On the Optimum Substrate Selection in a Wideband Microstrip Patch Antenna Design

This paper provides a general guideline to reduce surface wave (SW) excitations in a microstrip patch antenna, while maintaining wide impedance bandwidth and a stable gain performance. The design approach involves efficient selection of substrate parameters, viz. $h\sqrt {{\varepsilon _r}} /\lambda $, such that only a lower magnitude of the dominant TM 0 mode is excited, while restricting the excitation of all higher order SW modes. Results from the proposed design approach show that very wide antenna bandwidth, reduced E-plane coupling and stable boresight gain can be obtained.