Effects of superstrates on the resonant frequency of rectangular microstrip antennas

Abstract

AbstractThis article presents the extended expression to calculate the environmental effect on resonant frequency of multilayer rectangular microstrip antennas. The expression has been investigated for effective dielectric constant εeff and resonant frequency fr. The effective dielectric constant εeff of Present Method has been compared with full wave numerical technique with and without loading. These are in good agreement within 1% accuracy. It has been observed that % change in fr due to cover and substrate thickness is around 3.2% and 20%, respectively, as their thickness is varying 19 times of its initial value. This variation is drastic for h3/h2 = 0.01. The maximum % variation in fr for one substrate and two superstrate is around 5% as h4 varies from 1 mm to 5 mm. In case of unwanted air (h3), the % variation in fr of present method in comparison to experimental value is less than 1.0% for small air‐gap and 0.4% for large air‐gap for various spaced dielectric (εr4), which reveals that the effect of superstrate in fr is small than substrate above the ground plane. The resonant frequency in suspended substrate microstrip antenna with and without superstrate is 21.8% and 28.15%, respectively, as h1/h2 varies from 0.065 to 1.94. The resonant frequency of all the possible configuration is in good agreement with the experimental results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2946–2950, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22954