S-Band Wide-Beam High-Gain Dual Circular Polarization Array Antenna

This paper presents the design and implementation of a microstrip array antenna operating in the 2.2 GHz to 2.5 GHz frequency range. The array antenna achieves a half-power beamwidth greater than $21^{\circ} \times 60^{\circ}$ while maintaining a gain of over 12 dB across the entire frequency band. Comprising three air microstrip antenna elements, the array utilizes two one-to-three T-junctions to connect three 3dB branch-line couplers, further extending the impedance bandwidth and enabling dual circular polarization for the array antenna.