Design of a satellite RF receiver at Ku-Band for tropical region

Abstract

Receivers designed at Ku-Band are very critical and challenging. Satellite signals travel a very long path and consequently losses and noises are high. Hence, the design of low noise amplifier, bandpass filter, and downconverter need careful consideration at satellite receivers, especially at Ku-Band. A Low Noise Amplifier (LNA) is designed with 8.90 dB gain and 2.188 dB noise figure at Ku-Band. Bandpass filter is designed with operating frequency ranges from 11.966GHz to 12.052GHz and bandwidth of 86MHz. Downconverter is also designed to converts 12GHz to 1GHz at Ku Band with bandwidth of 475MHz. All designs are based on Microwave Office Simulator (AWR) 2006 version and optimized through many simulation and analysis of results. Tropical region suffers from high humidity, high temperature, and heavy rainfall. These factors critically affect the captured signal especially when the frequency goes above 10GHz. Three characteristics of atmospheric losses at Ku-Band link budget are investigated: scintillation, Cross-Polarization Depolarization (XPD), and rain fade attenuation. All designed components (LNA, BPF, DC) are also simulated in system level using Visual Simulation System (VSS). The performance of the designed receiver at clear air and raining condition are investigated using various modulation schemes. The performance during raining condition using vertical, horizontal, and circular polarizations with different availabilities is also investigated and presented in this thesis. A comparison between 16-PSK and 16-QAM is done and presented in this work. The 16-PSK values for the availability A0.1%, A0.01%, and A0.001% in vertical polarization are found to be better than the results in 16-QAM. The designed satellite receiver at A0.1% availability gives the best BER with vertical polarization. At the same time, the values of the bit error rate are proportional with the availability.