Resistance-Loaded Ultra-Wideband Dual-Polarized Quad-Ridged Flare Horn Probe Antenna

A resistance-loaded ultra-wideband dual-polarized Quad-ridged flare horn (QRFH) probe antenna applied to near-field measurement is proposed in this paper to realize miniaturization and further make the phase center more stable. By loading resistors, low frequency signals that cannot be radiated at the end of the ridge are absorbed by resistors, which expands the low frequency bandwidth. As a result, while the overall size of the antenna is only
$\mathbf{41}\mathbf{mm}^{\ast}\mathbf{40}\mathbf{mm}^{\ast}\mathbf{40}\mathbf{mm}$
, the antenna can still work in the frequency band of 2GHz-18GHz. The simulated results show that in 2GHz-18GHz the voltage standing-wave ratio (VSWR) of two ports is less than 3 and the isolation between two ports is greater than 34.9dB. More importantly, the fluctuation of phase center is within 9.6mm, which is significant for near-field measurement.