Simple Techniques to enhance convergence of Integrals used in the Frequency Domain Moment Method for Rectangular Microstrip Antennas

Moment method in the spectral domain (SDA) is very popular for the analysis of microstrip antennas and offers some relative advantages in comparison with the space domain technique. Appropriate basis functions for microstrip antennas can be used to incorporate the qualitative nature of the true current distribution in the patch such as the edge condition. This eliminates the use of a large number of basis functions to accurately represent unknown current distributions. The SDA analysis for rectangular microstrip antennas normally requires a double infinite integration involving a product of two Bessel functions of order zero. This paper presents a new algorithm to directly perform this double infinite integration by using a simple technique to accelerate convergence of the integrand and an mW transformation to extrapolate its convergence. The new approach is found to be very efficient and easy to use, and is suitable to a variety of basis functions including mixed type basis functions sets. Other different structures can also benefit from this technique