The Folded Fan as a Broad-Band Antenna

High-frequency model studies are reported which promise an antenna which operates over a 4-to-1 frequency range with a maximum power loss, due to mismatch, of 18.5 per cent. In the projected naval application, this loss is not unusual with currently used antenna systems. The antenna consists of an ordinary fan-type antenna folded back to ground, that is, electrically connected at the top to an identical fan grounded at its base. A means is described for matching the antenna to 52-ohm transmission line, although the folded structures center at about 160 ohms. The model described in detail is not necessarily of absolutely optimum proportions. The maximum variation with azimuth of the radiation intensity of the antenna is less than 10 db. In the vertical plane, the antenna illuminates the horizon adequately, wasting no appreciable portion of the energy on the zenith.