Hughes Aircraft Company

Hughes Electronics Corporation

Ivo Tammaru

Robert G Ripley

Sunder S Rajan

Roger S Hollister

Tore Wessel-Berg

Jon A Davis

Steve L Bosma

E Allen Adler

John W Eldridge

James W Hansen

Christine G Thoma

A self-biasing element is formed by coupling an electron accumulator to a collector stage of a linear-beam microwave tube with a base which has a selected resistance. The electron accumulator has a secondary emission coefficient less than one and is positioned to intercept a portion of the electrons in the electron beam of the linear-beam microwave tube. The electron accumulator thus acquires a negative voltage whose magnitude is controlled by selecting the base resistance and the radial and axial position of the self-biasing element within the collector. Various arrangements of self-biasing elements and collector stages are disclosed which improve the efficiency and RF performance of the microwave tube.

Self-biasing collector elements for linear-beam microwave tubes

Apparatus compensating for gain variations versus frequency of a traveling wave tube (TWT) is disclosed. The apparatus provides an RF interaction circuit section designed with specified mismatches causing internal reflections of the RF waves, such that the overall gain response is flattened out or inverted.

TWT with mismatched section for controlled gain variation with frequency

Lossy slabs are provided in linear-beam tubes such as coupled-cavity TWTs and klystrons to produce a more level tube response over its full operating band, and to eliminate oscillations at the upper cut-off frequency in the TWTs. The slab thicknesses are selected to produce a substantially non-resonant field of about one-quarter wavelength within the slab when the tube is operated within its passband. The slabs are formed from a dielectric material with a conductive mixture of at least about 15%.

Linear-beam cavity circuits with non-resonant RF loss slabs

A traveling wave tube (10) includes a coupled cavity type slow wave structure (100) having a driver stage (52) and an output section (101) with a primary section (64) and a velocity taper section (82) which in combinattion produce maximum signal gain at a predetermined frequency. A gain flattening section (104) is preferably disposed between the driver stage (52) and the primary section (64) of the output section (101), and is designed to operate at a reduced phase velocity selected to produce minimum or negative signal gain at approximately the predetermined frequency. The gain characteristics of the driver stage (52), gain flattening section (104), primary section (64), and velocity taper section (82) combine to produce minimum signal gain variation over an operating frequency range which spans the predetermined frequency, and expand the bandwidth of the traveling wave tube (10).

Traveling wave tube with gain flattening slow wave structure

Two or more signal interaction structures (16,18), which may be klystron or traveling wave structures (32,50), are axially disposed in series between an electron gun (12) and a collector (14) for selectively velocity modulating an electron beam (20) generated by the gun (12) with a microwave input signal (IN1,IN2) and extracting a resulting amplified microwave output signal (OUT1,OUT2) from the beam (20). The interaction structures (16,18) are designed to operate in different frequency bands, for example the X and Ku bands, with only one of the structures (16,18) having an input signal (IN1,IN2) applied thereto at any given time. The interaction structures (16,18) are further designed such that the structures (16,18) which are not being used do not affect the structure (16,18) which is being used.

Velocity modulation microwave amplifier with multiple band interaction

Extra loss is introduced in coupled cavity and klystron RF circuits by applying a surface coating to selected parts of circuit elements used in the circuits. The coating is applied in the form of a slurry, which is then sintered. The slurry comprises a mixture of an iron-base powder (such as a stainless steel) and a dielectric glass ceramic, suspended in a binder dissolved in a solvent. Circuits with the loss coating are easier to match than by other prior art techniques. The loss coating of the invention reduces the fabrication cost of coupled-cavity traveling wave tubes, while improving the performance by minimizing the gain ripple. Higher average power operation is possible, due to elimination of loss buttons previously employed in the prior art.

Surface coated RF circuit element and method

A gyrocon deflection system can provide circular beam deflection using a single RF coupler, without providing a phase difference between the two beam deflection signals to account for electron beam transit time between the two sets of deflection plates. The two sets of deflection plates are internally connected pairwise together so that both deflection regions are in RF phase, and the midplanes of the two sets are spaced 90.degree. apart electrically at the desired operating voltage and frequency.

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Rancho Palos Verdes, CA, United States of America

Ivo Tammaru