Some HP system design considerations for aircraft

The author discusses the fundamental limitations of electrically small radiators and their significance to electrically small antennas. Some of the parameters are derived. Systems incorporating electrically small radiators are constrained by fundamental limitations to be either inefficient or narrowband. These conditions are apparent in the case of aircraft HF (2-30 MHz) antenna systems, particularly for small aircraft at the low end of the band. The author discusses the HF antenna problems for aircraft, in particular the need to distinguish between the airframe and the antenna. The types of antenna used, loops and notches, are discussed. Examples of measurements for a BAC 1-11 airliner and a helicopter are given.