Synthesis method for broad-band tapered wire antennas and its experimental verification

A method for synthesizing the geometry of extremely broadband tapered wire antennas used as part of a broadband spectrometer for millimeter and submillimeter waves is presented. The antenna is designed to have a nearly constant gain and a low voltage standing-wave ratio (VSWR) over a bandwidth of at least 20:1. After the synthesis, the characteristics of the antenna are analyzed by the moment method using a system of reaction integrals as described by Richmond (1974). An antenna version with resistively loaded ends of the wires has a mean gain of 5.7 dBi and a maximum gain variation of +or-1.25 dB. The VSWR is equal to 1.7 over almost the entire frequency range peaking only to 2.6 at the lowest frequency. These theoretical results were verified by measurements in the frequency range from 1 to 18 GHz with a scaled model of the tapered wire antenna.<
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