Development Of Superconductor Semi-lumped Tuning Receiver Front-end

With the rapid development of wireless communication technology,a large number of communication devices have an increasing demand for spectrum resources,resulting in an increasingly tight spectrum resource.Due to the development of high-temperature superconducting microwave technology,superconducting receivers have better performance than receivers made of conventional materials at this stage,and thus have important research significance in marine and aviation communication systems.In response to the increasing spectrum constraint and the poor performance of conventional tuned receiver front-end,this paper develops a semi-lumped element receiver front-end system operating in the VHF band based on superconducting thin-film materials,which is mainly composed of two components: an electrically tuned bandpass filter and a lowtemperature low-noise amplifier.This system consists of two main components,an electrically tuned bandpass filter and a low-temperature low-noise amplifier.For superconducting electrically tuned bandpass filters,first analyze the structure of different types of resonators,and then a high Q fixed capacitor is loaded at the end of the resonator to design a suitable semi-lumped resonant unit.The coupling coefficient of the resonator is analyzed by using a variety of electromagnetic simulation software,a superconducting electrically tuned bandpass filter with a continuously adjustable center frequency from 59 MHz to 73 MHz,a bandwidth of about 500 KHz,an insertion loss of less than 1.6d B and a return loss of more than 14 d B is finally jointly designed in the simulation software.For the low-temperature low-noise amplifier,the low-temperature characteristics of the transistor are first analysed,and a MMIC chip with a frequency band,gain and noise coefficient that meets the index requirements and has good temperature stability is selected.The chip is produced by Mini-Circuits with a small noise coefficient,low power consumption and good heat dissipation,and is suitable for operation in a low-temperature Dewar cavity.The transistor is then modelled in electromagnetic simulation software to analyse its S-parameters,stability,noise factor and other indicators.The amplifier was finally machined and fabricated according to the simulation design,and the assembly and testing of the circuit devices were completed.The amplifier operates at a low temperature of 70 K in the frequency range of 30MHz?100MHz with a gain of 21±1d B and a noise figure of less than 1d B.According to the system link structure of the filter and amplifier for cascade assembly and testing,the final superconducting semi-collective parametric tuning receiver front-end.The indicators of the system were measured under the cryogenic platform,the operating band tuning range is 59?73MHz,the bandwidth is about 500 KHz,the system gain is about 20 d B,the system noise factor is less than 2.6d B,which basically meets the design objectives of this paper.