An improved directional equiangular spiral antenna with wide CP band and high gain is proposed, in which the impedance bandwidth is 2~12 GHz, CP bandwidth 4.5~7 GHz, and gain 6~9.5 dBi. The antenna includes 4 layers. The top layer is equiangular spiral antenna, and the bottom layer is ground. The middle two layers are parasitic metal films with irregular rectangular holes, which are introduced to improve the performance of equiangular spiral antenna and reduce the profile. The measured results are in good agreement with the simulated ones.
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