Hey folks! Got a few questions about the nikiml NEC program for simulating antennas that I hope I can get some answers for from the members at this site.
If this is not posted in the proper section, my apologies and hopefully a moderator/admin will place it in the more appropriate section.
I have recently started trying to learn the ins & outs of simulating antenna builds in the NEC program and of course I am having some questions.
1) I have ran a few different nec files through the optimization and I have witnesed some files are created with the name of 'bestx_xxx' & other nec files are created with the name of best-x.xxx'. all f the files that are created seem to decrease in the 'x_xxx' values, but I am wondering why some are positive values & others are negative values? Does the positive/negative naming convention indicate that something is inherently wrong with the results with one or the other named files? Will the 'bestx_xxx' named files eventually reduce to 'best-x_xxx' as they improve? Is the NEC program designed to stop running after it figures that there can be no more improvements or will it just keep running until it hits the default of 10k iterations? Is there a file name that would be created when NEC believes it has acheived the maximum potential of the simulation?
2) AGT correction - I have noticed that if I adjust an nec file wire size to show an AGT of 0.95 - 1.05 in 4nec2, after I run the optimization in NEC, the AGT in 4nec2 is no longer within the range of 0.95 - 1.05. Well normally I would just adjust the wire size again and repeat, today I can't adjust the wire size any more to get the AGT into the acceptable range of 0.95 - 1.05. Is there anything else that I can adjust to get the AGT back to the acceptable range? I think I recall that the 'EX' card is tied into it somehow, but I haven't seen what all of the 'EX' settings are for.
3) The '-F TARGET_FUNCTION, --target-function=TARGET_FUNCTION'. The 'formulas' for this I have seen, appear to try and do a smarter optimiztion. I am confused on where the numbers are coming from and what the formulas attempt to do:
For Example:
CMD--OPT --target-function=-.5*min_net_gain-.5*ave_net_gain - I have tested this one and it appears to create a gain plot that attempts to have a similar lowest/highest frequency value & in the middle of the range it is a higher value, in other words it slopes up to the middle of the frequency range & then slopes back down to the end of the frequency range.
I have also seen the following which I am confused as to where the values are coming from and what the formulas are attempting to achieve as far as plotting goes:
CMD--OPT --target-function=(2*max_ml+8*max_gain_diff)/10
CMD--OPT --target-function=5+.5*ave_max_gain_diff-.5*ave_net_gain
CMD--OPT --target-function=.2*ave_max_gain_diff+.8*ave_gain_diff
Sorry for the abundance of questions, they have been building up & I haven't been able to solve them on my own thus far.
Thank you in advance for any members that attempt to weed through those barrage of questions!
If this is not posted in the proper section, my apologies and hopefully a moderator/admin will place it in the more appropriate section.
I have recently started trying to learn the ins & outs of simulating antenna builds in the NEC program and of course I am having some questions.
1) I have ran a few different nec files through the optimization and I have witnesed some files are created with the name of 'bestx_xxx' & other nec files are created with the name of best-x.xxx'. all f the files that are created seem to decrease in the 'x_xxx' values, but I am wondering why some are positive values & others are negative values? Does the positive/negative naming convention indicate that something is inherently wrong with the results with one or the other named files? Will the 'bestx_xxx' named files eventually reduce to 'best-x_xxx' as they improve? Is the NEC program designed to stop running after it figures that there can be no more improvements or will it just keep running until it hits the default of 10k iterations? Is there a file name that would be created when NEC believes it has acheived the maximum potential of the simulation?
2) AGT correction - I have noticed that if I adjust an nec file wire size to show an AGT of 0.95 - 1.05 in 4nec2, after I run the optimization in NEC, the AGT in 4nec2 is no longer within the range of 0.95 - 1.05. Well normally I would just adjust the wire size again and repeat, today I can't adjust the wire size any more to get the AGT into the acceptable range of 0.95 - 1.05. Is there anything else that I can adjust to get the AGT back to the acceptable range? I think I recall that the 'EX' card is tied into it somehow, but I haven't seen what all of the 'EX' settings are for.
3) The '-F TARGET_FUNCTION, --target-function=TARGET_FUNCTION'. The 'formulas' for this I have seen, appear to try and do a smarter optimiztion. I am confused on where the numbers are coming from and what the formulas attempt to do:
For Example:
CMD--OPT --target-function=-.5*min_net_gain-.5*ave_net_gain - I have tested this one and it appears to create a gain plot that attempts to have a similar lowest/highest frequency value & in the middle of the range it is a higher value, in other words it slopes up to the middle of the frequency range & then slopes back down to the end of the frequency range.
I have also seen the following which I am confused as to where the values are coming from and what the formulas are attempting to achieve as far as plotting goes:
CMD--OPT --target-function=(2*max_ml+8*max_gain_diff)/10
CMD--OPT --target-function=5+.5*ave_max_gain_diff-.5*ave_net_gain
CMD--OPT --target-function=.2*ave_max_gain_diff+.8*ave_gain_diff
Sorry for the abundance of questions, they have been building up & I haven't been able to solve them on my own thus far.
Thank you in advance for any members that attempt to weed through those barrage of questions!