Cavity-Backed Patch Antenna with Coaxial Line Band-Pass Filter for Nonlinear Radar Receiver

This paper proposes a cavity-backed patch antenna with a coaxial line band-pass filter for nonlinear radar applications. The proposed antenna operates within the frequency range of 6~6.4 GHz. A seventh-order Chebyshev low-pass filter is incorporated within the coaxial line feed of the cavity-backed patch antenna, and a planar dielectric structure is added in series to achieve a band-pass filter with a suppression of approximately −32 dB in the 3~3.2 GHz range. The measured maximum gain in the operating frequency range and suppression band are 6.03 dBi and −51.81 dBi, respectively. This represents a suppression level of approximately 36.7 dB compared to the unfiltered maximum gain of −13.05 dBi.