Abstract: A low-profile, tri-filar, helix antenna having circular polarization (CP) includes a single feed, in the absence of an internal feed network. The antenna includes three metal, bent, quarter-wave monopoles that are physically positioned at 0, 120, and 240 degrees, respectively, on a top flat surface of the antenna. One of the monopoles is directly-fed, and the other two monopoles are parasitically coupled to the directly-fed monopole. Metal perturbations on one or both of the two parasitic monopoles control their coupling-phase to the directly-fed monopole. One of the parasitic monopoles couples at positive 120 degrees to the directly-fed monopole, and the other parasitic monopole couples at negative 120 degrees to the directly-fed monopole. Various perturbation options generate this CP phasing.

Abstract: A low-profile, tri-filar, helix antenna having either linear polarization or circular polarization (CP) includes a single feed and does not include an internal feed network. The antenna includes three metal, bent, quarter-wave monopoles that are physically positioned at 0, 120, and 240 degrees, respectively, on a top flat surface of the antenna. One of the monopoles is directly fed, and the other two monopoles are parasitically coupled to the fed monopole. Metal perturbations on one or both of the two parasitic monopoles control their coupling phase to the fed monopole, and also determine whether the antenna is linear polarized or CP. In order to induce linear polarization, no metal perturbations are provided on the parasitic monopoles, and both parasitic monopoles are coupled to the fed monopole at +120 degrees. In order to induce CP, one of the parasitic monopoles couples at positive 120 degrees to the fed monopole, and the other parasitic monopole couples at negative 120 degrees to the fed monopole.

Abstract: A low-profile, tri-filar, helix antenna having circular polarization (CP) includes a single feed, in the absence of an internal feed network. The antenna includes three metal, bent, quarter-wave monopoles that are physically positioned at 0, 120, and 240 degrees, respectively, on a top flat surface of the antenna. One of the monopoles is directly-fed, and the other two monopoles are parasitically coupled to the directly-fed monopole. Metal perturbations on one or both of the two parasitic monopoles control their coupling-phase to the directly-fed monopole. One of the parasitic monopoles couples at positive 120 degrees to the directly-fed monopole, and the other parasitic monopole couples at negative 120 degrees to the directly-fed monopole. Various perturbation options generate this CP phasing.

Abstract: A low-profile, tri-filar, helix antenna with linear polarization or circular polarization (CP) includes a single feed without an internal feed network. The antenna includes three metal, bent, quarter-wave monopoles positioned at 0°, 120°, and 240° on a top surface of the antenna. One of the monopoles is directly fed, and the other two are parasitically coupled to the fed monopole. Metal perturbations on the parasitic monopoles control their coupling phase to the fed monopole, and determine the antenna's polarization. Without metal perturbations, the parasitic monopoles are linear polarized and both monopoles are coupled to the fed monopole at ±120. With metal perturbations, the parasitic monopoles are CP polarized and coupled at +120 degrees to the fed monopole. Various perturbations, capacitive and inductive shunts options are possible. The three monopoles are supported by a dielectric substrate, or they are freestanding.