Abstract: An antenna structure has a rotatable dipole array constituting a driven antenna element, a cup mounted around the dipole, a first conductor connected to and extending from the antenna, and a first dielectric mounted around the first conductor. A second conductor is mounted around the first dielectric, and a second dielectric is mounted around the second conductor. A third conductor is mounted around the second dielectric, and the first and second conductors form a quarter-wavelength transformer. The first dielectric maintains a uniform spacing between the first and second conductors, and the third conductor defines a radio-frequency coupling cavity. The second dielectric electrically enlarges the cavity. Thus the physical dimensions of the structure can be reduced without sacrifice of its electrical properties.

Abstract: A mass programmable FM assistive listening system preferably consists of an FM transmitter adapted to send audio signals on a selected one of a plurality of predetermined available channels. The system includes a plurality of portable receivers which may be mass programmed to receive a selected one of said predetermined channels from a membrane style keypad. The audio signal is preferably stereo, sound equalized and within the frequency range of from about 72 to about 76 megahertz.

Abstract: A dual band signal receiver is provided with inner and outer relatively coaxial cylindrical waveguides electromagnetically coupled to respective upper and lower band rectangular waveguides and ports through suitable polarization switching probe assemblies. The rectangular waveguides are mounted adjacent one end of the outer cylindrical waveguide. The rotatable probe assembly of the inner cylindrical waveguide is electromagnetically coupled to the high band rectangular waveguide by a suitable transmission line extending substantially along the longitudinal axis or centerline of the outer cylindrical waveguide.

Abstract: A drive system for a twistable septum in a feedhorn for use in satellite communications antenna systems. The drive system includes a flexible drive rod, coupled to a drive motor, which bends to accommodate off-center coupling with the septum drive wheel.

Abstract: A high-frequency signal receiver has two separate probes arranged within a waveguide for receiving both modes of an orthogonally polarized signal. A first probe protrudes directly into a rectangular cavity located at the receiving end of a circular waveguide and a second probe is specially shaped to employ the walls of the rectangular cavity and the circular waveguide as a ground plane, thereby to form a transmission line connected to a receiver probe portion arranged in the circular waveguide that receives the other of the orthogonal polarization not received by the first probe but which is reflected outwardly by the rectangular cavity.