Abstract: A modulated retroreflection system for secure two-way communication and identification includes a transceiver at a first location and a transponder at a second location. The transponder receiving, modulating, and reflecting the signal back to the transceiver includes a retroreflector having a at least one reflective surface coated with an electro-responsive material. The electro-responsive material modulating the reflection coefficient of the reflective surface thereby modulating signals reflected by the surface. The transponder further includes a modulator electrically connected to the electro-responsive material for applying a modulated bias voltage thereby modulating the refractive index and consequently the electrical phase, and/or amplitude of the reflected signal.

Abstract: A voltage-variable ceramic capacitance device which has a plurality of las in a matching lattice structure and which possesses a symmetric voltage characteristic and a determinable voltage breakdown and has a high resistance to overbiasing or reverse biasing from an applied voltage. The device consists of a carrier substrate layer, a high temperature superconducting metallic layer deposited on the substrate, a thin film ferroelectric deposited on the metallic layer, and a plurality of metallic conductive means disposed on the thin film ferroelectric which are placed in electrical contact with RF transmission lines in tuning devices.

Abstract: A high-temperature superconductor (HT.sub.c S) in a microstrip configurat which is electrically related to a superconducting coupler and which is controlled by a heater disposed over the superconducting microstrip line. This limiter configuration is used in a series configuration with other circuitry and utilizes the low loss characteristics of the HT.sub.c S material and the wide bandwidth characteristics of microstrip. The structure itself is a five layer microstrip geometry which includes a normal metal ground plane; a dielectric substrate disposed on the metal ground plane; a superconducting microstrip transmission disposed on the substrate; a dielectric film layer disposed on the superconducting microstrip; and a heating element disposed on the dielectric film layer and over the superconducting microstrip.

Abstract: A phase shifter having a single or monolithic ferroelectric material and a lurality of ferroelectric transmission lines formed thereon, each having a different effective physical length and associated delay or phase shift. The plurality of different lengths of ferroelectric transmission lines has a voltage source associated therewith for applying a predetermined bias voltage, resulting in a change in permitivity in the ferroelectric substrate material. The different lengths of ferroelectric transmission line formed on the single substrate have a predetermined relationship between their effective physical linear lengths. By selectively activating the different lengths of ferroelectric transmission line by applying a bias voltage in different combinations, a desired or predetermined phase shift is obtained. The single or monolithic ferroelectric substrate used greatly reduces the overall length of the ferroelectric phase shifter.

Abstract: A system that provides an automated simultaneous measurement of the electal characteristics of a ferromagnetic material as a function of temperature and electric potential. The system utilizes a personal computer that interfaces with a DUT fixture through an interface measuring circuit that provides a means for remote control of the measurement process and insures a more timely and less manually intensive measuring process. The interface measuring circuit is composed of a temperature measuring circuit for measuring the temperature applied to the DUT, a capacitor measuring circuit for measuring the electric potential applied to the DUT, a high voltage power supply, a temperature plate power supply, a high voltage power supply driver, a digital voltage meter (DVM), and a DVM multiplexer. The system can utilize a humidity-free "dry" chamber (i.e. a desiccation chamber) to insure that the measurements of the DUT are reliable and accurate.

Abstract: A ferroelectric phase shifter for shifting the phase of a radio frequency F) signal. The phase shifter includes a conductor line, a ground plane and a ferroelectric element between the conductor line and the ground plane to form a microstrip circuit through which the RF signal propagates. The ferroelectric element has a dielectric constant that can be varied as a function of a DC voltage applied to the ferroelectric element wherein the speed of the RF signal propagating through the ferroelectric element is a function of the dielectric constant. The phase shifter further includes a DC voltage source connected across the conductor line and the ground plane. The DC voltage source applies a variable DC voltage to the ferroelectric element in response to a control signal thereby to vary the dielectric constant of the ferroelectric element.

Abstract: A device for measuring the electrical characteristics of a ferromagnetic erial as a function of temperature, such as its dielectric constant verses temperature characteristics. The device having a quick mount fixture that utilizes a gravity feed and thermal grease to insure a quick reliable thermal connection between the temperature controller and the device under test (DUT). In addition, the device can be remotely controlled by a computer to automate the measuring procedure, thus reducing measuring time and alleviating the intensive manual procedure of making such measurements. Moreover, the device is easily mountable in a humidity-free or desiccation chamber to insure the measurements are reliable and accurate.

Abstract: A tetrahedral junction waveguide switch having a first length of hollow rangular waveguide and a second length of hollow rectangular waveguide adjacent each other with a ferrite rod longitudinally disposed therebetween. A magnetic field is created by a superconducting switching coil placed around the junction of the two lengths of waveguide. The normally magnetically biased ferrite rod permits electromagnetic wave energy to be transmitted through the first and second lengths of waveguide. An open circuit control means selectively and controllably interrupts the current flowing around the superconducting switching coil causing the longitudinal magnetic field to be removed from the normally magnetically biased ferrite rod. The waveguide switch is thereby placed in a cut off, nontransmission, or reflective mode preventing transmission of electromagnetic wave energy.

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 ferroelectric phase shifter, especially for the X-band, may be made from n elongated slab of ferroelectric material, which has a high dielectric constant that can be varied by applying an electric field. A narrow signal conductor is formed extending across a first surface of the slab, and a ground plane conductor is formed an opposite surface, forming a microstripline. An overall RF phase shifting circuit can be made by forming input and output circuits corresponding to the above-described signal conductor and interposing and connecting the signal conductor between the input and output circuits. The input and output circuits can be formed on respective, discrete substrates, with the ferroelectric slab being interposed between the substrates, or the input and output circuits can be formed on a common substrate, with the ferroelectric material inserted into a slot formed in the common substrate.

Abstract: A circuit for measuring capacitor properties under high DC bias voltage. A apacitor is subject to a high DC bias by a high voltage supply having low AC impedance. A triangle wave voltage is applied to the capacitor at the terminal opposite the high bias voltage. A current is thereby induced due to the voltage difference across the capacitor generated by the triangle wave. The induced current is measured and properties of the capacitor calculated therefrom. The measuring circuitry is isolated from the high DC bias voltage applied to the capacitor. Therefore, the biasing voltage applied to the capacitor is limited only by the breakdown voltage of the capacitor under test.

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 planar stripline type of ferroelectric phase shifter which includes a set f series coupled phase shifter sections, each having mutually different and binary weighted lengths of ferroelectric phase shifting material. Fixed amplitude control voltages are respectively applied to one or more lengths of ferroelectric material the permittivity and effective electrical length of which change to provide a desired composite phase shift. The phase shifter, moreover, employs half wavelength spacings between elements or matching networks therebetween so that the microwave signal propagating through the phase shift will be minimally impeded between the input end and an output end.

Abstract: A microstrip transmission line substrate to substrate transition is provi comprising a pair of spaced-apart dielectric substrates having facing inner surfaces and ground planes on the non-facing outer surfaces and a parallelepiped-shaped dielectric waveguide element sandwiched between the substrate inner surfaces. The waveguide element has a pair of rhomboidal-shaped sides and a pair of sloping ends. A first microstrip conductor is disposed on the inner surface of one of the substrates and the upwardly-sloping end of the waveguide element contiguous to that surface. A second microstrip conductor is disposed on the inner surface of the other substrate and the other sloping end of the waveguide element, so that a pair of mutually-inverted microstrip transmission lines is formed. The dielectric constant of the material of the substrates is preferably much less than the dielectric constant of the waveguide element material.

Abstract: A microstrip electronic scan antenna array is provided comprising a hollow elongated octagonal-shaped housing formed by four quadrantially-disposed microstrip patch antenna arrays and four filler panels extending between the patch arrays. Three, independently-switchable microstrip Y-junction circulators are tandem interconnected in a double-ended wye configuration on a common dielectric substrate forming an octagonal end cover for the housing. Each of the three circulators acts as a single pole-double throw switch and the sequence of energization of the four microstrip patch antenna arrays is determined by controlling the sequence and direction of circulator coupling action of the three circulators.

Abstract: A DC high voltage block comprising coupled lines etched upon a substrate and covered with a bubble-free, polyurethane insulating layer. The polyurethane insulating layer prevents DC voltage breakdown through air. This DC voltage block provides a planar, noncomplex circuit that can effectively provide voltage blockage up to 4500 volts. High voltage DC blocks of this nature have applications in vacuum tubes and IMPATT devices, as well as ferro-electric or electro-optic phase shifters. They are also employed to protect bias tees and electrical devices that employ bias tees.

Abstract: A planar ferro-electric phase shifter which is compatible with commonly-u microwave transmission media to include microstrip, inverted microstrip, and slot line. The ferro-electric material, Ba.sub.x Sr.sub.1-x TiO.sub.3, which has a high dielectric-constant, is the phase shifting element. In the microstrip embodiment, the microstrip circuit consists of a ferro-electric element interposed between a conductor line and a ground plane. A DC voltage is applied between the conductor line and the ground plane, thereby controlling the dielectric constant of the ferro-electric material. The dielectric constant of the ferro-electric element in turn controls the speed of the microwave signal, which causes a phase shift. Microwave energy is prevented from entering the DC supply by either a high-impedance, low pass filter, or by an inductive coil. DC voltage is blocked from traveling through the microstrip circuit by a capacitive high-voltage DC bias blocking circuit in the ground plane.

Abstract: An rf, phase-array, microstrip antenna having a slotted ground plane mounted on one surface of a dielectric substrate. A network of strip lines is mounted on an opposed surface of the dielectric substrate. The network includes eight parallel rows of coupling strip lines mounted in superposition with eight rows of radiating slots. The slots in each row form a linear array. The slot spacing in each row is uniform and is different form different rows. The network further includes an input/output strip line, a plurality of switchable microstrip circulators and a plurality of branching strip lines connected to the circulators in a tree network. A scanning circuit is connected to the control terminals of the circulators for selectively completing an rf transmission path between the input/output strip line and the coupling strip lines. Each linear array is directional, having a major lobe, and each major lobe is oriented in a different direction.

Abstract: An antenna comprises a microstrip transmission line which includes a strip conductor and a ground plane conductor separated by a dielectric substrate; a portion of the substrate being adapted to enable energy within the substrate to radiate away from the microstrip transmission line. To permit frequency-scanning, the substrate has an antenna portion formed therein which is adapted to permit RF energy supplied to the microstrip transmission line to be directionally radiated away from the microstrip transmission line at the antenna portion, the direction of radiation being a function of the frequency of the supplied energy. The substrate may have greater capacitance at said antenna portion than at other portions of said substrate.

Abstract: A microstrip circuit having a plurality of coplanar microstrips mounted on a common dielectric substrate. A planar circulator is coupled to a junction of the microstrips. The circulator includes a ferrite disc which lies in the plane of the substrate. The circulator also includes a biasing permanent magnet in the form of a planar, toroidal-shaped magnet having magnetic sections that are embedded in the dielectric substrate. The magnetic sections from a split cylinder that encircles the ferrite material while permitting the microstrips to pass therethrough.