A Highly Miniaturized Multiband Microstrip Antenna for WiMAX and WLAN Applications

Abstract

This work presents a highly miniaturized multiband microstrip patch antenna for WiMAX and WLAN applications at 2.4 GHz, 3.6 GHz, 5.25 GHz and 5.725 GHz. The antenna is designed and simulated by using CST Microwave Studio® software. The substrate material is FR-4 with a dielectric constant, εr of 4.3, loss tangent, tan δ of 0.02 and thickness, h of 1.6 mm. Defected ground structure (DGS) is introduced by inserting two pairs of inverted-E shaped slots and a pair inverted-F shaped slots on the ground plane which play a huge role to miniaturize the size of the antenna. In this work, a simple rectangular patch is used as a radiating structure but with multiple slots introduced on it to generate multiband resonant frequencies of operation. Upon optimization, a H-shaped slot, inverted-U shaped slot and a vertical slot have been applied which dictate the production of multiband resonant frequencies for WiMAX and WLAN applications. The combination of slots on the rectangular radiating patch and DGS offers a good performance of the antenna in terms of size reduction, reflection coefficient, bandwidth and gain. The main contribution of this work is a highly miniaturized antenna with 15 × 15 mm2 in total dimension. The simulation results show convincing linear characteristics at WiMAX and WLAN frequency bands. From the results, the reflection coefficient, S11 at 2.4 GHz (WLAN band) is -11.097 dB with a bandwidth of 7.8 MHz, the S11 at 3.6 GHz (WiMAX band) is -23.402 dB with a bandwidth of 64.6 MHz, the S11 at 5.25 GHz (Lower WLAN band) is -16.747 dB with a bandwidth of 567.7 MHz and last but not least, the S11 at 5.725 GHz (Upper WLAN band) is -15.98 dB with a bandwidth of 215.9 MHz. Based on the results, it is safe to conclude that the proposed antenna in this work may be employed for WiMAX and WLAN applications.