Link Budget Analysis for FMCW Radio Altimeter

In this paper, the link budget analysis for the airborne Frequency Modulated Continuous Wave “FMCW” radio altimeter is introduced. The FMCW radio altimeter is based on homodyne configuration with decoupled MIMO antenna for simultaneously transmit and receive (Quasi-mono static) in C-band (typically at 4.3 GHz). The effect of the isolation introduced between the transmitting and the receiving antenna on the link budget analysis and on the measurement, accuracy is addressed. The achieved port-to-port isolation between the transmitting and receiving antennas is more than 50 dB which in turn reduces the receiver equivalent noise temperature from 1905k to 1740k which in turn enhanced the measurement accuracy by 6%