Compact Crossed-Dipole Antennas Loaded With Near-Field Resonant Parasitic Elements

Two compact planar crossed-dipole antennas loaded with near-field resonant parasitic (NFRP) elements are reported. The NFRP and crossed-dipole elements are designed for the desired circularly polarized (CP) radiation. By placing the NFRP element over the driven element at angles of 0° and 45°, respectively, dual-band and broadband CP antennas are realized. All radiating elements of antennas are 35 mm × 35 mm × 0.508 mm (0.187 λ0× 0.187λ0× 0.0027λ0at 1.6 GHz) in size. The dual-band CP antenna has a measured |S11|11| <; -10-dB bandwidth of 218 MHz (1.491-1.709 GHz) and a 3-dB AR bandwidth of 145 MHz (1.490-1.635 GHz). These compact antennas yield bidirectional electromagnetic fields with high radiation efficiency across their operational bandwidths.