Research of circular polarisation quality by broadband antennas up to 40 GHz

This paper presents the investigation of circular polarization quality by using a dual polarized broadband antenna and a hybrid coupler in comparison with broadband spiral antenna up to 40 GHz. The hybrid coupler shifts phase of signals between outgoing ports. By means of the phase shifted signals incoming into dual polarized antenna the circular polarization is achieved. The influence of polarization quality on the component´s parameters is discussed and the analysis and measurement are presented as well. The aim of this paper is to compare the polarization quality by the spiral antennas and the dual polarized antennas, then further to evaluate advantages and disadvantages of individual antennas as well.