Author(s)

D. Poljak & C. A. Brebbia

Abstract

This paper deals with a time domain analysis of dielectric coated wire antennas in free space. The formulation is based on the Hallen integral equation for loaded wires having a dielectric coating. The coating has been taken into account by means of an equivalent magnetic coating load term. The numerical solution has been carried out via the time domain variant of Galerkin-Bubnov indirect Boundary Element Method (GB-IBEM). 1 Introduction Dielectric coated antennas are usually used for packaging or for the isolation of wire antennas [1]. Using such antennas the undesirable contact between them and the surrounding medium is avoided and the radiation properties of these antennas can be also modified appreciably [1, 2]. An important application of coated antennas is also the treatment of cancer by heating the malignant tissue. This tissue heating must be localized to maintain the temperature within the tumor tissue up to 43°C, for a given time period, while the neighbouring tissue temperature level must be kept far below 43°C [2]. Dielectric coated wire antennas have been analyzed in the frequency domain in a number of papers, e.g. [2–5]. The approximate formulas for the near field generated by an insulated dipole antenna immersed in a lossy medium have been proposed by King et al. in [3] while a more rigorous Method of Moments (MoM) approach to the near field analysis, based on the solution of the corresponding Pocklington equation by using piecewise sinusoids have been presented in [2].

Keywords