Broadband 60 GHz Antennas Fed by Substrate Integrated Gap Waveguides

The first antenna based on substrate integrated gap waveguide (SIGW) is presented. Using two contacted metal strips to build the required conducting ridge, the SIGW addresses the defects inherent in the printed gap waveguide at millimeter-wave frequencies. Moreover, a bandwidth enhancement method is proposed and demonstrated by tuning the cavity that excites the slot antenna. The achieved bandwidth can be more than 21 GHz centered at 60 GHz (35%). Different tuning configurations are carefully investigated, and a design guideline is provided, in which different substrates for the gap and via layers of the SIGW are considered. Two fabricated antennas using low-cost PCB verify the simulation results and design guidelines. The first one is a single-slot antenna, and the second is a four-slot linear array. The measured S-11, realized gain, and radiation patterns of the fabricated antennas have good agreement with the simulated counterparts.