Microstrip to Ridge Gap Waveguide Transition for 28 GHz Steerable Slot Array Antennas

In this paper three types of contactless vertical transitions from microstrip to double ridge waveguide are presented. The designs are compact in size and robust, with improved isolation by employing a pin structure, making them ideal for 5G mmWave phased arrays. All transitions cover the 26.5 – 29.5 GHz band, their dimensions are less than half a wavelength in pitch and have insertion losses less than 0.6 dB. The three designs apply different matching strategies and offer a trade-off between bandwidth and PCB areas. Finally, the behavior within an array configuration is analyzed.