HF 125 W half-loop antennas in ALE and ECCM for land mobile, navy and helicopter use

This paper describes a small sized mobile HF half-loop antenna and its integrated agile coupler designed to work with a 125 W transceiver in automatic link establishment (ALE) and/or frequency hopping (FH). This equipment is a 50 Ω antenna which comprises a digital tuning circuit for fast switching in transmission-reception (traffic mode), and an active wide-band circuit for continuous reception (scanning mode). The half-loop concept can apply to small vehicles, shelters, ships, helicopters and airplanes, and can be extended to base stations and large ships with a full loop configuration using the same tuning circuits.