L Band Array Antenna for Combined Interrogator Transponder (CIT) suitable for airborne applications

In this paper, the design and development of L band array antenna for Combined Interrogator Transponder (CIT) is presented. In order to achieve the functionality for Combined Interrogator Transponder (CIT), a 2x2 array antenna is used which provides required sum and azimuth & elevation difference radiation patterns (ΔAZ, ΔEL). A special printed dipole based antenna element is used. A 2:1 impedance bandwidth of 8% is achieved for the array antenna to cover the 1030±12 MHz transmit and 1090±12 MHz receive band. The gain of antenna is 12.5 dB and null depth better than -30dB in the E and H planes. Fabricated antenna is validated through bench level and near field measurements.