Point Multicast Receiver Rf Front-end Design And Research

Microwave one-spot with multi-address communication system, which is developed from microwave radio relay communication, is able to satisfy the requirements of minor communications traffic with advantages of being high speed, lower cost, easy to maintain operation, high quality communication. Microwave one-spot with multi-address communication system is just the solution for areas with large acreage, decentralized users, lower popularity density, small telephone traffic as well as the complicated-terrain mountains and islands that can not be reachable by the cable.The research and development work in association with the manufacture of receiver for microwave one-spot with multi-address communication system has been done in this paper. The receiver adopts the traditional heterodyne architecture, of which the low noise amplifier(LNA) located in RF front and the filter at the rear are critical instruments in the receiver circuit. Based on the foregoing, the author has focused his analysis and research on these two critical instruments in the receiver. The paper introduces the characteristics of microwave one-spot with multi-address communication system as well as the present situation on research of filter and LNA. Then the article briefs the general theory and methodology used in designing filter, especially the designing method of microstrip filter. The traditional design methodology is associated with the modern simulation software HFSS to modeling, simulate and optimize which have ultimately resulted in the successful design of microstrip filter adopted in 1.5GHz one-spot with multi-address communication system through experiments. The new design of filter which has been put into production in large quantities has met the requirements of the system due to its decreased volume and cost.It is found that the index of microstrip tapped-line is better than parallel coupling by comparable analysis on the two input and output modes in microstrip filter. This is also the reason why tapped-line is applied in the design. The design of filter demonstrates that it is feasible to combine the traditional design methodology with the simulation software. Moreover, by doing so, the adjusting workload and period to research is cut down and reduced which leads to more efficiency in regards to R & D. The reliability of the LNA which located in front of the filter is essential to the reliability of the whole receiver. Given the foregoing, the balanced LNA is studied for purpose of improving the whole system's reliability. The coupler in the traditional balance type usually employs microstrip which usually requires larger space. The article discusses the methods mentioned in documents used to reduce the acreage of coupler and assumes the possibility of adoption of lumped-element. The study of simulation is done by using ADS software. The result has demonstrated the feasibility of the assumption and that the area of balanced LNA has been reduced significantly. Additionally, it can also be used in the design of other active circuit which expands the adoption of balanced amplifier in RF circuit and lays the foundation for microwave one-spot with multi-address communication system's further continuous improvement.