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Figure 2-17A.—Magnetron.
Figure 2-17B.—Magnetron.
The magnetron is classed as a diode because it has no grid. A magnetic field located in the space
between the plate (anode) and the cathode serves as a grid. The plate of a magnetron does not have the
same physical appearance as the plate of an ordinary electron tube. Since conventional inductive-
capacitive (LC) networks become impractical at microwave frequencies, the plate is fabricated into a
cylindrical copper block containing resonant cavities which serve as tuned circuits. The magnetron base
differs considerably from the conventional tube base. The magnetron base is short in length and has large
diameter leads that are carefully sealed into the tube and shielded.
The cathode and filament are at the center of the tube and are supported by the filament leads. The
filament leads are large and rigid enough to keep the cathode and filament structure fixed in position. The
