Comparison of EBG substrates with and without vias for GALILEO/GPS applications

The analysis presented in this paper is part of a dedicated antenna design for geodesic applications using the future Galileo system. Such antennas are characterised by an ultra-low multi-path behaviour resulting in a very stable phase centre. In the past, choke ring structures have been used to obtain this effect, yet they are heavy and bulky. The antenna presented here uses instead electronic band gap (EBG) technology. Several types of EBG structures have been investigated for this purpose, focusing both on EBG substrates with and without vias. The resulting printed EBG structures with vias are low-weight, low-cost and low-profile. The investigations have shown that EBG substrates without vias are not suited for this application. The use of the mushroom substrate with vias results into a very compact and commercially interesting antenna module with good performance.