The RA957 is a folded monopole antenna enclosed in a robust fibreglass radome supported above an inclined counterpoise consisting of three ¼ wave radial elements. The antenna operates over the frequency range 115-150MHz and can therefore be used at any frequency in the aeronautical VHF band. The horizontal radiation pattern is omni-directional while the vertical pattern is similar to that of a dipole antenna.

Designed for military use it has been fully tested environmentally and can operate over the wide temperature range of –40degrees to +55degrees, in driving rain and snow or when covered in ice. Tests carried out in accordance with the relevant sections of British Defence Standard DEF-STAN 07-55 included solar radiation, high/low temperature, salt water corrosion, dust/sand, driving rain and fungal growth.

Each antenna has a concentric clamp that allows the antenna to be mounted to tubes of between 35 and 60mm diameter. RF connection is made through an N type connector in the base and the overall design incorporates a DC static discharge path to ground.