Investigation of electrically small VHF and HF cavity-type antennas

The paper describes some ways of designing electrically small antennas over the VHF and HF bands that allow the obtaining of some control over their imput impedance, overall diameter and bandwidth. It is shown that at higher frequencies ferrite coated monopoles with useful characteristics can be designed, dependent on the availability and processing of suitable material, but at lower frequencies the attendant weight, bulk and cost is a disadvantage. However, the resonant cavity action taking place can be simulated with counter and double wound wire configurations which are likely to be useful at low frequencies, where low cost is important. Finally, it is shown that the higher input impedance of both ferrite and wire antennas relieves the associated loss in matching units.