A liquid metal wire phase shifter based on dielectric integrated suspension

Abstract

The present invention relates to a liquid metal wire phase shifter based on dielectric integrated suspension. A polydimethylsiloxane (PDMS) hose filled with gallium-indium liquid metal is placed on the phase shifter's dielectric substrate. A SISL cavity is then formed within the phase shifter's multilayer dielectric substrate. A stepper motor connects the PDMS hose filled with gallium-indium liquid metal within the SISL cavity via an inelastic wire, thereby varying the length of the hose. This invention features wide bandwidth, low loss, and a simple structure, enabling continuous phase modulation within the UWB frequency band.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave phase shifters, in particular to a liquid metal wire phase shifter based on dielectric integrated suspension. Background Art

[0002] In RF microwave circuits, phase shifters are devices used to adjust the transmission phase in the system. With the increasing requirements for beamforming and beam scanning in phased array radar and 5G communications, phase shifters, as a key component in transceiver systems, have gained increasing attention. Furthermore, as the application of the electromagnetic spectrum continues to expand, the demand for broadband circuits is also gradually increasing. In broadband systems, broadband phase shifters are generally implemented as differential phase shifters, where the phase difference between each branch is fixed and unadjustable. Continuously adjustable phase shifters, on the other hand, enable more precise beam scanning and therefore have a wide range of application scenarios.

[0003] To enhance the tuning capabilities of RF microwave circuits, more technologies and materials are being explored for circuit design. As a low-melting-point alloy, eutectic gallium–indium (EGaIn) remains liquid at room temperature, making it a novel metal material for circuit design. Currently, liquid metals are being used in antennas, frequency selective surfaces, open-circuit stub resonators, RF switches, filters, and coaxial cables.

[0004] Substrate Integrated Suspended Line (SISL), a new multilayer processing technology, has been widely used in circuit design. Because SISL technology can form one or more cavities within a multilayer PCB, various metals, dielectrics, and other materials can be added to the original planar circuit, enhancing circuit design flexibility. SISL technology also offers advantages such as self-packaging, low loss, miniaturization, and low cost. Currently, achieving good matching and amplitude balance are two major challenges facing continuously adjustable phase shifters within the ultra-wideband (UWB) frequency band. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and propose a liquid metal wire phase shifter based on dielectric integrated suspension, which has the characteristics of wide bandwidth, low loss and simple structure, and can achieve continuous phase modulation in the UWB frequency band.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] A liquid metal line phase shifter based on dielectric integrated suspension includes: gallium indium liquid metal, a polydimethylsiloxane hose, a dielectric substrate, and a stepper motor. The gallium indium liquid metal is injected into the elastic polydimethylsiloxane hose, the polydimethylsiloxane hose filled with the gallium indium liquid metal is arranged on the dielectric substrate of the phase shifter, and a SISL cavity is provided on the multi-layer dielectric substrate of the phase shifter. The stepper motor is connected to the polydimethylsiloxane hose filled with the gallium indium liquid metal in the SISL cavity via an inelastic wire, and is used to change the length of the polydimethylsiloxane hose filled with the gallium indium liquid metal.

[0008] Furthermore, the phase shifter dielectric substrate includes: a dielectric substrate Sub1, a dielectric substrate Sub2, a dielectric substrate Sub3, a dielectric substrate Sub4, and a dielectric substrate Sub5, wherein the dielectric substrates Sub1, Sub2, Sub3, Sub4, and Sub5 are sequentially arranged from top to bottom, the dielectric substrate Sub1 serves as a top plate for upward positioning of the SISL cavity, and the dielectric substrate Sub5 serves as a bottom plate for downward positioning of the SISL cavity. A polydimethylsiloxane hose filled with gallium-indium liquid metal is disposed on the dielectric substrate Sub3, and two identical SISL cavities are defined below the polydimethylsiloxane hose filled with gallium-indium liquid metal on the dielectric substrates Sub2, Sub3, and Sub4, and the gallium-indium liquid metal forms a quasi-coaxial transmission line.

[0009] Moreover, the SISL cavity is provided with a notch at the edge of the dielectric substrate in the pulling direction for connecting the stepping motor and the polydimethylsiloxane hose filled with gallium indium liquid metal.

[0010] Furthermore, the dielectric substrate Sub3 is connected to the gallium-indium liquid metal and the copper cladding of the dielectric substrate Sub3 via metal wires.

[0011] Furthermore, the dielectric substrate Sub1 , dielectric substrate Sub2 , dielectric substrate Sub3 , dielectric substrate Sub4 and dielectric substrate Sub5 are riveted together by rivets to provide electromagnetic shielding for internal circuits and form a closed space in the mechanical structure.

[0012] The advantages and positive effects of the present invention are:

[0013] 1. This invention places a polydimethylsiloxane (PDMS) hose filled with gallium-indium liquid metal on a dielectric substrate of a phase shifter, and then sets a SISL cavity within the multilayer dielectric substrate. A stepper motor connects the PDMS hose filled with gallium-indium liquid metal inside the SISL cavity via an inelastic wire, thereby varying the length of the PDMS hose. This invention features wide bandwidth, low loss, and a simple structure, enabling continuous phase modulation within the UWB frequency band.

[0014] 2. The phase shifter of the present invention is connected to a transmission line (i.e., a metal line) made of copper on SISL and a gallium-indium liquid metal transmission line. Experiments have shown that, under the premise of properly controlling the impedance of the two lines, it can have lower loss and better matching within the UWB frequency band (3.1-10.6GHz).

[0015] 3. The polydimethylsiloxane (PDMS) hose used in this invention can be stretched to more than twice its original length under normal conditions, thereby increasing the transmission phase shift by up to 1 times its original length. Because the phase shift is positively correlated with frequency, the phase shift increases with increasing frequency, thus enabling wide-range phase modulation.

[0016] 4. The present invention combines non-planar circuits and SISL multi-layer circuits, expanding the scope of circuit design. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the layered overall structure of a liquid metal phase shifter based on dielectric integrated suspension wires in an embodiment of the present invention;

[0018] Figure 2 This is a structural diagram of a dielectric substrate of a phase shifter according to an embodiment of the present invention;

[0019] Figure 3 This is a diagram of S-parameter simulation results in an embodiment of the present invention;

[0020] Figure 4 This is a diagram of phase parameter simulation results in an embodiment of the present invention;

[0021] Figure 5 This is the overall phase shifter tuning system in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings.

[0023] A liquid metal wire phase shifter based on dielectric integrated suspension includes: gallium-indium liquid metal, a polydimethylsiloxane hose, a dielectric substrate, and a stepper motor. The gallium-indium liquid metal is injected into the elastic polydimethylsiloxane hose, which is then placed on the phase shifter's dielectric substrate. A SISL cavity is also provided on the phase shifter's multilayer dielectric substrate. The stepper motor is connected to the polydimethylsiloxane hose containing the gallium-indium liquid metal within the SISL cavity via an inelastic wire, thereby varying the length of the polydimethylsiloxane hose. The stepper motor converts electrical pulses into fixed angular displacements. Combined with a suitably sized circular wheel mounted on the stepper motor, the length of the gallium-indium liquid metal can be precisely controlled. Other motors capable of precisely controlling rotation can also be used in conjunction with gear sets, pull rods, and other structures to achieve precise pulling of a fixed length.

[0024] like Figure 1 As shown, the phase shifter uses SISL technology, partially hollowing out the dielectric to create a SISL cavity, including: dielectric substrate Sub1, dielectric substrate Sub2, dielectric substrate Sub3, dielectric substrate Sub4, and dielectric substrate Sub5. The dielectric substrates Sub1, Sub2, Sub3, Sub4, and Sub5 are sequentially arranged from top to bottom. The dielectric substrate Sub1 serves as the top plate for upward positioning of the SISL cavity, and the dielectric substrate Sub5 serves as the bottom plate for downward positioning of the SISL cavity. A polydimethylsiloxane hose filled with gallium indium liquid metal is disposed on the dielectric substrate Sub3. The dielectric substrates Sub2 and Sub4 each define a SISL cavity above and below the polydimethylsiloxane hose filled with gallium indium liquid metal, respectively. The gallium indium liquid metal forms a quasi-coaxial transmission line.

[0025] The SISL cavity has a notch at the edge of the dielectric substrate in the pulling direction for connecting the stepper motor and the polydimethylsiloxane hose filled with gallium indium liquid metal.

[0026] like Figure 2 As shown, the dielectric substrate Sub3 is connected to the gallium indium liquid metal and the copper clad of the dielectric substrate Sub3 through a metal wire, thereby realizing the connection between the liquid metal wire and the circuit on the standard PCB process.

[0027] Since SISL has the self-encapsulation feature, the dielectric substrates Sub1, Sub2, Sub3, Sub4 and Sub5 can be riveted together to be used for electromagnetic shielding of internal circuits and to form a closed space in a mechanical structure.

[0028] The stepper motor model in this embodiment is 28BYJ-48, which is a four-phase eight-beat permanent magnet reduction stepper motor with an outer diameter of 28 mm. The step angle of this stepper motor is 5.625° / 64, which can achieve good pulling distance accuracy. A motor wheel with a radius of 30 mm is used, and an inelastic nylon wire is installed on the wheel to transmit the pulling force. The other end of the nylon wire is connected to the liquid metal wire in the SISL cavity. The pulling distance is calculated by the radius of the motor connection wheel and the motor step angle. The motor control system is as follows Figure 5 As shown in the figure, a computer sends commands to the STM32F103C8T6 microcontroller, which converts them into corresponding control signals to the ULN2003 motor driver, causing the stepper motor to rotate the desired angle. The above computer control components can also be integrated into an embedded system such as the STM32, reducing system size and cost.

[0029] Figure 2 The two arrows indicate the direction of external pulling. To achieve a greater length change within a smaller pulling distance, two cavity channels are designed for simultaneous pulling. The liquid metal wire has an outer radius of 0.7mm and an inner radius of 0.35mm. To ensure optimal alignment, the dielectric substrate Sub2 is 1.5mm tall, while the dielectric substrate Sub3 is 0.6mm tall, forming the upper and lower parts of the cavity. The left and right widths of the cavity are 2.4mm, meaning the outer edges of the liquid metal wire placed in the center of the cavity are 0.5mm from both the left and right cavity walls. To ensure the liquid metal wire maintains a distance from the cavity walls and prevent direct contact between the wire edges, a support block structure is designed on the dielectric substrate Sub2 to secure the liquid metal wire in place. The thickness of the dielectric substrates Sub1 and Sub5 is 0.6mm, and the thickness of the third dielectric substrate Sub3, where the main circuit resides, is 0.127mm. All five dielectric layers are made of FR4. The SISL line connected to the liquid metal line is designed to have a width of 2.15 mm. After a transition structure, it can match a 50Ω device or instrument.

[0030] Figure 4 The S-parameter simulation results of the phase shifter under four pulling lengths are shown in the figure. In the UWB band of 3.1-10.6GHz, the insertion loss is less than 1.5dB and the return loss is less than 10dB. Figure 5 As shown, the total phase shift is 222° at 3.1 GHz, and when the frequency is greater than 5 GHz, the total phase shift is greater than 360°.

[0031] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific embodiments. Any other embodiments derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A liquid metal wire phase shifter based on dielectric integrated suspension, characterized by: include; Gallium-indium liquid metal, a polydimethylsiloxane hose, a dielectric substrate, and a stepper motor, wherein the gallium-indium liquid metal is injected into the elastic polydimethylsiloxane hose, the polydimethylsiloxane hose filled with the gallium-indium liquid metal is arranged on the dielectric substrate of the phase shifter, and a SISL cavity is arranged on the multi-layer dielectric substrate of the phase shifter. The stepper motor is connected to the polydimethylsiloxane hose filled with the gallium-indium liquid metal in the SISL cavity via an inelastic wire, and is used to change the length of the polydimethylsiloxane hose filled with the gallium-indium liquid metal; The phase shifter dielectric substrates include: dielectric substrate Sub1, dielectric substrate Sub2, dielectric substrate Sub3, dielectric substrate Sub4, and dielectric substrate Sub5. The dielectric substrates Sub1, Sub2, Sub3, Sub4, and Sub5 are sequentially arranged from top to bottom. Dielectric substrate Sub1 serves as the top plate for upward positioning of the SISL cavity, and dielectric substrate Sub5 serves as the bottom plate for downward positioning of the SISL cavity. A polydimethylsiloxane hose filled with gallium-indium liquid metal is disposed on dielectric substrate Sub3. Two identical SISL cavities are defined below the polydimethylsiloxane hose filled with gallium-indium liquid metal on dielectric substrates Sub2, Sub3, and Sub4. The gallium-indium liquid metal forms a quasi-coaxial transmission line.

2. The liquid metal wire phase shifter based on dielectric integrated suspension according to claim 1, characterized in that: The SISL cavity is provided with a notch at the edge of the dielectric substrate in the pulling direction for connecting the stepper motor and the polydimethylsiloxane hose filled with gallium indium liquid metal.

3. The liquid metal wire phase shifter based on dielectric integrated suspension according to claim 1, characterized in that: The dielectric substrate Sub3 is connected to the gallium-indium liquid metal and the copper cladding of the dielectric substrate Sub3 through metal wires.

4. The liquid metal wire phase shifter based on dielectric integrated suspension according to claim 1, characterized in that: The dielectric substrate Sub1 , dielectric substrate Sub2 , dielectric substrate Sub3 , dielectric substrate Sub4 and dielectric substrate Sub5 are riveted together by rivets to provide electromagnetic shielding for internal circuits and form a closed space in the mechanical structure.

Images