Modeling of Vertical Dipole Above Lossy Dielectric Half-Space: Characteristic Mode Theory

TL;DR

This paper extends characteristic mode theory to analyze a vertical dipole above a lossy dielectric half-space, introducing an orthogonal modal formulation that accurately models interactions with lossy ground effects.

Contribution

It proposes a new orthogonal characteristic mode formulation for lossy dielectric half-spaces, improving analysis accuracy over traditional methods.

Findings

Modal results closely match method of moment solutions.

The formulation accurately predicts the influence of lossy ground on dipole modes.

Provides insights into mode interactions near lossy half-spaces.

Abstract

This work introduces a theoretical extension of the characteristic mode formulation for analysing the vertical electric dipole lying above a lossy dielectric half-space. As the conventional characteristic formulation fails to maintain the orthogonality of the characteristic field modes over the infinite sphere, an alternate modal formulation is proposed here to maintain the orthogonality for both the current and field modes. The modal results are found to match closely with its method of moment counterparts. Later, the modes of an isolated dipole with no ground plane have been used to predict the role of the lossy ground plane through a theory of the linear combination of the eigenvectors. The proposed formulations have been studied with different heights from the ground plane and are compared with the direct modal solutions to validate its accuracy. It helps to provide a thorough understanding of how the isolated modes interact among each other to constitute the perturbed modes in the presence of the lossy half-space. It can find application to include the lossy earth effect in the study of the lightning fields and the path loss modelling of the antennas over the lossy ground.