Development of Cavity Backed U-Shaped Cross Dipole Antenna with Reconfigurable Characteristics

The need for directional antennas possessing high gain, wideband and circular polarization characteristics for different wireless applications has increased considerably. In this research paper, a slotted coaxial line fed cavity backed U-shaped cross dipole antenna is developed to achieve wide bandwidth and reconfigurable circular polarization. The cross dipole consists of two orthogonal U-shaped dipoles. These dipoles are mounted on the outer conductor of the coaxial line. The feeding and tuning screws are used for impedance matching and increasing impedance bandwidth. A novel technique is developed to generate reconfigurable circular polarization using cross dipole configuration. The sub-reflector is supported by the feed line, thus requiring no extra support. The antenna is developed on elliptical ground plane with dielectric rim making fabrication of antenna easy. It is demonstrated that antenna achieves voltage standing wave ratio (VSWR) bandwidth of 32.14% for 2:1 VSWR, axial ratio of 0.2 dB with axial ratio (≤ 3dB) bandwidth of 2.14% and a gain of more than12 dBic. The experimental results for the designed antenna structure are in close agreement with computer simulations. Index Term-U-shaped dipole, Wideband antenna, Circularly