抄録
This paper presents an electrically small and circularly polarized antenna with omnidirectional radiation pattern. This antenna consists of a horizontal loop element with double U-shaped parasitic structures and a vertical element from a feeding point to generate circular polarization. An omnidirectional radiation pattern of circular polarization is obtained in 360-degree azimuth directions with the maximum gain of -1.9 dBic in the parallel direction to the ground plane at 900 MHz band. The overall size of the proposed antenna including the ground plane is 48 mm × 20 mm × 12.8 mm (0.14λ × 0.06λ × 0.04λ) with ka = 0.46 < 0.5 (k: wavenumber at the resonant frequency, a: radius of a sphere surrounding the antenna), corresponding to a definition of electrically small antenna. The measured results show that the fabricated circularly polarized antenna has the omnidirectional radiation pattern. The simulated and measured results are also demonstrated and discussed.
