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Load Effects on Passive Networks 373
15
10
8
t
M" 4
5
2
P L (d8)
Po 0 SL= 1
Min 2
1_ 5 4
8
-10
16
SL=32
S,_
-15
1 2 4 8 16 32 64 128
Figure 9.38.
power.
Power from a complex source to a complex load relative to the I : I SWR load
Reference the load power to that delivered to the normalizing resistance Ro.
Call this Po and set SL equal to I in (9.76); this yields
Po _ 4S,
Pa> - (S,+ 1)2'
Therefore, dividing (9.76) by (9.77) yields the minimum relative power:
(9.77)
. P L
SL(S,+ 1)2
mm-=. (9.78)
Po (S,SL+I)2
Note that (9.73) is a strictly increasing function of S. By (9.74) and (9.75),
S,