Design and Implementation of a Directional Antenna for a Traffic Alert and Collision Avoidance System (TCAS)

This paper presents the design and implementation of directional antenna for a Traffic alert and Collision Avoidance avionic System (TCAS ). It is a circular patch antenna implemented on Roger 5880 with ε_r =2.2, height; h= 3.18 mm and loss tangent of 0.0009. It is fed using a coaxial cable of 50 Ω. Slots are cut to include a second resonance. It operates at 1.03 GHz and 1.09 GHz for transmission and reception respectively. The antenna conducts similar parameters comparing to the standard conventional existing TCAS II directional antenna. It satisfies the avionics instruments and federal aviation administration (FAA) standards. It is designed using CST microwave studio tool. The beamwidth of the antenna covers the full surveillance area of the protected aircraft. High directivity of 7 dBi and low side lobe level are achieved. The gain approaches 6.59 dB and 6.36 dB in the transmission and reception respectively which is nearly the double gain values of the standard TCAS II directional antenna and those mentioned in literature which extend the range of the surveillance area covered by the TCAS system. The antenna is measured using vector network analyzer and Satimo star lab.