Other

Eaton Corporation

Litton Systems, Inc.

Litton Industries, Inc.

William J Keane

John A Mezak

Dirk M Hoekstra

Christopher F Schiebold

Cristopher F Schiebold

A frequency synthesizer using a fixed oscillator driving a comb line generator to generate a spectrum of comb lines, one of which is selected by a switched array of fixed-tuned, YIG passband filters. The selected comb line is combined in a mixer with a signal from a local oscillator, which, preferably, is a direct digital synthesizer. The output of the mixer is fed to another switched array of fixed-tuned YIG passband filters where only the desired sideband is selected and the comb line and the other sideband is filtered out. In various alternative embodiments, tunable YIG filters are substituted for each array. Some embodiments also use a reverse slope equalizer to break up the coherent energy in the comb line spectrum at the output of the comb line generator to allow RF amplification to be applied without saturating the amplifier.

Fast tuning YIG frequency synthesizer

A nonreciprocally coupled ferrimagnetic band reject and bandpass filter having passbands from 2-18 GHz and 6-18 GHz respectively. The band reject filter comprises one or more ferrimagnetic spheres shielded from each other by placement in nonmagnetic, electrically conductive cavities in a block placed in the flux gap of a tuning magnet. Nonreciprocal coupling is achieved by using full RF coupling loops and establishing all factors that affect the transmission line delay for travel of signals from one point in the filter to another such as loop length and size, cavity size, sphere size and spacing, dielectric constant, RF coupling loop wire size and spacing etc. such that the effective electrical length from the center of one full RF coupling loop to the centerline of the neighboring RF coupling loop is 1/4 wavelength, i.e., an electrical phase change of 90 degrees occurs, and by placing the ferrimagnetic spheres outside the planes of their respective RF coupling loops to minimize the effect of (2,2,0) Walker modes. A ferrimagnetic passband filter comprises at least an input ferrimagnetic sphere in a cavity and an output ferrimagnetic sphere in a cavity in a nonmagnetic, conductive block located in the flux gap of a tuning magnet. Both the input and output spheres are coupled to full RF coupling loops coupling an RF input and an RF output, respectively, to the ferrimagnetic spheres and to ground. The effective electrical length between the RF input or RF output and ground through the respective RF coupling loops is 1/4 wavelength. Coupling is set tight to achieve wide bandwidth. The ferrimagnetic spheres are offset from the plane of the loop to achieve nonreciprocal coupling thereby allowing the (2,2,0) Walker mode spurious responses to be eliminated from the tunable passband.

Yig tuned high performance filters using full loop, nonreciprocal

A YIG notch filter using full RF coupling loops and having a notch filter center frequency tunable as high as 18 GHz comprising a plurality of undoped YIG spheres of much smaller volume than used in the prior art and linearly arranged in a air gap. The spheres are suspended in cavities in a nonmagnetic block which are spaced much more closely than in the prior art. The 50 ohm stripline impedance inverters formed on a substrate and connecting the RF coupling loops of the spheres used in the prior art are eliminated. The quarter-wavelength impedance inverter function necessary to fabricate a notch filter is implemented by using the RF coupling loops themselves and measuring the distance from centerline to centerline of adjacent RF coupling loops. Twin insulated wires with up to one diameter separation for the RF coupling loops are preferred with the wires soldered together between the spheres.

YIG tuned band reject filter for 2-18 GHz with full one-quarter

A frequency discriminator having at least one ferrimagnetic resonator in a band pass or band reject configuration, the frequency of which is swept over a frequency band of interest, a detector receives the filter output, and the timing relationship between the detector output and the swept frequency is compared to generate the discriminator output. The discriminator has a bandwidth variable from a relatively narrow range to a very wide range in which the center frequency is simultaneously tunable over an extremely wide frequency range. The discriminator is insensitive to amplitude variations of the input signal and is capable of demodulating low level signals. The frequency discriminator is particularly useful for microwave frequency applications, for example, as a discriminator in a simple microwave FM receiver.

Frequency discriminator apparatus

Compact, simple, ferromagnetic-filter coupling structures which provide a very high, effective-quality factor Q in the VHF, UHF, and microwave frequency ranges achieved by means of offsetting the ferromagnetic element from the plane of the coupling loops and by phase shifting the current in one of the coupling loops to produce an orthogonal field in the vicinity of the ferromagnetic element.

High performance ferromagnetic filters applicable from the VHF through

Compact, simple, ferromagnetic-filter coupling structures which provide a very high, effective-quality factor Q in the VHF, UHF, and microwave frequency ranges.

Compact RF structure for nonreciprocal ferromagnetic resonance coupling

A frequency discriminator having a bandwidth variable from a relatively narrow range to a very wide range in which the center frequency is simultaneously tunable over an extremely wide frequency range. The discriminator is insensitive to amplitude variations of the input signal and is capable of demodulating low level signals. The frequency discriminator is particularly useful for microwave frequency applications wherein the basic discriminator element is a ferrimagnetic resonator. The frequency discriminator forms a portion of several preferred embodiments including devices for the frequency control of signal sources, frequency measurement of signal sources, demodulation of frequency modulated signals and frequency tracking control for other ferrimagnetic devices.

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San Jose, CA, United States of America

William J Keane