Re: NEC-LIST: Combining results from different frequencies

Good day Dan,

You are okay for the first three steps. After that, you
have to take the results and convert them to time domain,
because of the two different frequencies. You can then add
the time functions for each frequency to get the total
response for each component. As long as the two excitations
are harmonically related, you can talk about a periodic
waveform and find rms and peak values.

I believe NEC will correctly account for the coupling
effects at each frequency. Since this is a linear system,
the above remarks still apply.

Regards,
Doug Miron

"Dan Maguire" <bethdan_at_pacbell.net> writes:

frequencies

Suppose I have dipole A that is intended to operate at 10
MHz and dipole B
that is intended to operate at 20 MHz. Each has a simple
voltage source at
the center. The two dipoles are separated by a distance of,
say, 100 meters
such that mutual coupling is not a factor. Now further
suppose that I want
to know the total electric field strength at some arbitrary
point C, perhaps
midway between A and B, when both A and B are transmitting
at the same time
on their respective frequencies. I'd also like to know the
current that is
induced on a wire of arbitrary length and orientation,
located in the
vicinity of C.

My thoughts are to:
1. Include all the A, B, and C wires in one set of GW cards.
2. Keep the source on dipole A but temporarily eliminate the
source on
dipole B, run NEC at 10 MHz, save the results.
3. Eliminate the A source, restore the B source, change the
frequency to 20
MHz, run and save the results.
4. Do a vector sum of the near field Ex components from the
two runs. Same
for Ey and Ez. Calculate Etot from the three sums.
5. Vector sum the currents on wire C from the two runs.

>>From a technical point of view, is this a valid way to
model the scenario
and compute the results? In practical terms, is there a
better and/or
easier way? What if A and B are much closer such that there
is significant
interaction between them, would that matter?

Thanks,

Dan

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