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A novel broadband circularly polarized square-slot antenna with parasitic elements is presented in this article. The proposed antenna with dimensions of 77.6 × 77.6 × 1.6 mm3 is composed of a L-shaped strip, a pair of rectangular slots, a L-shaped branch, and an inverted L-shaped feeding line. First, a pair of rectangular slots are used to excite an impedance resonance point that appears near 4.8 GHz and improve the axial ratio bandwidth (ARBW). Second, a L-shaped strip etched into the square-slot ground plane is used to enhance the ARBW. Third, a L-shaped branch is inserted into the inverted L-shaped feeding line to improve the impedance matching at high frequencies. At a result, the multiple circularly polarized (CP) resonant points could be excited by using these slot and strips as perturbation elements to alter the surface current distribution of the antenna. To demonstrate the design rationality, a designed antenna model is simulated, manufactured, and measured. The tested results show the proposed antenna has a wider −10-dB impedance bandwidth from 2.6 to 6.6 GHz (86.9%) and a broad 3-dB ARBW from 2.35 to 5.80 GHz (84.7%). In addition, the measured peak gain of the antenna is 4.8 dBi. The presented antenna has a potential application value in C band wireless communication. [ABSTRACT FROM AUTHOR]

In this article, we propose a wide square-slot CPA loaded with a semi ellipse patch. The proposed antenna consists of a sequential rotation feeding structure, a square-slot ground-plane with corner cuts, and an asymmetric U-shaped feeding strip. In contrast to the traditional strips and slots etched into the square-slot ground-plane, semi ellipse patch is first inserted into the ground-plane to increase the antenna bandwidth. In addition, four rectangular slots are used to adjust the impedance matching. The slot CPAA could excite multipole CP resonant modes using these slots and patches, which result in the wideband radiation. The proposed slot CPAA has outstanding characteristics of 85.7% (2.0–5.0 GHz) −10-dB IBW and 68.3% (2.20–4.48 GHz) 3-dB ARBW, which would be a potential candidate in the wideband communication. [ABSTRACT FROM AUTHOR]