Dualband Omnidirectional Circularly Polarized Antenna

Adual-bandomnidirectionalcircularlypolarizedantennaisproposed.Theantennacomprisesback-to-backmicrostrippatchesfedbyacoplanarwaveguide.Averylowfrequencyratioof1.182hasbeenachieved,whichcanbeeasilytunedbyadjustingfourlumpedcapacitorsincorporatedintotheantenna.Ananalysisoftheomnidirectiona