60 GHz PRGW slot antenna array with small separation and low mutual coupling

A simple and low-cost solution to reduce the coupling between two slot antennas working at 60 GHz is presented. The slot antennas formed in the top plate of printed ridge gap waveguide (PRGW) structure to avoid the losses associated with conventional feeding mechanisms. The coupling reduction of more than 10 dB is achieved by removing a part of the top metallic plate of the PRGW between the two slots. Coupling reduction is achieved while maintaining a small distance of half free-space wavelength between the two slots. Also, the coupling reduction covers nearly all the 12% impedance bandwidth of the slot antennas.