An UWB Antenna with Broad Beamwidth and Dual-circular-polarization Performance

In this paper, a four-fed metallic antenna with two feeding networks, which has switchable dual-circular-polarization performance in an ultra wide frequency band, is presented. The antenna is an improvement of a slot patch antenna, combining broadband feeding structure and metal ground structure for parasitical radiation. The feeding network is composed of two three-ports 180 degrees phase-shifters and a low profile 3dB 90 degrees-hybrid coupler chip. This antenna achieves circular polarization switching by hybridizing two 180 degrees phase-shifters with 90 degrees phase difference between their inputs. The antenna is designed and optimized to cover X band(8-12GHz).