Dual frequency band quadrifilar helix antenna systems and methods

摘要: A quadrifilar helix antenna system capable of providing a positive gain, quasi-hemispherical pattern over widely separate transmit and receive frequency bands. This new comprises concentrically arranged, but electrically isolated, antennas, each which two bifilar helices arranged orthogonally excited in phase quadrature. In the preferred embodiment, elements forming are short-circuited at their distal ends, energy is induced from coupled to via 90° hybrid couplers connected loops respective antennas. Also provided switches or other disconnection means used isolate during periods when receiving signal transmission. embodiments, these disconnecting implemented as PIN diodes radio Gallium arsenide field effect transistor switches.