Abstract: A balun comprises seven adjacently disposed coupled lines in a substantially symmetrical arrangement about a central one (33) of the seven lines. Corresponding first ends of the two outermost lines (30, 36), of the two thereto adjacent lines (31, 35) and of the central line are connected to each other and to an unbalanced port input (37) (Port 1). Corresponding first ends of the two lines (32, 34) adjacent the central line (33) are grounded, as are corresponding second ends of the central line (33) and of the two lines (31, 35) adjacent the outermost lines. Corresponding second ends of the outermost line (30) on one side of the central line (33) and the next but one line (32) on that same side form a first balanced port (Port 2), while equivalent second ends on the other side of the central line (33) form a second balanced port (Port 3). The balun may form part of a single-sideband mixer or of a downconverter.

Abstract: A stabilized microwave oscillator having a selected operating frequency range, composed of a rectangular waveguide dimensioned to have a cutoff frequency above the selected operating frequency range, at least one active semiconductor element and components connected for supplying a direct operating voltage to the element, mounted in the rectangular waveguide, a transmission resonator, and a coupling device coupling the rectangular waveguide to the resonator, the coupling device including a waveguide section having a length of about .lambda./2, where .lambda. is the wavelength of the center frequency of the operating frequency range, and dimensioned at least in part to operate as an evanescent mode waveguide and/or a waveguide having a cutoff frequency in the vicinity of the upper end of the selected operating frequency range.

Abstract: A circuit arrangement for generating and stably amplifying broadband rf signals. The circuit arrangement includes a first rectangular waveguide designed for operation in a frequency range below its cutoff frequency and a second rectangular waveguide for operation at the operating frequency. An active semiconductor element is disposed in the first rectangular waveguide and a direct voltage is supplied to the semiconductor element. At least one waveguide section is provided for connecting the first and second rectangular waveguides and has the same width as the second rectangular waveguide and a height less than the second rectangular waveguide. The waveguide section matches the cross section of the first rectangular waveguide to the cross section of the second rectangular waveguide.