Resonance Characteristics of Non-Uniform Width Square Ring Antennas

This paper presents a study of the effects of line width on the resonance frequency and bandwidth of a microstrip square-ring antenna at its primary resonance frequency. Although such ring antennas operating in TM11 mode are smaller than regular patch antennas, they are not explored much as they are considered to have poor bandwidth and efficiency at this mode. We have used a transmission line model to study their input characteristics and found that a non-uniform width ring antenna has significantly better (nearly double) bandwidth and radiation efficiency than a uniform width square ring antenna. Extensive simulations were done and a prototype non-uniform width square ring antenna is fabricated and tested to verify these results.