The numbers you get seem about right. For the DE, the 7.6 amps implies
a feedpoint resistance of about 26 ohms. Which is reasonable for a
yagi. The other element currents seem about right too. Since some of
the power is going forward, the REF current is going to be less. Since
some of the power is leaked into other directions, the DIR current will
be less than the DE current but more than the REF current.
4nec2 works well if you are careful about making well formed antennas.
If you run the version with the DirectX graphics, you can get a nice 3D
visualization of the currents on the elements. This is sometimes very
useful in figuring out why things aren't working as expected.
73,
Erich, N6FD
On 12/22/2010 6:28 PM, Kevin Normoyle wrote:
> On 12/22/2010 5:46 PM, Al Williams wrote:
>> I am surprised that YO or 4nec2 don't include actual current measurement
>> in the parasitic elements.
> 4nec2 includes the nec2 output file with numbers if you want them.
> I use File/Save Nec output file, then look at the file (after a calculate)
>
> If you specify the voltage magnitude correctly on your input deck (assuming
> that's how you drive the thing)..the numbers in the output are correct amps,
> aren't they?
>
> i.e. it looks like this. (these segs are tips..low current0
>
> - - - CURRENTS AND LOCATION - - -
>
> DISTANCES IN WAVELENGTHS
>
>
> SEG. TAG COORD. OF SEG. CENTER SEG. - - - CURRENT
> (AMPS) - - -
> NO. NO. X Y Z LENGTH REAL IMAG.
> MAG. PHASE
> 1 1 -0.2336 -0.0118 1.0088 0.01168 3.4782E-01 3.1149E-01
> 4.6691E-01 41.845
> 2 1 -0.2220 -0.0118 1.0088 0.01168 8.6683E-01 7.7849E-01
> 1.1651E+00 41.927
> 3 1 -0.2103 -0.0118 1.0088 0.01168 1.3280E+00 1.1962E+00
> 1.7873E+00 42.010
> 4 1 -0.1986 -0.0118 1.0088 0.01168 1.7632E+00 1.5929E+00
> 2.3762E+00 42.095
>
> 4nec2x also can generate plots of current mag/phase/real/img (from the
> Geometry/plot). Those currents seem to track the "input power" setting. I'm
> not
> sure how they are connected to the nec2 output file.
>
> as a for instance:
> for example, a 3 element 20 at 70', Zl=25, 1" Al, with an LC match
> the plot shows current magnitudes: (max at center). 1500w input power
> 7.6 for the de
> 4.5 for the dir
> 3.1 for the ref
>
> relatively, those numbers seem right. Absolute, maybe seems high..Not sure.
> That doesn't seem to track changes to the voltage magnitude I use in the
> input,
> but the nec2 output file does track the voltage magnitude I use on the input.
>
> -kevin
> ad6z
>
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