Varian Associates, Inc.

Stanford Research Institute

Other

Communications & Power Industries, Inc.

Mitsubishi Electric and Electronics U.s.a., Inc.

Mitsubishi Electronics America, Inc.

Terrastar, Inc.

Arthur Karp

Bruce B Lusignan

Erling L Lien

Leo Young

Donald R Chambers

Tohru Takagi

Kazuo Hosono

Allen F Podell

David S Stone

Arthur E Schoennauer

Gary A Biggs

Seymour B Cohn

An antenna feed horn assembly includes a circular feed horn having an electrically conductive wall with an edge defining a circular aperture. The antenna feed horn assembly further includes a circular waveguide mounted to the base of the circular feed horn and including an endplate. An cylindrical rod extends from the center of the endplate towards the center of the feed horn aperture along a longitudinal axis of the antenna feed horn assembly to minimize undesired reflections produced by transitions between electrically conductive material and non-electrically conductive material or dielectric within the antenna feed horn assembly. An antenna feed horn assembly can also include a splash plate opposite the endplate, the center from which another cylindrical rod extends towards the center of the endplate along the longitudinal axis of the antenna feed horn assembly to further minimize undesired reflections.

Antenna feed having centerline conductor

A receiving antenna includes a parabolic reflector and a feed horn. The feed horn includes an electrically conductive wall with an edge forming an aperture. The feed horn further includes a plurality of electrical conductors that extend from the edge to the center of the feed horn in a substantially coplanar relationship with the aperture. Each of the electrical conductors differentially affect a first polarized electrical field perpendicular to the edge adjacent the electrical conductor and a second polarized electrical field parallel to the edge adjacent the electrical conductor. In this manner, the electrical conductors can be configured to reduce the effective aperture of the feed horn in a plane, so that a first polarized horn radiation pattern produced by the feed horn can be circularized. The electrical conductors with respect to a vertical plane preferably match the electrical conductors with respect to a horizontal plane, so that first and second polarized horn radiation patterns produced by the feed horn can be simultaneously circularized. Another receiving antenna includes a splash plate and a feed horn that respectively include opposing edges that form an annular aperture. The feed horn further includes a plurality of electrical conductors that extend from the feed horn edge towards the splash plate edge in a coplanar relationship with the aperture. Again, the electrical conductors can be configured to reduce the effective width of the annular aperture in a plane, so that a first polarized horn radiation pattern produced by the feed horn can be circularized, while at the same time a second polarized horn radiation pattern produced by the feed horn can be circularized.

Antenna feed having electrical conductors differentially affecting

The frequency of an AC signal is multiplied by a factor N, where N is an integer greater than one, by an electron tube including a cathode for emitting an electron beam and a grid including N segments in proximity to the cathode. The grid is biased and coupled to the signal so the beam is formed as N groups of electron bunches during each cycle of the signal. Each segment accelerates one group of bunches for a duration of about 1/N th of each cycle of the signal. Different groups of bunches associated with the different segments are accelerated at phases displaced from each other during each cycle of the signal. In response to the N groups of bunches an output signal having a frequency N times that of the signal is derived.

Frequency multiplier including grid having plural segments

A vacuum tube for amplifying an r.f. signal includes an assembly containing a cathode and grid for current modulating an electron beam derived from the cathode. One of the electrodes of the assembly includes a slow wave structure approximately resonant to the frequency of the signal. A cavity resonant to the frequency of the signal, positioned between the grid and a collector for the beam, is coupled to the beam. In one embodiment, the slow-wave structure is mounted in a support for the grid, while in a second embodiment, the grid is configured as plural, parallel meander lines forming the slow-wave structure. In the latter embodiment, the beam is preferably annular and the meander line geometry, in certain modifications, is adjusted so that there is a relatively small electric-field variation with radius over the portion of the grid through which the annular beam passes. In a further embodiment, the grid is configured as two interlaced spirals, driven by complementary replicas of the r.f. signal so the beam is formed at twice the frequency of the r.f. signal. Focusing electrodes configured as a perforated sheet, contacting the cathode, or as electrodes just downstream of the control grid, or both, collimate ,the beam, whether hollow or not.

Vacuum tube including grid-cathode assembly with resonant slow-wave

To selectively and controllably increase RF surface power loss in microwave components, the component surfaces are overcoated with a suspension of conductive particles in a viscous binder of thickness less than a wavelength at the operating frequency. The binder is compounded so as to fire to a glassy matrix that is a durable, heat-resistant and vacuum-compatible dielectric. The metal particle size, which is selected to fit within the coating thickness, is preferably large compared with the RF skin depth of the conductive particles, but no smaller than one-quarter skin depth.

Microwave components with a surface coating which imparts a very high RF

The 'comb-quad' slow-wave interaction circuit for a traveling-wave tube consists of a pair of metallic ladders whose rungs cross, the rungs of one ladder passing through the spaces between the rung of the other ladder. The phase velocity of the circuit wave is tapered to a lower value at the output end by gradually enlarging the axial open spaces between the longitudinal bases of the ladders and the surrounding envelope. The periodic elements of the ladders are all exactly alike, simplifying the construction. The slowing of the wave velocity is greater at the lower-frequency end of the passband, providing improved efficiency over the operating band.

Velocity tapering of comb-quad traveling-wave tubes

A slow-wave circuit suitable for a high-frequency traveling-wave tube has an array of metallic ladder rungs extending transversely across an elongated envelope and not in contact with the envelope except at the ends of the rungs. The envelope has a cross-shaped section to provide a fundamental backward wave. The rungs preferably have aligned apertures to pass a beam of electrons in traveling-wave interaction with the circuit. By making the rungs transversely broader than a critical value, the lowest passband of the circuit has poles of impedance at both its ends, whereby more efficient interaction is obtained, along with greater stability.

TWT Interaction circuit with broad ladder rungs

This invention concerns a slow-wave circuit which is electrically equivalent to the well-known folded-waveguide or coupled-cavity circuit with staggered coupling slots. The central portion of the circuit is a metallic ladder. The ladder rungs are wide and flat to form the equivalent of flat cavities. The rungs have axially aligned holes thru their centers for beam passage. A pair of coupling ladders are joined to opposite sides of the central ladder. They have apertures or recesses spaced at twice the pitch of the central ladder; the recesses are aligned to provide a coupling duct between each pair of adjacent cavities, and cavity-closing walls at the ends of the pair. The coupling recesses in the two coupling ladders are staggered by the cavity pitch so that the coupling ducts are on alternating sides of the cavities.

TWT Slow-wave structure assembled from three ladder-like slabs

A window assembly for a hollow waveguide of circular cross-section, with improved bandwidth and cooling capability for handling high microwave power transmissions over wide frequency ranges, is disclosed. A plate or disc of dielectric of refractive index n.sub.1 extends sealingly across the waveguide and has two parallel faces which exhibit a pattern of corrugations. One of these faces is in contact with a dielectric fluid of refractive index n.sub.2, and means are provided for cooling and circulating the fluid over said one face. Each of the corrugations extends into the fluid a distance proportional to the inverse of the geometric mean of the product of the refractive indices n.sub.1, n.sub.2. In a preferred embodiment, a second plate is included, separated from the first by a region in which said dielectric fluid is circulated, and in which at least both the faces in contact with the fluid are corrugated. The corrugations not only result in greatly improved matching over a broad band, but also greatly improved fluid flow and surface contact thereof over said one face, for enhanced cooling and thus power handling capability of the window assembly.

Broadband high-power microwave window assembly

In a travelling-wave tube for very high frequencies the slow-wave circuit is formed of four metal combs having teeth pointed toward the electron beam. The combs are arranged in two pairs. The teeth of the two combs in each pair extend inward from opposite sides of the beam and are axially aligned to form the electrical equivalent of a half-wave bar or ladder structure. They may or may not be joined at the tips because those are low-current points. The teeth of one pair are at right angles to those of the other pair and are displaced axially to interleave with them. Each comb is preferably made from a single piece of copper to provide better dimensional precision, low circuit loss, mechanical durability and high thermal capability.

Slow-wave circuit for traveling-wave tubes

Oscillations due to backward waves in a high-power traveling-wave tube (TWT) are inhibited by a non-reciprocal attenuating device which essentially absorbs only backward waves. A directional coupler mediates the exchange of energy between the TWT interaction circuit and an external circuit containing a non-reciprocal loss element such as a ferrite isolator. In such embodiments the high-frequency power handled by the isolator is much less than the power in the TWT interaction circuit. The frequency band handled by the isolator is much narrower than that handled by the TWT. Coupling to the loss element is through one or more resonant circuit elements such that a 'notch' of attenuation is obtained for a backward wave only, at a certain frequency where oscillations are prone, such as the frequency associated with 2.pi. phase shift per cavity in a coalesced-mode coupled-cavity TWT.

Traveling wave tube with non-reciprocal attenuating adjunct

In a waveguide resonator, either coaxial or noncoaxial, there are inserted spaced slots which establish inductances in series with the waveguide structure at the location of each slot. These slots tune the resonance of the waveguide cavity, which would generally be used in a bandpass filter. Switch means are provided for each slot for discretely altering the value of the inductance established, whereby the resonator or filter may be tuned to a large number of different frequencies.

Electromagnetic resonators having slot-located switches for tuning to

A coupling circuit for use at microwave frequencies comprising two conductors each having substantially the shape of a W, which conductors are deposited on a substrate in a manner so that the bases of W's oppose one another to form two semi-lumped capacitances of different susceptance, separated by phasing line lengths.

Semi-lumped element coupler

A proximity coupler is provided for high frequency circuits wherein conductors are deposited on a substrate in the shape of a hollow dumbbell intersected by an X. Coupling is provided primarily across sawtoothed shaped gaps in the dumbbell center section and secondarily across a gap formed by spaced parallel connectors in said center section. The parallel conductors have phase delaying loops at opposite ends, and the resulting coupling characteristics of the proximity coupler can be modified by dimensional changes of the loops.

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Palo Alto, CA, United States of America

Arthur Karp