A shallow ridged-cavity crossed-slot antenna for the 240- to 400-MHz frequency range

An experimental study has been made of a shallow ridged-cavity crossed-slot antenna to determine its feasibility for operation in the 240- to 400-MHz band. The various trends are summarized for the VSWR response characteristics as the cavity and slot parameters are varied. The wideband antenna characteristics using a ridged cavity configuration are demonstrated. Based on the limited amount of data obtained from the experimental model, the VSWR is < 2.7:1 from 240 to 270 MHz and < 2.1:1 from 290 to 400 MHz for a cavity with a maximum dimension of 33 by 33 by 4 in. Measured radiation patterns with the cavity mounted on a finite-size fiat ground plane are shown.