Design of a miniaturized ultra-wideband compound spiral antenna

This paper presents an ultra-wideband compound spiral antenna fed by a wideband balun. The antenna is studied as an isolated element and as a part of a spiral-based ground-penetrating radar (GPR) detection system. The geometry of this antenna combine equiangular spiral and Archimedean spiral smoothly. The outer of spiral line is made a complex deformation. Moreover, an especial reflection cavity is used to achieve a good directionality. The final antenna has a size of φ 60mm × 60mm, which is only 10.9% than the conventional planar spiral antenna. Result shows the antenna achieved a good performance of VSWR, axial ratio and gain from 1GHz~18.5GHz, which meets the needs of the UWB GPR detection system.