NEAR FIELDS OF MICROSTRIP ANTENNAS

The paper presents an iterative method for the computation of the near fields of single layer microstrip patch antennas. A judicious combina tion of the advantages of the MPIE (mixed potential integral equation) method, the FFT algorithm and the biconjugate gradient leads to an ef ficient numerical solution. The scheme can deal with patches of arbitr ary shapes and is capable of dealing with a very large number of unkno wns. Near field computation is done in a straightforward manner by com puting the weighted near fields. For illustration, three patches belon ging to the family of generalized annular sector have been chosen. Com puted results of input impedances with a coaxial probe excitation have been compared with measurements. Computed near field amplitudes have also been compared with measured results where possible. Computed far field characteristics have been correlated with the near field informa tion.