An experimental investigation of cavity-mounted helical antennas

This paper presents the results of an experimental investigation which led to the development of cavity-mounted helical antennas for airborne applications. The effects on patterns and impedance of various antenna parameters, such as number of turns, cavity size and shape, helix pitch, angle, and conductor size, were investigated. Methods of feeding the helix which produce an input impedance near 50 ohms, without external compensation, throughout the axial mode frequency range are discussed. Some of the types of cavity-mounted helices developed and typical performance data are described.