Design of a CPW-fed slot antenna with small size and ultra-broadband circularly polarized radiation

Abstract

In this research, a coplanar waveguide (CPW)-fed slot antenna is proposed with a compact size and an ultra-broadband circularly polarized (CP) radiation. The proposed antenna, just with a small size of 40 mm × 40 mm × 1 mm in overall configuration, achieves an ultra-broad CP bandwidth of 68.1% from 3.05 to 6.2 GHz, suitable for both WiMAX (3.3–3.8 GHz) and WLAN (5.15–5.35 GHz/5.725–5.825 GHz) systems. The presented antenna proposes two linked rectangular slots in the ground to obtain CP radiations. The linked slots can also be considered as a square slot with two perturbations in the corners. The perturbations can split the fundamental resonant mode into two near-degenerate modes, leading to CP waves. The adjacent excited CP modes are merged for ultra-wideband CP radiation. With a symmetric series impedance line connected to CPW feedline, broadband input impedance matching from 2.65 to 6.8 GHz can be obtained. The proposed design has been verified by the simulated and measured results. The future MIMO potential of the proposed CP antenna has also been studied.

Keywords:

• coplanar waveguide (CPW) fed slot antenna
• compact size
• wideband circularly polarized (CP) radiation
• linked rectangular slots
• series impedance line

Acknowledgments

This work is supported by the NSFC under Contract No. 61101066, No. 61072017, Fundamental Research Funds for the Central Universities (JB140232) and Natural Science Basic Research Plan in Shaanxi Province of China (No. 2010JQ8013).