Metal Horns as Directive Receivers of Ultra-Short Waves

The following paper describes some experiments made to determine the directive properties of metal pipes and horns when used as receivers of electromagnetic waves. The experiments were of two kinds. One consisted of measurements of received power, with and without the horn in place, and the other of the determination of the directional patterns of the horns in two perpendicular planes. The results indicate that electromagnetic horns of this kind provide a simple and convenient way of obtaining effective power ratios of a hundred or more (20 decibels). The effects of varying the several horn parameters are investigated. It is shown that there is an optimum angle of flare. The possibility of forming arrays of pipes or horns is mentioned.