Multifilar-curl antenna

Multifilar-curl antennas that can radiate circularly polarized waves are analyzed in detail. The antenna is fed directly or electromagnetically coupled by an inverted-L wire section to improve its impedance matching. The method of moments (MoM) is used to model the antenna structure in the presence of an infinite ground plane. The radiation characteristics of a single curl antenna are compared with available measurements to validate the analysis. A quadrifilar-curl antenna on an infinite ground plane is considered. The current distribution along the antenna, the radiation patterns, the axial ratio, the antenna gain, the input impedance, and VSWR are calculated. An octafilar-curl antenna on an infinite ground plane is proposed to increase the gain of the antenna and to improve the circular polarization characteristics. Also, quadrifilar- and octafilar-curl antennas without a ground plane are presented. The radiation characteristics are calculated. The frequency response of the input impedance, VSWR and the antenna gain are depicted.