Thorn Emi-varian Limited

Thorn Microwave Devices Limited

Melvin G England

A coaxial magnetron incorporates a quantity of dielectric material within the coaxial cavity between the resonant cavity and the outer wall of the magnetron. The dielectric material has sufficiently high relative permittivity, and Q factor, and is provided in sufficient quantity that the size of the cavity may be reduced for a given frequency and power output.

Coaxial magnetrons with dielectrically loaded output cavity

In a magnetron having a rotatable tuning member in the form of a spinner (121), a rotation sensor and an associated processor (10) generates an indication signal (11) representing the instantaneous magnetron frequency. Three level discriminators 13(1), 13(2), 13(3) are arranged to compare the indication signal (11) with respective threshold signals 14(1), 14(2), 14(3) representing different, preset frequencies. The level discriminators produce a trigger signal T effective to initiate transmission of a pulse of radiation whenever the instantaneous magnetron frequency matches one of the preset frequencies.

Magnetron with frequency control means

In a magnetron a spinner (22), rotatable on a longitudinal axis (x) has a number of evenly spaced markings formed circumferentially on an exterior surface. The markings are sensed, as the spinner rotates, by a photo sensitive transistor (PT) coupled to window (26) in the vacuum envelope of the magnetron by a fiber optic pipe (FP1). The periodicity of pulses, generated by the transistor in response to movement of markings past the window, is divided in a network (43) to generate a succession of further pulses. The further pulses are then counted in circuit (44) and the instantaneous count compared with reference frequency values stored in memory (46) to generate an output signal O/P(1) related to the instantaneous magnetron frequency.

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Ashford Common, United Kingdom

Melvin G England