A polarisation-independent dual-polarized pattern reconfigurable antenna

Abstract

The application discloses a dual-polarized pattern reconfigurable antenna with polarization independent adjustment, and solves the problem that each polarization of a reconfigurable antenna using a single reconfiguration device can only be one-dimensionally scanned through the particularity of a horizontal polarization layer and a vertical polarization layer. Each polarization can be two-dimensionally deflected in an E plane and an H plane, that is, can be deflected up, down, left and right. The reconfigurable antenna controls surface current, and the two polarized antennas are respectively located on the upper and lower surfaces of a dielectric substrate, and the surface current cannot pass through the dielectric, so the control of the two polarizations of the dual-polarized antenna does not affect each other. When the reconfigurable antenna is applied to a base station array antenna, the two polarizations can be simultaneously deflected in different directions, so that a multi-beam antenna can be realized, and different users in different directions can be simultaneously served. On the premise of not increasing the number of array antennas, the communication capacity of the base station antenna is greatly improved. As a pattern reconfigurable antenna, the problem of gain collapse when the array antenna is large-angle scanned can be compensated.

Description

Technical Field

[0001] This invention belongs to the field of electronic information technology and relates to a dual-polarization pattern reconfigurable antenna with independently adjustable polarization. Background Technology

[0002] Compared to 4G and earlier generations of wireless communication systems, 5G wireless communication systems face more severe challenges in terms of high channel capacity, wide coverage, and low latency. Small cell concepts and multiple-input multiple-output (MIMO) antennas are currently key approaches to meeting the performance requirements of 5G systems. However, due to the fixed performance of traditional antennas—their operating frequency, radiation direction, and other properties remain unchanged once installed—meeting the requirements of low power consumption, low cost, and complexity is challenging when MIMO systems use a large number of traditional single-function antennas. Therefore, reconfigurable antennas have emerged and have received extensive research in recent years. Reconfigurable antennas can be classified according to their reconfiguration performance into frequency-reconfigurable antennas, polarization-reconfigurable antennas, bandwidth-reconfigurable antennas, and pattern-reconfigurable antennas, etc.

[0003] A pattern-reconfigurable antenna is a single antenna whose main lobe radiation direction can be changed, offering advantages such as improved channel capacity, reduced system power consumption, and improved antenna array beam scanning range. Existing pattern-reconfigurable methods mainly fall into four categories: mechanical control, optical control, alteration of material properties, and electronic control using radio frequency devices. Electronically controlled reconfigurable antennas are widely studied due to their advantages such as fast response speed and ease of implementation. Implementation methods for electronically controlled reconfigurable antennas mainly include: covering the antenna with an electromagnetic modulation device on its upper layer or surrounding area, controlling the feed network to change its radiation mode, adding directors and reflectors, and introducing metamaterial structures.

[0004] Mechanically controlled reconfigurable antennas offer good robustness but suffer from long response times and inconvenient adjustment; optically controlled reconfigurable antennas, while eliminating the need for bias circuits, are costly and difficult to integrate; reconfigurable antennas that modify material properties have poor reconfigurability due to material limitations. Therefore, electrically controlled reconfigurable antennas are currently the mainstream research direction. In electrically controlled implementations, covering the antenna with an electromagnetic control device on its upper or surrounding layers requires secondary modulation of the radiated electromagnetic waves, leading to reduced radiation efficiency. Controlling the feed network to alter its radiation mode significantly increases the requirements for antenna compatibility with end-users when used as a base station antenna. Directors and reflectors are mostly polarization-sensitive and only applicable to single-polarization antennas; metamaterial structures cannot distinguish polarization and can only control two polarizations simultaneously. Meanwhile, dual-polarization antennas are widely used because they can reduce multipath effects and improve channel capacity through polarization diversity. Since most existing technologies are polarization-sensitive, single-polarization reconfigurable antennas constitute the majority of research. A small number of dual-polarized reconfigurable antennas do not separate the two polarizations; the radiation patterns of the two polarizations can only be deflected in one direction and in one dimension. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that existing dual-polarization reconfigurable antennas do not separate the two polarizations, and the radiation patterns of the two polarizations can only be deflected in one direction and in one dimension. This invention provides a dual-polarization pattern reconfigurable antenna with independently adjustable polarization.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] The present invention proposes a dual-polarization pattern reconfigurable antenna with independently adjustable polarization, comprising a horizontal polarization layer, a dielectric substrate layer, a vertical polarization layer, a reflector ground plane, and a connecting dielectric.

[0008] The horizontal polarization layer is installed on the upper surface of the dielectric substrate layer, and the vertical polarization layer is installed on the lower surface of the dielectric substrate layer; both the horizontal polarization layer and the vertical polarization layer are connected to the reflective ground plane through a connecting medium;

[0009] A first diode mechanism is installed on the horizontal polarization layer, a second diode mechanism is installed on the vertical polarization layer, and a third diode mechanism is installed on the reflective floor.

[0010] Preferably, the horizontal polarization layer includes a horizontally polarized butterfly patch antenna, a first EBG structure, a second EBG structure, a first parasitic branch, and a second parasitic branch;

[0011] The first EBG structure, the second EBG structure, the first parasitic branch, and the second parasitic branch are respectively located around the horizontally polarized butterfly patch antenna; the first EBG structure and the second EBG structure are symmetrically arranged, and the first parasitic branch and the second parasitic branch are symmetrically arranged.

[0012] Both the first EBG structure and the second EBG structure are connected to the reflective floor via a connecting medium.

[0013] Preferably, the vertical polarization layer includes a vertically polarized butterfly patch antenna, a third EBG structure, a fourth EBG structure, a third parasitic branch, and a fourth parasitic branch;

[0014] The third EBG structure, the fourth EBG structure, the third parasitic stub, and the fourth parasitic stub are respectively located around the vertically polarized butterfly patch antenna; the third EBG structure and the fourth EBG structure are symmetrically arranged, and the third parasitic stub and the fourth parasitic stub are symmetrically arranged.

[0015] Both the third EBG structure and the fourth EBG structure are connected to the reflective floor via a connecting medium.

[0016] Preferably, the first diode mechanism includes PIN1 and PIN2, wherein PIN1 is mounted on the first parasitic branch and PIN2 is mounted on the second parasitic branch.

[0017] Preferably, the second diode mechanism includes PIN3 and PIN4, wherein PIN3 is mounted on the third parasitic branch and PIN4 is mounted on the fourth parasitic branch.

[0018] Preferably, the third diode mechanism includes PIN5, PIN6, PIN7, PIN8, PIN9, PIN10, PIN11 and PIN12;

[0019] PIN5 and PIN6 are loaded on the reflective floor to control the on / off state of the third EBG structure; PIN7 and PIN8 are loaded on the reflective floor to control the on / off state of the first EBG structure; PIN9 and PIN10 are loaded on the reflective floor to control the on / off state of the fourth EBG structure; PIN11 and PIN12 are loaded on the reflective floor to control the on / off state of the second EBG structure.

[0020] Preferably, the first EBG structure, the second EBG structure, the third EBG structure and the fourth EBG structure are all rhomboid EBG structures.

[0021] Preferably, the horizontal polarization layer and the vertical polarization layer are printed on the dielectric substrate layer.

[0022] Preferably, the connecting medium is a metal column.

[0023] Preferably, the horizontal polarization layer, the vertical polarization layer, and the reflective ground plane are all made of metallic copper;

[0024] The dielectric substrate is made of FR4 dielectric board with a dielectric constant of 2.2.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention proposes a dual-polarization pattern reconfigurable antenna with independently adjustable polarization. The reconfigurable devices are placed on both sides of the antenna, on the same plane as the antenna. By controlling only the distribution of the surface current, the radiation direction is determined before radiation, resulting in higher and more stable radiation efficiency compared to reconfigurable antennas with additional electromagnetic wave control devices. The special characteristics of the horizontal and vertical polarization layers solve the problem of one-dimensional scanning for each polarization in reconfigurable antennas using individual reconfigurable devices. Each polarization can be deflected in two dimensions in the E-plane and H-plane, meaning it can deflect in all directions. The reconfigurable antenna controls the surface current. The two polarized antennas are located on the upper and lower surfaces of the dielectric substrate, respectively. Since the surface current cannot pass through the dielectric, the control of the two polarizations in the dual-polarization antenna does not affect each other. When applied to base station array antennas, because the two polarizations can deflect simultaneously in different directions, a multi-beam antenna can be realized, serving different users in different locations simultaneously. This significantly increases the communication capacity of the base station antenna without increasing the number of array antennas. Furthermore, as a pattern reconfigurable antenna, it also compensates for gain collapse during large-angle scanning of the array antenna.

[0027] Furthermore, the selection of FR4 dielectric substrate with a dielectric constant of 2.2 is based on considerations of both antenna bandwidth and actual processing. Generally, the lower the dielectric constant of the dielectric, the wider the antenna bandwidth. Therefore, it is advisable to select a dielectric with a dielectric constant as close to 1 as possible. However, it is also necessary to consider whether there is a substrate available in the actual processing. Currently, the lowest dielectric constant for commercially available FR4 substrate is 2.2.

[0028] Furthermore, copper is chosen for the antenna radiating structure because copper has suitable electrical conductivity and stable performance, and will not generate a large amount of Joule heat and lose energy.

[0029] Furthermore, the use of a diamond-shaped EBG periodic structure is to increase the antenna's radiation pattern bandwidth. The diamond-shaped EBG periodic structure gradually narrows from the center outwards, and the operating frequency also gradually increases. This allows the EBG structure to operate not at a single frequency point, but rather within a frequency band, thus increasing the antenna's radiation pattern bandwidth. The size of each element in the diamond-shaped EBG structure is gradually changing, therefore the operating frequency can also gradually change, achieving the goal of increasing bandwidth. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a structural diagram of the dual-polarization pattern reconfigurable antenna with independently adjustable polarization according to the present invention.

[0032] Figure 2 This is a structural diagram of the horizontal polarization layer of the present invention.

[0033] Figure 3 This is a structural diagram of the vertical polarization layer of the present invention.

[0034] Figure 4 This is an overall view of the horizontal polarization layer and the vertical polarization layer of the present invention combined. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0039] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0041] The present invention will now be described in further detail with reference to the accompanying drawings:

[0042] This invention proposes a dual-polarization pattern reconfigurable antenna with independently adjustable polarization, such as... Figure 1 As shown, a horizontal polarization layer L1 is mounted on the upper surface of the dielectric substrate layer L2, and a vertical polarization layer L3 is mounted on the lower surface of the dielectric substrate layer L2. Both the horizontal polarization layer L1 and the vertical polarization layer L3 are connected to the reflective ground plane L4 via a connecting medium. A first diode mechanism is mounted on the horizontal polarization layer L1, a second diode mechanism is mounted on the vertical polarization layer L3, and a third diode mechanism is mounted on the reflective ground plane L4. The connecting medium is a metal pillar.

[0043] Among them, such as Figure 2 and Figure 4As shown, the horizontal polarization layer L1 includes a horizontally polarized butterfly patch antenna A1, a first EBG structure E1, a second EBG structure E2, a first parasitic stub P1, and a second parasitic stub P2. The first EBG structure E1, the second EBG structure E2, the first parasitic stub P1, and the second parasitic stub P2 are located around the horizontally polarized butterfly patch antenna A1. The first EBG structure E1 and the second EBG structure E2 are symmetrically arranged, as are the first parasitic stub P1 and the second parasitic stub P2. Both the first EBG structure E1 and the second EBG structure E2 are connected to the reflector ground plane L4 via a connecting medium. The first diode mechanism includes PIN1 and PIN2, with PIN1 mounted on the first parasitic stub P1 and PIN2 mounted on the second parasitic stub P2.

[0044] E3 and E4 are the EBG structures that control the E-plane radiation pattern of the antenna, and P3 and P4 are parasitic stubs that control the H-plane radiation pattern of the antenna.

[0045] like Figure 3 and Figure 4 As shown, the vertical polarization layer L3 includes a vertically polarized butterfly patch antenna A2, a third EBG structure E3, a fourth EBG structure E4, a third parasitic stub P3, and a fourth parasitic stub P4. The third EBG structure E3, the fourth EBG structure E4, the third parasitic stub P3, and the fourth parasitic stub P4 are located around the vertically polarized butterfly patch antenna A2. The third EBG structure E3 and the fourth EBG structure E4 are symmetrically arranged, as are the third parasitic stub P3 and the fourth parasitic stub P4. Both the third EBG structure E3 and the fourth EBG structure E4 are connected to the reflector ground plane L4 via a connecting medium. The second diode mechanism includes PIN3 and PIN4; PIN3 is mounted on the third parasitic stub P3, and PIN4 is mounted on the fourth parasitic stub P4.

[0046] E3 and E4 are the EBG structures that control the E-plane radiation pattern of the antenna, and P3 and P4 are parasitic stubs that control the H-plane radiation pattern of the antenna.

[0047] The first EBG structure E1, the second EBG structure E2, the third EBG structure E3, and the fourth EBG structure E4 are all rhomboid EBG structures. The use of a rhomboid-like periodic EBG structure is to increase the antenna's radiation pattern bandwidth. The rhomboid EBG periodic structure gradually narrows from the center to both sides, and the operating frequency also gradually increases. This allows the EBG structure to operate within a frequency band rather than a single frequency point, thus increasing the antenna's radiation pattern bandwidth. The size of each element in the rhomboid EBG structure is gradually changing, therefore the operating frequency can also gradually change, achieving the goal of increasing bandwidth.

[0048] The third diode assembly includes PIN5, PIN6, PIN7, PIN8, PIN9, PIN10, PIN11, and PIN12. PIN5 and PIN6 are mounted on the reflective floor to control the on / off state of the third EBG structure E3; PIN7 and PIN8 are mounted on the reflective floor to control the on / off state of the first EBG structure E1; PIN9 and PIN10 are mounted on the reflective floor to control the on / off state of the fourth EBG structure E4; and PIN11 and PIN12 are mounted on the reflective floor to control the on / off state of the second EBG structure E2. PIN5 to PIN12 are mounted on L4 to control the on / off state between E1 to E4 and L4.

[0049] The structures of the horizontal polarization layer L1 and the vertical polarization layer L3 are printed on the upper and lower surfaces of the dielectric substrate L2, respectively. The distance from the lower surface of the dielectric substrate L2 to the reflector ground plane L4 is H = 28 mm. The horizontal polarization layer L1, the vertical polarization layer L3, and the reflector ground plane L4 are all made of copper. The dielectric substrate L2 is made of FR4 dielectric substrate with a dielectric constant of 2.2. The overall size of the antenna is D1 = 160 mm. The dielectric substrate L2 and the reflector ground plane L4 are supported by metal pillars (VIA) of an electromagnetic band gap structure (EBG). The antenna operates in the range of 1.7 GHz to 2.2 GHz.

[0050] For horizontal polarization, when PIN7 and PIN8 are open and PIN1, PIN2, PIN11, and PIN12 are disconnected: E1 is connected to L4, forming a resonant circuit. In this case, E1 suppresses the surface wave present on the upper surface of L2, thus reflecting the surface current to the right. Since E2 is not connected to L4, the resonant circuit is disrupted, and the electrical size of a single EBG structure (6mm) is much smaller than the center operating wavelength (186mm), therefore it has no effect on the surface current. Similarly, since PIN1 and PIN3 are disconnected, the electrical size of P1 and P2, which is comparable to the operating wavelength, is disrupted, thus having no effect on the surface current distribution. Therefore, in this case, the surface current exhibits a distribution characteristic of being sparse on the left and dense on the right. Since the antenna pattern depends on the current distribution, the antenna pattern deflects to the right in this case. When PIN1 is open and PIN2, 7, 8, 11 and 12 are closed, E1, E2 and P2 are not working. At this time, P1 is connected, and its length is slightly greater than half the working wavelength. Its function is similar to the reflector of the Yagi antenna, reflecting electromagnetic waves. Therefore, the radiation pattern is deflected downwards at this time.

[0051] For vertical polarization, it can be simply understood as rotating the horizontal polarization by 90 degrees and then shifting it downwards to the lower surface of L2. Since it controls the distribution of the surface current of the antenna, and the surface current only exists at the interface between the two media, the current distributions of L1 and L3 are unaffected, thus achieving independent control of polarization. That is, when the horizontal polarization is biased in one direction, the vertical polarization can be biased in any direction.

[0052] This invention proposes a dual-polarization pattern reconfigurable antenna with independently adjustable polarization, which has the following advantages: 1) This device places the reconfigurable components on both sides of the radiating antenna, on the same plane as the radiating antenna. It only controls the distribution of the surface current of the antenna, determining the radiation direction before radiation. Therefore, compared to reconfigurable antennas with additional electromagnetic wave control devices, the radiation efficiency is higher and more stable, exceeding 80% in all radiation directions. 2) This device effectively integrates two different reconfigurable components, solving the problem of polarization sensitivity of individual reconfigurable components. This device uses an EBG structure to control the E-plane pattern deflection of each polarization and parasitic stubs to control the H-plane pattern of each polarization. This solves the problem that reconfigurable antennas using individual reconfigurable components can only scan one-dimensionally for each polarization. Each polarization of this antenna can be deflected in two dimensions in both the E-plane and H-plane, i.e., it can deflect in all directions. 3) As stated in point 1, this device regulates surface current. The two polarized antennas are located on the upper and lower surfaces of the dielectric substrate, respectively. Since surface current cannot pass through the dielectric, the regulation of the two polarizations in this dual-polarized antenna does not affect each other. As stated in point 2, each polarization can undergo two-dimensional deflection, resulting in 25 possible combinations including the non-deflection state. When this device is applied to a base station array antenna, because the two polarizations can deflect in different directions simultaneously, a multi-beam antenna can be implemented, serving different users in different locations. This significantly increases the communication capacity of the base station antenna without increasing the number of array antennas. Furthermore, as a pattern-reconfigurable antenna, it also compensates for gain collapse during large-angle scanning of the array antenna.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-polarization pattern reconfigurable antenna with independently adjustable polarization, characterized in that, It includes a horizontal polarization layer (L1), a dielectric substrate layer (L2), a vertical polarization layer (L3), a reflective floor (L4), and a connecting medium; The horizontal polarization layer (L1) is installed on the upper surface of the dielectric substrate layer (L2), and the vertical polarization layer (L3) is installed on the lower surface of the dielectric substrate layer (L2); both the horizontal polarization layer (L1) and the vertical polarization layer (L3) are connected to the reflective ground plane (L4) through a connecting medium. A first diode mechanism is installed on the horizontal polarization layer (L1), a second diode mechanism is installed on the vertical polarization layer (L3), and a third diode mechanism is installed on the reflective ground plane (L4). The horizontal polarization layer (L1) includes a horizontally polarized butterfly patch antenna (A1), a first EBG structure (E1), a second EBG structure (E2), a first parasitic stub (P1), and a second parasitic stub (P2); the first EBG structure (E1), the second EBG structure (E2), the first parasitic stub (P1), and the second parasitic stub (P2) are respectively located around the horizontally polarized butterfly patch antenna (A1); the first EBG structure (E1) and the second EBG structure (E2) are both connected to the reflector ground plane (L4) through a connecting medium; The vertical polarization layer (L3) includes a vertically polarized butterfly patch antenna (A2), a third EBG structure (E3), a fourth EBG structure (E4), a third parasitic stub (P3), and a fourth parasitic stub (P4); the third EBG structure (E3), the fourth EBG structure (E4), the third parasitic stub (P3), and the fourth parasitic stub (P4) are respectively located around the vertically polarized butterfly patch antenna (A2); the third EBG structure (E3) and the fourth EBG structure (E4) are both connected to the reflector ground plane (L4) through a connecting medium; The first diode mechanism includes PIN1 and PIN2, wherein PIN1 is mounted on the first parasitic branch (P1) and PIN2 is mounted on the second parasitic branch (P2); The second diode mechanism includes PIN3 and PIN4, wherein PIN3 is mounted on the third parasitic branch (P3) and PIN4 is mounted on the fourth parasitic branch (P4); The third diode mechanism includes PIN5, PIN6, PIN7, PIN8, PIN9, PIN10, PIN11, and PIN12; PIN5 and PIN6 are loaded on the reflective floor to control the on / off state of the third EBG structure (E3); PIN7 and PIN8 are loaded on the reflective floor to control the on / off state of the first EBG structure (E1); PIN9 and PIN10 are loaded on the reflective floor to control the on / off state of the fourth EBG structure (E4); and PIN11 and PIN12 are loaded on the reflective floor to control the on / off state of the second EBG structure (E2).

2. The polarization-independently adjustable dual-polarization pattern reconfigurable antenna according to claim 1, characterized in that, The first EBG structure (E1) and the second EBG structure (E2) are symmetrically arranged, and the first parasitic branch (P1) and the second parasitic branch (P2) are symmetrically arranged.

3. The polarization-independently adjustable dual-polarization pattern reconfigurable antenna according to claim 2, characterized in that, The third EBG structure (E3) and the fourth EBG structure (E4) are symmetrically arranged, as are the third parasitic branch (P3) and the fourth parasitic branch (P4).

4. The polarization-independently adjustable dual-polarization pattern reconfigurable antenna according to claim 1, characterized in that, The first EBG structure (E1), the second EBG structure (E2), the third EBG structure (E3), and the fourth EBG structure (E4) are all rhomboid EBG structures.

5. The polarization-independently tunable dual-polarization pattern reconfigurable antenna according to claim 1, characterized in that, The horizontal polarization layer (L1) and the vertical polarization layer (L3) are printed on the dielectric substrate layer (L2).

6. The polarization-independently tunable dual-polarization pattern reconfigurable antenna according to claim 1, characterized in that, The connecting medium is a metal column.

7. The polarization-independently adjustable dual-polarization pattern reconfigurable antenna according to claim 1, characterized in that, The horizontal polarization layer (L1), the vertical polarization layer (L3), and the reflective floor (L4) are all made of copper. The dielectric substrate (L2) is made of FR4 dielectric substrate with a dielectric constant of 2.2.

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