A circularly polarized dual-band microstrip antenna

In this paper, we present a dual-band CP patch antenna based on the branch-line coupler feeding technique. The compactness of the dual-band antenna is obtained by inserting a small high-frequency patch into a large low-frequency one. Both patches are printed on the same upper substrate and electromagnetically fed through two perpendicular slots etched in their ground planes. A good coverage of the two frequency bandwidths is obtained by feeding these slots by two different 90° microstrip branch-line couplers on a stacked lower substrate. The antenna can be positioned at the focal point of a parabolic reflector to simultaneously work in the L and X bands for meteosat satellite communications.