A compact flush-mounting antenna with direction finding and steerable cardioid pattern capability

A flush-mounting antenna is described which could be used, in lieu of present antennas, to provide direction finding and steerable directional pattern capability in airborne beacon transponder systems. The antenna is comparable in size to the existing, omni-directional antennas presently used for air-traffic control and military identification, friend or foe (IFF) functions. The design and performance of an experimental model of the antenna are discussed.