Broadband 1-bit reconfigurable reflection unit

Abstract

The invention belongs to the technical field of antennas, and particularly relates to a broadband 1-bit reconfigurable reflection unit. The reflection unit comprises a top metal radiation layer, a first dielectric substrate, a middle metal radiation layer, a second dielectric substrate, a circuit metal layer and a bottom metal plate layer. The top metal radiation layer, the first dielectric substrate, the middle metal radiation layer, the second dielectric substrate and the circuit metal layer are sequentially stacked, and the circuit metal layer and the bottom metal plate layer are separated by an air layer; the first dielectric substrate, the second dielectric substrate and the bottom metal plate layer are equal in size and coincide in central point; according to the invention, the working bandwidth of the unit is improved, the reflection loss is reduced, the design complexity is reduced, and the application prospect is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of antennas, and in particular relates to a broadband 1-bit reconfigurable reflection unit. Background Art

[0002] Reconfigurable metasurfaces, with their core advantage of dynamically controlling the amplitude, phase, and polarization of electromagnetic waves, can overcome the limitations of physical reconfiguration of traditional electromagnetic devices and present broad engineering application prospects in the microwave to terahertz frequency range. As the core functional carrier of metasurface systems, the operating characteristics of reconfigurable units (including bandwidth, loss, and control accuracy) are highly dependent on the electromagnetic coupling mechanism and reconfiguration mechanism design of the unit structure.

[0003] Typical implementations of 1-bit reconfigurable reflective metasurface units currently include: electrically controlled switchable structures based on PIN diodes or varactor diodes (such as dual-patch coupling, C-shaped open-ring loaded RF switches), MEMS tunable resonant units, and dynamic control of liquid crystal materials. The PIN diode solution achieves a 180° phase difference by switching the surface current path between the on and off states (such as metal branch switching, resonant ring open and closed loop reconstruction), and has the advantages of fast high-frequency response and simple biasing, but requires the design of an isolated DC feed network. The varactor diode solution uses capacitor tuning to achieve phase mutations, but suffers from problems such as high loss and limited linearity. MEMS technology mechanically reconstructs the unit's geometric parameters, offering low insertion loss characteristics but slow dynamic response.

[0004] Existing technologies often design 1-bit reconfigurable reflective units based on PIN diode tunable elements. However, this has the following disadvantages:

[0005] (1) The reconfigurable reflector unit has a narrow bandwidth. To achieve a 180° phase difference, the unit typically relies on the inherent quality factor (Q value) of the resonant structure. Although a single patch or other high-Q resonator can provide a steep phase response, its inherent narrowband characteristics directly limit the overall unit operating bandwidth.

[0006] (2) The reconfigurable reflective unit has large reflection losses. The PIN diode is loaded on the radiation surface of the unit structure. The metal electrode of the diode will interfere with the surface current distribution, which may affect the radiation characteristics of the unit, thereby increasing the reflection loss of the unit.

[0007] In summary, there is an urgent need to design a 1-bit reconfigurable reflection unit with both broadband and low-loss characteristics to expand the working bandwidth and reduce the reflection loss. Summary of the Invention

[0008] To address the shortcomings of the existing technology, the present invention proposes a broadband 1-bit reconfigurable reflector unit, which includes: a top metal radiation layer, a first dielectric substrate, an intermediate metal radiation layer, a second dielectric substrate, a circuit metal layer, and a bottom metal plate layer; the top metal radiation layer, the first dielectric substrate, the intermediate metal radiation layer, the second dielectric substrate, and the circuit metal layer are stacked in sequence, and the circuit metal layer and the bottom metal plate layer are separated by an air layer; the first dielectric substrate, the second dielectric substrate, and the bottom metal plate layer are equal in size and their center points coincide.

[0009] Preferably, the top metal radiation layer and the middle metal radiation layer are both smaller than the dielectric substrate, and the two metal radiation layers are equal in size and their center points coincide with each other.

[0010] Furthermore, the circuit metal layer includes four microstrip lines and a PIN diode; every two microstrip lines are perpendicular to each other to form a T-shaped microstrip line group, the vertical parts of the two T-shaped microstrip line groups are located on the same straight line and are arranged opposite to each other, and the PIN diode is parallelly connected between the vertical parts of the two T-shaped microstrip line groups.

[0011] Furthermore, the center point of the PIN diode coincides with the center points of the two metal radiation layers.

[0012] Furthermore, the transverse lengths of the two T-shaped microstrip line groups are equal.

[0013] Furthermore, the vertical lengths of the two T-shaped microstrip line groups are equal.

[0014] Preferably, the bottom metal plate layer is a floor, which is located at the bottom layer of the reconfigurable reflection unit and is used to reduce the reflection loss of the unit.

[0015] The beneficial effects of the present invention are as follows: Based on the principle of a double-layer stacked structure and by adding a unit resonant structure, the present invention designs a broadband 1-bit linearly polarized reconfigurable reflector unit. By controlling the on-off state of the PIN diode, two phase states with a phase difference of 180±20° can be provided within the frequency range of 9GHz-13GHz, thereby improving the bandwidth, with a relative bandwidth of 36.36%. The broadband 1-bit reconfigurable reflector unit designed by the present invention uses a patch antenna as the radiation structure, reducing the design complexity. At the same time, the floor is placed in the last layer to reduce the reflection loss of the unit within the operating frequency band. Simulation results show that the reflection loss of the present invention is less than 0.1dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the broadband 1-bit reconfigurable reflection unit structure in the present invention;

[0017] Figure 2 is the reflection phase image of the 1-bit reconfigurable reflection unit in the present invention;

[0018] Figure 3 It is the reflection coefficient map of the 1-bit reconfigurable reflection unit in the present invention. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] The present invention proposes a broadband 1-bit reconfigurable reflection unit, such as Figure 1 As shown, the reflector unit includes: a top metal radiation layer, a first dielectric substrate, a middle metal radiation layer, a second dielectric substrate, a circuit metal layer, and a bottom metal plate layer. The top metal radiation layer, the first dielectric substrate, the middle metal radiation layer, the second dielectric substrate, and the circuit metal layer are stacked in sequence. The circuit metal layer and the bottom metal plate layer are separated by an air layer to ensure sufficient space for diode soldering. The first dielectric substrate, the second dielectric substrate, and the bottom metal plate layer are of equal size and have their centers coincident. Preferably, both the first and second dielectric substrates are made of F4B.

[0021] In some preferred embodiments of the present invention, the top metal radiation layer and the middle metal radiation layer are both smaller than the dielectric substrate, and the two metal radiation layers are equal in size and have the same center point.

[0022] The main radiation structure of the reconfigurable reflector unit adopts a completely identical double-layer metal patch design, that is, the top metal radiation layer and the middle metal radiation layer have the same structure. The unit's operating characteristics can be controlled simply by adjusting the patch size, effectively reducing the complexity of the unit design.

[0023] In some preferred embodiments of the present invention, the circuit metal layer includes four microstrip lines and a PIN diode. Two microstrip lines are perpendicular to each other to form a T-shaped microstrip line group. The vertical portions of the two T-shaped microstrip line groups are located on the same straight line and are arranged opposite each other. The PIN diode is connected parallel to and spans between the vertical portions of the two T-shaped microstrip line groups. The center point of the PIN diode coincides with the center point of the two metal radiation layers.

[0024] The PIN diode is placed parallel to the microstrip line of the circuit metal layer so that the direction of the PIN diode's conduction current remains parallel to the polarization of the incident electromagnetic wave, ensuring the normal operation of the diode. The input and output circuits of the diode are composed of two high-impedance microstrip lines perpendicular to the microstrip line on which it is located.

[0025] In some preferred embodiments of the present invention, the horizontal lengths of the two T-shaped microstrip line groups are equal, and the vertical lengths of the two T-shaped microstrip line groups are equal, that is, the two T-shaped microstrip line groups are centrally symmetrical about the PIN diode.

[0026] The height of the air gap between the bottom metal plate and the circuit metal layer primarily determines the phase response of the cell's reflection path. In actual manufacturing, brackets can be used to secure the bottom metal plate and circuit metal layer to create this air gap. The bottom metal plate also serves as the floor of the cell structure, located at the last layer of the cell structure. This ensures that incident electromagnetic waves are fully reflected, minimizing reflection losses.

[0027] The working principle of the 1-bit reconfigurable reflector unit designed in the present invention is:

[0028] The unit primarily radiates energy through the top and middle metal radiation layers. When an electromagnetic wave is incident on the unit structure, the reflection path of the electromagnetic wave is controlled by controlling the PIN diode's two operating states: on ("0") and off ("1"), thereby adjusting the unit's reflection phase response. The different reflection paths of the electromagnetic wave when the PIN diode is on and off determine the phase response of the reconfigurable reflector unit, while the height of the air layer, i.e., the reflection path, determines the magnitude of the reflection phase.

[0029] The present invention is simulated:

[0030] The unit structure is simulated using periodic boundary conditions in HFSS. The simulation results of the unit characteristics are as follows: Figure 2 and Figure 3 As shown in the figure, the 1-bit reconfigurable reflector unit can provide two phase states with a phase difference of 180±20° within the 9 GHz-13 GHz frequency range, with a relative bandwidth of 36.36%. Furthermore, the unit's reflection loss is less than 0.1 dB within the operating frequency range. Simulation results demonstrate that the 1-bit reconfigurable reflector unit maintains stable reflection phase and amplitude response across a wide frequency band, with the reflection phase error remaining within ±20°. The unit exhibits good operating characteristics and is feasible.

[0031] In summary, the present invention designs a broadband 1-bit reconfigurable reflection unit based on a multi-layer stacking structure. The unit adopts a double-layer stacked dielectric substrate structure, and realizes broadband resonance characteristics through a composite topological structure of a metal radiation patch and a square resonant ring, wherein the PIN diode connected across the center of the microstrip circuit feed branch constitutes a key adjustable element. By controlling the on and off states of the PIN diode, the reflection path of the unit changes, thereby realizing 1-bit phase control of the unit. Moreover, the unit period size is only 12mm, and the occurrence of grating lobes can be effectively reduced after the array is formed. The present invention designs the antenna radiation structure and the phase shift network separately, and places the PIN diode in the middle of the microstrip line feed branch. The microstrip line feed branch is located below the radiation structure, which reduces the possibility of causing parasitic resonance and radiation loss at high frequencies.

[0032] The above embodiments further illustrate the purpose, technical solutions and advantages of the present invention in detail. It should be understood that the above embodiments are only preferred implementation plans of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A broadband 1-bit reconfigurable reflector unit, characterized in that: include: a top metal radiation layer, a first dielectric substrate, an intermediate metal radiation layer, a second dielectric substrate, a circuit metal layer, and a bottom metal plate layer; The top metal radiation layer, the first dielectric substrate, the middle metal radiation layer, the second dielectric substrate, and the circuit metal layer are stacked in sequence, and the circuit metal layer is separated from the bottom metal plate layer by an air layer; the first dielectric substrate, the second dielectric substrate, and the bottom metal plate layer are equal in size and their center points coincide with each other.

2. The broadband 1-bit reconfigurable reflection unit according to claim 1, characterized in that: The top metal radiation layer and the middle metal radiation layer are both smaller than the dielectric substrate, and the two metal radiation layers are equal in size and their center points coincide with each other.

3. The broadband 1-bit reconfigurable reflection unit according to claim 2, characterized in that: The circuit metal layer includes four microstrip lines and a PIN diode; every two microstrip lines are perpendicular to each other to form a T-shaped microstrip line group, the vertical parts of the two T-shaped microstrip line groups are located on the same straight line and are arranged opposite to each other, and the PIN diode is parallelly connected between the vertical parts of the two T-shaped microstrip line groups.

4. The broadband 1-bit reconfigurable reflection unit according to claim 3, characterized in that: The center point of the PIN diode coincides with the center points of the two metal radiation layers.

5. The broadband 1-bit reconfigurable reflection unit according to claim 3, characterized in that: The transverse lengths of the two T-shaped microstrip line groups are equal.

6. The broadband 1-bit reconfigurable reflection unit according to claim 3, characterized in that: The vertical lengths of the two T-shaped microstrip line groups are equal.

7. The broadband 1-bit reconfigurable reflection unit according to claim 1, characterized in that: The bottom metal plate layer is the floor, which is located at the bottom layer of the reconfigurable reflection unit and is used to reduce the reflection loss of the unit.

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