Optimized Cavity-Backed Slot Antennas for Phased Arrays

The resonance frequency of a cavity-backed slot antenna and also the Q-factor are highly dependent of the dimensions of the cavity and of the dielectric filling of the cavity. A low Q-factor is desired for wideband frequency performance. Recently, the author published the values of the dimensions of the cavity which gave the lowest Q-factor of a slot antenna at prescribed resonance frequency, slot dimensions, and dielectric constant of the homogeneous cavity filling. However, the optimal cavity dimensions for the slot antenna are too big for using it in a wide scanning square lattice phased array. This paper presents design datas for slot antennas backed by a homogenous filled and optimized cavity where dimension restrictions have been considered. A new design with partially filled cavities will also be presented. Hereby several advantages have been obtained, for example, lower Q-factor, lower weight, better economy, and possibility for a more convenient feeding arrangement.