NEC4WIN95VM v3 new features
NEC4WIN95VM v3 contains these new features:
- 3D Near Field display.
- Smith Chart impedance output.
- Loop correction switch for loops and Quads
- ICEPAC file generation.
Fields 3D View
NEC4WIN95VM will display a graphic 3D view
of Near Fields. You
can display the Near Field for different heights between the limits
you specified at calculations.
Graphs can be displayed in Log, Linear
or Percent units.
The 3D view is freely rotated on the screen using the Mouse
and the CTRL Key.
Smith Chart Impedance output
In addition to the standard rectangular
impedance plot NEC4WIN95VM v3 can also display impedance on a frequency
range in Smith Chart format. The reference impedance can be changed
on the fly without recomputing
values. The Chart can be printed and copied to other Windows
programs using Cut and Paste.
ICEPAC 13 file
ICEPAC, the Ionospheric Communications Enhanced Profile
Analysis and Circuit Prediction Program predicts the expected performance of high
frequency (HF) broadcast systems for the four seasons, different sunspot activities, hours
of the day, and geographic location. It is a high level propagation analysis software
derived from IONCAP, designed by the ITS Institute for Telecommunication
Sciences and distributed freely on Internet on a US Dept. of
Commerce site maintained by Gregory R. Hand. You can
download from there a version of ICEPAC for Windows 95/98 and NT called HFWIN32.
ICEPAC model 13 files are specially
formatted 3D gain data for an antenna that can be used directly in ICEPAC, IONCAP, VOACAP,
HFANT and most other programs found in the ITS package. The gain table file is an ASCII
table with 360 * 90 values of the antenna gain. The file is generated with an ICEPAC model
13 (3D Gain table) header and can be used directly in ICEPAC as an antenna definition file
to generate propagation HF forecasts.
We think that many amateurs and
professionals can benefit from this option and hope that it will trigger an increased
interest in ICEPAC.
HFANT is an antenna pattern plot included
in the ICEPAC software.
HFANT azimuth pattern for the 4-square demo project
As you can see below ICEPAC and ICEAREA can
generate very complex forecasts of all sorts. You have here just 3 samples of the dozen
reports than can be generated by ICEPAC using the new NEC4WIN95VM feature.
Sample reports below generated for December
1999, assuming a Solar Sunspot Number SSN = 120 from
AFB on all HF bands from 2 to 30MHz using 4 different antennas: a 4-square on
3.795Mhz, a 7dBi gain on 7.05MHz and an 8dBi beam on 21 and 28MHz.
Required Power/Antenna gain
Signal to Noise
Forecasted December MUF from Montreal to Japan "short
path" (Red line)
The original algorithms of
Mininec3 have problems with Quads and loops because of the "corner problem".
Quad models will always resonate too high in frequency. The recommended technique for
better results was to taper segments near the corners, but this implies more wires and
segments, longer simulations etc...
The new Loop correction switch
modifies standard Mininec3 algorithms to simulate loops and quads with greater
accuracy without increasing the number of segments or adding any tapering. Tests and
simulations show that results are very close to NEC2 as demonstrated below on a few
Three element Quad
from ARRL antenna handbook
Here is the NEC4WIN95 file, the equivalent NEC2 file and the results:
Without correction.........Z =
34.8 Ohms at Fres= 14.37MHz
With Loop correction......Z = 34.75 Ohms at Fres = 14.165MHz
NEC2 simulation............Z = 35 Ohms at Fres = 14.163MHz
Quagi 144.5MHz from ARRL antenna handbook (18-33)
This quagi was modeled from the ARRL antenna handbook. The
NEC4WIN95 model was not tapered and segmented to have around 20 segments/wavelength.
- NEC2 File