BANDWIDTH ENHANCEMENT OF PIFA ANTENNAS FOR WIRELESS APPLICATIONS BY GROUND PLANE OPTIMIZATION

Abstract

Planar Inverted-F Antennas (PIFAs) are widely used in wireless applications because of their simple design, low profile, light weight, low cost, relatively low specific absorption rate (SAR), and good performance. However, they suffer from narrow bandwidth, which affects their performance in modern wireless applications. This research focuses on enhancing the bandwidth performance of PIFA antennas through ground plane optimization. The objective of the optimization was to maximize the bandwidth (S11 ≤ -6 dB) at 900 MHz, by modifying the geometry and dimensions of the ground plane. A basic PIFA antenna with dimensions of 100 mm x 40 mm x 1.6 mm was designed and simulated on an FR4 substrate (relative permittivity (εr) of 4.4 and loss tangent of 0.02) at 900 MHz, using High-Frequency Structure Simulator (HFSS) software. Then, as a bandwidth enhancement technique, slots were introduced on the ground plane. Initially, a single slot was created, and the position of the slot and its dimensions were optimized using parametric optimization. It was observed that the slot’s position significantly affected the performance of bandwidth, with the highest bandwidth improvement achieved when a 30 mm x 5 mm horizontal slot was placed under the radiating patch. The bandwidth (S11 ≤ -6 dB) increased to 23.3% with a single slot, compared to 17.7% without any slot. Subsequently, a second slot with the same dimensions as the first was introduced, and its position was optimized through parametric optimization. The bandwidth was further improved up to 24.4% after inserting the second slot. The results confirm that ground plane optimization techniques, such as inserting slots, enhance the bandwidth of PIFAs.