Development Of S-Band Superconducting Tunable Linear Phase Receiver Front-End

With the application of the Internet of Things,satellite communication,as an important part of the Internet of Things and the Internet,is also developing towards the trend of large capacity and miniaturization.In order to make full use of frequency resources,as well as alleviate the shortage of spectrum resources and complex frequency combination caused by the development of wireless communication technology,higher requirements are also put forward for the performance of the receiver.Therefore,it is of great significance to develop the receiver front-end with tunability,low noise factor,high sensitivity and good group delay in the tuning process.The first task of this thesis is to develop high performance filters conducting on high temperature superconducting(HTS)thin film materials that conduct very low insertion loss,linear phase in the passband,high stopband inhibition,tunability,and miniaturization.The specific research idea is to find the implementation structure that takes into account both linear phase and high out-of-band suppression through the study of coupling topology.Secondly,by improving the resonator element and adding the perturbation structure,it can satisfy the miniaturization and the above characteristics,and take into account the tunable structure design.Finally,by comparing the tunable schemes,this thesis uses a way to increase the tuning range for design.Based on the above filter design methods,this thesis firstly designs and tests two linear phase superconducting filters.Considering the system index and the ability to accommodate tunability,this thesis uses the spiral structure with perturbation to design tunable filters,the test results show that the relative bandwidth is 100 MHz,the tuning range of the center frequency is between 2.05 GHz and 2.55 GHz,the insertion loss is less than 1.1d B,the group delay fluctuation is less than ±0.52 ns in the bandwidth range of more than 50%,the return loss is more than 10.05 d B,and the out-of-band suppression is more than 55 d B,which has good out-of-band suppression ability.The second task of this thesis is to design low-temperature and low-noise amplifier.Firstly,the amplifier chip that meets the gain requirements and has low noise factor is found through selection.Then,the design process is completed through bias circuit design and stability analysis.The test results show that the gain of the amplifier is 19±0.2d B and the noise factor is less than 0.5d B in 2～3GHz at 77 K low temperature.Finally,the S-band high temperature superconducting tunable linear phase front-end is assembled and tested.The test results on the low temperature platform show that the tuning range of the center frequency of the front-end system is about 20%,the bandwidth is about 100 MHz,the system gain is about 18 d B,and the system noise factor is less than1.6d B,the group delay response is less than ±0.63 ns within the bandwidth range of more than 50%.The above indexes all meet the design requirements.