Hi all,
Wow looks like I missed lots of fray.
I don't know which theory is right (if either).
Sorry this post turned out a little long winded despite my attempts to keep it short.
Shockwave :
For repeatedly belittling with such authority 4nec2 and nec engine software in general even though you had no idea what you were talking about.
I do think you should eat a little crow.
If I missed that post please someone point to it.
Henry hpsd:
Nice article it was an interesting read.
You make a very persuasive argument.
I was happy you mentioned the model I posted though I wish I could have offered a more polished model instead.
The original is a useful model but small ring dimensions cause the AGT to go astray due to the very acute angle of radial to main element.
The one below gets 2.68 dBi at the horizon (free space) and tolerates quite small ring dimensions.
I added small stubs to attach the radials at a better angle.
I also set the SY variables to set it a lot closer to the actual dimensions of the sigma.
Code:
CM 11 meter cb by ghz24
CE
SY z=324 'driven element length
SY rh=108 'ring height
SY zp=12 'avoid segment errors during sweeps
SY rsf=0.976 'changes ring diameter
GW 1 5 0 0 0 0 0 zp 0.07
GW 2 101 0 0 zp 0 0 z 0.05260011
GW 6 49 0 2 0 0 30*rsf rh 0.05260011
GW 7 49 0 -2 0 0 -30*rsf rh 0.05260011
GW 8 49 -2 0 0 -30*rsf 0 rh 0.05260011
GW 9 49 2 0 0 30*rsf 0 rh 0.05260011
GW 16 1 0 0 0 0 2 0 0.05260011
GW 17 1 0 0 0 0 -2 0 0.05260011
GW 18 1 0 0 0 -2 0 0 0.05260011
GW 19 1 0 0 0 2 0 0 0.05260011
GW 100 3 29.99994*rsf 0*rsf 0+rh 27.7163225*rsf 11.4804889*rsf 0+rh 0.05260011
GW 101 3 27.7163225*rsf 11.4804889*rsf 0+rh 21.2131466*rsf 21.2131466*rsf 0+rh 0.05260011
GW 102 3 21.2131466*rsf 21.2131466*rsf 0+rh 11.4804889*rsf 27.7163225*rsf 0+rh 0.05260011
GW 103 3 11.4804889*rsf 27.7163225*rsf 0+rh 0*rsf 29.99994*rsf 0+rh 0.05260011
GW 104 3 0*rsf 29.99994*rsf 0+rh -11.480489*rsf 27.7163225*rsf 0+rh 0.05260011
GW 105 3 -11.480489*rsf 27.7163225*rsf 0+rh -21.213147*rsf 21.2131466*rsf 0+rh 0.05260011
GW 106 3 -21.213147*rsf 21.2131466*rsf 0+rh -27.716323*rsf 11.4804889*rsf 0+rh 0.05260011
GW 107 3 -27.716323*rsf 11.4804889*rsf 0+rh -29.99994*rsf 0*rsf 0+rh 0.05260011
GW 108 3 -29.99994*rsf 0*rsf 0+rh -27.716323*rsf -11.480489*rsf 0+rh 0.05260011
GW 109 3 -27.716323*rsf -11.480489*rsf 0+rh -21.213147*rsf -21.213147*rsf 0+rh 0.05260011
GW 110 3 -21.213147*rsf -21.213147*rsf 0+rh -11.480489*rsf -27.716323*rsf 0+rh 0.05260011
GW 111 3 -11.480489*rsf -27.716323*rsf 0+rh 0*rsf -29.99994*rsf 0+rh 0.05260011
GW 112 3 0*rsf -29.99994*rsf 0+rh 11.4804889*rsf -27.716323*rsf 0+rh 0.05260011
GW 113 3 11.4804889*rsf -27.716323*rsf 0+rh 21.2131466*rsf -21.213147*rsf 0+rh 0.05260011
GW 114 3 21.2131466*rsf -21.213147*rsf 0+rh 27.7163225*rsf -11.480489*rsf 0+rh 0.05260011
GW 115 3 27.7163225*rsf -11.480489*rsf 0+rh 29.99994*rsf 0*rsf 0+rh 0.05260011
GS 0 0 0.0254
GE 0
GN -1
EK
EX 0 1 1 0 1 0 0
FR 0 0 0 0 27.18 0
EN
DB:
Good job.
Part of the reason I left the posted model so far from a stock sigma was to incite someone to use the variables to "fix" the dimensions.The other was so they would definitely see it was not an exact dimensional clone of any of the stock models.
It was also where one particular "optimization" run left the dimensions
When I first started to model I learned a lot more by breaking and butchering other peoples models.
In that spirit I'll start a thread and post some of the more interesting models I have made.
I haven't had a chance to run the model you modified but I'll get to it soon
Marconni :
If I've insulted you let me apologize.
I gave you the strongest argument I could find to help support the accuracy of your models.
It had to do with the separation of the current maximums not being far enough apart to induce the gains claimed.
Some where I found an equation relating collinear gain to separation of the current maximums.
Your reservations about including the model due to dimensional differences just points out that you don't get the point of he model.
You called it broken and butchered but you missed that it's flexible you or the computer can test the dimensions of hundreds of slightly altered versions and spot trends. Learning things by slightly breaking the model in a thousand ways and seeing the results.
How long would it take you to alter one of your models to have a ring 36" with radials 100" long?
It would take me about 2-3 minutes to match almost any dimensions you can name.
4nec2 can use the model to sweep through 200 consecutively larger rings or longer radials in a couple minutes
It is a what if model.
If you just tasted that power you'd be hooked.
I don't understand how "your goose is cooked"
Seems like your models are right in the right neighbourhood if not right on target.
Does goose cooked mean vindicated where you're from?
BTW I'm the one with optimizer issues I'll post a log file that will point out why at the end.
Hommer :
You're a homebrew antenna master.
I watch for your input and must give weight to your (and others) experience even though it is somewhat anecdotal.
But I'm sort of your opposite it's not that I don't care how it works It peaks my curiosity but getting a handle on the gain capabilities of this type and hearing that the highly tauted CST gets the same results I saw is more exciting.
It takes you even longer to alter one of your models.
Don't sell yourself short, running an existing model someone else
has built is not a very steep curve for someone like you.
4nec2 runs under wine.
It is a little clunky and all the features may not work.
But maybe I made some incorrect choices when I installed it on my ubuntu 14.04 R-60 thinkpad, ( I was trying to avoid windows when XP died)
Even still it's usable just may not get 3D viewer.
This log file points out the optimizer passing up better results.
It may be easier to copy the text into a text editor with the word wrap off so you can see the format
You can study the whole thing if you want but I just want to point out the line at the start of the 2nd run it gets a value of 2.21 dBi then ignores that value to "decide" that
1.45 dBi was the optimum gain.
The optimizer still has some value and doesn't always get lost like this and when I scan the results I can go back and find the variable value that created the higher gain and start from there myself.
The point is the optimizer doesn't always pick the best available model.
There is a solution but this post is long enough I'll get into that later in a different thread.
Code:
Run SWR Gain F/B F/R R-a X-a Eff. %Res. %Stp z rh rsf
1-0 1.3538 0.6 0 -1.43 36.99 -1.317 99.35 0 0 338 61 1
1 1.3509 0.58 0 -1.45 37.012 0.1445 99.36 -8e-3 0.1 338.34 61 1
1 1.3535 0.61 0 -1.41 36.992 -1.254 99.35 0.011 0.1 338 61.061 1
1 1.3531 0.6 0 -1.42 37.003 -1.231 99.35 9.e-4 0.1 338 61 1.001
1-1 -1.259 1.61 0.1307
1-2 11.592 2.21 0 -0.02 58.825 -168.5 97.93 -0.06 10 295.44 70.821 1.0131
2 1.3509 0.58 0 -1.45 37.012 0.1445 99.36 -8e-3 0.1 338.34 61 1
2 1.3535 0.61 0 -1.41 36.992 -1.254 99.35 0.011 0.1 338 61.061 1
2 1.3531 0.6 0 -1.42 37.003 -1.231 99.35 9.e-4 0.1 338 61 1.001
2-1 -1.259 1.61 0.1307
2-2 2.2982 1.23 0 -0.67 37.521 -34.93 98.97 0.296 2 329.49 62.964 1.0026
2-3 4.0234 1.66 0 -0.27 39.838 -66.5 98.59 0.112 2 321.19 64.992 1.0052
2-4 6.1486 1.94 0.01 -0.11 43.787 -96.95 98.3 -0.03 2 313.1 67.085 1.0079
3 6.0481 1.93 0 -0.12 43.624 -95.65 98.31 3.e-3 0.1 313.41 67.085 1.0079
3 6.1385 1.94 0.01 -0.11 43.804 -96.86 98.3 9.e-4 0.1 313.1 67.152 1.0079
3 6.1425 1.94 0.01 -0.11 43.806 -96.91 98.3 5.e-4 0.1 313.1 67.085 1.0089
3-1 2.1048 0.6008 0.2945
3-2 2.5572 1.58 0 -0.35 39.036 -41.6 98.66 0.202 2 326.28 67.891 1.0138
3-3 1.6109 0.93 0 -1.03 37.843 17.047 99.24 -0.4 2 340.01 68.706 1.0198
4 1.6545 0.91 0 -1.06 37.861 18.515 99.26 -0.03 0.1 340.35 68.706 1.0198
4 1.6128 0.93 0 -1.03 37.849 17.119 99.24 -7e-4 0.1 340.01 68.775 1.0198
4 1.613 0.93 0 -1.03 37.858 17.132 99.24 -9e-4 0.1 340.01 68.706 1.0208
4-1 -2.87 -0.059 -0.07
4-2 1.3372 1.22 0 -0.7 37.873 -3.736 99 0.423 0.5 335.13 68.686 1.0194
4-3 1.8116 1.45 0 -0.45 38.42 -23.76 98.79 0.029 0.5 330.33 68.666 1.019
4-4 2.6229 1.64 0 -0.3 39.435 -43.22 98.6 -6e-3 0.5 325.58 68.645 1.0187
5 2.559 1.63 1.e-2 -0.3 39.35 -41.9 98.61 3.e-3 0.1 325.91 68.645 1.0187
5 2.6181 1.64 0 -0.3 39.448 -43.14 98.6 8.e-4 0.1 325.58 68.714 1.0187
5 2.619 1.64 0 -0.3 39.452 -43.16 98.6 6.e-4 0.1 325.58 68.645 1.0197
5-1 2.1009 0.5114 0.3877
5-2 2.4528 1.61 0 -0.32 39.232 -39.65 98.63 6.e-3 0.125 326.44 68.689 1.0192
5-3 2.2912 1.58 0 -0.35 39.044 -36.06 98.66 6.e-3 0.125 327.3 68.733 1.0197
5-4 2.1382 1.55 0.01 -0.37 38.869 -32.46 98.69 6.e-3 0.125 328.16 68.777 1.0202
5-5 1.9942 1.51 0 -0.41 38.709 -28.84 98.73 -3e-3 0.125 329.02 68.821 1.0207
6 1.9432 1.5 0 -0.41 38.646 -27.49 98.74 4.e-3 0.1 329.35 68.821 1.0207
6 1.9906 1.52 0.01 -0.4 38.721 -28.76 98.72 0.011 0.1 329.02 68.89 1.0207
6 1.9909 1.51 0 -0.41 38.726 -28.77 98.72 7.e-4 0.1 329.02 68.821 1.0217
6-1 0.7189 2.1453 0.1359
6-2 1.9384 1.51 0 -0.4 38.687 -27.4 98.73 0.014 0.125 329.31 69.005 1.0208
6-3 1.8843 1.5 0 -0.41 38.666 -25.96 98.74 5.e-3 0.125 329.61 69.19 1.021
6-4 1.8318 1.5 0 -0.41 38.647 -24.52 98.74 0.014 0.125 329.91 69.376 1.0212
6-5 1.7811 1.49 0 -0.42 38.629 -23.07 98.75 5.e-3 0.125 330.2 69.562 1.0214
6-6 1.732 1.49 0 -0.42 38.613 -21.62 98.76 0.014 0.125 330.5 69.749 1.0215
6-7 1.6847 1.48 0 -0.43 38.598 -20.18 98.76 5.e-3 0.125 330.8 69.936 1.0217
6-8 1.6393 1.48 0 -0.43 38.584 -18.73 98.77 0.015 0.125 331.09 70.123 1.0219
6-9 1.5958 1.47 0 -0.44 38.573 -17.27 98.77 5.e-3 0.125 331.39 70.311 1.0221
6-10 1.5543 1.47 0 -0.44 38.561 -15.82 98.78 0.015 0.125 331.69 70.5 1.0222
6-11 1.5149 1.46 0 -0.45 38.552 -14.36 98.79 5.e-3 0.125 331.99 70.689 1.0224
6-12 1.4778 1.46 0 -0.45 38.546 -12.91 98.79 0.015 0.125 332.29 70.878 1.0226
6-13 1.4433 1.45 0 -0.46 38.541 -11.45 98.8 5.e-3 0.125 332.58 71.068 1.0227
6-14 1.4115 1.45 0 -0.46 38.536 -9.984 98.81 0.015 0.125 332.88 71.259 1.0229
6-15 1.3827 1.44 0 -0.47 38.533 -8.52 98.81 5.e-3 0.125 333.18 71.45 1.0231
6-16 1.3574 1.44 0 -0.47 38.532 -7.054 98.82 0.015 0.125 333.48 71.642 1.0233
6-17 1.3359 1.43 0 -0.48 38.533 -5.585 98.83 5.e-3 0.125 333.78 71.834 1.0234
6-18 1.3187 1.43 0.01 -0.48 38.534 -4.114 98.83 0.015 0.125 334.08 72.026 1.0236
6-19 1.3063 1.42 0 -0.49 38.537 -2.64 98.84 5.e-3 0.125 334.38 72.22 1.0238
6-20 1.299 1.42 0.01 -0.49 38.542 -1.164 98.85 0.015 0.125 334.68 72.413 1.024
6-21 1.2972 1.41 0 -0.5 38.549 0.3141 98.86 -1e-3 0.125 334.98 72.607 1.0241
7 1.3018 1.39 0 -0.52 38.517 1.707 98.87 -0.03 0.1 335.32 72.607 1.0241
7 1.2968 1.41 0 -0.5 38.561 0.3952 98.85 -8e-4 0.1 334.98 72.68 1.0241
7 1.2967 1.41 0 -0.5 38.565 0.3891 98.85 -7e-4 0.1 334.98 72.607 1.0252
7-1 -2.868 -0.069 -0.064
7-2 1.2972 1.42 0 -0.49 38.578 -0.935 98.84 4.e-3 0.031 334.68 72.606 1.0241
7-3 1.3011 1.44 0 -0.47 38.609 -2.182 98.83 7.e-3 0.031 334.38 72.604 1.0241
7-4 1.3088 1.45 0 -0.46 38.642 -3.426 98.81 -2e-3 0.031 334.08 72.603 1.0241
8 1.3057 1.45 0 -0.46 38.63 -2.994 98.82 4.e-3 0.031 334.19 72.603 1.0241
8 1.3084 1.45 0 -0.46 38.647 -3.401 98.81 3.e-4 0.031 334.08 72.625 1.0241
8 1.3084 1.45 0 -0.46 38.648 -3.403 98.81 2.e-4 0.031 334.08 72.603 1.0244
8-1 2.6972 0.1594 0.1435
8-2 1.3066 1.45 0 -0.46 38.635 -3.133 98.82 3.e-3 8.e-3 334.15 72.604 1.0241
