Dual-Band Circularly Polarized Shared-Aperture Antenna With Simplified Feeding Configuration Based on Phase Difference Compensation Technique for Smartphone Applications

This paper presents a simplified dual-band circularly polarized (CP) antenna for smartphones, operating at 1.575 GHz and 3.8 GHz. Firstly, two folded dipoles are introduced and integrated into the upper and right bezels of the handset, achieving dual-band resonant performance. Secondly, lumped-element loading technique, e.g., series capacitors and inductors loading is proposed to adjust the 1st and 3rd order mode resonances to the desired frequencies. Thirdly, only one power divider as well as phase shifter is introduced as sequentially rotated feeding (SRF) configuration, achieving CP performance at 1.575 GHz. Fourthly, phase difference compensation technique (PDCT) is applied to adjust the phase difference at 3.8 GHz without destroying the CP performance at 1.575 GHz. Finally, dual-band CP performance can be obtained due to the proposed PDCT. A prototype was fabricated and tested, indicating gratifying dual-band CP performance of −6 dB impedance bandwidth of 115 MHz, 3-dB AR bandwidth of 450 MHz at 1.575 GHz, and impedance bandwidth of 300 MHz, 3-dB AR bandwidth of 160 MHz at 3.8 GHz. The proposed antenna features a simple structure for integration into handset, offering a novel approach for achieving dual-band CP performance.