Large Circular Loop Antenna Research Articles

The Exact Analytical Solution for Large Circular Loops Radiating Around a Dielectric Coated Conducting Sphere

In this paper, the electromagnetic field of electrically large circular loop antennas, with different radii and different nonuniform current values, around a dielectric coated conducting sphere is considered. One or more loop antennas are located on the outer surface of a spherical dielectric shell covering a conducting sphere. Eigenfunction series solutions for the field are assumed in two regions. The current distribution on the wire loop, driven by a voltage source, is determined by Fourier series expansion and all necessary harmonics are taken into account. Exact analytical field expressions in closed forms are derived and field patterns are plotted. The antenna model and formulation presented in this paper offer exact analytical solutions to several loop antenna problems.

Fast, Simple and Accurate Computation of the Currents on an Arbitrarily Large Circular Loop Antenna

This paper is presenting a very efficient method for computing the currents on a circular loop antenna with arbitrarily large size. Pocklington's integral equation is formulated for the circular loop geometry, and the method of moments with point matching is applied to cast the equation's discrete counterpart. The basis functions are chosen in such a way that the relevant square matrix is circulant, and therefore amenable to exact eigenvalue analysis. Subsequently, the matrix is diagonalized and inverted analytically, yielding simple, analytical expressions for the weights of the basis functions, and hence the current and the input admittance of the antenna. The algorithm utilizes mainly elementary mathematical functions, as opposed to already known expressions in the literature, and yields results in the form of a rapidly convergent, single series, applicable to extremely large loops

Efficient algorithm for input susceptance of arbitrarily large circular loop antenna

A very efficient computational technique for the input susceptance of an arbitrarily large circular loop antenna is presented. The Moment Method matrix is analytically inverted, owing to its circulant property. A magnetic frill excitation is utilised to ensure a well-defined finite susceptance. Results are very accurate, although the algorithm is based on elementary mathematical concepts.

Electromagnetic Fields of Two Thin Circular Loop Antennas in a Radially Multilayered Biisotropic Cylinder - Abstract

The technique of dyadic Green's function in terms of the normalized cylindrical vector wave functions is adopted for investigating the electromagnetic radiation characteristics of two thin circular loop antennas in a radially multilayered biisotropic cylinder in this study, and the radiated fields in both near and far field zones are derived and expressed as a superposition of the right- and left-handed circularly polarized waves. Numerical results are presented to demonstrate the constitutive and geometrical parameter effects of a three-layer biisotropic cylindrical shell on the radiation patterns and polarized characteristics of the radiated fields for electrically large circular loop antennas excited by uniform currents.

Method-of-moments analysis of electrically large circular-loop antennas: Nonuniform currents

A method-of-moments analysis is carried out so as to obtain, in closed form, the nonuniform current distributions, and their resulted radiation patterns in both near and far zones, of circular loop antennas with electrically larger circumferences. An oblique incident field in its general form is considered in the formulation of the nonuniform current distributions. In Galerkin's method-of-moments analysis, the Fourier cosine series is considered as the full-domain basis-function series. As a result, the current distributions along the circular loops are expressed analytically in terms of the azimuth angle for various diameters of large loops. Finally, the radiated electromagnetic (EM) fields and their power pattern in both near and far zones are determined by applying the dyadic Green's function (DGF) in spherical co-ordinates and plotted using a commercial software package, respectively.

Impedance of a large circular loop antenna in a magnetoplasma

The input impedance of a large circular loop antenna with arbitrary orientation in a cold magnetoplasma is calculated by using a transmission line theory. New impedance resonances for antennas of finite size in a magnetoplasma in the frequency region below and near the electron cyclotron frequency are indicated theoretically. The resonance peak of the impedance at the lower hybrid resonance frequency is also predicted to exist for arbitrarily oriented antennas of finite size. The experiments on the impedance of a large circular loop antenna are carried out for the cases of normal and parallel orientation of the magnetic field with respect to the plane of the loop immersed in a radio frequency-generated laboratory plasma. The newly predicted impedance resonances for the antenna of finite size are observed. It is also shown that the measured impedances agree fairly well with the calculated ones.

Far field of large circular loop antennas: Theoretical and experimental results

Far field patterns of large circular loop antennas of circumferences up to two and one-half wavelengths were calculated using Storer's theory for the current distribution on the antenna. To verify the theory, radiation pattern measurements were made at 3 GHz; the experimental results are in good qualitative agreement with theory.