ERROR ALERT: GH10 Drawing - also Wire Size Implications

[300ohm]

The 35.295 inch from the bottom figure for the top vee is incorrect, it should read 41.713 inches. The millimeter figure underneath is correct though. I must have looked at something cross eyed, heh.

Ill double check over the rest of the figures tomorrow before reposting the drawing. If anyone sees something else thats wrong or wants some other figures included in the drawing, please post.

Similarly for the GH array, 4nec2 can easily model sharp right-angled bends and the distance between the diagonal sub-sections is defined from center to center.

Ive always wondered about that too. Since the 4nec2 modeling is very sharp angles, much sharper than humanly possible, I wonder about the effect of that. When I find time, Ill split the angles into many segments to form a slower curve and see what happens.

Mclapp,
I was thinking of making a template from a big piece of old plexiglass (or glass or that thicker mylar used for greenhouses) and drawing the elements exactly on it with a magic marker. Then when forming on the jig, I could check for dead center exactness very easily. Also, that plumbing coil spring bender works well for unbending tubing, using the correct size coil spring. All that is needed afterwards is a touch up with a plastic mallet and delicate touch to make it perfectly straight.

[Autofils]

For those who will be building the GH10, I ran 4nec2 GH10 model for two other wire diameter values, and here are the model results for three different materials, that you can use to build a GH10.

1. CoatHanger ( Typical coat hangers in my closet had a wd= 2.2mm)
Its cheap and quite stiff, but a bit of a pain to bend

2. #9 Alu wire (wd=1/8" or 3.175mm)
Relatively cheap, reasonably stiff and very easy to bend

3. Solid Alu Rod wd=5/16", which measured at 7mm



Raw Gain Summary

Freq ........... CoatHanger ............ 1/8" ...................5/16"

510 ............ 14.29 ................... 14.55 ................. 15.02
570 ............ 15.13 ................... 15.23 ................. 15.47
610 ............ 15.32 ................... 15.44 ................. 15.67
630 ............ 14.75 ................... 14.93 ................. 15.25

If you want to run these variations in 4nec2, you only have to change the wire radius values for the GH10 UHF-Mid nec file, already posted.
The values are given in the table below, in meters. ( Tag1 value is to set AGT test for a best result)

Tag # ...............CoatHanger ........... 1/8" ................... 5/16"

1 .................... 0.000838 ............ 0.001245 .............. 0.0029
All other tags .... 0.0011 ........... 0.0015875 ............ 0.0035

SWR and Raw Gain Plots

Note: This forum only allows 4 images per post. I had 6, so I deleted the 7mm images, which are availble in post #106. ( ...man...what a pain, any chance that the limit could be increased to 6? )


SWR Plots




RawGain Plots





7mm Plot Link
http://www.digitalhome.ca/forum/show...t=85987&page=8

[mlord]

Mmm.. that's useful information, Autofils. Does the simulator know that this is all aluminum wire? In which case using thin copper (say, AWG10 from some 10/2 romex) would probably do almost as well as the thicker 7mm aluminum, due to the lower impedance of copper.

And coathangers, being steel, are probably somewhat worse than above.

??

[ctgottapee]

that is a good point about the wire

for the reflectors i doubt i matters as just a surface area reflection is needed, so any type of metal, hallow or filled will work

but for the elements does the 7mm assume any specific type of material, and does it assume that the 7mm is solid/filled pipe or can it be hallow?

i was thinking about just asking a local plumber to bend up the elements for me.... gotta imagine they have the process down and could whip out the thing in no time

[Autofils]

Originally Posted by mlord

Mmm.. that's useful information, Autofils. Does the simulator know that this is all aluminum wire? In which case using thin copper (say, AWG10 from some 10/2 romex) would probably do almost as well as the thicker 7mm aluminum, due to the lower impedance of copper.

And coathangers, being steel, are probably somewhat worse than above.

??

4nec2 does have the following wire conductivity values, which can be used in the LD card.

Wire conductivity

Below a wire conductivity table to be used for LD card type 5, wire loading

Material Conductivity
S/m
Perfect 9.9e99 (lossless)
Silver 6.29e7
Copper 5.80e7
Pure Alumin. 3.77e7
Al. 6063-T832 3.08e7
Al. 6061-T6 2.49e7
Brass 1.56e7
Phospor bronze 9.09e6
Stnlss Stl 302 1.39e6

I checked the nec files I used for the wire diameter variations, and all were done with Alu-T6, but you can re-run the nec file, with whatever material you wish. I think you'll find that the differences are quite small.

Anyone what to do this and post the results?
Please don't expect me to do all the work, I currently don't have the time.

Just change the last parameter in the LD card with the appropriate value from the above table.
In the GH10 nec file, the LD card for Alu-T6 is:
"LD 5 0 0 0 24900000"

Here is a link for the LD card definitions, for those that wish to dabble with 4nec2 and take a crack at this.
http://www.nec2.org/part_3/cards/ld.html

The Wire Diameter variation post #145 has the info for the wire radius for the coat-hanger(2.2mm), 1/8" and 7mm.

You can also set the wire conductivity type in the 4nec2 editor (ctrl f4) in the source/load tab and set the "show loads" box.

[jdogmoney]

Thanks again Autofils. Based on this information (post #145) I feel at ease using 6 gauge copper wire. It doesn't sound like it would be inferior to 1/4" copper tubing at all.

Anyone want to do this and post the results?
Please don't expect me to do all the work, I currently don't have the time.

If I could I would. Messing around with 4nec2 is like messing around in a cockpit to me. I don't know which button to press!
IMO the info you've just given about wire diameters should answer any questions at all regarding this. If a steel coathanger yields only 0.5-0.75 db less than 5/16" aluminum tubing, then I don't think wire diameter/type is of great concern.

I got some work done on the GH10 this evening. Next step is colinear rods (never attemted before)

[Autofils]

Just to give some encouragement for folks that wish to explore the effect of wire conductivity, here are the results for the GH10 with wire diam of 2.2mm.

I would encourage any who have an interest in 4nec2 models, to give this a try.

In reference to post #148, the conductivity values of GH10 wd=2.2mm were run for three different values of conductivity:
perfect ( ie lossless) 9.9e99
Al. 6061-T6 2.49e7
Stnlss Stl 302 1.39e6

Raw Gain (dBi) Summary for GH10 Coat Hanger wd=2.2mm


Freq ......... StnlssStl .................. Alu-6..................Perfect

510 ............ 14.23 ................... 14.29 ................. 14.31
570 ............ 15.07................... 15.13 ................. 15.15
610 ............ 15.23 ................... 15.32 ................. 15.34
630 ............ 14.61 ................... 14.75 ................. 14.79

As I had mentioned in post #148, the model results show very slight variations in Raw gain.
If you trust the model results, then wire conductivity is not a significant factor.

Perhaps someone could repeat these runs to test the validity of this result and post their results ?
Any takers...any nerd club members...anybody....?
There has to be someone willing to give this a shot

[Autofils]

Originally Posted by jdogmoney

Thanks again Autofils.
........
If a steel coathanger yields only 0.5-0.75 db less than 5/16" aluminum tubing, then I don't think wire diameter/type is of great concern.

Raw gain is not the only consideration. The SWR is another important factor, and if you examine the SWR plots, the improvement of SWR with the 7mm becomes very apparent. The better ( ie lower) the SWR, then the closer the Net gain approaches the Raw gain and the better is the antenna....at least that's the theory. Personally, I'd stick to the 7mm design to squeeze the most for distant stations, but if you are not trying to receive Rx(dBm) of -110dBm to -125dBm, then wd is not all that significant.

The limit of 4 photos per post, prevented me from showing the 7mm RawGain and SWR plots in post #145, so here are the Swr comparisons of 7mm and 2.mm.




When I was using EZNECv3(which is not freeware) with 1st Generation GH, it was quite easy to present NetGain, but with 4nec2 calculating the net gain is a lot more work. Since the 7mm design had an excellent SWR, the need for netgain plots was less important. And the main point for me was that since 4nec2 is a freeware and excellent modeling program, I posted the complete 4nec2 design info for 2nd Generation GH, so readers of this forum could "test-drive" the modeling product and perhaps make further improvements using the freeware 4nec2 program.

My earlier attempts at getting a NerdClub established, had very limited success, so this 4nec2 approach is the only other possible route for others that wish to expand on my initial design efforts.

[300ohm]

Well, I ran it for the copper gauges I was interested in.

610mhz - Raw gain 10 gauge copper wire = 16.4dbi
610mhz - Raw gain 6 gauge copper wire = 16.1dbi

510mhz - Raw gain 10 gauge copper wire = 15.6dbi
510mhz - Raw gain 6 gauge copper wire = 15.4dbi

A little different than what I was expecting. I just used the drop down selections for the gauges and wire materials in 4nec2x ver 5.7.2.

[Autofils]

Originally Posted by 300ohm

Well, I ran it for the copper gauges I was interested in.

610mhz - Raw gain 10 gauge copper wire = 16.4dbi

610mhz - Raw gain 6 gauge copper wire = 16.1dbi

A little different than what I was expecting. I just used the drop down selections for the gauges and wire materials in 4nec2x ver 5.7.2.

300 ohm,

Is this for GH10 UHF-Mid collinear nec file that I posted?
If so, please post the nec file, since my peak gain for the GH10 UHF-Mid collinear was only 15.67 dBi, and I'm quite interested in getting gain >16dBi.

...thanks


I just ran GH10 collinear with Cu Wire and Wire radius set as #4.
I get an AGT test result of 1.03(0.12) and raw gain at 610 Mhz of 15.72
Applying the AGT test result correction: Rawgain = 15.72-0.12 = 15.6

Here is the nec file
-----------------------------------------------------------
CM SBGH Gen2 GH10 Collinear Rod reflectors
CE
SY y=0.095 'FeedGap
SY x=0.094 'Length of Array Horizontal Stub
SY h=0.163 'Length of Array diagonal = (Sqrt(2) * h) = 0.231
SY s=0.094 'Reflector Spacing
SY g=0.05 'Reflector Gap
SY R1=0.227 'Collinear Rod Reflector Lengths
SY R2=0.370
SY R3=0.495
SY R4=0.268
SY R5=0.392
GW 1 5 0 0 0 0 y 0 #4
GW 2 10 0 y 0 0 y+h h #4
GW 3 10 0 y+h h 0 y 2h #4
GW 4 10 0 y 2h 0 y+h 3h #4
GW 5 10 0 y+h 3h 0 y+h+x 3h #4
GW 6 10 0 y 0 0 y+h -h #4
GW 7 10 0 y+h -h 0 y -2h #4
GW 8 10 0 y -2h 0 y+h -3h #4
GW 9 10 0 y+h -3h 0 y+h+x -3h #4
GW 10 10 0 0 0 0 -h h #4
GW 11 10 0 -h h 0 0 2h #4
GW 12 10 0 0 2h 0 -h 3h #4
GW 13 10 0 -h 3h 0 -(h+x) 3h #4
GW 14 10 0 0 0 0 -h -h #4
GW 15 10 0 -h -h 0 0 -2h #4
GW 16 10 0 0 -2h 0 -h -3h #4
GW 17 10 0 -h -3h 0 -(h+x) -3h #4
GW 18 18 -s (R1+y/2+g/2) -4.5h -s y/2+g/2 -4.5h #4
GW 19 18 -s -(R1-y/2+g/2) -4.5h -s y/2-g/2 -4.5h #4
GW 22 18 -s (R2+y/2+g/2) -3.5h -s y/2+g/2 -3.5h #4
GW 23 18 -s -(R2-y/2+g/2) -3.5h -s y/2-g/2 -3.5h #4
GW 30 18 -s (R3+y/2+g/2) -2.5h -s y/2+g/2 -2.5h #4
GW 31 18 -s -(R3-y/2+g/2) -2.5h -s y/2-g/2 -2.5h #4
GW 38 18 -s (R4+y/2+g/2) -1.5h -s y/2+g/2 -1.5h #4
GW 39 18 -s -(R4-y/2+g/2) -1.5h -s y/2-g/2 -1.5h #4
GW 46 18 -s (R5+y/2+g/2) -0.5h -s y/2+g/2 -0.5h #4
GW 47 18 -s -(R5-y/2+g/2) -0.5h -s y/2-g/2 -0.5h #4
GW 52 18 -s (R5+y/2+g/2) 0.5h -s y/2+g/2 0.5h #4
GW 53 18 -s -(R5-y/2+g/2) 0.5h -s y/2-g/2 0.5h #4
GW 60 18 -s (R4+y/2+g/2) 1.5h -s y/2+g/2 1.5h #4
GW 61 18 -s -(R4-y/2+g/2) 1.5h -s y/2-g/2 1.5h #4
GW 68 18 -s (R3+y/2+g/2) 2.5h -s y/2+g/2 2.5h #4
GW 69 18 -s -(R3-y/2+g/2) 2.5h -s y/2-g/2 2.5h #4
GW 76 18 -s (R2+y/2+g/2) 3.5h -s y/2+g/2 3.5h #4
GW 77 18 -s -(R2-y/2+g/2) 3.5h -s y/2-g/2 3.5h #4
GW 80 18 -s (R1+y/2+g/2) 4.5h -s y/2+g/2 4.5h #4
GW 81 18 -s -(R1-y/2+g/2) 4.5h -s y/2-g/2 4.5h #4
GE 0
LD 5 0 0 0 58000000
GN -1
EK
EX 0 1 3 00 1 0
FR 0 0 0 0 585 0
EN

------------------------------------------------------------------------------

[300ohm]

Good thing I havent changed it again, heh. This is your original file, with copper wire instead of aluminum and the different gauges, but I did a group copy move for all the wires to put the bottom reflector on zero, and have noticed that the SY cards change to real values when moving. (Thats how I got the drawing done so quickly, heh) So if using SY cards in 4nec2, it may be a good idea to start Z (height) at a typical rooftop height, like 25ft for a 1 story house. That way, future fancy modeling included with 4nec2 can be done on various ground effects without messing up the SY cards.


CM SBGH Gen2 GH10 Collinear Rod reflectors
CE
GW 1 7 0 0 0 0 3.74015748 0 0.11417323
GW 2 17 0 3.74015748 0 0 10.1574803 6.41732283 0.05094856
GW 3 17 0 10.1574803 6.41732283 0 3.74015748 12.8346457 0.05094856
GW 4 17 0 3.74015748 12.8346457 0 10.1574803 19.2519685 0.05094856
GW 5 7 0 10.1574803 19.2519685 0 13.8582677 19.2519685 0.05094856
GW 6 17 0 3.74015748 0 0 10.1574803 -6.4173228 0.05094856
GW 7 17 0 10.1574803 -6.4173228 0 3.74015748 -12.834646 0.05094856
GW 8 17 0 3.74015748 -12.834646 0 10.1574803 -19.251969 0.05094856
GW 9 7 0 10.1574803 -19.251969 0 13.8582677 -19.251969 0.05094856
GW 10 17 0 0 0 0 -6.4173228 6.41732283 0.05094856
GW 11 17 0 -6.4173228 6.41732283 0 0 12.8346457 0.05094856
GW 12 17 0 0 12.8346457 0 -6.4173228 19.2519685 0.05094856
GW 13 7 0 -6.4173228 19.2519685 0 -10.11811 19.2519685 0.05094856
GW 14 17 0 0 0 0 -6.4173228 -6.4173228 0.05094856
GW 15 17 0 -6.4173228 -6.4173228 0 0 -13 0.05094856
GW 16 17 0 0 -13 0 -6.4173228 -19.417323 0.05094856
GW 17 7 0 -6.4173228 -19.417323 0 -10.11811 -19.251969 0.05094856
GW 18 15 -3.700787 11.791339 -28.87795 -3.700787 2.8543307 -28.87795 0.1377953
GW 19 15 -3.700787 -8.051181 -28.87795 -3.700787 0.8858268 -28.87795 0.1377953
GW 22 25 -3.700787 17.42126 -22.46063 -3.700787 2.8543307 -22.46063 0.1377953
GW 23 25 -3.700787 -13.6811 -22.46063 -3.700787 0.8858268 -22.46063 0.1377953
GW 30 35 -3.700787 22.34252 -16.04331 -3.700787 2.8543307 -16.04331 0.1377953
GW 31 35 -3.700787 -18.60236 -16.04331 -3.700787 0.8858268 -16.04331 0.1377953
GW 38 19 -3.700787 13.405512 -9.625984 -3.700787 2.8543307 -9.625984 0.1377953
GW 39 19 -3.700787 -9.665354 -9.625984 -3.700787 0.8858268 -9.625984 0.1377953
GW 46 27 -3.700787 18.287402 -3.208661 -3.700787 2.8543307 -3.208661 0.1377953
GW 47 27 -3.700787 -14.54724 -3.208661 -3.700787 0.8858268 -3.208661 0.1377953
GW 52 27 -3.700787 18.287402 3.2086614 -3.700787 2.8543307 3.2086614 0.1377953
GW 53 27 -3.700787 -14.54724 3.2086614 -3.700787 0.8858268 3.2086614 0.1377953
GW 60 19 -3.700787 13.405512 9.6259843 -3.700787 2.8543307 9.6259843 0.1377953
GW 61 19 -3.700787 -9.665354 9.6259843 -3.700787 0.8858268 9.6259843 0.1377953
GW 68 35 -3.700787 22.34252 16.043307 -3.700787 2.8543307 16.043307 0.1377953
GW 69 35 -3.700787 -18.60236 16.043307 -3.700787 0.8858268 16.043307 0.1377953
GW 76 25 -3.700787 17.42126 22.46063 -3.700787 2.8543307 22.46063 0.1377953
GW 77 25 -3.700787 -13.6811 22.46063 -3.700787 0.8858268 22.46063 0.1377953
GW 80 15 -3.700787 11.791339 28.877953 -3.700787 2.8543307 28.877953 0.1377953
GW 81 15 -3.700787 -8.051181 28.877953 -3.700787 0.8858268 28.877953 0.1377953
GS 0 0 0.0254 ' All in in.
GE 0
EK
LD 5 0 0 0 58000000 0
EX 0 1 4 0 1 0
GN -1

[300ohm]

When I was using EZNECv3(which is not freeware) with 1st Generation GH, it was quite easy to present NetGain, but with 4nec2 calculating the net gain is a lot more work. Since the 7mm design had an excellent SWR, the need for netgain plots was less important. And the main point for me was that since 4nec2 is a freeware and excellent modeling program, I posted the complete 4nec2 design info for 2nd Generation GH, so readers of this forum could "test-drive" the modeling product and perhaps make further improvements using the freeware 4nec2 program.

Yeah, net gain is a pain with 4nec2, so if you find an easy way, please post immediately, heh.

Maybe we should ask Arie Voors to consider incorporating it into his program in future versions.

Along with the ability to annotate the Geometry Edit screens with arrows, lines and alphanumeric characters that will not be part of the nec2 input data. Then it would be easy and neat to do a screen capture of the model for detailed building plans.

Unless someone already has a easy bmp/jpg file editor that can do that easily ??? Anyone ??

[Autofils]

Originally Posted by 300ohm

Good thing I havent changed it again, heh. This is your original file, with copper wire instead of aluminum and the different gauges, but I did a group copy move for all the wires to put the bottom reflector on zero, and have noticed that the SY cards change to real values when moving. (Thats how I got the drawing done so quickly, heh) So if using SY cards in 4nec2, it may be a good idea to start Z (height) at a typical rooftop height, like 25ft for a 1 story house. That way, future fancy modeling included with 4nec2 can be done on various ground effects without messing up the SY cards.

300 ohm,

Thanks for your nec file. I had a look and here are the main factors I found:

Wire diameter for array elements = 2.58818mm
Wire diameter for reflectors = 7mm
Wire conductivity = Copper

The Raw gain at 610 Mhz was 16.41 dBi, but the AGT test result was 1.11(0.46dB). Typically this means that the raw gains are 0.46 too high.
So the estimated raw gain with this AGT test correction factor is 15.95.

I adjusted the Vsource (Tag1) to 9 segments and a wire radius of 1.10 and the EX card segments to 5 to keep the VSource in the middle of tag1 and then re-ran your nec file.
This provides an AGT test results of 1.0(4e-3dB) and the raw gain at 610 Mhz is now calculated as 15.76 dBi.

I see that you have increased the segments in your file, and ..(note to self...I really should run a few convergence tests on GH10...)

Final Results
Your nec file (AGT adjusted) with more segments and CU wire has 15.76 dBi at 610 Mhz.
My orig GH10 nec file with fewer segments and Alu-T6 wire has 15.67 dBi at 610 MHz.

Your earlier post mentioned #6 Cu wire, (wd=4.1148 mm). Do you have another nec file with array and reflectors using #6 Cu wire?

I have attached your nec file, with the VSource changes for the AGT result 1.0(4e-3dB).
It's important to always adjust the Vsource for an AGT test result of 1.0 (xxx).
My thanks goes out to Ken Nist, who originally taught me the ins and outs of the AGT test and now this is getting past on to readers (4nec2 students) of this forum.

Regards

-----------------------------------------------------------------------

CM SBGH Gen2 GH10 Collinear Rod reflectors
CE
GW 1 9 0 0 0 0 0.095 0 0.0011
GW 2 17 0 0.095 0 0 0.258 0.163 1.29409e-3
GW 3 17 0 0.258 0.163 0 0.095 0.326 1.29409e-3
GW 4 17 0 0.095 0.326 0 0.258 0.489 1.29409e-3
GW 5 7 0 0.258 0.489 0 0.352 0.489 1.29409e-3
GW 6 17 0 0.095 0 0 0.258 -0.163 1.29409e-3
GW 7 17 0 0.258 -0.163 0 0.095 -0.326 1.29409e-3
GW 8 17 0 0.095 -0.326 0 0.258 -0.489 1.29409e-3
GW 9 7 0 0.258 -0.489 0 0.352 -0.489 1.29409e-3
GW 10 17 0 0 0 0 -0.163 0.163 1.29409e-3
GW 11 17 0 -0.163 0.163 0 0 0.326 1.29409e-3
GW 12 17 0 0 0.326 0 -0.163 0.489 1.29409e-3
GW 13 7 0 -0.163 0.489 0 -0.257 0.489 1.29409e-3
GW 14 17 0 0 0 0 -0.163 -0.163 1.29409e-3
GW 15 17 0 -0.163 -0.163 0 0 -0.3302 1.29409e-3
GW 16 17 0 0 -0.3302 0 -0.163 -0.4932 1.29409e-3
GW 17 7 0 -0.163 -0.4932 0 -0.257 -0.489 1.29409e-3
GW 18 15 -0.094 0.29950001 -0.7334999 -0.094 0.0725 -0.7334999 3.5e-3
GW 19 15 -0.094 -0.2045 -0.7334999 -0.094 0.0225 -0.7334999 3.5e-3
GW 22 25 -0.094 0.4425 -0.5705 -0.094 0.0725 -0.5705 3.5e-3
GW 23 25 -0.094 -0.3474999 -0.5705 -0.094 0.0225 -0.5705 3.5e-3
GW 30 35 -0.094 0.56750001 -0.4075001 -0.094 0.0725 -0.4075001 3.5e-3
GW 31 35 -0.094 -0.4724999 -0.4075001 -0.094 0.0225 -0.4075001 3.5e-3
GW 38 19 -0.094 0.3405 -0.2445 -0.094 0.0725 -0.2445 3.5e-3
GW 39 19 -0.094 -0.2455 -0.2445 -0.094 0.0225 -0.2445 3.5e-3
GW 46 27 -0.094 0.46450001 -0.0815 -0.094 0.0725 -0.0815 3.5e-3
GW 47 27 -0.094 -0.3694999 -0.0815 -0.094 0.0225 -0.0815 3.5e-3
GW 52 27 -0.094 0.46450001 0.0815 -0.094 0.0725 0.0815 3.5e-3
GW 53 27 -0.094 -0.3694999 0.0815 -0.094 0.0225 0.0815 3.5e-3
GW 60 19 -0.094 0.3405 0.2445 -0.094 0.0725 0.2445 3.5e-3
GW 61 19 -0.094 -0.2455 0.2445 -0.094 0.0225 0.2445 3.5e-3
GW 68 35 -0.094 0.56750001 0.4075 -0.094 0.0725 0.4075 3.5e-3
GW 69 35 -0.094 -0.4724999 0.4075 -0.094 0.0225 0.4075 3.5e-3
GW 76 25 -0.094 0.4425 0.5705 -0.094 0.0725 0.5705 3.5e-3
GW 77 25 -0.094 -0.3474999 0.5705 -0.094 0.0225 0.5705 3.5e-3
GW 80 15 -0.094 0.29950001 0.73350001 -0.094 0.0725 0.73350001 3.5e-3
GW 81 15 -0.094 -0.2045 0.73350001 -0.094 0.0225 0.73350001 3.5e-3
GE 0
LD 5 0 0 0 58000000
GN -1
EK
EX 0 1 5 0 1 0
FR 0 0 0 0 299.8 0
EN

--------------------------------------------------------------------

[Autofils]

Originally Posted by 300ohm

Yeah, net gain is a pain with 4nec2, so if you find an easy way, please post immediately, heh.

Maybe we should ask Arie Voors to consider incorporating it into his program in future versions.

I contacted Arie about 4 months ago and asked for it to be a future, but he declined the suggestion, mainly because of the amount of work that would be involved.

Another approach that could be taken, is to parse the f8 output file to extract the Raw gain data, and the real and imaginary complex antenna impedances at each frequency used in the test sweep. Then another program to read that extracted file into a spreadsheet...and "Bob's your uncle", the spreadsheet calculates the Net gain and provides plotting capability.

The only catch to this solution, is to find someone with the programming skills that would work on this.

Any volunteers ?

[300ohm]

Final Results
Your nec file (AGT adjusted) with more segments and CU wire has 15.76 dBi at 610 Mhz.
My orig GH10 nec file with fewer segments and Alu-T6 wire has 15.67 dBi at 610 MHz.

Yeah bottom line, copper is better than aluminum which is better than steel. But we knew that before we started, heh.
Well no, I dont have that nec file with the 4 gauge wire, because its the same file that I changed to 10 gauge wire.

I have attached your nec file, with the VSource changes for the AGT result 1.0(4e-3dB).
It's important to always adjust the Vsource for an AGT test result of 1.0 (xxx).
My thanks goes out to Ken Nist, who originally taught me the ins and outs of the AGT test and now this is getting past on to readers (4nec2 students) of this forum.

Can you go over specifically on how to adjust the Vsource again ?

I contacted Arie about 4 months ago and asked for it to be a future, but he declined the suggestion, mainly because of the amount of work that would be involved.

Kind of figured he would say that. The annotating the Geometry Edit screen may not be that hard, but maybe a good easy bmp/jpg editor already exists.

The only catch to this solution, is to find someone with the programming skills that would work on this.

Hmmm, with my old COBOL tools on my old Burroughs mainframe, it would be a fairly quick job (since the file is perfectly structured for COBOL and FORTRAN) to parse and output to a text file. But alas, those are long gone. Ill see if my son, whos proficient in C++ will do it. But before I ask him, well have to figure out all the specific variables we want parsed to a file from that f8 output file. (C:\4nec2\out\(name of file.out) Open up one of your .out files with notepad and see where the data you want is located, Im somewhat confused as to where to find impedence totals for a specific frequency. I see it in the Antenna Input Parameters, but thats input correct ?

Then another program to read that extracted file into a spreadsheet.

It would be the same program. Excels still allows importation of a text file I assume ?. (Ive been using Open Office for quite some time and it does, along with a lot of other file types.) Or what other easy to do file type would be better ?