Re: NEC-LIST: Gain Plot

Hello Mike (and others....),

some explanation concerning your Gain plot 'problem'

When using the default nec-2 frequency loop/sweep option in 4nec2
there are three different options:

1) No hor/ver pattern, just show forward gain in chart
2) Get 2D horizontal pattern for each frequency in sweep
3) Get 2D vertical pattern for each frequency in sweep

To get a Gain plot, you should use option 1). With this option you will have
to specify
the Phi/Azim and The/Elev angle of interest. For each frequency a '2 point'
RP card
is added so that both forward- and backward-gain are calculated with 4nec2.
Because gain is only calculated for two angles, no front to rear ratio is
available.
When using a none directional antenna (dipole, vertical, etc.) backward gain
will be
equal to forward gain, so the F/B ration will be zero for all frequency
steps.

When using option 2 or 3 a complete 2D pattern is generated for each
frequency for the
Phi- or Theta angle of interest. Because only the angle for the plane of
interest is
specified, no specific point in this plane is available for which the
Forward gain can
be computed. So for both these options only SWR, and impedance plots are
available.

However if you still want a gain-, F/R- and F/B-plot you can use the 4nec2
Optimiser
(F12 key)and select the 'Evaluate' option. To use this option you must
specify the
Frequency field in you 4nec2 input file as a variable. (See example below).
You can
than select this variable as the one to evaluate and specifie the stepsize
and number
of steps for which the frequency has to be changed.
After calculation you should see both Gain-, F/B and F/R plots (at least if
you used
some kind of directional antenna)
(Example-file will deliver same F/B and F/R values)

Success,
Arie.

p.s. Is the Nec-list still working properly I see strange things
happening.....

###########

CE 2-Element Phased Array by K6STI
'
SY L1 = 397, L2 = 386, SP = 169
'
GW 1 11 0 -L1 0 0 L1 0 1
GW 2 11 SP -L2 0 SP L2 0 1
GS 0 0 in
GE 0
'
EX 6 1 6 00 -.86 .508
EX 6 2 6 00 1.0 0.0
'
GN -1
'
SY freq = 7.1 ' Set freq as symbol
FR 0 1 0 0 freq ' to use in evaluator.
'
EN

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