A Wideband Resonant Cavity Antenna Utilizing Single Stepped Dielectric Superstrate

A very simple design of a resonant cavity antenna (RCA) with an enhanced gain-bandwidth product (GBP) is proposed. The superstrate is made up of a single stepped dielectric material having uniform permittivity. Thickness of the superstrate is varied, only in two steps, from the center of the superstrate towards its edge. Superstrate is designed in a way that its top remains flat while thickness is varied inside the resonant cavity. This results in a low profile RCA as compared to previously reported RCAs with stepped superstrates. Proposed superstrate is used to increase the gain of a waveguide-fed slot in an RCA configuration. An increase in gain of up to 15.6 dBi with 3-dB gain bandwidth of 48%, ranging from 10 to 16 GHz, is obtained for the designed RCA. The impedance is well matched throughout the operating band. The proposed superstrate is very easy to fabricate and results in a compact RCA with an aperture area of 3.14λ
_ο
²
and an overall height of 0.78λ
_o
where λ
_o
is the wavelength at center frequency of 13 GHz.