Abstract: An antenna is disclosed which provides a horizontally polarized omnidirectional radiation pattern. The antenna includes a coax to waveguide transition, one waveguide section, and two radiating elements. A probe is located symmetrically within the waveguide section to provide equal loads or terminations to the propagating mode, resulting in an equal phase and amplitude distribution at the throats of the radiating elements. The throats (or slots) of the two radiating elements are displaced 180 electrical degrees in the plane parallel to the electric field to compensate for the reversal of the electric field sectors in this plane. The radiating elements are identical and configured in the E-plane to provide an E-plane radiation pattern with a half power beam width of 180 degrees.

Abstract: This invention relates to a method and apparatus for producing the 135 Hz modulation component which is superimposed as the ninth harmonic on a 15 Hz component thereby producing the normally required Tacan radiation pattern. A cylindrical antenna is employed having located on and around its surface active elements such as dipoles. The 135 Hz component is produced by step-wise rotation of a binary current distribution around the cylindrical array of active elements. Since the system is binary, only two current states are employed, each having a predeterminedamplitude and phase. A predetermined number of the active elements are excited by one of the signals, and the remainder of the elements are excited by the second signal. This excitation is electronically rotated in a non-symmetric manner around the cylindrical array, thereby producing the required 135 Hz component.