Slotted ridged waveguide array designed with a reflection cancelling technique for multibeam applications in V-band

An array of slotted hollow ridged waveguides is proposed here as radiating part of a Butler matrix. The array is designed by using the “reflection cancelling technique” thanks to an original cell composed by a radiating slot and a reactive notch in the ridge of the waveguide. Reflection from the notch and the radiating slot cancel out, thus allowing travelling wave mode and broadband operation. The array has a cosecant beam pattern in the elevation plan for uniform illumination in fixed wireless access (FWA) systems in the 60-GHz band. The proposed antenna concept is combined to a dual layer Butler matrix realized with diffusion bonding technique at 61.5 GHz. The numerical results are validated experimentally.