RE: NEC-LIST:Proper Antenna Patterns

Chuck,
        When the dust settles, I will clarify my question and send out an example.

-----Original Message-----
From: nec-list-admin_at_gweep.ca [mailto:nec-list-admin_at_gweep.ca]On Behalf
Of Chuck Counselman
Sent: Thursday, October 11, 2001 11:00 AM
To: nec-list_at_gweep.ca
Subject: RE: NEC-LIST:Proper Antenna Patterns

At 9:35 AM -0500 10/11/01, KLysiak wrote:
>Because an antenna has it own characteristic impedance, the current
>distribution on the antenna is altered by the "source" impedance
>whether it is a receive or transmit antenna. Altering the
>current distribution in turn alters the pattern. This may not be noticeable
>on a simple dipole but becomes quit noticeable in complex scattering
>environments (even on simple Yagis).

I don't believe this. I invite you to post a NEC input file
describing an antenna excited by a single voltage source with a
nonzero "source impedance" in the same segment as the source (not
somewhere else!), for which "the current distribution on the antenna
is altered by the source impedance."

I will run your file with two substantially different values of the
source impedance (such as zero and 100% of the value you specify) and
report the results. Other list subscribers can do the same to
satisfy themselves. No one will have to guess, or wonder, which one
of us is correct.

The only difference that I expect to see between the two computed
current distributions is an overall, constant, position-independent,
scale-factor -- reflecting the fact that the source currents differed.

I invite you to post said file because there is no point in me
posting a negative result. You could just say that the model I
posted was somehow unsuitable for exhibiting the phenomenon that you
claim exists. E.g., you say "This may not be noticeable on a simple
dipole."

If it exists, show us an example.

-Chuck.

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