A discussion on electrically small antennas loaded with high permittivity and permeability materials

Abstract

Electrically small antennas have remained a significant topic of interest for a number of applications, particularly low frequency systems and wireless networks requiring small devices. As is well-known, there are a number of techniques whereby an electrically small antenna can be efficiently matched to a 50Ω system impedance. Ultimately, the primary design challenge is achieving as wide an efficient operating bandwidth as possible, within the constraints of manufacturing tolerance issues and de-tuning effects resulting from the surrounding operating environment. One common size reduction technique is the utilization of dielectric materials to capacitively load the antenna structure. In this paper, which is intended to be mostly a tutorial discussion, we focus on loss and bandwidth issues associated with material loading an antenna using high permittivity and/or high permeability materials. We particularly focus on how these materials impact overall efficiency and discuss the relationship between conductor and material losses within an impedance matched electrically small antenna.