Abstract: A discharge tube arrangement includes a discharge tube containing a fill and means for generating a discharge in the fill from a source of radio frequency (r.f.) power. An electrically conductive structure surrounds the discharge tube. The electrically conductive structure is formed of a plurality of waveguides which extend outwardly from the discharge tube. One or more waveguides has a cross-sectional area that increases with separation from the discharge tube. Each waveguide is dimensioned to support the propagation of electromagnetic radiation above a cut-off frequency.

Abstract: An antenna has a resonant cavity defined by electrically conducting plates and a sidewall, and has sixteen helical antenna elements each with five turns in the helical section and a probe at the opposite end, the stem of probe passing through an aperture in upper plate so that its end is within the resonant cavity common to all elements in that module.The cavity has a cross-section parallel to the plates essentially square in shape except for the presence of four inwardly-protruding buttresses, one situated mid-way along each side of the cavity to promote the formation of standing waves of different mode, and thereby enhance the frequency range of the array.

Abstract: An antenna is formed of four arrays each having sixteen helical antenna elements with probes located within a common resonant cavity. Thus cavity is used to combine all the outputs of elements.The elements of array are arranged over the surface of box such that the probes are located at the voltage antinodes of the resonance field patterns in order to maximize the coupling efficiency. Likewise the output probe for each cavity 6 is also located at a voltage antinode; output probe enables the signal combined in cavity to pass into a waveguide, also connected to other arrays and, for passage to the television receiver.