If you want to analyze an antenna, you can use simulation software or you can build an antenna and make measurements. [All Electroncs Channel] does both and show you how you can do it, too, in the video below.
The antenna in question is a loop antenna. He uses a professional VNA (Vector Network Analyzer) but you could get away with a hobby-grade VNA, too. The software for simulation is 4NEC2.
The VNA shows the electrical characteristics of the antenna, which is one of the things you can pull from the simulation software. You can also get a lot of other information. You’d need to use a field strength meter or something similar to get some of the other information in the real world.
The antenna simulation software is a powerful engine and 4NEC2 gives you an easy way to use it with a GUI. You can see all the graphs and plots easily, too. Unfortunately, it is Windows software, but we hear it will run under Wine.
The practical measurement is a little different from the simulation, often because the simulation is perfect and the real antenna has non-ideal elements. [Grégory] points out that changing simulation parameters is a great way to develop intuition about — in this case — antennas.
Want to dive into antennas? We can help with that. Or, you can start with a simple explanation.
“In Theory, Theory and Practice are the same.
In Practice, they are not!”
I feel obtaining and plugging in any kind of real world data (recorded or measured) into a simulation can get you quite far.
But at that point you aren’t purely simulating stuff.
Of course I’m taking about non rf stuff
Lots of “RF stuff” can be modeled and simulated just fine if you understand the variables, understand the theory, and use the right software. I’ve modeled MANY antennas, built them, and had them come out very close to the model. The biggest discrepancy I’ve had to deal with is that actual ground parameters are not easy to quantify and are often non-uniform anyway.
When they aren’t the same, it’s because one of two things:
Not enough of the real life variables were understood and quantified.
The person using the theory didn’t actually understand the theory.
Both are often the case, especially among those who deride theory.
In your theory, practice always overrules theory. In practice, when this happens it’s usually because someone’s not using the right theory. Often, the practices in place imply things work a completely different way than they actually do, but nobody can prove it without a better theory.
For Linux, there is xnec2c.
EZNEC has more capability than 4NEC2, and EZNEC Pro+ is freeware now. AutoEZ (not free) is a phenomenal piece of software that works in conjunction with EZNEC and allows (among many other things) the use of variables in the antenna design.
By the way, a terrific way to learn about any particular antenna is to model it and then look at the currents (magnitude and phase) at various points on the elements of the antenna since current is what radiates the RF.
It’s probably good to point out that these are different interfaces to the same kernel doing the analysis.
http://dg7ybn.de/Ant_soft/Ant_Software.htm#intro
That is true to a point, except that EZNEC can function with NEC5 (a much newer kernel) … which is considerably more powerful than the NEC2 in 4NEC2. EZNEC also has a version that works with NEC4.