Improving the Bandwidth of a Circular Microstrip Patch Antenna through Shape Modification

Abstract

An antenna is used in a communication system to radiate or receive radio waves. The most desired antenna is one which is small in size, light in weight, cheap and can easily fit to the surface attached. All these features are inherently possessed by microstrip patch antennas. However, no antenna is perfect. Microstrip patch antennas like all other types of antennas do have their associated disadvantages. One of the major disadvantages of this type of antenna is narrow bandwidth. In this study, the narrow bandwidth of a circular microstrip patch antenna was improved through shape modification. The bandwidth of the antenna was optimized by adding some parts to and removing some parts from the initial circular patch. Although the main aim was to improve the bandwidth, it had to be ensured that other important parameters of the antenna such as radiation efficiency, impedance matching and gain are not degraded in the process. Microstrip line feeding technique was utilized in the design. HFSS 13.0 full wave simulator based on Finite Element Method (FEM) was used to simulate the antenna. Simulation results were then presented. Simulation results of return loss showed that the antenna achieved a bandwidth of 13.16% at 1.755 GHz and a very broad bandwidth from 3.315-20 GHz. This is a great improvement when compared with the bandwidth of a conventional microstrip patch antenna of less than 3%. Simulation results of Z11 parameters showed that the antenna achieved satisfactory impedance matching with a 50Ω transmission line at 1.755 GHz, 3.65 GHz, 4.668 GHz and 7.031 GHz and with a 75Ω transmission line at 9.366 GHz, 14.634 GHz, 16.461 GHz, 17.304 GHz and 18.265 GHz. The antenna recorded satisfactory gains and excellent radiation efficiencies in all these frequencies. The antenna can be used for a wide range of applications because of its wider bandwidth.