In this report, radiation of sources inside layered media backed by a perfect electric conductor were studied. This problem has practical applications to antennas embedded inside composite material media for many applications. The traditional real-axis integration method was employed with a new formulation for calculating the Sommerfeld integral tail. This new method contains effects of the intrinsic wavenumber of the layer and hence appears physically more suitable for understanding effects of the various layers when the observation point moves in a vertical direction from one layer to the other. In addition, a new algorithm was developed to calculate the proper surface wave poles for electrically thick substrates. The discontinuities in the integrand of the Sommerfeld integral were eliminated upon subtraction of the residues at these poles, and subsequent numerical integration posed no difficulties. Additionally, the problem of stratified media was studied via the phase-integral method. It has been shown that the phase-integral method, with its attendant asymptotic expansions, has the potential for providing much improved solutions to the Green's functions for continuously stratified media by including effects across the Stokes lines.
The NECBSC high-frequency code solver is an efficient computational tool for solving electrically large problems. The features of the UTD-based algorithm in this solver is gainfully utilized to calculate the embedded element pattern of a 5 × 5 cylindrical dipole element array located before a PEC circular cylinder of electrical radius ka = 96.5. The central element of the dipole array, which is kept at 0.257λ off the curved surface of the cylinder, is excited with other dipoles terminated in a matched load of 50Ω. Since NECBSC formally does not calculate the array mutual coupling, this is included by calculating the induced currents on the elements derived from a full-wave integral equation based solver, FEKO. Comparison against the available experimental data shows remarkably good agreement between NECBSC, FEKO in the lit regions. The FEKO and NECBSC yield different results in the deep shadow regions dominated by creeping waves, indicating the necessity of further investigations.
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