Spiral antenna with parasitic radiating elements

This paper presents the integration of radiating elements over a two-arm Archimedean spiral antenna. The radiation bandwidth of a spiral antenna printed over a ground plane can be improved by these elements. In this way, a 1:10 bandwidth can be achieved with good performance. As an example, this paper presents a spiral antenna working from 1 to 10GHz with a constant gain thanks to two concentric rings placed 15mm above the antenna.