This letter presents a new filter to suppress radio frequency interference (RFI) in microwave remote sensing instruments, particularly a wideband autocorrelation radiometer (WiBAR). RFI increases the noise floor and results in a decreased signal-to-noise ratio (SNR) of the WiBAR delay peak. The proposed filter operates 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 frequencies of these bands are varied with an electrically adjustable phase shifter. The design of a comb filter with an airy finesse value of 20 has been verified by simulation and measurement.

中文翻译：

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一种新型频率可调射频梳状滤波器

这封信提出了一种新的滤波器来抑制微波遥感仪器中的射频干扰 (RFI)，特别是宽带自相关辐射计 (WiBAR)。RFI 增加了本底噪声并导致 WiBAR 延迟峰值的信噪比 (SNR) 降低。所提出的滤波器的工作原理类似于光学中的法布里-珀罗干涉仪 (FPI)，并且具有梳状滤波器的频率响应，具有许多均匀间隔的交替通带和阻带。这些频带的频率随电动可调移相器而变化。空气精细度值为 20 的梳状滤波器的设计已通过仿真和测量得到验证。