Numerical solution of radiation from single and multiple arbitrary apertures backed by a cavity

The equivalence principle and the generalized network formulation are used to model the tangential electric field of multiple apertures backed by a rectangular cavity, in terms of equivalent magnetic currents. The result is an integral equation for the unknown aperture current. This integral equation is reduced to a matrix equation using the method of moments. To formulate the problem the equivalence principle is used to separate the original problem into the regions on each side of the aperture. Application of the boundary conditions (the continuity of the tangential electric and magnetic fields) results in an integral equation. This operator can be solved numerically by the method of moments, to determine the equivalent magnetic current. The developed matrices are dependent only on the characteristic of each region and are independent of the other region. The only coupling is through the aperture, whose characteristics can be expressed by aperture admittance matrices, one for each region. The admittance of the aperture is thus the sum of two independent aperture admittance matrices of cavity and free-space regions. Once the equivalent magnetic current is computed, one can determine other parameters.<>