve the uniformity of beam vectors generated by multiple antennas (e.g., antennas 102 and 104). This reduces the dissimilarity of antenna radiation patterns and improves the angle-finding accuracy of antenna plate 100.

[0022] refer to Figures 3A-3C The diagram shows an EBG structure 300 according to some embodiments. Figure 3A This is a top view of a single EBG structure 300. Figure 3B It is a cross-sectional view of the EBG structure 300 taken along line 3B-3B, and... Figure 3C It is a top view of multiple EBG structures 300 manufactured in a periodic or repeating pattern.

[0023] refer to Figure 3A The EBG structure 300 includes a conductive region 302 and an H-shaped groove 301, which includes a first horizontal groove 304a, a second horizontal groove 304b, and a vertical groove 306. The vertical groove 306 connects the first horizontal groove 304a and the second horizontal groove 304b. In some embodiments, the vertical groove 306 is positioned equidistant from each end of the first horizontal groove 304a and the second horizontal groove 304b. It should be understood that the orientation of the H-shaped groove can be modified such that the H-shaped groove includes the first and second vertical grooves connected by the horizontal grooves (i.e., where the EBG structure is rotated 90°). As described above, in some embodiments, the H-shaped groove is etched into a planar conductive layer, thereby removing the conductive layer to expose the underlying antenna substrate layer 308. This is in Figure 3B The cross-sectional view shown indicates that, in Figure 3B In the process, the H-shaped groove 301 is etched into the conductive layer 302, wherein the conductive material is removed to expose the underlying antenna substrate layer 308. (See reference...) Figure 2B As described, the conductive region 302 is not connected to the bottom conductive layer 309 through a conductive via.

[0024] In some embodiments, the widths of the first horizontal groove 304a and the second horizontal groove 304b are defined by a distance L12, and the width of the vertical groove 306 is defined by a distance L13. In some embodiments, distances L12 and L13 are approximately equal. The distance between the first horizontal groove 304a and the second horizontal groove 304b is defined by a distance L14. In some embodiments, distance L14 is greater than the widths L12 and L13 of the grooves. In some embodiments, the length of the EBG structure 300 is defined by a distance L15, and the height of the EBG structure 300 is defined by a distance L16. In some embodiments, distance L15 is greater than distance L16, such that the shape of the EBG structure 300 is rectangular. In some embodiments, distance L15 is approximately equal to distance L16, such that the shape of the EBG structure 300 is approximately square. In some embodiments, distance L15 is between 0.9 and 1.1 mm, and distance L16 is between 0.6 and 0.8 mm. In some embodiments, the widths of slots L12 and L13 are between 0.1 and 0.2 mm, and the distance L14 between the first horizontal slot 304a and the second horizontal slot 304b is between 0.3 and 0.4 mm.

[0025] exist Figure 3C In the illustrated embodiment, multiple H-shaped EBG structures 300a, 300b, 300c, and 300d are positioned adjacent to each other to provide a repeating or periodic array utilized between adjacent antennas. In some embodiments, such as Figure 1A and 1B As shown, multiple EBG structures 300a-300d are utilized in the EBG region located between adjacent antennas. Depending on the application, between adjacent antennas (e.g., Figure 1A and 1B The number of EBG structures 300 used in a periodic pattern between the receiving antenna 102 and the transmitting antenna 104 shown may vary.

[0026] Reference Figure 4 A multiple-input multiple-output (MIMO) antenna board 400 is shown, which utilizes multiple antenna masts 404a, 404b, and 404c separated by multiple EBG regions 406a, 406b, 406c, and 406d. The MIMO antenna board 400 can be used as a multiple-input receive antenna and / or a multiple-output transmit antenna. The antenna board 400 includes multiple inputs / outputs 402a, 402b, and 402c, each input / output being connected to a corresponding antenna mast 404a, 404b, and 404c. Reference is made to embodiments using both transmit and receive antennas. Figure 1A and 1B For the same reasons discussed, it is desirable to reduce surface ripple between multiple antennas, thereby decoupling the antennas from one another.

[0027] exist Figure 4 In the illustrated embodiment, the plurality of EBG regions 406a, 406b, 406c, and 406d include a plurality of H-shaped EBG structures (such as... Figures 3A-3C (Those EBG structures shown). In Figure 4 In the illustrated embodiment, each of the plurality of EBG regions 406a, 406b, 406c, and 406d includes three columns of EBG structures. In other embodiments, additional or fewer columns of EBG structures may be utilized between each of the respective antenna masts 404a, 404b, and 404c. In other embodiments, additional columns of EBG structures may be utilized. Figure 2A-2C The EBG structure shown replaces the H-shaped EBG structure.

[0028] In some embodiments, the plurality of EBG regions 406a, 406b, 406c, and 406d reduce the surface ripple between adjacent antenna masts 404a, 404b, and 404c, which improves the uniformity of the beam vector generated by the MIMO antenna. This reduces the dissimilarity of the antenna radiation modes and improves the angular measurement accuracy of the MIMO antenna plate 400.

[0029] refer to Figure 5 The diagram illustrates transmit / receive (Tx / Rx) coupling between antennas with EBG structures and between antennas without EBG structures in the frequency band between 74 GHz and 82 GHz, according to some embodiments. Figure 5 The data shown is based on Figure 1A and Figure 1B The diagram illustrates the antenna plate 100 with and without the EBG structure 105. Line 500 shows the coupling between the transmitting and receiving antennas in the absence of the EBG region 105. Line 502 indicates the coupling between the antennas in the presence of the EBG region 105. The presence of the EBG structure reduces the coupling between individual antennas across the entire monitored frequency band (e.g., 74 GHz–82 GHz). One benefit of the disclosed EBG structure is the relatively wide bandwidth of the antenna plate system.

[0030] In this manner, the disclosed invention provides a 2D EBG structure for reducing coupling between adjacent antennas (such as slotted antennas, rod antennas, and microstrip antennas) fabricated on a planar antenna board. The 2D EBG structure is fabricated by etching slots in a repeating pattern in the top conductive layer without requiring modification of the underlying antenna substrate layer. As a result, the EBG structure is defined as two-dimensional because it only requires fabrication (e.g., etching) of the top conductive layer of the planar antenna board. The fabrication of the 2D EBG structure can be combined with etching for fabricating antenna slots and / or antenna rods, thus not significantly increasing the overall cost of the antenna board while providing significant decoupling of the antenna within the E-band operating frequencies.

[0031] Discussion of possible embodiments

[0032] The following is a non-exclusive description of possible embodiments of the present invention.

[0033] According to one aspect, an electromagnetic bandgap (EBG) structure includes an antenna substrate layer having a first planar surface and a first conductive region and a second conductive region formed on the first planar surface. The first conductive regions are separated from adjacent first conductive regions by a first distance. The second conductive regions are separated from the first conductive regions by a second distance and at least partially surround the first conductive regions.

[0034] The EBG structure of the preceding paragraph may optionally include (additionally and / or alternatively) any one or more of the following features, configurations and / or additional components.

[0035] For example, the EBG structure may include a bottom conductive layer positioned opposite the first planar surface (adjacent to the second planar surface of the antenna substrate), wherein the first conductive region and the second conductive region are separated from the bottom conductive layer by the antenna substrate layer.

[0036] The first conductive regions can be separated from each other by forming grooves that expose the antenna substrate layer. Similarly, the second conductive regions can be separated from the first conductive regions and separated from each other by forming grooves that expose the antenna substrate layer.

[0037] The second conductive region can have an "L" shaped geometry.

[0038] The first conductive region can have a square geometry.

[0039] The first distance between the first conductive regions (i.e., the first distance) can be approximately equal to the second distance between the first conductive region and the second conductive region.

[0040] The second conductive region can be separated from the adjacent second conductive region by a third distance.

[0041] The third distance can be equal to the first distance and the second distance.

[0042] The first conductive region may be defined by a first width, and the second conductive region may be defined by a second width, wherein the second width may be approximately equal to half of the first width.

[0043] According to another aspect, the planar antenna plate includes an antenna substrate layer, a top conductive layer, and a bottom conductive layer. The antenna substrate layer has a first planar surface and a second planar surface opposite to the first planar surface. The top conductive layer is located on the first planar surface, while the bottom conductive layer is located on the second planar surface. A first E-band antenna is fabricated in the top conductive layer, wherein the first E-band antenna is configured to receive / transmit radio frequency (RF) signals at E-band frequencies. A second E-band antenna is fabricated in the top conductive layer, wherein the second E-band antenna is configured to receive / transmit RF signals at E-band frequencies, wherein the second E-band antenna is offset relative to the first E-band antenna in the xy plane. A periodic array of two-dimensional electromagnetic bandgap (EBG) structures is also fabricated in the top conductive layer. The periodic array of 2D EBG structures is located between the first E-band antenna and the second E-band antenna, wherein each EBG structure includes a plurality of slots formed in the top conductive layer, wherein the periodic array of 2D EBG structures blocks surface waves in the E-band frequency range.

[0044] The planar antenna panel in the preceding section may optionally include (additionally and / or alternatively) any one or more of the following features, configurations and / or additional components.

[0045] For example, each EBG structure may include a conductive region having an H-shaped groove formed inside the conductive region.

[0046] The H-shaped groove may include a first groove, a second groove, and a third groove perpendicular to the first and second grooves, wherein the third groove extends between the middle portion of the first groove and the middle portion of the second groove.

[0047] Each EBG includes a first conductive region located on a first planar surface of the antenna substrate and separated from an adjacent first conductive region by a first distance, and a second conductive region located on the first planar surface, wherein the second conductive region is separated from the first conductive region by a second distance, and wherein the second conductive region at least partially surrounds the first conductive region.

[0048] The second conductive region can have an "L" shaped geometry.

[0049] The first conductive region can have a square geometry.

[0050] The first distance can be approximated as the second distance.

[0051] The second conductive region can be separated from the adjacent second conductive region by a third distance.

[0052] The third distance can be equal to the first distance and the second distance.

[0053] The first E-band antenna can be a transmitting antenna used in a radar sensing system, while the second E-band antenna can be a receiving antenna used in a radar sensing system.

[0054] A first E-band antenna and a second E-band antenna can be used in a multiple-input multiple-output (MIMO) antenna system.

Claims

1. An electromagnetic bandgap (EBG) structure for an E-band antenna, the EBG structure comprising: An antenna substrate layer having a first planar surface and a second planar surface; A first conductive region is located on the first planar surface of the antenna substrate layer and is separated from adjacent first conductive regions by a first distance. as well as A second conductive region located on the surface of the first planar surface, wherein the second conductive region is separated from the first conductive region by a second distance, and wherein the second conductive region at least partially surrounds the first conductive region; Wherein, the first distance is approximately equal to the second distance; The second conductive region is separated from the adjacent second conductive region by a third distance; and The third distance is equal to the first distance and the second distance.

2. The EBG structure of claim 1, further comprising a bottom conductive layer positioned adjacent to the second planar surface, wherein, The first conductive region and the second conductive region are separated from the bottom conductive layer by the antenna substrate layer.

3. The EBG structure as described in claim 2, wherein, The first planar surface of the antenna substrate layer is exposed in a groove that separates the first conductive regions from each other, a groove that separates the second conductive regions from each other, and a groove that separates the first conductive regions from the second conductive regions.

4. The EBG structure as described in claim 1, wherein, Each conductive region in the second conductive region is "L"-shaped, and each conductive region in the first conductive region is square.

5. The EBG structure as described in claim 1, wherein, The first conductive region is defined by a first width, and the second conductive region is defined by a second width, wherein the second width is approximately half of the first width.

6. A planar antenna board, comprising: An antenna substrate layer having a first planar surface and a second planar surface opposite to the first planar surface; The top conductive layer located on the surface of the first plane; The bottom conductive layer located on the second planar surface; A first E-band antenna is fabricated in the top conductive layer and is configured to receive / transmit radio frequency (RF) signals at E-band frequencies. A second E-band antenna is fabricated in the top conductive layer. This second E-band antenna is configured to receive / transmit RF signals at E-band frequencies. x - y Offset relative to the first E-band antenna in the plane; A periodic array of two-dimensional electromagnetic bandgap (EBG) structures fabricated in the top conductive layer, the periodic array of two-dimensional electromagnetic bandgap (EBG) structures being located between the first E-band antenna and the second E-band antenna, wherein each EBG structure includes a plurality of slots formed in the top conductive layer, wherein the periodic array of two-dimensional electromagnetic bandgap (EBG) structures blocks surface waves in the E-band frequency range. Each EBG includes a first conductive region and a second conductive region. The first conductive region is located on the first planar surface of the antenna substrate and is separated from the adjacent first conductive region by a first distance. The second conductive region is located on the first planar surface, and is separated from the first conductive region by a second distance. The second conductive region at least partially surrounds the first conductive region. Wherein, the first distance is approximately equal to the second distance; The second conductive region is separated from the adjacent second conductive region by a third distance; and The third distance is equal to the first distance and the second distance.

7. The planar antenna plate as described in claim 6, wherein, Each EBG structure includes a conductive region having an H-shaped groove formed inside the conductive region.

8. The planar antenna plate as described in claim 7, wherein, The H-shaped groove includes a first groove, a second groove, and a third groove perpendicular to the first groove and the second groove, wherein the third groove extends between the middle portion of the first groove and the middle portion of the second groove.

9. The planar antenna plate as described in claim 6, wherein, Each conductive region in the second conductive region is "L"-shaped, and each conductive region in the first conductive region is square.

10. The planar antenna plate as claimed in claim 6, wherein, The first E-band antenna is a transmitting antenna used in the radar sensing system, and the second E-band antenna is a receiving antenna used in the radar sensing system.

11. The planar antenna plate as claimed in claim 6, wherein, The first E-band antenna and the second E-band antenna are used in a multiple-input multiple-output (MIMO) antenna system.

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