SOME INVESTIGATIONS ON MICROSTRIP PATCH ANTENNAS

Abstract

In this work, the Green's function is derived for a covered microstrip patch antenna. The derivation is based on the solution of the wave equation in different regions when subjected to boundary conditions at various interfaces. The derived Green's function is fairly general in that a number of practical cases such as icsing of the patch, an air gap between the cover and the patch and the patch with no cover can be studied. Based on the derived Green's function, . computer programs have been written to evaluate the Green's function in the Fourier and space domain. Numerical results have been presen-ted for the convergence of the Green's function to that for a patch with infinite dielectric on the either side. The vali-dity of the derived Green's function has been established by comparing the results with those available in literature. Space domain Green's function is numerically evaluated for different 'integration limits of p and the program validity has been established by obtaining the Green's function at points whore boundary..condi.tions for..the electric field are known. Experiments have been carried out on microstrip patch antennas with a coaxial feed and iris —coupled waveguide . feed to find its properties, such as, the impedence behaviour, radiation pattern etc. The antenna performance with the wave—guide feed is studied more carefully because very little experimental results are available for this type of feed.