
471Microwave Tubes
Figure 12.48b is called a cookie-cutter tuner. It consists of a metal ring that is
inserted between the two rings of a double-strapped magnetron. It increases
the strap capacitance. Because of the associated mechanical and voltage
breakdown problems, cookie-cutter tuner is more suitable for use at longer
wavelengths.
Both the above methods allow frequency variation of up to 10% of the cen-
tral frequency. For obtaining larger tuning range, the two tuning methods
may be used in combination.
12.6.8 Mathematical Analysis
12.6.8.1 Electron Motion
In cylindrical (conventional) magnetron, a number of cavities are connected ...