Design of a UWB unidirectional radiation compound spiral antenna

The design of a modified unidirectional radiation miniaturized compound spiral antenna fed by an exponentially tapered balun is shown in this paper. The compound spiral antenna is designed by combining a typical equiangular spiral antenna with Archimedean spiral line. By taking advantage of a modified reflector to make the antenna into a microstrip form, the structure realizes a typical unidirectional radiation pattern for planar spiral antennas, which naturally increases radiation gain. In the range from 5 to 20 GHz, simulated radiation patterns, axial ratio plots and VSWR plots show good performance. The comparison with the compound spiral antenna and traditional UWB antennas shows the improvement of the axial ratio.