A Novel Frequency Reconfigurable Wideband Circularly Polarized Crossed Dipole Antenna

Abstract

In this letter, a novel dual-cavity-backed frequency reconfigurable wideband circularly polarized (CP) crossed dipole antenna is presented. The proposed antenna consists of two crossed Sierpinski fractal dipoles and four PIN diodes. Dual-cavity structure is used to achieve unidirectional radiation and increase the gain of the antenna. Particularly, the edge of the cavity acts as the second radiator, which can effectively improve the overall CP performance of the antenna. The antenna can operate in three different states by controlling four switching diodes. When the antenna is operating in the first state, the impedance bandwidth and axial-ratio (AR) bandwidth (ARBW) of the antenna are 68.7% (2.12GHz-4.34GHz) and 50.8% (2.37GHz-3.98GHz), respectively. When the antenna is operating in the second state, the impedance bandwidth and ARBW of the antenna are 28.3% (3.4GHz-4.52GHz) and 12% (3.91GHz-4.41GHz), respectively. When the antenna is operating in the third state, the impedance bandwidth and ARBW of the antenna are 9.5% (4.53GHz-4.98GHz) and 5.3% (4.59GHz-4.85GHz), respectively. The maximum gains of the antenna in the three states are 8.61dB, 9.03dB and 7.37dB, respectively.