Henry Kolesnik wrote:

Dave

Nice site, I like the "white paper" approach as I prefer the info without
the glitter. I've only read a few items and I
quote: "This is a plot of the attenuation provided by the stub. You can see
that it provides about 32db of attenuation at 28.25Mhz. " I've noticed that
the literature I've purused indicates that stubs either attenuate or reject.
None say reflect! I don't want to get into a discussion of word definitions
becasue reflect and feject are close but attenuate is not in the same class.
Comments...

They indeed do attenuate or reject. Reflections is the method by which
stubs accomplish the attenuation or rejection. If one is only interested
in implementing stubs, and not interested in how they work, one need not
deal with reflections. What one must realize, however, that the SWR inside
a resonant stub is as high as it can be. All the reflections take place at
the shorted or open end of a stub, i.e. at the physical discontinuity point
where rho = |1.0|.

I don't have any argument with people who say, "I only want to use stubs.
I don't care how or why they work." My argument is with people who falsely
describe how they work, e.g. "Since the impedance looking into a shorted
1/4WL lossless stub is infinite, no current flows into or out of the stub."
If that were really true, one could remove the stub without changing
anything. The net superposed current may be zero but the forward and reflected
currents exist there and can be very high values. In fact, I have melted the
insulating material at the end of a shorted coaxial stub due to high I^2*R losses.
--
73, Cecil http://www.qsl.net/w5dxp



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