Coaxial Magnetron

a magnetron with a coaxial resonator around the anode unit and connected by slots with the resonators of the unit. The connecting slots are parallel to the axis of the magnetron in the rear walls of every other resonator.

Coaxial magnetrons are used in various types of ground and airborne radar sets. They are produced only for operation in the pulsed mode, both with mechanisms for slow and rapid frequency tuning and for operation at fixed frequencies from 2 to 70 gigahertz and with power output from 1 kilowatt to 2 megawatts (in a pulse). The coaxial magnetron was proposed by the French engineer C. Azema in 1950; a more modern design was proposed by the American scientists R. Collier and J. Feinstein in 1955.

The coaxial resonator provides the following advantages: (1) an increase in the operating stability of the magnetron (in a coaxial magnetron the frequency drift caused by reflection of waves from the load, and also the width of the frequency spectrum and the intensity of side lobes in the spectrum, is approximately one-fifth as great as in ordinary magnetrons, and the frequency drift caused by variations in current strength, as well as misfires, is one-tenth as great); (2) sufficiently great separation of the frequency of a uniform resonator anode unit so that the use of straps is unnecessary; (3) the possibility of increasing the operating surface of the cathode and the anode unit and thereby reducing the electron flux density, which increases the service life of a coaxial magnetron by a factor of 3-4 as compared to an ordinary magnetron; (4) mechanical frequency tuning of 6-13 percent by moving a piston in the coaxial resonator, with no appreciable change in the power output.