A Single-Layer Dual-Band Shorted-Patch Antenna with Same Circularly Polarization Based on Multi-Resonant Modes

A shorted-patch antenna (SPA) towards dual-band and circularly-polarization (CP) is proposed. Initially, several modes are selected to require the orthogonal electric-field components for CP generation. Next, the short pins are inserted below the rectangular patch to turn up TM
0,1/2
mode closely to TM
1,1/2
mode. Besides, a narrow rectangular slot is properly etched on the top-layer of the SPA to move down TM3,3/2 mode in proximity to TM
0,3/2
mode. In addition, an annular slot is properly etched around the feeding port for good impedance matching. Finally, the results illustrate that its effective bandwidth
$(\vert S_{11}\vert <-10\text{dB}$
and
$\text{AR} < 3 \text{dB}$
) is held around 1.19% (2.684-2.716 GHz) in low frequency band and 1.05% (5.683-5.743 GHz) in high frequency band. Additionally, the proposed SPA achieves CP radiation performances in dual bands, while keeping low-profile, single feeding and single-element properties.