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Invulnerable Filters 379
20 t
lmin
15
dB
10
Figure 9.43.
oL-......;iii;iii~
.2 .5
1.0
W-
2.
Selectivity curves for the invulnerable bridged-T network.
5.
10.
Bartlett's bisection theorem to convert the bridged-T network in Figure 9.41 to
a symmetric lattice, which is a constant resistance when d = 1 (see Guillemin,
1957). When d= I, implying that R=A/c, bridged-T networks may be
cascaded so that the overall L min
is just the sum of the individual L min values.
Equations (9.92) and (9.98) provided the design curves in Figure 9.43. Note
that (9.98) gives the same result for d and 1/d; the curves in Figure 9.43 are
64
32
16
B
4
2
1
.2 .5 1. 2. 5. 10.
Figure 9.44.
w-
Maximum possible SWR for bridged-T invulnerable filters.