A modified feed U‐slot patch antenna array for airborne very high frequency ice‐penetrating radar

Abstract

This article presents a 3 × 2 element U‐slot patch antenna array with modified feed for airborne very high frequency applications. The antenna array is designed to upgrade the Multichannel Coherent Radar Depth Sounder/Imager on board the National Aeronautics and Space Administration DC‐8 aircraft. The antenna array is placed in an aerodynamic fairing structure designed for airborne operation. The major objective is to design an antenna array with a wider impedance bandwidth compared to the existing array. Impedance bandwidth improvement is achieved in two steps. First step is by increasing the bandwidth of antenna element itself and the second step is by utilizing the mutual coupling between the elements of the array. To avoid the problem associated with a rigid probe feed, a modified flexible feed is designed, which can withstand the atmospheric and aerodynamic forces at high altitudes. A matching network is used at each antenna element in this array to further improve the impedance matching. The final antenna array with fairing structure achieved a fractional bandwidth of the 62.5% at center frequency of 243.75 MHz.