New designs for single and dual band quadrifilar spiral antennas (QSA) for satellite-mobile handsets

A novel quadrifilar spiral antenna is proposed for use in personal communications mobile terminals exploiting the `big low Earth orbit” (big-LEO) satellite system, using the uplink and downlink bands of 1.61-1.6265 GHz and 2.4835-2.5 GHz respectively. Feeding of the antenna from the outer periphery is proposed, to avoid the complexity and space requirements of a centre feed: an externally-fed antenna can also be fed either by coaxial cables or stripline. Moreover, the hybrid phasing network and the matching network (if required) can be located outside and possibly printed in the same plane as the antenna structure. Versions of the design were investigated using the method of moments and in hardware realisations. These had a finite ground plane with an air dielectric between the spirals and ground plane. Performance suitable for satellite mobile system applications was demonstrated, including dual-band matching