Radiating Characteristics of Short-Wave Loop Aerials

An experimental method of measuring current distribution and time-phase relations in short-wave single-turn rectangular loops is described and the results used to classify these antennas in three groups according to the ratio of their perimeter to the wavelength. The space characteristics of these loops are discussed and it is shown that in the first of these groups radiation may be calculated by ordinary loop theory; in the second, radiation may be calculated from information given in this paper; and in the third, radiating characteristics are best obtained by measurement. It is also shown that loops in the third group have unidirectional characteristics which, when accentuated by loading, give the loop some signal gain over other types of antenna of comparable dimensions.