Ku-band Satellite Communications Transceiver Rf Front-end Development

Satellite Communication is a quickly growing communication form, many states have sent satellites working on different frequency band to fulfill the requirement of communication. The C band ,uplink on 6GHz and downlink on 4GHz ,with small decline by rain, was developed early. But the space resource went short of, and it has big aperture antenna and terminal unit. While nowadays resource of Ku band is rich and aperture of antenna is smaller, so VSAT(Very Small Aperture Terminal) working on Ku band is growing faster.RF front end of the transceiver of satellite communication system is a very important components of the system. In this paper, the design of the Ku-band front-end circuit of satellite transceiver , is presented. It has many distinct advantages such as high sensitivity ,low noise ,low cost ,simple structure, small volume. First the analysis of the transceiver front-end block diagram are given, and followed link budget and specification allocation (such as noise figure). Then, all the sub-circuits , including filters, low noise amplifier, mixer, multiplier are described in details. Finally the test circuits are designed, manufactured and measured.The subject is part of"Ku band satellite communication earth station", the project of Chengdu Sine Science and Technology Ltd.. The author is responsible for the RF front end part in it. The system adopted the structure of one exterior LO(local oscillator) providing with transmitter channel and receiver channel by multiplying, to take up small space and cost low. A distinct characteristic of it is almost all sub-circuits(except the power amplifier)are made by discrete transistors. At the same time, parallel coupling microstrip filter was used to make the board compact. Finally, the test results showed high sensitivity ,low noise and large dynamic range of the complete system.