How to use 4NEC2 Antenna Modelling Software Part 5 - using the optimiser

[@vidasvv]

I watched the 1st 4 videos and found them a little too much "all over the place" but I did pick up a few pointers. I remember letting these programs run ALL weekend back in the day LOL TNX 4 the uploads ! 73 N8AUM

[@hamradioguy-g0ksc96]

Sorry it did not meet your expectations.

[@rickvincent2201]

Justin I just found your channel and love it. I built your 6 element 50mhz about 4 years ago and it plays wonderful. I hope in the future you cover building some HF antennas, multiband for the higher bands and wires or phased verticals on lower bands. Looking forward to more videos. 73 W8AT

[@hamradioguy-g0ksc96]

Glad it has helped, will cover multiband Yagis at a later stage

[@ChaplainDaveSparks]

My observation is that 4NEC2 doesn’t seem to like *END FED* wire antennas (or maybe I’m doing something wrong). I entered a couple of designs that *WORK* for other hams, but when I analyze them, I get wildly high SWR figures. Yes, I have set the characteristic impedance to 450Ω or 2450Ω to account for the UNUN ratio, but it’s hard to see how they’d work. Ive added a counterpoise and allowed 4NEC2 to optimize the radiator and counterpoise lengths, but if/when they produce a _”reasonable”_ SWR, the resultant values are wildly impractical. Also (this may be covered in a subsequent video), is there a way to get 4NEC2 to optimize for multiple bands, in the case of a multi-band antenna? *73 de AF6AS in **_“DM13”_** land*

[@hamradioguy-g0ksc96]

yes, you just change the frequency of optimisation and only allow it to optimise wires for the given band. when that is done, move to the next. it is important to do lowest band first and work up. for example, a 20m, 15m and 10m should have 20m optimised first, then 15m then 10m.

[@tomstevelt9641]

Is the optimzer smart enough to stop at some point? I don't see where you enter target values to achieve, eg. SWR < 1.1:1 or F/R > 25.

[@hamradioguy-g0ksc96]

it will work its best 'magic' until it cannot improve any more. it does not mean in every instance it will achieve 1:1, you may have to move stuff and change things manually before this happens.

[@bbigboy01]

Great Presentation. Could you direct me to a file that is a simple wire vertical, with no top hat, but with the ability to add my own ground plane radials? Using 4NEC v 5.9, how would I be able to change the loading point to the bottom of the vertical wire segment? I would also like to know how to add a bottom loading coil to the wire segment; Thanks!

[@arjunratheesh7743]

Nice explanation, thanks. I had a question: What's the difference between F/B and F/ Rear ratios? I tried searching almost everywhere but I could not find it.

[@eanmitchell5641]

How do you add geometry when you have stepped elements ?

[@EA1DDO]

Hi Justin, How you calculate the segmentation? Cheer, Maximo

[@hamradioguy-g0ksc96]

Generally 11 to 13 segments per half wave is good for small to medium diameter elements on VHF/UHF, 20 segment son tapered HF elements. NEC based engines use a thin wire kernel.

[@43WR155]

Hi Justin, when creating quads, deltas and loops do you use type wire or P-triang / P-rectan etc.

[@hamradioguy-g0ksc96]

individual wires for each. it is a good idea to break the wires near each corner an made a new, small wire with greater density of segmentation at each corner to help with the accuracy. This is one reason I make my LFA-Qs with trombone fit ends so they are easily finalised in the real world.

[@43WR155]

@@hamradioguy-g0ksc96 Learning heaps from these vids,. Its all starting to come together , thank you.