Abstract: The present invention is a superconducting flux flow mixer which has two control lines. Preferably, the mixer comprises a grounded superconducting signal line wherein portions of the superconducting signal line are etched away to form superconducting weak links within the superconducting signal line, a local oscillator and RF control line disposed on either side of the superconducting weak links, and a substrate upon which the control lines and superconducting signal line are disposed. When cooled to a temperature close to the critical temperature of the superconducting weak links, the resistance of the weak links can be manipulated by a magnetic field created by current flowing through the local oscillator and RF control lines. By using two control lines, better control of frequency is attained while at the same time providing better stability and a decrease in size of prior art mixers.

Abstract: A magnetic flux-enhanced control line for a superconducting flux flow transistor (SFFT). The SFFT includes a pair of superconducting electrodes which provide a voltage output, a region of weakened superconductor connecting the electrodes and a control line. The region of weakened superconductor carries a current I.sub.body and the control line carries a current I.sub.Control. The control line further has a portion thereof proximate the weakened region for providing a localized magnetic field through the weakened region as a function of I.sub.Control. The magnetic flux through the weakened region induces vortices therein which have a resistance r.sub.o. The proximate portion of the control line forms a tortuous current path whereby the magnetic flux through the weakened region is increased for increasing r.sub.o so that the output voltage of the transistor is increased without increasing I.sub.Control.

Abstract: A remote temperature sensor includes a microwave oscillator which generates n output signal having a frequency which is proportional to the temperature of the environment in which it is located. The oscillator includes a relatively high transition temperature superconducting (HTSC) ring coupled to a transistor in a plurality of microstrip line oscillator configurations including those of a reaction oscillator, a transmission oscillator, a reflection oscillator and a parallel feedback oscillator. The superconducting ring operates below its transition temperature and in so doing, acts as a high Q resonator whose resonant frequency is proportional to temperature.

Abstract: A microstrip-to-inverted-microstrip transition for providing a low-loss cection of a microstrip to an inverted microstrip in planar microwave devices. One embodiment includes tapered dielectric and conductor sections that provide a gradual or tapered change in the effective dielectric constant and a substantially constant characteristic impedance across the transition. A second embodiment employs a series of microstrip transformers that are one-quarter wavelength long. The transformers have dielectric members that have successively decreasing dielectric constants to provide a gradual dielectric match. The geometries of the microstrip transformers are chosen so that there will be an impedance match across the transition. A third embodiment employs the microwave interaction that takes place with the supporting dielectrics of the inverted microstrip to produce a dielectric match.

Abstract: An ambient condition sensor is embodied in an oscillator which generates an output signal having a frequency which is proportional to the ambient condition of the environment in which it is located. The oscillator includes a ring resonator consisting of a metallic ring located in the output plane of a grounded source gallium arsenide MESFET type transistor oscillator formed on a temperature sensitive dielectric substrate. The circumference of the ring is directly related to the ring resonator's resonant frequency. More particularly, the circumference of the ring is a multiple of the wavelength of the oscillator's output signal. Such a device permits unmanned, remote and inexpensive temperature sensing in places generally unsuited for operator presence.

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 test fixture for inverted microcircuits having spaced shelf assemblies h parallel shelves for respectively supporting a substrate for a microcircuit and a substrate for a ground plane in such a manner that the distance between them can be varied while test signals are coupled to the microcircuit via a coaxial cable coupled to a fitting on one shelf assembly and signals are coupled from the microcircuit via a coaxial cable coupled to a fitting on the other shelf assembly to test apparatus for determining the performance of the circuit.

Abstract: A resonant microwave isolator is described in which a diagonal slot is fod in the top conductor of a microstrip, a strip of ferromagnetic material is mounted over at least a portion of the slot and magnetic flux is established in the ferromagnetic material in a direction intersecting the slot.