Abstract: A multi-mode, common-aperture antenna system capable of simultaneously transmitting and/or receiving electromagnetic radiation in at least two frequency bands. The antenna system includes a first beam antenna comprised of a parabolic reflector and four open-ended waveguides that act as an antenna feed. The parabolic reflector focuses radiation along a first beam axis that may be scanned electronically or mechanically. The four waveguides extend from the focus of the parabolic reflector to transceivers that transmit and/or receive radiation in a first mode. The transceivers mount at the rear of the reflector. The antenna system also includes a second beam antenna which operates in a second mode, e.g. optical or infrared (IR) mode. The second beam antenna includes a small opening in the parabolic reflector that acts as an optical aperture for a focusing lens mounted at the rear of the reflector and positioned coaxially with the small opening. An optical apparatus occupies the focal plane of the focusing lens.

Abstract: A tunable bandpass filter comprises a flat ferrite body having first and ond spaced, coextensive microstrip conductive lines on its upper surface. A winding encircles the ferrite and conductive lines so that a variable d-c current in the winding varies the magnetic permeability of the ferrite and thus the center frequency of the filter.

Abstract: A mm wavelength power combiner comprising an open resonator comprising a r of confronting concave reflectors which can be either spherical or parabolic. The resonator dimensions are many times the wavelength of the energy sources to be combined. A plurality of mm wave energy sources are applied to the resonator in such a way that the great majority of the energy bounces back and forth between the reflectors near the axis thereof in the fundamental or Gaussian mode. The design minimizes multimoding and diffraction losses.