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Questions tagged [antenna-modeling]

Use for questions about using antenna modeling software to simulate an antenna system and determine its gain and radiation pattern.

The correct spelling in English-speaking countries outside the US is antenna-modelling.

With modeling software, you can determine the pattern, feed point impedance and even the SWR of your antenna system before cutting one piece of wire or one tube of aluminum. This can save an awful lot of tree and tower climbing.

Antenna modeling used to be the domain of scientists and engineers with very expensive antenna ranges covering acres and acres of land strewn with expensive equipment. However, with the proliferation of personal computers and affordable (even free) software, antenna modeling has become a popular amateur activity.

From http://www.arrl.org/antenna-modeling

Popular antenna modeling software

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How to correctly model a small helix antenna

I am getting weird results trying to model a small 433 MHz helix antenna similar to this one with 4nec2: In particular I am not able to obtain a resonable SWR value. This is the antenna an example of the nec file. CE SY L=0.0205 'Length of helix SY…
stenio
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4nec2: What does "#12/in" mean?

I've been seeing this #nnn pattern in SY cards a few times, but I can't find any mention of it in the documentation. I'm guessing it's an AWG specification, but then I see something like this: SY D = #12/in So maybe #12 specifies 12 AWG in m and…
mcmayer
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Does 4nec2 allow SY variables/formulas in integer fields?

I've looked at the various guides I found on the 'web, and I cannot find a single example of a 4nec2 deck that has a variable or formula in one of the integer fields. But at the same time, none of those documents say you can't put one there. I'm on…
Maury Markowitz
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GS cards in NEC decks

I'm trying to understand the use of GS cards in NEC2 decks. The documentation is rather vague! Consider a basic stack: CM My antenna CE GW 1 3 0 1 4 0 1.707 4.707 0.057 GS 0 0 .5 LD ... RP ... EN As I understand it, in the…
Maury Markowitz
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4nec2: simulating the effect of walls over the far-field pattern

I live at the 15th floor and am interested on a pair of window-mount antennas for the 40 meters band: a top-fed vertical; and a loaded monopole, which I've already used with pretty decent results. I'd like to run some simulations of both on 4nec2,…
Rodrigo Magalhães
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Where can I find London borough outlines for SPLAT!

Splat seems like it's a great tool for modelling what RF coverage I should have. It can create a nice circle around me, after I download topology data from USGS, namely SRTM-1. But when the coverage map (created using -L 17) gets created it looks…
Thomas
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How to model a curved element in 4NEC2

I am in kindergarten with 4NEC2 and trying to model a Gray-Hoverman TV antenna. I have someone else's model and understand most of the file parameters. I have added VHF elements that have S curves at each end but I can't find any info as to how to…
ruggb
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Modeling a multiband Yagi in 4NEC2?

I tried to model a multiband yagi. I added radiators for 10-15-20M, and reflectors spaced .15 wavelenghts away. This gave a nice result with three sharp dips in SWR in the 10-15-20M center frequencies. For some limitation of NEC2, I had to make…
hjf
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4NEC2 shortening factor "x"

I read on pg5 of Antenna Simulation with 4NEC2 about shortening factor "x". It is very specific and I can't figure out how to use it in a general nec file. It sounds like SY x=0.907 in the nec file will shorten all the Y parameters, but that doesn't…
ruggb
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