Analysis of Ultra-Wideband Double-Ridge Open-Ended Waveguide Antennas for Millimeter-Wave Communications

A comprehensive study is performed to evaluate the performance of ultra-wideband double-ridge open-ended waveguide antennas (OEWAs) at millimeter-wave (mm-wave) regime. Specifically, two double-ridge OEWAs with 15–40-GHz and 40– 110-GHz bandwidths are designed and fabricated. Each antenna demonstrates |S
11
|<–10 dB and stable and symmetric radiation patterns across 15–40 GHz and 40–110 GHz with aperture sizes of 9.47×5.79 mm
²
and 3.78×2.27 mm
²
, respectively. To evaluate the performance of the proposed double-ridge OEWAs for ultra-wideband millimeter-wave communications, time and frequency domain performance metrics such as fidelity factor and group delay are investigated for face-to-face and side-by-side orientations. Results indicate that the proposed antennas feature fidelity factors more than 86.33% and a linear variation of transmission coefficients phases with group delay variations less than 0.25 ns.