This paper reports the design and performance of a compact planar arrangement of concentric rings designed with defected ground plane. The radiating circular patch and ground plane of antenna are modified in several steps to achieve a broadband circularly polarized antenna. In each stage of modification, antenna is simulated by applying CST Microwave Studio simulator, and finally, a prototype is developed and tested in free space. The developed prototype efficiently operates at frequencies 2.34 GHz and 4.41 GHz, and provides an overall impedance bandwidth close to 2.31 GHz or 67.45% with respect to central frequency 3.425 GHz. This antenna provides nearly flat gain in the desired frequency band with maximum measured gain close to 2.94 dBi at frequency 3.02 GHz. It also provides circularly polarized radiations in the frequency bands extended from 2.67 to 3.05 GHz and 3.44 to 3.57 GHz. The co-polar and cross-polar radiation patterns of the antenna in azimuth and elevation planes are obtained at frequencies 2.316 GHz and 4.41 GHz. The proposed antenna can be used for mobile and lower bands of Wi-Max and UWB communication systems.
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