A low‐profile wideband spiral antenna with multiple stopbands

Abstract

A low‐profile spiral antenna with three stopbands (2.55 GHz band, 3.85 GHz band, and 5.45 GHz band) is developed. The stopbands are generated using three pairs of slots cut into the spiral arms. The antenna height is 0.077 wavelength at a low band edge frequency of 2 GHz. Firstly, the effects of the slot dimensions (length, width, ending angle, and position) on the stopbands are analysed, where the spiral antenna floating in free space radiates a bi‐directional beam. It is found that the stopband centre frequency is determined by the slot length, and the stopband bandwidth is determined by the slot width, ending angle, and position. Secondly, the fabrication tolerances are investigated. Thirdly, the bi‐directional beam from the floating spiral antenna is transformed into a unidirectional beam by using a low‐profile cavity. It is revealed that three stopbands are maintained. Finally, a prototype of the antenna is fabricated and measured to verify the analysed results.

Compact Archimedean spiral antenna with high gain for electrostatic discharge detection

“…The single-arm spiral antenna is preferred owing to its merits of circular polarization mode, wide polarization band, simple feed method and so on. The miniaturisation methods of spiral antenna mainly include current path extension [10][11][12], loading balun [11,13], conformal transformation [11,14], introducing parasitic parameters [15,16] and loading impedance [17]. The ESD signals received by antenna may have a small amplitude and be drowned out by noise as a consequence of the weak EM radiation of ESD, especially for the electrostatic corona discharge.…”