CN-117539082-B - Liquid crystal phase shifter with broadside coupling transition structure

CN117539082BCN 117539082 BCN117539082 BCN 117539082BCN-117539082-B

Abstract

The invention provides a liquid crystal phase shifter with a broadside coupling transition structure, which at least comprises a same-side coupling structure, a delay line type liquid crystal phase shifter and an opposite-side coupling structure, wherein the same-side coupling structure refers to a coupling structure on the same side of a liquid crystal layer metal ground, and the opposite-side coupling structure refers to a coupling structure on the upper side and the lower side of the liquid crystal layer metal ground. By designing two different cross-layer coupling transition structures, the transmission of signals inside and outside the glass layer of the electric control liquid crystal element is realized, and the ultra-wideband working frequency band and lower loss are realized.

Inventors

ZHANG YAN
DU ZHONGHUA
LI SHIZE
GAO YUCHUN

Assignees

北京航空航天大学

Dates

Publication Date: 20260512
Application Date: 20231116

Claims (2)

1. The liquid crystal phase shifter with the broadside coupling transition structure is characterized by at least comprising a same-side coupling structure, a delay line type liquid crystal phase shifter and an opposite-side coupling structure, wherein the same-side coupling structure refers to a coupling structure on the same side of a liquid crystal layer metal ground, namely a middle layer slotted metal floor (8), and the opposite-side coupling structure refers to a coupling structure on the upper side and the lower side of the liquid crystal layer metal ground; The same-side coupling structure comprises a lower metal floor (1), a first metal via hole (2), a lower dielectric substrate (3), a lower coupling line (4), a lower glass substrate (5), an upper coupling line (6-1), a liquid crystal layer (7), a middle slotted metal floor (8), wherein signals are transmitted to the lower coupling line (4) through the first metal via hole (2) by a coaxial connector and further coupled to the upper coupling line (6-1), and the upper coupling line (6-1) is connected with a phase shifting line (6-2) of the delay line type liquid crystal phase shifter, so that the phase shifting line (6-2) is vertically interconnected with an external structure of the lower layer; The delay line type liquid crystal phase shifter comprises a lower glass substrate (5), a phase shifting line (6-2), a liquid crystal layer (7), a middle slotted metal floor (8) and an upper glass substrate (9), wherein all the structures form an inverted microstrip line structure, and the phase shifting line (6-2) is used for realizing the function of continuous phase modulation by changing the bias voltage applied to the liquid crystal layer (7); the heterolateral coupling structure comprises a lower metal floor (1), a lower dielectric substrate (3), a lower glass substrate (5), a lower coupling patch (6-3), a liquid crystal layer (7), a middle slotted metal floor (8), an upper glass substrate (9), an upper coupling patch (10), an upper dielectric substrate (11) and an upper metal floor (13), wherein all the structures form a slotted metal ground-based cross-layer transition structure under the condition of non-uniform dielectric, a phase shift line (6-2) is connected with the lower coupling patch (6-3), and signals are coupled to the upper coupling patch (10) through the lower coupling patch (6-3), so that vertical interconnection of the phase shift line (6-2) and an upper outer structure is realized.
2. The liquid crystal phase shifter according to claim 1, wherein the whole transmission path of the signal is that the signal is firstly input into a feeder line through a coaxial connector, is coupled to a phase shifting line (6-2) on the inner side of a lower glass substrate (5) through a same-side coupling structure, achieves the purpose of phase shifting by applying bias voltage to liquid crystal to change the dielectric constant of the liquid crystal, and then is coupled to an upper coupling patch (10) of an upper glass substrate (9) through a different-side coupling structure at the tail end of the phase shifting line (6-2) and is output through the coaxial connector.

Description

Liquid crystal phase shifter with broadside coupling transition structure Technical Field The invention relates to the field of liquid crystal phase shifters, in particular to a liquid crystal phase shifter with a broadside coupling transition structure. Background The phase shifter is a key component in the phased array radar and the communication system, plays a vital role in the performance of the whole system, and has higher and higher requirements on the phase shifter along with the high-speed development of the communication industry, and has great significance in developing the phase shifter with low loss, large phase difference, compact structure and low cost. The current phase shifter phase shift amount adjustment mode is mainly electric tuning, and is generally based on PIN diodes, varactors, MEMS, ferroelectrics or ferrites and the like. The PIN diode cannot realize continuous phase adjustment, and has larger loss and parasitic effect in a high-frequency band. Phase shifters based on varactors can achieve phase continuous tuning, but also have large losses and parasitics in the high frequency band. MEMS-device based phase shifters are superior to PIN diodes and varactors in performance, but are costly and not easily integrated. The ferroelectric material can be tuned in a larger range of dielectric constants, has good performance in a lower frequency band, but requires higher bias voltage to tune the material, and meanwhile, with the increase of frequency, the loss of the material is increased, so that the loss of the phase shifter is increased, and therefore, the ferroelectric material is not suitable for being applied to a Ku or even higher frequency range. The phase shifter based on ferrite material can use external magnetic field to influence the magnetic permeability of the material so as to change the phase velocity of electromagnetic wave, but has higher driving power and larger volume weight, and is unfavorable for the miniaturization of the tunable phase shifter. The above materials are difficult to meet the requirements of compactness, low cost, continuous tuning and the like at the same time. Liquid crystals have attracted attention from researchers for many years due to their wide application in the optical and non-optical fields. Because the liquid crystal molecules are sensitive to electromagnetic fields, the liquid crystal molecules have relatively low dielectric loss, and the manufacturing cost of related devices is low, so that the liquid crystal molecules have important research value in microwave and millimeter wave circuits. The liquid crystal has strong electric tunable capability, the characteristics of the liquid crystal can be controlled by surface anchoring, an external electric field or a magnetic field, and the liquid crystal shows different dielectric constants under different voltages. Accordingly, liquid crystals are increasingly used in different microwave devices than other tunable media, such as tunable phase shifters, antennas, capacitors, resonators, filters, and the like. The phase shifter based on the liquid crystal material has the advantages of continuous phase modulation, miniaturization, low cost and the like, but according to search, the conventional liquid crystal phase shifter is mostly used for a narrow band, covers C, X, ku frequency bands and has low loss, so that the design is difficult to realize. Disclosure of Invention The invention aims to solve the technical problems that the prior high-precision liquid crystal packaging material mainly adopts glass, however, the glass is difficult to realize metal via holes in the process, so that the physical vertical connection between a transmission line in a phase shifter and the outside of the phase shifter is difficult. The defects of the prior art are overcome, and the transmission of signals inside and outside the glass layer of the electric control liquid crystal element is realized by designing two different cross-layer coupling structures, so that the ultra-wideband working frequency band and lower loss are realized. In order to achieve the above purpose, the liquid crystal phase shifter with the broadside coupling transition structure at least comprises a same-side coupling structure, a delay line type liquid crystal phase shifter and a different-side coupling structure. The same side coupling structure refers to a coupling structure on the same side of the liquid crystal layer metal ground, namely the middle layer grooved metal floor 8, and the different side coupling structure refers to a coupling structure on two sides of the liquid crystal layer metal ground. The homolateral coupling structure has: The metal floor comprises a lower metal floor 1, a first metal via hole 2, a lower dielectric substrate 3, a lower coupling line 4, a lower glass substrate 5, an upper coupling line 6-1, a liquid crystal layer 7 and a middle grooved metal floor 8. The structure forms a broadside coupling strip line s