The Environment sheet is opened by clicking on the
Environment button in the spreadsheet window. This is where
you set the frequency, ground parameters and ground radials
for your antenna model.
You can choose a single fixed frequency to analyze your
antenna model, or apply a sweep between two frequency
limits, or select up to four arbitrary frequencies.
If you choose a frequency sweep, you can specify the total
number of frequency steps and you have the option to use
linear frequency steps or geometric frequency steps.
You can also choose to use up to four arbitrary
frequencies. This mode can be useful when you are modeling
a multiband antennas where you would like to see the feed
point impedances for all the bands on the same plot in the
Output window. If you need fewer than four frequencies, you
can leave the unused text fields empty.
The Ground panel in the Environment sheet lets you
set the relative dielectric constant and the conductivity
of the ground under your antenna.
There are some preset "grounds" (i.e., relative dielectric
constant - conductivity pairs of numbers) that are
selectable with the pop up menu in the Ground panel.
By picking Other... you can enter your own
You can use the more accurate Sommerfeld ground
approximation by checking the Use Sommerfeld/Norton
The Radials panel allows you to include a ground
screen under your antenna.
Selecting the None option will cause your antenna
to be modeled in the absence of any radials. By selecting
the Radials option, you can create a set of wires
centered at (x,y,z) each one with the given length and with
the given wire radius. The advantage of generating radials
this way is that the wires are specially tagged so that the
Output display can choose to draw them or not draw them.
Radials generated this way, however, are not suitable for
use with ground mounted vertical antennas since NEC-2 does
not allow wires to be close to ground.
To model ground mounted vertical antennas, you should use
the NEC-2 Radials option. When you choose to use
NEC-2 ground radials, the center of the radials must be
placed at x=0, y=0 and z=0. Your ground mounted vertical
antenna must therefore have one end at (0,0,0). NEC-2
radials are not drawn in the geometry view of the Output