Substrate Effects on Performance Enhancement in a Gap Coupled E-Shaped Microstrip Antenna with Air gap for S-BandApplications

In this paper, a novel design of the E-shaped gap-couple patch antenna for performance improvement in S-band application is proposed and analyzed. The air gap can be used to improve impedance matching and broaden bandwidth due to the reduced effective permittivity and the field distribution alteration around the radiating structure. In order to investigate the effect of substrate selection, three substrates e.g., RT/Duroid 5880, Rogers RO4003 and FR-4 were examined in the light of bandwidth, gain, radiation efficiency and axial ratio.Additionally, the impact of the dielectric constant and loss tangent of each substrate on current distribution, field confinement, surface-wave excitation and coupling behaviour is also discussed in this work. Simulation results have demonstrated that RT/Duroid 5880 would be the best option as it achieves maximum gain, higher efficiency and wider bandwidth with low permittivity and loss. In comparison FR-4 has higher losses while providing worse performance and Rogers RO4003 is a nicely balanced option in terms of cost versus antenna efficiency. In general, the results indicate that substrates have a great impact on the performance of air-gap-coupled patch antennas and they are useful for guiding preparation of suitable materialsfor S-band applications.