Upgrading The Settings of a Microwave Experimental Setup for Better Accuracy in Bistatic Radar Cross Section Measurement

Abstract

Bistatic Radar Cross Section (RCS) measurement represents a particular challenge, compared to monostatic measurement. First, bistatic RCS measurement requires a background subtraction to compensate the direct incidence from the source to the receiver. Second, the measurement accuracy varies as function of the amplitude of the received signal which, by itself, varies as a function of the receiver’s position with respect to the source. In the forward scattering direction when the receiving and transmitting antennas are facing each other, the Signal to Noise Ratio (SNR) is usually satisfactory but the signal level must be maintained beyond the non-linear region of the receiving devices. However, in the backward scattering direction the SNR is quite low [1]. When measuring low RCS targets, these issues become very critical because the total field (measured with the presence of the target) and the incident field (background subtraction) become very similar, and the extraction of the RCS quantity from their subtraction becomes very vulnerable to the random noise. This problem has limited in the past the accurate measurement of low RCS targets, with dimensions smaller than the wavelength and/or with low relative permittivity, that may have RCS values down to −60 dBm2. Since the measurement setup of the CCRM was recently renewed, it became possible with the new apparatuses to apply a “smart” selection of the setup settings to enhance the measurement accuracy over all the bistatic range. In this study our goal is to evaluate the impact of the noise control, which can be obtained through the proposed setting adjustment, on the RCS measurement.