In this work, modal characteristics have been rigorously studied which germinate an improved, accurate, and efficient computer-aided design (CAD) formulation to estimate the resonant frequency of sectorial circular microstrip antennas printed on anisotropic suspended and composite substrates. The obtained results demonstrated that the resonant frequencies of the sectorial circular microstrip patch on suspended and composite substrates can be adjusted to obtain the maximum operating frequency of the antenna. The computed results show a fairly good agreement with measured results. Such theoretical validation and results may prove to be more useful for design engineers and further investigation.