Calculation of radiation characteristics of cavity‐backed aperture antennas using a combined finite element method, method of moments, and geometrical theory of diffraction technique

Abstract

Radiation pattern prediction analysis of elliptically polarized cavity‐backed aperture antennas in a finite ground plane is carried out using a combination of the finite element method (FEM), method of moments (MoM), and geometrical theory of diffraction (GTD). The magnetic current on the cavity‐backed aperture in an infinite ground plane is calculated using the combined FEM‐MoM analysis. GTD is used to calculate the diffracted fields due to both soft and hard polarizations at the edges of the finite ground plane. The slope of the incident magnetic field at the diffraction points is derived and analytical expressions are presented. Numerical results for the radiation patterns of a cavity‐backed coaxial cavity and also a cavity‐backed circular spiral microstrip patch antenna excited by a coaxial probe in a finite rectangular ground plane are computed and compared with measured results.

Radiation From Cavity-Backed Fractal Aperture Antennas

“…The surface integral over the input surface at the bottom of cavity is computed by expanding the electric field as the sum of incident and reflected fields. The procedure is same as that described in [11]. The combination of these three integrals can be expressed is matrix form as A(k)e(k) = b(k) (5) where b(k) is the excitation vector, e(k) denotes the coefficient vector and A(k) is a partly sparse and partly dense matrix which is a combination of three matrices and may be written as…”

“…Once the matrix equation 5is solved for the unknown coefficients, the field over the aperture surface can be calculated. The input reflection coefficient at the incident plane (z 1 = 0) is then given by [11]…”

Radiation characteristics of cavity backed aperture antennas in finite ground plane using the hybrid FEM/MoM technique and geometrical theory of diffraction

“…For a detailed derivation of equation (6), the reader is referred to [10]. Using equations (3), (4), and (6), equation (2) may be written as…”