Figure4:QuadrifilarHelicalAntenna(a)Schematic(b)Simulatedbeampattern(c)Simulatedreflectioncoefficient.SimulationresultsshowsthatdesignedQHAhasmaximumgainofabout5dBiat0°elevationangle.Ithasahemisphericalbeampatternabovegroundplanewith3dBbeamwidthcloseto120°.Figure5showsthefabricatedQHAanditsmeasuredS11parameter.Centrefrequencyof402MHzandreturnlossofbetterthan45dBisobtainedforthefabricatedQHA.Table3:QHADimensions