The Single Ridge Waveguide Cavity Backed Slot Antenna

A highly compact cavity backed slot antenna is described. The antenna consists of a transverse slot in the flat broadwall of a deep single ridge waveguide cavity. Without dielectric loading radiation occurs when the slot length is approximately 0,3λ compared to 0,5λ or greater for conventional cavity backed slots. By placing standard dielectric substrate in the ridge waveguide gap the radiation frequency can be significantly further reduced. For example with fibreglass printed circuit board substrate (ε
_r
≃ 4,8) radiation takes place with the slot length approximately λ/6. The antenna occupies a rectangular volume of merely λ/5 × λ/6 × λ/12.