A conical four-arm sinuous antenna

A conical four-arm sinuous antenna with unidirectional radiation is presented. The proposed antenna consists of four sinuous metal arms printed on a conical dielectric substrate, an auxiliary feeding patch, and two modified exponentially-tapered baluns. The simulated results of active VSWR, realized gain and axial ratio in broadside direction reveal that the antenna can effectively radiate left-handed and right-handed circularly-polarized waves at frequencies ranging from 0.82-3GHz.