US Government As Represented by the Secretary of the Army

Tracor Aerospace Electronic Systems, Inc.

Richard W Babbitt

Richard A Stern

Thomas E Koscica

William C Drach

Adam Rachlin

Roland Cadotte, Jr

John Joseph Borowick

Michael T Cummings

Xiaoguang G Sun

Elio A Mariani

William D Wilber

Ernest Potenziani, Ii

Lothar Wandinger

William T Bayha

Gerald F Mikucki

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.

Modulated retroreflection system for secure communication and

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. The voltage breakdown of the device is easily designed by selecting the appropriate thickness of the ceramic, thus enabling a highly capacitive device that can be placed in a position of maximum standing wave voltage in a tuning circuit or tuning mechanism to provide a maximum effect on tunability, especially in high power applications, based on the changes in dielectric constant of the device.

Thin film ferroelectric varactor

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.

Low-loss, wide bandwidth limiter

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. Additionally, less complex drive circuits are needed relative to analog type ferroelectric phase shifters.

Single substrate planar digital ferroelectric phase shifter

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.

Low cost automated system for evaluating the electrical characteristics

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. The phase shifter further includes a controller circuit operating at a test frequency having a synchronous detector for detecting changes in the dielectric constant of the ferroelectric element. The controller circuit provides the control signal to the DC voltage source to vary the applied DC voltage as a function of the detected changes. In this manner, changes in the dielectric constant over time are compensated for and the phase shift is maintained substantially constant.

System and method for calibrating a ferroelectric phase shifter

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.

Quick-mount measuring device for evaluating the electrical

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. The waveguide switch of the present invention has reduced size and weight and improved switching speed than that of prior waveguide switching devices.

Millimeter wave ferrite switch utilizing a superconducting switching coil

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.

Signal mixing device utilizing a superconducting strip line with

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.

Microwave circulator with a planar, biasing, permanent magnet

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.

Microwave ferroelectric phase shifters and methods for fabricating the

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.

Circuit for measuring capacitance at high DC bias voltage

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.

Superconducting ring resonator microwave oscillator for operating as a

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.

Planar digital ferroelectric phase shifter

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.

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Fair Haven, NJ, United States of America

Richard W Babbitt