Designing an electrically small ferrite-loaded loop antenna for Optimum Performance

The design of small ferrite-loaded loop antennas is complicated by the number of parameters involved - frequency, size, shape, core material, and number of turns - as well as by the geometry. Even though ferrite-loaded loops have long been known to have certain advantages over air-core loops of similar size, their use has been limited to low-frequency reception where approximate design concepts have been found to be more or less adequate. More recently, it has been shown that quasistatic field theory (QS) may be used to analyze small spheroidal loops yielding electrical properties in closed form. Optimum design, however, has been an elusive concept. The purpose of this paper is to present QS results for the hollow-core ferrite-loaded loop antenna and, by comparing with solid-core results, to show that hollow cores give the maximum bandwidth and efficiency for a given volume of ferrite.