Dual-Slot Cavity Antenna for mm-Wave Beamforming Array

A cavity-fed, dual-slot element and its 4-element linear array configurations for beam-steering applications at 28 GHz are described. The element cavity is formed from rectangular substrate integrated waveguide (SIW), perturbed at one of its corners to excite dual slots for increasing the impedance bandwidth. With a mobile terminal in mind, we look to both classical array principles and to the available theories for finite arrays with mutual coupling, to help guide the design. The impact of the finite ground-plane required to support the slot elements and array is investigated by simulation, including the impact on the patterns of using a cellphone chassis as a platform. A chassis-born 4-element (8 slots) configuration, suitable for beamforming in 28 GHz 5G networks is demonstrated for both linear polarizations. The simulation results are supported by pattern measurements of prototypes, a challenging task at 28 GHz.