Numerical assessment of uniform asymptotic solutions for a class of Sommerfeld integrals for microstrip antenna problems

Uniform asymptotic solution of Sommerfeld integrals for microstrip antenna problems, related to topologies with single- or double-layered dielectrics backed by a perfect electric conductor (PEC), are most suitable for electrically large problems. In this context a numerical comparison of Sommerfeld integrals evaluated by asymptotic and rigorous methods is presented. The focus of this comparison is to assess the numerical accuracy of the asymptotic solution for electrically small lateral separations with applications to mutual coupling between elements in densely packed microstrip antenna arrays. The two methods of evaluation are also distinct because the uniform asymptotic method requires TM0 proper surface wave pole contribution, while the alternate rigorous approach is immune from considering surface wave pole effects. Preliminary results for single-layer geometry,included here, show that the uniform asymptotic solution remains remarkably accurate even for small lateral separations (ρ over λ ≈ 0.3).