Abstract: Similar input and output mode exciters are each comprised of a coaxial line having an inner conductor and an outer conductor. The coaxial lines have proximal ends coupled through a coupling assembly whereby one of the mode exciters is axially rotatable relative to the other. There are eight coaxial ports in each of the outer conductors. The ports of the input mode exciter and the ports of the output mode exciter are connected to similar first and second bilateral networks, respectively. Additionally, a pair of terminals of the first network are respectively connected to first and second signal sources, whereby input signal power is applied to the input mode exciter through the first network. In response to the application of the input power, a pair of terminals of the second network provide output power independent of the relative rotational position of the mode exciters.

Abstract: An omnidirectional circularly-polarized antenna system includes a plurality of dipoles equally spaced in a horizontal circle about a metal support mast. The dipoles are tilted at an angle with respect to the plane of the horizontal circle to excite circularly-polarized waves. The dipoles are fed in phase rotation with adjacent dipoles 90.degree. out of phase.

Abstract: A linear/circularly polarized antenna system is provided by four conductive elements. The conductive elements are joined in pairs at their ends with the joined ends spaced by a conductive support member from a flat reflector. The lengths of the conductive elements of each dipole element are changed from being equal lengths of approximately a quarter operating frequency wavelength to one slightly longer and the other slightly less than a quarter wavelength to selectively change operation from that of a linearly polarized antenna to that of a circularly polarized antenna.

Abstract: A truncated conical member of conductive material is mounted forward of a pair of crossed dipoles, the legs of which are inclined toward a reflector. The pair of dipoles cross orthogonal to each other at the dipole centers with the dipole halves being fed with equal power in the relative phase rotation of 0.degree., 90.degree., 180.degree. and 270.degree..

Abstract: A dual- band Cassegrain antenna system operable at any polarization is described wherein the hyperbolic subreflector is made to reflect signals at a first band of frequencies and to transmit or pass signals at a second lower band of frequencies. The hyperbolic subreflector according to one embodiment is a square grid mesh with conductive rings centered along the connecting legs of the square grid mesh. The rings are approximately one-third wavelength in diameter at the first band of frequencies and act capacitively at the second lower band of frequencies. The inductive reactance provided by the conductive connecting legs of the grid mesh together with the capacitive reactance provided by the rings at the lower band of frequencies causes the subreflector to transmit signals at the second lower band of frequencies.

Abstract: A broadband turnstile antenna system is provided by four triangular fan-shaped radiating elements spaced about a vertical tower. Each of the triangular radiating elements is constructed and arranged to present a minimum of vertical height at a feed point near the tower and a vertical height that increases to maximum at the end remote from the tower. The radiating elements are fed with equal power in the relative phase rotation of 0.degree., 90.degree., 180.degree. and 270.degree..