the help of these roof-top functions and the use of the asymptotic
form of Green's function, a convergence problem that occurred in
[2], where piecewise sinusoids were used as basis functions, can be
resolved. It is also noted that the selection of the expansion current
modes on the microstrip antenna and the division intervals where the
subsectional roof-top basis functions are defined are different from
those used in [2]. These differences will be discussed subsequently.
Two experiments are performed to verify our theory. In both cases,
comparisons between computed and measured reflection coefficients
and input impedances show that our theory is indeed very accurate.