A modified four-arm, mode-2, wide-beam archimedean spiral antenna

A modified wideband and wide-beam Archimedean spiral antenna, with the characteristics of circularly polarization, four arms and mode-2 operation, is presented in this paper. The antenna features a modified cup-shaped cavity and a dielectric substrate with twelve metal patches printed on it. The simulated results show that the voltage standing wave ratio (VSWR) is better than 2 over the operating band of 8∼12GHz. The beamwidth of the modified spiral antenna is greatly broadened compared with the conventional antenna. Over the whole operating frequency band, the beamwidth of the modified Archimedean spiral antenna is about ± (15°∼75°).