Theory and Applications of Infinitesimal Dipole Models for Computational Electromagnetics

Abstract

The recently introduced quantum particle swarm optimization (QPSO) algorithm is employed to find infinitesimal dipole models (IDM) for antennas with known near-fields (measured or computed). The IDM can predict accurately both the near-fields and the far-fields of the antenna. A theory is developed to explain the mechanism behind the IDM using the multipole expansion method. The IDM obtained from single frequency solutions is extrapolated over a frequency range around the design frequency. The method is demonstrated by analyzing conductingand dielectric-type antennas. A calibration procedure is proposed to systematically implement infinitesimal dipoles within existing method of moment (MoM) codes. The interaction of the IDM with passive and active objects is studied through several examples. The IDM proved to predict the interaction efficiently. A closed-form expression for the mutual admittance between similar or dissimilar antennas, with arbitrary orientations and/or locations, is derived using the reaction theorem.Index Terms-Infinitesimal dipole model, multipole expansion, mutual coupling.

Focusing Properties of Ultra Wideband Transient Arrays

“…This is because the IDM is used to obtain the normalized spatial distribution of the near field, but not the real values that depend on the excitation amplitude of the antenna. The real field values due to the excitation of V 0 can be achieved by multiplying all the dipole moments with a factor of V 0 P a /P d [39].…”

“…The idea was formulated in [35][36][37][38] to find sets of infinitesimal dipoles by using a genetic algorithm. Later, the concept was extended by applying quantum particle swarm optimization to the problem, and a method of predicting the mutual coupling between antenna elements was proposed [39]. In [40,41] IDMs for dielectric resonators in multi-layer structures is obtained by using the particle swarm optimization method.…”

A new method for the design of slot antenna arrays: Theory and experiment

“…Once the slot has been replaced by a magnetic current, the current itself can be discretized by replacing it by an array of magnetic infinitesimal dipole (MIDs). The infinitesimal dipole model method has been used successfully in many applications, ranging from mutual coupling and antenna modeling [8] to near-field focusing [9] and MIMO antenna design [10]. In the present paper we propose applying the method to develop a slot array design method.…”

Application of Invasive Weed Optimization in designing aperiodic antenna arrays using dipole models

“…A simple closed form expression presented in [22] is used to calculate the mutual admittance between two elements replaced by IDMs. The self admittance of any antenna, y 11 , can also be computed using the reaction theorem [27].…”