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 TM0 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.