The component values for the 7 resonant circuits are at the bottom of the printout. See the low pass filter description for assistance with the exponential notation of part values.
The schematic show
all of the component values:
Not shown on the schematic is the impedance level, which from the design
print out we see is 50 Ohms. We can simulate the overall
response:
This plot shows the insertion loss in a 50-Ohm system as the red curve, MS21 or "magnitude of S21>" It also shows in blue the magnitude of the reflected wave, MS11. This latter quantity, shown in dB is a measure of the impedance match looking into one port of the filter with the other port terminated in 50 Ohms. The curves correspond to lossless components. It can be seen that the 0.25 dB ripple response produces a worst case reflection of about -13 dB. It is difficult to see in the plot, but the ripple dips are 0.25 dB, and these occur at the frequencies of highest MS11.
Some people refer to MS11 as return loss. It would seem to be return gain, as it is plotted. But, that term would certainly cause confusion. You can't win.
Filter of this wide pass band tend to have modest insertion
loss, without requiring extremely high Q inductors. For
instance, with a Qu of 150 the mid-band insertion loss is about
0.8 dB. With this low an insertion loss, the 0.25 dB ripple shape
is still seen, but the edges of the pass band do have added insertion loss
of just over 2 dB.
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This page was last updated and Copyrighted 11 December 2013, Robert S. Larkin
Please email comments or corrections to bob 'the at
sign' janbob dot com