[3D Near Fields] [Smith Chart] [ICEPAC file generation] [Loop correction switch]

Frequently Asked Questions
Support, Discussion, Search

Web Orders

Other Links



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 simulation.
  • ICEPAC file generation.

Near 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.

3x3nf.gif (23194 bytes)

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.

smith.gif (12581 bytes)

ICEPAC 13 file generation

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.

hfant4sqaz.jpg (16024 bytes)
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 Montreal to YOKOTA 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.

Mtl2JARP120.jpg (44229 bytes)
Required Power/Antenna gain

Mtl2JASN120.jpg (43613 bytes)
Signal to Noise

ICEAREA.jpg (57921 bytes)
Forecasted December MUF from Montreal to Japan "short path" (Red line)


Loop/Quad correction

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 examples.

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

Uncorrected Quad 3el

n4wv36Z.jpg (12307 bytes)

NEC2Z.jpg (15216 bytes)

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.

NEC4WIN95 file   -  NEC2 File

quagistdswr.gif (3159 bytes)

quagicorswr.gif (3009 bytes)

Q144snec.gif (6539 bytes)

quagi.gif (2122 bytes)


Copyright 2005 ORION Microsystems.