Synthesis Method of Broadband Tapered Strip Antennas on Thin Low-Permittivity Substrates

A broadband tapered strip antenna on a thin low-permittivity substrate is designed by a new synthesis method for the geometry. The antenna is needed for a broadband spectrometer. Therefore, the antenna gain in at least one direction should be frequency independent over a bandwidth of at least 20:1. The influence of the substrate is approximated by a constant phase velocity of the travelling wave along the strips of the antenna. The gain-frequency characteristic is measured with a scaled, resistively loaded model in the range from 1 to 18 GHz. This antenna version has a average gain of about 2 dBi and a gain variation of about +/- 2 dB over bandwidth of at least 10:1.