High Isolation and Band Enhanced Radio Altimeter Antenna for Avionics Applications

Concept of ringed stacked patch antenna with low side lobe level and enhanced bandwidth is introduced for radio altimeter avionics applications. One dimensional electromagnetic band gap is designed using metallic vias with circular rings along the radiating patches on multilayered substrate for providing high isolation in H-plane and reducing lateral surface currents. A stacked patch antenna configuration is used for enhancing the bandwidth of the antenna. Simulation and analysis are performed for the optimization of the frequency response and sidelobe levels of the proposed antenna. Gain of more than 12 dB with sidelobe levels less than −42 dB were measured for a fabricated prototype. Signal to interference ratio of 85 dB is achieved between two adjacent antennas, which is 5dB better than commercial antennas due to increased gain and reduced sidelobe levels. The antenna is designed for enhanced frequency bandwidth from 4.06 GHz to 4.53 GHz. Computed drag coefficient of the antenna mounted on the fuselage of Cessna 210 aircraft show that the drag is essentially negligible.