US Government as Represented by the Secretary of the Army

American Telephone and Telegraph, Co.

At&t Bell Laboratories

Charles D Hechtman

Erik H Lenzing

Madan Dubey

James Louis Lewandowski

Scott Davidson

Ilyoung Kim

George F McLane

Harry F Lenzing

Daryl C Lu

Norman J Horing

Hong Liang Cui

Victor J Velasco

The present invention is achieved by layering a dielectric slab between a ground plane and a two dimensional quasi quantum well heterostructure and by switching between an unbiased state and a negative potential which is established between the quantum well heterostructure and the ground plane. In the unbiased state, the device supports wave propagation in the dielectric with a phase velocity similar to that of a wave propagating in a parallel plate waveguide. Upon application of the bias voltage, that is establishing a negative potential difference between contacts based on either side of the quantum well heterostructure, the conductivity of the quantum well decreases. Therefore, as the carrier wave propagates the wave interacts with a boundary similar to that of a dielectric-air interface. This new boundary condition, in turn, produces a faster phase velocity. Hence, toggling the bias modulates the quantum well conductivity which changes the phase velocity of the carrier wave.

Quantum well optical waveguide phase shifter

A hybrid antenna in which the flared end of a parallel plate of a transmion line is coupled to a frequency independent antenna so as to take the place of the higher frequency radiating portion of the antenna.

High power ultra broadband antenna

The present invention is a superconducting opto-electronic phase shifter which is achieved by illuminating a superconducting microstrip line, which is fabricated on a dielectric substrate, with an optical beam of a predetermined intensity and shape. Because the superconducting microstrip will exhibit a local surface resistance when and where illuminated, the microstrip line will be artificially narrowed thereby producing a phase shift. This occurs because as the width of a superconducting microstrip line narrows the velocity of the carder signal increases. Therefore, if the illumination of the superconducting microstrip line causes a local surface resistance, then the surface impedance of the microstrip line is increased causing the effective width of the microstrip line to decrease. Hence, the artificial decrease in the width of the microstrip will cause the phase of the carrier signal to shift.

High T.sub.c superconducting microstrip phase shifter having tapered

The present disclosure is directed to a technique for assigning each of a plurality of test points (34) on a first surface of a translator board (24) to an appropriate one of a set of grid points (36) on an opposed surface of the board. Such an assignment is accomplished by first mapping the grid points (36) and a successive one of the test points (34) into an array (49a) of uniformly spaced cells (49b). An initial group of cells (49b), surrounding the mapped test point (34), is then searched to locate the four grid points (36) closest to the test point. Among the four closest grid points (36), the one which satisfies a particular constraint is designated. A check is then made to determine whether the designated grid point (36) is appropriate for the test point (34). If so, the grid point (36) is assigned to the test point (34) and the grid point is removed from the array before mapping the next test point. Otherwise, the designated grid point is disqualified, and the area searched is expanded in the direction of the now-disqualified grid point until an edge of the array is reached.

Method for routing conductive paths

A driver circuit for alternately sourcing current to, and sinking current from a load (12) comprises a pair of field effect transistors (20 and 22), each having its drain-to-source portion coupled between the load and a separate one of a pair of voltage sources (V.sub.H and V.sub.L) which serve to source and sink current, respectively. Each of a second pair of field effect transistors (24 and 26) has its drain-to-source portion coupled between the gate of a separate one of the first pair of field effect transistors and a current source (28). The gate of each of the field effect transistors of the second pair is supplied with a separate one of a pair of electrical signals V.sub.i ' and V.sub.i '* which alternately shift in amplitude. The control signals V.sub.i ' and V.sub.i '* render the field effect transistors of the second pair alternately nonconductive, thereby rendering the first pair of field effect transistors (20 and 22) alternately conductive to sink and source current, respectively.

Method and apparatus for sourcing and sinking current

A sheet (10) of anisotropically conductive material may be fabricated by mixing a quantity of electrically conductive, ferromagnetic particles (16), typically spheres, in an uncured polymer (12). The polymer is then cured in a magnetic field which causes the particles to align in chains (14) each parallel to the lines of the field. In accordance with the invention, a spatially varying magnetic field, comprised of first and second substantially uniformly spaced regions (22 and 24) of high and low field strength, respectively, is applied to the polymer (12) during curing. The difference in the strength of the magnetic field in the first and second regions is such as to give rise to a lateral force on the particles which urges them into the first regions of high field strength where the particles align into chains. Since the first regions of high field strength are substantially uniformly spaced, the chains of particles in the polymer will be likewise substantially uniformly spaced.

Method and apparatus for fabricating anisotropically conductive material

A driver circuit (10) for sourcing current to, and sinking current from, a load (12) comprises a pair of field effect transistors (18,20) each having their gate-to-source portion coupled between the load and one of a pair of voltage sources which serve to sink and source current, respectively. First and second bias networks (48,119) are each coupled to the gate and source of each of the field effect transistors, respectively. First and second junction transistors (42 and 100) are each coupled between a separate one of the first and second bias networks ( 48 and 119), respectively, and a current source (64) to provide a conductive path therebetween. The first junction transistor is rendered conductive to pass current to the first bias network so that a voltage of sufficient magnitude appears between the source and gate of the first field effect transistor to prevent the conduction thereof. The second junction transistor is rendered conductive alternately with the first junction transistor to divert current away from the first bias network and into the second bias network to render the second field effect transistor substantially non-conductive.

Growing community of inventors

Hopewell, NJ, United States of America

Charles D Hechtman