Alternating-phase fed single-layer slotted waveguide arrays with chokes dispensing with narrow wall contacts

Demand for high-gain and mass-producible planar antennas is rapidly increasing. In the alternating-phase fed array, the radiating waveguides are excited in amplitude but 180-degree out-of-phase between adjacent waveguides by a series of T-junctions. High-gain and high-efficiency slot design has succeeded in obtaining 35.5 dBi gain with 67% efficiency in a 25 GHz antenna. This paper proposes an alternating-phase fed array with a choke surrounding the periphery. The choke can prevent leakage between the slot plate and the feed structure. It dispenses with any tight contacts between them. This structure is very suitable for mass-production. The choke in straight waveguides is discussed and transmission loss is measured. Then, an application to the alternating-phase array of the choke is demonstrated