Rectangular Ring Antenna Excited by Circular Disc Monopole for WiMAX System

Abstract

This research presents a rectangular ring antenna excited by a circular disc monopole (CDM) mounted in front of a square reflector. The proposed antenna is designed to cover a frequency range of 2.300–5.825 GHz and thereby is suitable for WiMAX applications. Multiple parametric studies were carried out using the CST Microwave Studio simulation program. A prototype antenna was fabricated and experimented. The measurements were taken and compared with the simulation results, which indicates good agreement between both results. The prototype antenna produces an impedance bandwidth (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mo stretchy="false">|</mml:mo><mml:msub><mml:mrow><mml:mi>S</mml:mi></mml:mrow><mml:mrow><mml:mn>11</mml:mn></mml:mrow></mml:msub><mml:mo stretchy="false">|</mml:mo></mml:math>&lt; −10 dB) that covers the WiMAX frequency range and a constant unidirectional radiation pattern (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi mathvariant="normal">θ</mml:mi><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>°</mml:mo></mml:mrow></mml:msup></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi mathvariant="normal">∅</mml:mi><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mn>90</mml:mn></mml:mrow><mml:mrow><mml:mo>°</mml:mo></mml:mrow></mml:msup></mml:math>). The minimum and maximum gains are 3.7 and 8.7 dBi, respectively. The proposed antenna is of compact size and has good unidirectional radiation performance. Thus, it is very suitable for a multitude of WiMAX applications.