Abstract: A multiplexer/demultiplexer for combining/separating a large number of contiguous frequency channels in microwave bands while incurring low insertion loss. The invention, in a demultiplexer mode, includes a power divider, to form a multiplicity of samples of an input signal; delay lines to non-dispersively differentially delay the samples in accordance with a first arithmetic progression; phase shifters to add fixed phase shifts to samples in accordance with a second arithmetic progression; and a Butler matrix to coherently combine the samples selectively at different output ports for different input signal frequencies. In a multiplexer mode, input signals are applied to the Butler matrix. The Butler matrix, phase shifters, delay lines, and power divider perform in reverse of the demultiplexer mode (the power divider thus performing as a power combiner). The present invention minimizes insertion loss by eliminating any requirement for resonators and any means for isolating resonators.

Abstract: During fabrication of monolithic microwave integrated circuits, active devices having sources, gates, drains, and/or Schottky barrier junctions are first provided for an epitaxial layers. Then many layers of metals and oxides are produced thereover in situ without removing the circuit from its environmental chamber. Circuit elements are then defined by processing of the many layers sequentially by photolithography and other processes from the top of the chip downward. Certain combinations of metals, oxides, and processes are selected to enable fabrication of circuits from the top down in this way. This reduces inclusion of contaminating chemical films and particles between the desired layers. Lumped and distributed capacitors, resistors, inductors, transmission lines, contacts, and complete active devices are monolithically defined, with a reduced number of process steps.

Abstract: A method for passively locating in range and azimuth both active, such as radar, and passive objects. The present invention uses existing direction finding equipment located on a platform, such as an aircraft or ship. At the platform, the invention includes measuring the scan period of the radar, the time of intercept of the main beam of the radar, the angle of arrival of the radar main beam, the time of arrival of a bistatic signal echo from a passive object which has been illuminated by the radar, and the angle of arrival of the echo; calculating the difference between the angle of arrival of the echo and the angle of arrival of the radar main beam to obtain an angle .theta.; determining an angle .phi.

Abstract: The angle of arrival (.theta.) of an RF signal is determined using only two widely spaced antennas (A, B). A coarse/fine measurement system (40) is disclosed wherein the actual time delay between zero-crossings responsive to the same RF carrier cycle within the pulse envelope arriving at each antenna is determined. There is no need for additional antenna pairs with different baselines to otherwise resolve ambiguity.

Abstract: A receiver time delay calibration device designed for low cost retrofitting of airborne equipment and more specifically DME equipment. In this system, the output of a VFO is applied to the RF input port of the receiver to be tested. The VFO is swept through a frequency range of the receiver until the receiver provides an output, which occurs at the operating frequency of the receiver, f.sub.t. The receiver's output at f.sub.t is used to stop the sweep of the VFO and maintain it at f.sub.t. The output of the VFO is then pulse modulated and the delay between the RF pulse applied to the input of the receiver and the corresponding video output pulse from the receiver is measured to determine the receiver delay time.

Abstract: A wide band receiver has connected to its input a series of narrow band channels. The incoming signal is processed through these narrow band channels with the greatest energy being produced in the narrow band channel closest to the incoming signal frequency. During the steady state portion of the signal the energy differences between the narrow band channel coinciding with the incoming signal frequency and channels higher and lower in frequency are maximum and exceed an established channel to channel ratio (CCR) level. A signal is produced by measuring the associated narrow band channel energy differences and comparing them to the channel CCR's. As the CCR comparison only produces a logic signal during the steady state portion of the incoming signal pulse, a clear unambiguous indication is provided of the relative energies between the narrow band channels.

Abstract: A pulse signal is received at the input of a wide band receiver. The signal is then processed through a plurality of narrow band channels. Each of the narrow band channels are compared to adjacent channels to produce a series of "ESS" curves whose amplitude is responsive to frequency of the incoming signal. The absolute magnitude of these "ESS" curves are compared one to the other to determine the greater of the relative energys in each of the narrow band channels and logic signals are produced therefrom indicative of the incoming signal frequency.

Abstract: A tunnel diode having a generally rectangular junction area in the 10.sup.-10 to 10.sup.-11 cm.sup.2 range formed in a quasi-planar structure of a first metal, an oxide of the first metal and a second metal. The first metal may be tantalum or other similarly slow oxidizable metals. The second metal may be selected from a group also including tantalum. For a symmetrical junction, the first and second metals are the same, however, for an asymmetrical junction the first and second metals are different. To reduce the diode series electrical and thermal resistance, a gold layer is deposited over the first and second metals. The gold layer over the first metal is deposited everywhere except at or within a few microns of the junction. The device provides a small junction area and also negligible parasitic shunt capacitance which are necessary for efficient room temperature operation at frequencies in the submillimeter to optical region.