Quote:
Fine, but I still dont understand the "why" of massive segmentation of a simple wire in the program. Its one of things that gives me "brain freezes" about the program.
You know, like something you buy in a bookstore about shortcuts to Microsoft Word, Excel etc, all the main functions laid out in a page or two.
300ohm,
Here is a partial quote from the nec2 wiki page....
The Numerical Electromagnetics Code (NEC), credited to Gerald Burke, is an algorithm and generic computer application, originally written in FORTRAN. Developed in the 1970s, it is a popular antenna modeling method for wire and surface antennas.
NEC models can include wires buried in a homogeneous ground, insulated wires and impedance loads. The code is based on the method of moments solution of the electric field integral equation for thin wires and the magnetic field integral equation for closed, conducting surfaces. The algorithm has no theoretical limit and can be applied to very large arrays or for detailed modeling of very small antenna systems.
So this method of moments of the electric field and magnetic fields is a complex mathematical integration process that calculates values for every small segment and then integrates that over the complete antenna structure.
If you visualize drawing a circle by using only straight lines, then the smaller the length of your straight line segments, the closer you get to defining a circle. By taking this to very, very small lengths, you approach a perfect circle. This is in essence what segmentation is all about with nec2.
In fact, if you read up on the "Convergence Test" in 4nec2's General help, you'll see that this test is very similar to drawing the circle with smaller line segments. You'll get a more accurate model, by using more segments, but the CPU execution time increases ( It is roughly proportional to the (Number of segs)^2. So by running the convergence test, you can make an appropriate trade-off for accuracy vs cpu execution time. If you stick to the safe segmentation rules discussed in an earlier post, convergence tests are probably not that important to run.
Re the cheat sheet for 4nec2:
I haven't seen anything other than Arie Voor's first page in 4nec2's General help file. If other forum members have some info, please share it.
If you want more info on the nec2, Arie's web site makes the Nec2 user manual available, as well as a four part series on "Beginners Guide to NEC Modeling".
http://home.ict.nl/~arivoors/
Links to the
Beginners Guide is at the bottom of the main page, and the NEC2 user guide is available from the
NEC2 support files link.