Antenna Range Reflection Mitigation Via Channel Estimation

Antenna range reflections are commonly removed in continuous wave (CW) measurements with the Fourier transform and time gating. However, for system or subsystem measurements, it is frequently desired to measure radiated non-CW waveforms, which are unsuitable for the typical time-gating technique. This paper introduces an algorithm appropriate for mitigating antenna range reflections for both CW and non-CW waveforms (no limitation on waveform type or parameters). Specifically, channel estimation is utilized to predict and remove undesired reflections in the measured signals, allowing testing in non-ideal antenna range environments. Several manageable limitations are identified including necessitating signal-to-noise ratios (SNRs) greater than 20dB, a short characterization waveform pulsewidth (Table I), and a linear system response between the sample points. To validate the algorithm, a FEKO modeled antenna measurement with a single specular reflection is investigated showing the algorithm performance variation with changes in SNR. Next, measurements on an outdoor range with a metallic sheet reflector are described for various transmit waveforms. Finally, measurements on an outdoor range with multiple sources of reflection are explored, revealing the algorithm performance in a realistic reflection environment. In all cases, significant error mitigation is achieved and quantified.