Radar System Engineering

328 THE MAGNETRON AND THE PULSER [SEC. 102
oscillation is at least one less than the number of oscillators. Figure 10.S
shows the distribution of charge
and electric field for a magnetron
oscillating in the r/2-mode.
A comparison of the electric fields
with those of the r-mode shown
in Figs. 10.6a, b, and c indicates a
fourfold, instead of eightfold, symmetry,
and shows that the field
falls off less rapidly toward the
cathode. Experience has shown
that magnetron operation in any
/
output boll
FIG, 10,7,—View from cathode of anode
block opened out to show longitudinal distribution
of magneticfield.
but the r-mode is unsatisfactory.
Possible modes for an 8-oscillator
magnetron total seven: two 7r/4-
modes, two r/2-modes, two 3r/4-modes, and one mmode. In general,
because of differences in the effective inductance and capacity of the
FIG. 108.-Distribution of r-f fields and chargesin a hole-and-slotanode block oscillating
in the T/2 anode.
oscillating circuits, each of these modes has a different frequency of
oscillation. One of the objectives of magnetron design is to arrange