Ultra Low Profile Wideband Antenna with Ferrite Loading

As is well known, traditional HF/VUF/UHF antennas are often protruding and have large size blades, which are greater than 1 meter tall. Such obtrusive antennas are undesirable for modern aircraft. Therefore, there is a strong need for low profile antennas that can still operate efficiently at HF/VUF/UHF bands. This paper presents ultra low profile wideband antenna operating from 30MHz to 400MHz. The aperture diameter and height are 24” and 2”, respectively, which are λ/16 and λ/200 in electrical size at 30MHz. Without question, such an extremely small height presents us with wide significant design challenges particularly, as the antenna must deliver V.P. radiation along the horizon as depicted in Fig. 1. The main goal of this design is to have −15dB realized gain along horizon at the lowest frequency, which is close to the theoretical limit [1], and a nominal gain of 0dB at higher frequencies (see Fig. 2). A key aspect of our design is the use of ferrite loading. It is shown that strategically placed ferrite loading increases realized gain up to the theoretical limit.