A Wideband Open-Slot Antenna With Dual-Band Circular Polarization

A wideband microstrip-fed open-slot antenna with dual-band circular polarization (CP) has been presented. A bent feeding structure and three slots, including a T-shaped and two inverted-L topologies etched in the ground plane, are designed to excite two orthogonal vectors with equal amplitude and 90 phase difference (PD) for a radiating right-hand circularly polarized (RHCP) wave at 1.57 GHz and left-hand circularly polarized (LHCP) wave at 2.33 GHz. The two bands are the operated bandwidth of the global positioning system (GPS) and satellite digital audio radio (SDAR) service system. To improve the impedance bandwidth at the low-frequency band, a parasitic rectangular patch is added on the top plane of the substrate. Several resonances are merged, and thus, a wide impedance bandwidth is obtained. The measured impedance bandwidth of a reflection coefficient <; -10 dB ranges from 1.45 to 3.93 GHz, and thus covers most of the commercial wireless communication systems, such as GPS, DCS, PCS, IMT-2000, WLAN, LTE, and WiMAX. The axial-ratio bandwidths are 65 MHz at the lower band (1.57 GHz) and 107 MHz at the upper band (2.33 GHz).