A wideband 2-bits reconfigurable intelligent surface based on guided-wave structure

Abstract

The application discloses a kind of based on waveguide structure's wideband 2-bits reconfigurable intelligent surface, which includes: waveguide structure and wideband 2-bits phase shift circuit, waveguide structure and wideband 2-bits phase shift circuit are connected by metal via hole;Waveguide structure includes metal patch, first dielectric substrate and second dielectric substrate;First dielectric substrate is connected with second dielectric substrate, and first dielectric substrate is above second dielectric substrate;Metal patch is located at the top of first dielectric substrate, and the upper surface of metal patch is etched with U-shaped groove, and wideband 2-bits phase shift circuit is located at the bottom of second dielectric substrate;Wideband 2-bits phase shift circuit includes PIN diode, microstrip transmission line and DC bias circuit;DC bias circuit and PIN diode are connected by microstrip transmission line, and DC bias circuit is used to control the connection state of PIN diode.The wideband 2-bits reconfigurable intelligent surface provided by the application has a wide working frequency band and high bit phase encoding characteristics.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a broadband 2-bit reconfigurable smart surface based on a waveguide structure. Background Technology

[0002] Radar detection technology plays a vital role in military, aerospace, and other fields, operating on the principle of detecting targets by utilizing the electromagnetic waves reflected from them. With continuous technological advancements, the performance of radar systems has significantly improved, particularly in high-precision target identification, complex environment monitoring, and long-range remote sensing. However, traditional radar systems still face numerous limitations in long-range target detection in complex environments. These challenges primarily focus on two aspects: limited detection range and insufficient anti-jamming capabilities. Traditional solutions typically enhance radar detection and anti-jamming capabilities by improving the performance of the transmitter, receiver, or antenna, such as increasing transmission power, enhancing receiver sensitivity, or increasing antenna gain. However, these methods often come with high costs and a mismatch between performance gains, limiting their application in practical scenarios.

[0003] To overcome this bottleneck, reconfigurable smart surfaces, as a novel electromagnetic material with low profile, low cost, and easy deployment, have shown broad development prospects. Reconfigurable smart surfaces can independently control their surface units, flexibly changing the phase, amplitude, frequency, and polarization characteristics of spatial electromagnetic waves, thereby achieving multiple functions such as beam focusing and intelligent sensing. In the radar field, the unique physical layer coding characteristics of reconfigurable smart surfaces can be used to adaptively construct radar echo links, effectively improving the echo signal-to-noise ratio and enhancing the radar's detection performance and anti-jamming capabilities.

[0004] However, the application of reconfigurable smart surfaces still faces key technological challenges, namely the fabrication of high-bit-width reconfigurable smart surfaces. As is well known, existing radar systems typically operate in wide bandwidths to support the transmission and reception of large time-bandwidth product waveforms, such as linear frequency modulated waveforms, phase-coded waveforms, or frequency-agile operating mechanisms, to improve radar range resolution and anti-jamming capabilities. This places higher demands on the bandwidth characteristics of reconfigurable smart surfaces. Furthermore, the higher the number of bits per unit cell in a reconfigurable smart surface, the smaller the quantization phase error, enabling more precise spatial beam control.

[0005] Therefore, improving the bandwidth and bit count of reconfigurable smart surfaces is a pressing technical problem that needs to be solved. Summary of the Invention

[0006] To address the issue of improving the bandwidth and bit count of reconfigurable smart surfaces, this invention provides a broadband 2-bit reconfigurable smart surface based on a waveguide structure. The technical problem to be solved by this invention is achieved through the following technical solution:

[0007] This invention provides a broadband 2-bit reconfigurable smart surface based on a waveguide structure, comprising:

[0008] A waveguide structure and a broadband 2-bit phase shift circuit are connected through a metal via. The waveguide structure receives incident spatial electromagnetic waves and converts them into incident guided waves. The broadband 2-bit phase shift circuit receives the incident guided waves through the metal via, adjusts the phase of the incident guided waves, and returns the adjusted incident guided waves to the waveguide structure, so that the waveguide structure converts the adjusted incident guided waves into reflected spatial electromagnetic waves and reflects them for output.

[0009] The waveguide structure includes a metal patch, a first dielectric substrate, and a second dielectric substrate;

[0010] The first dielectric substrate is connected to the second dielectric substrate, and the first dielectric substrate is above the second dielectric substrate; the metal patch is located on the top of the first dielectric substrate, and the upper surface of the metal patch is etched with a U-shaped groove; the broadband 2-bit phase shift circuit is located at the bottom of the second dielectric substrate.

[0011] The broadband 2-bit phase shift circuit includes PIN diodes, microstrip transmission lines, and DC bias circuitry.

[0012] The DC bias circuit and the PIN diode are connected via a microstrip transmission line. The DC bias circuit is used to control the connection state of the PIN diode to adjust the phase of the incident guided wave.

[0013] In one embodiment of the present invention, the first end of the metal via is located at the center of the U-shaped groove of the waveguide structure, and the second end of the metal via is located on the microstrip transmission line of the broadband 2-bit phase shift circuit.

[0014] In one embodiment of the present invention, the broadband 2-bit phase shift circuit further includes a capacitor, and the microstrip transmission line includes a matching microstrip transmission line and an impedance-gradient microstrip transmission line, wherein the matching microstrip transmission line is connected to the impedance-gradient microstrip transmission line through a capacitor.

[0015] The first end of the metal via is located at the center of the U-shaped groove of the waveguide structure, and the second end of the metal via is located on the matching microstrip transmission line, so that the matching microstrip transmission line is the input terminal of the broadband 2-bit phase shift circuit.

[0016] Impedance-gradient microstrip transmission lines are used to adjust the bandwidth of broadband 2-bit phase shift circuits.

[0017] In one embodiment of the present invention, the PIN diode includes PIN diode D1, PIN diode D2, PIN diode D3, and PIN diode D4;

[0018] In this configuration, PIN diodes D1 and D2 are oriented in the same direction. The cathode of PIN diode D1 is connected to the DC bias circuit via a matching microstrip transmission line, the anode of PIN diode D1 is connected to the anode of PIN diode D2 via a matching microstrip transmission line, and the cathode of PIN diode D2 is connected to the DC bias circuit via a matching microstrip transmission line.

[0019] PIN diodes D3 and D4 are reverse-biased. The cathode of PIN diode D3 is connected to an impedance-gradient microstrip transmission line, and the anode of PIN diode D3 is connected to a DC bias circuit through the impedance-gradient microstrip transmission line. The cathode of PIN diode D4 is connected to a DC bias circuit through the impedance-gradient microstrip transmission line, and the anode of PIN diode D4 is connected to the impedance-gradient microstrip transmission line.

[0020] In one embodiment of the present invention, the DC bias circuit includes a first DC bias port and a second DC bias port;

[0021] The first DC bias port is used to control the connection status of PIN diodes D1 and D2, and the second DC bias port is used to control the connection status of PIN diodes D3 and D4.

[0022] In one embodiment of the present invention, a first DC bias port is used to control the connection state of PIN diodes D1 and D2, and a second DC bias port is used to control the connection state of PIN diodes D3 and D4, including:

[0023] When the first DC bias port input is high, PIN diode D1 is in the on state and PIN diode D2 is in the off state. When the first DC bias port input is low, PIN diode D1 is in the off state and PIN diode D2 is in the on state.

[0024] When the second DC bias port input is high, PIN diode D3 is in the on state and PIN diode D4 is in the off state. When the second DC bias port input is low, PIN diode D3 is in the off state and PIN diode D4 is in the on state.

[0025] In one embodiment of the present invention, the broadband 2-bit phase shift circuit further includes a fan-shaped open stub, the endpoint of which is located on a DC bias circuit to suppress high-frequency current.

[0026] In one embodiment of the present invention, the first dielectric substrate and the second dielectric substrate are connected by a polypropylene adhesive.

[0027] In one embodiment of the present invention, the width of the first dielectric substrate and the second dielectric substrate is 15 mm, and the length of the first dielectric substrate and the second dielectric substrate is 15 mm.

[0028] The metal patch is 11mm long and 7.5mm wide.

[0029] The length of the U-shaped groove is 3.8mm, and the width of the U-shaped groove is 5.6mm;

[0030] The diameter of the metal through hole is 0.4 mm.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) This invention proposes a broadband 2-bit reconfigurable smart surface based on a waveguide structure. Unlike existing reconfigurable smart surfaces with resonant structures, the reconfigurable smart surface proposed in this invention adopts a waveguide structure. Through the waveguide structure consisting of a metal patch with a U-shaped groove etched on the upper surface, a metal through hole, and two dielectric substrates (i.e., the first dielectric substrate and the second dielectric substrate), the mutual conversion between spatial incident electromagnetic waves and guided waves in a wide frequency range can be realized.

[0033] (2) The reconfigurable smart surface proposed in this invention achieves multi-bit control of the guided wave phase through a broadband 2-bit phase shift circuit composed of a microstrip transmission line with loaded PIN diodes and a DC bias circuit. Ultimately, the designed reconfigurable smart surface has a wide operating bandwidth and high-bit phase coding characteristics, and is capable of adapting to multiple waveforms and operating modes of existing radar systems.

[0034] (3) The reconfigurable smart surface proposed in this invention controls the connection state (i.e., on / off) of the PIN diode through a DC bias circuit, which greatly simplifies the complexity of the broadband 2-bit phase shift circuit and realizes the multi-bit control of the waveguide current phase by the reconfigurable smart surface.

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a broadband 2-bit reconfigurable smart surface based on a waveguide structure provided in an embodiment of the present invention;

[0037] Figure 2 This is a top view of the first dielectric substrate provided in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram illustrating the working principle of the waveguide structure provided in this embodiment of the invention;

[0039] Figure 4 This is a schematic diagram of the structure of the broadband 2-bit phase shift circuit provided in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of the simulation results of the frequency domain transmission characteristics of the waveguide structure provided in the embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of the amplitude-frequency characteristics simulation results of a broadband 2-bit reconfigurable smart surface based on a waveguide structure provided in an embodiment of the present invention;

[0042] Figure 7 This is a schematic diagram of the phase frequency characteristics simulation results of a broadband 2-bit reconfigurable smart surface based on a waveguide structure provided in an embodiment of the present invention. Detailed Implementation

[0043] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, describes a broadband 2-bit reconfigurable smart surface based on a waveguide structure proposed in accordance with the present invention.

[0044] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0045] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes said element.

[0046] This invention addresses the problem of improving the bandwidth and bit count of reconfigurable smart surfaces by proposing a broadband 2-bit reconfigurable smart surface based on a waveguide structure. Please refer to [link to relevant documentation]. Figure 1The smart surface 100 includes a waveguide structure 110 and a broadband 2-bit phase shift circuit 120.

[0047] like Figure 1 As shown, the waveguide structure 110 and the broadband 2-bit phase shift circuit 120 are connected through a metal via 130.

[0048] The waveguide structure 110 is used to receive incident spatial electromagnetic waves and convert them into incident guided waves. The broadband 2-bit phase shift circuit 120 receives the incident guided waves through the metal via 130, adjusts the phase of the incident guided waves, and returns the adjusted incident guided waves to the waveguide structure 110, so that the waveguide structure 110 converts the adjusted incident guided waves into reflected spatial electromagnetic waves and reflects them out.

[0049] The specific structure of waveguide structure 110 will be described in detail below.

[0050] In an example of the present invention, such as Figure 1 As shown, the waveguide structure 110 includes a metal patch 1101, a first dielectric substrate 1102 (also referred to as dielectric substrate 1), and a second dielectric substrate 1103 (also referred to as dielectric substrate 2).

[0051] Specifically, the first dielectric substrate 1102 is connected to the second dielectric substrate 1103, and the first dielectric substrate 1102 is above the second dielectric substrate 1103; the metal patch 1101 is located on top of the first dielectric substrate 1102, and the upper surface of the metal patch 1101 is etched with a U-shaped groove 1104; the broadband 2-bit phase shift circuit 120 is located at the bottom of the second dielectric substrate 1103.

[0052] Optionally, you can also... Figure 1 The rectangular metal patch 1101 is replaced with a circular metal patch. That is, as long as the metal patch located on the top of the first dielectric substrate 1102 meets the broadband index, the shape of the metal patch 1101 is not specifically limited in this embodiment of the invention.

[0053] Specifically, such as Figure 1 As shown, the first dielectric substrate 1102 and the second dielectric substrate 1103 are connected by polypropylene adhesive, i.e., PP glue 1105.

[0054] In an example of the present invention, such as Figure 1As shown, a metal ground layer 1106 is disposed above the second dielectric substrate 1103. The reason for disposing of the metal ground layer 1106 is that a broadband 2-bit phase shift circuit 120 is printed on the bottom of the second dielectric substrate 1103. Since the circuit is essentially composed of a microstrip transmission line 1202, and the metal ground layer 1106 is a necessary part of the microstrip transmission line 1202, a metal ground layer 1106 needs to be disposed above the second dielectric substrate 1103 in order to ensure the effective transmission of electromagnetic waves.

[0055] It should be noted that etching a U-shaped groove 1104 on the metal patch 1101 can change its induced current distribution to generate multimode resonance, thereby broadening the operating bandwidth of the traditional rectangular patch antenna.

[0056] In this embodiment of the invention, the metal patch 1101 is made of copper and is printed on the top of the first dielectric substrate 1102. It is connected to the microstrip transmission line of the broadband 2-bit phase shift circuit printed on the bottom of the second dielectric substrate 1103 through the metal through-hole 130 to form the designed waveguide structure 110.

[0057] The first dielectric substrate 1102 is a high-frequency dielectric substrate F4BM-265, and the relative permittivity of the high-frequency dielectric substrate F4BM-265 is... Dielectric loss tangent ,thickness The second dielectric substrate 1103 is a high-frequency dielectric substrate Rogers RO4350, and the relative permittivity of the high-frequency dielectric substrate Rogers RO4350 is... Dielectric loss tangent ,thickness It is understandable that the dielectric loss tangent, also known as the dielectric loss angle tangent, refers to the energy consumed by a dielectric per unit volume per unit time to convert electrical energy into heat energy (in the form of heating). It is a physical quantity that characterizes the magnitude of dielectric loss of a dielectric material after an electric field is applied.

[0058] For further details, please see Figure 2 , Figure 2 This is a top view of the first dielectric substrate provided in an embodiment of the present invention, as shown below. Figure 2As shown, in this embodiment of the invention, the length Sx of the first dielectric substrate 1102 is 15 mm, and the width Sy of the first dielectric substrate 1102 is 15 mm; the length Px of the metal patch 1101 is 11 mm, and the width Py of the metal patch 1101 is 7.5 mm; the length Wx of the U-shaped groove 1104 is 3.8 mm, and the width Wy of the U-shaped groove 1104 is 5.6 mm; the diameter Vd of the metal through-hole 130 is 0.4 mm; and the bottom opening width Lw of the U-shaped groove 1104 is 1 mm. It should be noted that a slot is designed at the bottom of the U-shaped groove 1104, which can further improve the transmission characteristics of the waveguide structure 110.

[0059] It should be noted that the length and width of the second dielectric substrate 1103 are the same as the length and width of the first dielectric substrate 1102.

[0060] To better understand the waveguide structure 110 provided in this embodiment of the invention, please refer to [link / reference]. Figure 3 , Figure 3 This is a schematic diagram illustrating the working principle of the waveguide structure 110 provided in an embodiment of the present invention. (Combined with...) Figure 3 It is understood that when an incident spatial electromagnetic wave (such as a radar signal) is incident at a certain angle onto the metal patch 1101 above the first dielectric substrate 1102, the metal patch 1101 reflects a portion of the incident spatial wave and couples the energy of the other portion of the incident spatial wave into the first dielectric substrate 1102 below. The electromagnetic energy coupled into the first dielectric substrate 1102 forms an incident guided wave, which is further transmitted to the second dielectric substrate 1103 through the metal via 130, so that the broadband 2-bit phase shift circuit 120 printed on the bottom of the second dielectric substrate 1103 can be processed. The phase of the incident waveguide is adjusted. After being adjusted by the broadband 2-bit phase shift circuit 120, the incident waveguide is transmitted to the metal ground layer 1106. After total reflection by the metal ground layer 1106, a reflected waveguide is formed therein. The reflected waveguide returns to the first dielectric substrate 1102 through the metal via 130 and continues to propagate upward to the metal patch 1101 above the first dielectric substrate 1102. In the metal patch 1101 layer, the reflected waveguide is converted into a reflected spatial electromagnetic wave and radiates out from the metal patch 1101 with a specific direction and phase, thus completing the function of the entire waveguide structure 110.

[0061] It should be noted that patch antennas have advantages over other antenna structures, such as small size, light weight, and ease of integration. Composed of a radiating layer, a dielectric substrate, and a metal ground layer, its simple and compact structure makes it ideal as the main structure for reconfigurable smart surfaces with low profile and lightweight design requirements.

[0062] After introducing the specific structure of waveguide structure 110, the specific structure of broadband 2-bit phase shift circuit 120 will be described in detail next.

[0063] In an example of the present invention, such as Figure 1 As shown, the broadband 2-bit phase shift circuit 120 includes a PIN diode 1201, a microstrip transmission line 1202, and a DC bias circuit 1203. The PIN diode 1201, microstrip transmission line 1202, and DC bias circuit 1203 are marked in black, yellow, and blue, respectively.

[0064] It should be noted that, as Figure 4 As shown, the broadband 2-bit phase shift circuit 120 may also include a capacitor 1204. The capacitor 1204 and the PIN diode 1201 can be collectively referred to as radio frequency devices. The PIN diode 1201 is a MADP-000907 manufactured by MCOM Corporation, USA, and the capacitor 1204 is a GJM0225C1C4R7WB01 manufactured by Murata Manufacturing Co., Ltd., Japan.

[0065] Specifically, the DC bias circuit 1203, the PIN diode 1201, and the capacitor 1204 are connected through the microstrip transmission line 1202. The DC bias circuit 1203 is used to control the connection state of the PIN diode 120 to adjust the phase of the incident guided wave.

[0066] It should be noted that the first end of the metal via 130 is located at the center of the U-shaped groove 1104 of the waveguide structure 110, and the second end of the metal via 130 is located on the microstrip transmission line 1202 of the broadband 2-bit phase shift circuit 120.

[0067] Furthermore, such as Figure 4 As shown, the microstrip transmission line 1202 includes a matching microstrip transmission line 1205 and an impedance-gradient microstrip transmission line 1206. The matching microstrip transmission line 1205 is connected to the impedance-gradient microstrip transmission line 1206 through a capacitor 1204.

[0068] Specifically, the first end of the metal via is located at the center of the U-shaped groove of the waveguide structure, and the second end of the metal via 130 (also called the waveguide port) is located on the matching microstrip transmission line 1205, so that the matching microstrip transmission line 1205 is the input terminal of the broadband 2-bit phase shift circuit 120, and the impedance-gradient microstrip transmission line 1206 is used to adjust the bandwidth of the broadband 2-bit phase shift circuit 120.

[0069] It should be noted that by co-optimizing the structure of the microstrip transmission line 1202 (i.e., the matching microstrip transmission line 1205 and the impedance-gradient transmission line 1204) and the DC bias circuit 1203, the limitation of existing multi-bit reconfigurable smart surfaces in balancing bandwidth and high degree of freedom of control has been overcome. This design provides a new technical solution for flexible control of spatial broadband electromagnetic signals.

[0070] Its design mainly relies on the following two key parts:

[0071] The characteristic impedance of the matched microstrip transmission line 1205 is 50 ohms. This value was chosen because it strikes a good balance between signal processing capability and power transmission loss. 50 ohms is close to the characteristic impedance of an air-dielectric coaxial line, effectively reducing insertion loss and facilitating manufacturing and impedance matching. This characteristic makes it an ideal choice for microwave transmission lines. Using a 50-ohm matched microstrip transmission line as the input impedance reference for the broadband 2-bit phase shift circuit ensures good matching between the reconfigurable smart surface waveguide structure 110 and the broadband 2-bit phase shift circuit, enabling efficient conversion and transmission between space electromagnetic waves and guided waves.

[0072] The impedance-gradient transmission line 1204 is unique in that its characteristic impedance gradually changes along the axial direction. Commonly used in broadband impedance matching techniques, it effectively reduces return loss of broadband guided wave signals and improves phase stability, enabling efficient transmission and precise phase control of broadband signals. This makes it suitable for microwave transmission systems requiring wideband designs. The impedance-gradient transmission line 1204 primarily adjusts two parameters: the length and width of the transmission line. Firstly, by varying the width of the transmission line, the input impedance of the impedance-gradient transmission line carrying the RF device can be well matched with that of the 50-ohm microstrip transmission line, significantly improving the bandwidth performance of the broadband 2-bit phase shift circuit and ensuring stable transmission efficiency of the reconfigurable smart surface over a wide bandwidth. Secondly, by varying the length of the transmission line, a balance is found between phase control accuracy and effective bandwidth. Since the electrical length of the transmission line directly affects its phase frequency response and effective operating bandwidth, a reasonable length design can achieve precise phase control without sacrificing bandwidth.

[0073] In an example of the present invention, such as Figure 4 As shown, PIN diode 1201 includes PIN diode D1, PIN diode D2, PIN diode D3 and PIN diode D4.

[0074] In this configuration, PIN diodes D1 and D2 are oriented in the same direction. Specifically, the cathode of PIN diode D1 is connected to the DC bias circuit via a matching microstrip transmission line, the anode of PIN diode D1 is connected to the anode of PIN diode D2 via a matching microstrip transmission line, and the cathode of PIN diode D2 is connected to the DC bias circuit via a matching microstrip transmission line.

[0075] PIN diodes D3 and D4 are reverse-biased. Specifically, the cathode of PIN diode D3 is connected to an impedance-gradient microstrip transmission line, and the anode of PIN diode D3 is connected to a DC bias circuit through the impedance-gradient microstrip transmission line. The cathode of PIN diode D4 is connected to a DC bias circuit through the impedance-gradient microstrip transmission line, and the anode of PIN diode D4 is connected to the impedance-gradient microstrip transmission line.

[0076] In an example of the present invention, such as Figure 4 As shown, the DC bias circuit 1203 includes a first DC bias port A1 and a second DC bias port A2.

[0077] The first DC bias port A1 controls the connection state of PIN diodes D1 and D2, while the second DC bias port A2 controls the connection state of PIN diodes D3 and D4. This means that regardless of whether the first DC bias port A1 is high or low, one and only one of PIN diodes D1 and D2 will always be in a conducting state, allowing the two parallel branches to be encoded and selected. Similarly, the second DC bias port A2 controls the connection state of PIN diodes D3 and D4, thus enabling the selection and control of the corresponding parallel branches.

[0078] Specifically, when the first DC bias port A1 is high, PIN diode D1 is on and PIN diode D2 is off; when the first DC bias port A1 is low, PIN diode D1 is off and PIN diode D2 is on. When the second DC bias port A2 is high, PIN diode D3 is on and PIN diode D4 is off; when the second DC bias port A2 is low, PIN diode D3 is off and PIN diode D4 is on.

[0079] Specifically, the connection state of PIN diodes D1 and D2 is controlled by encoding the high / low level input of the first DC bias port A1, thereby controlling the selection of the corresponding parallel branch. Simultaneously, the connection state of PIN diodes D3 and D4 is controlled by encoding the high / low level input of the second DC bias port A2, thereby controlling the selection of the corresponding branch. When the encoding sets the input levels of the first DC bias port A1 and the second DC bias port A2, the guided wave will propagate along the corresponding selected path, and after passing through the metal via 130, it will be reflected back along the original path to the metal patch 1101 layer, where it will be converted into reflected spatial wave radiation, completing the phase shifting operation of the incident spatial electromagnetic wave. The principle is as follows. Figure 3As shown. Thus, the designed broadband 2-bit phase shift circuit 120 can achieve 2-bit encoded control of the guided wave phase. The correspondence between the encoding definition, the input level of each DC bias port, and the connection state of the corresponding PIN diode is shown in Table 1 below:

[0080] Table 1

[0081]

[0082] In an example of the present invention, such as Figure 4 As shown, the broadband 2-bit phase shift circuit 120 also includes a fan-shaped open stub 1207, the endpoint of which is located on the DC bias circuit 1203 to suppress high-frequency current in order to avoid mutual interference between the guided wave current and the bias DC.

[0083] In summary, the broadband 2-bit reconfigurable smart surface based on waveguide structure provided by the embodiments of the present invention is different from the existing resonant structure reconfigurable smart surface. The reconfigurable smart surface proposed in the present invention adopts a waveguide structure, which is composed of a metal patch with a U-shaped groove etched on the upper surface, a metal through hole, and two dielectric substrates (i.e., the first dielectric substrate and the second dielectric substrate), thereby realizing the mutual conversion between spatial incident electromagnetic waves and guided waves in a wide frequency range.

[0084] Furthermore, the reconfigurable smart surface proposed in this invention achieves multi-bit control of the guided wave phase through a broadband 2-bit phase shift circuit composed of a microstrip transmission line with loaded PIN diodes and a DC bias circuit. Ultimately, the designed reconfigurable smart surface possesses a wide operating bandwidth and high-bit phase coding characteristics, enabling it to adapt to multiple waveforms and operating modes in existing radar systems.

[0085] In addition, the reconfigurable smart surface proposed in this invention controls the connection state (i.e., on / off) of the PIN diode through a DC bias circuit, which greatly simplifies the complexity of the broadband 2-bit phase shift circuit and realizes multi-bit control of the waveguide current phase by the reconfigurable smart surface.

[0086] After introducing the structure of the waveguide structure 110 and the broadband 2-bit phase shift circuit 120 provided in the example of this invention, the waveguide structure 110 will be modeled using the full-wave simulation software Ansys-HFSS.

[0087] Specifically, an infinite periodic model of the waveguide structure 110 was established using master-slave boundary conditions in the full-wave simulation software Ansys-HFSS. A Floquet port was set as the incident end for the spatial electromagnetic wave. A 50-ohm matched microstrip transmission line was loaded at the bottom layer of the waveguide structure 110, and a lumped port was set at its end as the matched receiver. Full-wave simulation calculations were performed on the designed waveguide structure 110, and its frequency domain transmission characteristics were analyzed. The simulation results for the waveguide structure 110 are as follows: Figure 5 As shown, simulation results indicate that the insertion loss (S21) of the designed waveguide structure 110 is no greater than 1 dB in the frequency range of 8.26~11.77 GHz; and its return loss (S11) is no less than 10 dB in the frequency range of 8.53~11.49 GHz. Therefore, the designed waveguide structure 110 has a relative operating bandwidth of 29.6%, which meets the wideband design requirements.

[0088] After modeling the waveguide structure 110 using the full-wave simulation software Ansys-HFSS, the broadband 2-bit reconfigurable smart surface based on the waveguide structure is modeled using the full-wave simulation software Ansys-HFSS.

[0089] Specifically, the broadband 2-bit reconfigurable smart surface based on a waveguide structure provided in this embodiment of the invention is modeled in Ansys-HFSS software. Master-slave boundary conditions and a Floquet incident port are set, and the calculation frequency band is set to the X-band (8GHz~12GHz) with a center frequency of 10GHz. The simulation results of the amplitude-frequency characteristics of the broadband 2-bit reconfigurable smart surface based on a waveguide structure provided in this embodiment of the invention are as follows: Figure 6 As shown, simulation results indicate that within the 9.18GHz to 10.41GHz frequency band, the return loss, |S11|, corresponding to each coded state (Code00, Code01, Code10, Code11) of the broadband 2-bit reconfigurable smart surface based on waveguide structure provided in this embodiment of the invention is no greater than 3dB, exhibiting good broadband characteristics with a relative bandwidth of 12.6%. The simulation calculation results of the phase-frequency characteristics of the broadband 2-bit reconfigurable smart surface based on waveguide structure provided in this embodiment of the invention are as follows: Figure 7 As shown, simulation results demonstrate that within the 9.1 GHz to 10.1 GHz frequency band, the broadband 2-bit reconfigurable smart surface based on waveguide structure provided in this embodiment of the invention achieves 2-bit phase resolution for phase modulation of each coded state, with a relative bandwidth of 10.4%. In summary, the broadband 2-bit reconfigurable smart surface based on waveguide structure provided in this embodiment of the invention possesses broadband characteristics, with a relative operating bandwidth of 10.4%.

[0090] It should be understood that in the several embodiments provided by the present invention, the division of modules / structures is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple modules / structures or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0091] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A wideband 2-bits reconfigurable intelligent surface based on guided-wave structure, characterized in that, The application relates to a waveguide structure and a broadband 2-bits phase shift circuit connected through a metal via; the waveguide structure is used for receiving incident space electromagnetic waves and converting the incident space electromagnetic waves into incident guided waves; the broadband 2-bits phase shift circuit receives the incident guided waves through the metal via, adjusts the phase of the incident guided waves, and returns the adjusted incident guided waves to the waveguide structure, so that the waveguide structure converts the adjusted incident guided waves into reflected space electromagnetic waves and reflects and outputs the reflected space electromagnetic waves. The waveguide structure comprises a metal patch, a first dielectric substrate and a second dielectric substrate. The first dielectric substrate is connected to the second dielectric substrate, and the first dielectric substrate is above the second dielectric substrate; the metal patch is located on the top of the first dielectric substrate, and the upper surface of the metal patch is etched with a U-shaped groove; the broadband 2-bits phase shift circuit is located on the bottom of the second dielectric substrate. The broadband 2-bits phase shift circuit comprises a PIN diode, a microstrip transmission line and a DC bias circuit. The DC bias circuit and the PIN diode are connected through the microstrip transmission line; the DC bias circuit is used for controlling the connection state of the PIN diode to adjust the phase of the incident guided waves. The broadband 2-bits phase shift circuit further comprises a capacitor; the microstrip transmission line comprises a matching microstrip transmission line and an impedance-gradual microstrip transmission line; the matching microstrip transmission line connects the impedance-gradual microstrip transmission line through the capacitor. The first end of the metal via is located at the center of the U-shaped groove of the waveguide structure, and the second end of the metal via is located on the matching microstrip transmission line, so that the matching microstrip transmission line is the input end of the broadband 2-bits phase shift circuit. The impedance-gradual microstrip transmission line is used for adjusting the bandwidth of the broadband 2-bits phase shift circuit. The PIN diode comprises a PIN diode D1, a PIN diode D2, a PIN diode D2 and a PIN diode D4. The PIN diode D1 and the PIN diode D2 are arranged in the same direction; the cathode of the PIN diode D1 is connected to the DC bias circuit through the matching microstrip transmission line; the anode of the PIN diode D1 is connected to the anode of the PIN diode D2 through the matching microstrip transmission line; the cathode of the PIN diode D2 is connected to the DC bias circuit through the matching microstrip transmission line. The PIN diode D3 and the PIN diode D4 are arranged in opposite directions; the cathode of the PIN diode D3 is connected to the impedance-gradual microstrip transmission line; the anode of the PIN diode D3 is connected to the DC bias circuit through the impedance-gradual microstrip transmission line; the cathode of the PIN diode D4 is connected to the DC bias circuit through the impedance-gradual microstrip transmission line; and the anode of the PIN diode D4 is connected to the impedance-gradual microstrip transmission line. ​ The wideband 2-bits phase shift circuit further comprises three fan-shaped open stubs, whose end points are located on the DC bias circuit, for suppressing high-frequency current.

2. The wideband 2-bits reconfigurable intelligent surface based on guided-wave structure according to claim 1, wherein, The first end of the metal via is located at the center of the U-shaped slot of the waveguide structure, and the second end of the metal via is located on the microstrip transmission line of the wideband 2-bits phase shift circuit.

3. The wideband 2-bits reconfigurable intelligent surface based on guided- wave structure of claim 2, wherein, The DC bias circuit comprises a first DC bias port and a second DC bias port. The first DC bias port is used to control the connection state of the PIN diode D1 and the PIN diode D2, and the second DC bias port is used to control the connection state of the PIN diode D3 and the PIN diode D4.

4. The wideband 2-bits reconfigurable intelligent surface based on waveguide structure of claim 3, wherein, The first DC bias port is used to control the connection state of the PIN diode D1 and the PIN diode D2, and the second DC bias port is used to control the connection state of the PIN diode D3 and the PIN diode D4. When the first DC bias port inputs high level, the PIN diode D1 is in the on state, and the PIN diode D2 is in the off state; when the first DC bias port inputs low level, the PIN diode D1 is in the off state, and the PIN diode D2 is in the on state. When the second DC bias port inputs high level, the PIN diode D3 is in the on state, and the PIN diode D4 is in the off state; when the second DC bias port inputs low level, the PIN diode D3 is in the off state, and the PIN diode D4 is in the on state.

5. The wideband 2-bits reconfigurable intelligent surface based on guided- wave structure of claim 1, wherein, The first dielectric substrate and the second dielectric substrate are connected by a polypropylene adhesive.

6. The wideband 2-bits reconfigurable intelligent surface based on guided- wave structure of claim 1, wherein, The width of the first dielectric substrate and the second dielectric substrate is 15mm, and the length of the first dielectric substrate and the second dielectric substrate is 15mm. The length of the metal patch is 11mm, and the width of the metal patch is 7.5mm. The length of the U-shaped slot is 3.8mm, and the width of the U-shaped slot is 5.6mm. The diameter of the metal via is 0.4mm.

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