RFI Mitigation Using a New Comb Filter for Wideband Autocorrelation Radiometry

This paper presents a new method to suppress radio frequency interference (RFI) for a recently developed microwave radiometer technique, known as wideband autocorrelation radiometry (WiBAR). WiBAR is a method which can measure directly the thickness of a low-loss layer like lake ice or snow on the ground. However, the RFI in the received signal increases the noise floor and results in a decreased signal to noise ratio (SNR) of the WiBAR delay peak in the autocorrelation function. We propose a new filter which acts like a Fabry-Perot interferometer (FPI) in optics and has the frequency response of a comb filter with many evenly spaced alternating pass and stop bands. The response of an ideal comb filter applied to the polluted spectrum captured by WiBAR's receiver to mitigate the RFI in the received signal.