Ultrawideband spiral antenna used for stepped frequency radar

Abstract

This paper refers to a special type of antenna, called frequency independent antenna, used in Stepped Frequency Continuous Wave (SFCW) radar employed for humanitarian demining. The radar transmits 128 frequencies within the frequency range from 400 MHz to 4845 GHz in groups of 8 simultaneously transmitted frequencies. It has been built at the International Research Centre for Telecommunications transmission and Radar (IRCTR), Delft University of Technology.
Two Archimedean spiral antennas with opposite sense of rotation, in order to decrease coupling signal below - 55dB, have been chosen. Precise behavior charcterization is needed because SFCW radar is phase sensitive.
The paper is focused on antenna footprint measurements, translating data from frequency domain to time domain and going in order to remove any unwanted signals. Some phase and amplitude pattern using gatinf measurements are presented.