Modal analysis of substrate permittivities in microstrip patch antennas

The Theory of Characteristic Modes is proposed as a systematic approach to antenna design to achieve the goal of finding the antenna structure with optimum broadband behavior. This theory provides a physical insight to the radiating nature of microstrip patch antennas and reduces the design optimization time. In this paper, the resonant behavior of different substrate permittivities are analyzed using this theory. The modal analysis concludes that εr = 4.4 substrate is the most resonant dielectric and hence is a good candidate to achieve the highest impedance bandwidth.