Summary: A slotted waveguide planar array using a single-layer feed circuit is applied to high frequency and high gain use. The remarkable efficiency of 75.6% is realized for the gain of 35.9 dBi in 22 GHz band and 64% is realized for 35.1 dBi in 60 GHz band. Each antenna consists of only two components; a slotted plate and a groove base plate, and are highly mass produceable.