A novel broadband circularly polarization microstrip antenna

Based on negative refraction circuit theory, a novel broadband Wilkonson balun which is constructed by conventional transmission line with lumped-element series capacitors and shunt inductors is proposed in this paper. And the realization method of broadening impedance and circular polarization axis ratio bandwidth is analyzed. A novel CP microstripe antenna using the balun is proposed which central frequence is 1.40GHz , and the axis ratio bandwidth achieved 52.37%, The VSWR is always below 2 in the bandwidth.