[300ohm]

That does produce excellent vhf-hi gains for a SBGH. The square top hat NAROD still has that annoying dip in the gain curve from CH 32 - 36. The curved top hat NAROD may eliminate that.

 

[300ohm]

Yep, like this General Purpose ch 7 - 13 Top Hat NAROD :

Might need to be adjusted a little for JEDs GH10 model. (maybe the curves not needed but just a double backing over the stub ?) Xauto and Ramkat worked on it in Area 51.

NEC file with two of them:

CE
GW	1000	7	0	68	16	0	77.5	16	0.05721178
GW	1001	1	0	77.5	16	0	77.75	15.75	0.05721178
GW	1002	1	0	77.75	15.75	0	77.75	15.25	0.05721178
GW	1003	1	0	77.75	15.25	0	77.5	15	0.05721178
GW	1004	1	0	77.5	15	0	76	15	0.05721178
GW	1005	1	0	76	15	0	75.75	14.75	0.05721178
GW	1006	1	0	75.75	14.75	0	75.75	14.25	0.05721178
GW	1007	1	0	75.75	14.25	0	76	14	0.05721178
GW	1008	3	0	80.125	14	0	76	14	0.05721178
GW	1009	7	0	68	16	0	58.5	16	0.05721178
GW	1010	1	0	58.5	16	0	58.25	15.75	0.05721178
GW	1011	1	0	58.25	15.75	0	58.25	15.25	0.05721178
GW	1012	1	0	58.25	15.25	0	58.5	15	0.05721178
GW	1013	1	0	58.5	15	0	60	15	0.05721178
GW	1014	1	0	60	15	0	60.25	14.75	0.05721178
GW	1015	1	0	60.25	14.75	0	60.25	14.37	0.05721178
GW	1016	1	0	60.25	14.37	0	60	14	0.05721178
GW	1017	3	0	60	14	0	55.875	14	0.05721178
GW	1018	7	0	68	-19	0	77.5	-19	0.05721178
GW	1019	1	0	77.5	-19	0	77.75	-18.75	0.05721178
GW	1020	1	0	77.75	-18.75	0	77.75	-18.25	0.05721178
GW	1021	1	0	77.75	-18.25	0	77.5	-18	0.05721178
GW	1022	1	0	77.5	-18	0	76	-18	0.05721178
GW	1023	1	0	76	-18	0	75.75	-17.75	0.05721178
GW	1024	1	0	75.75	-17.75	0	75.75	-17.25	0.05721178
GW	1025	1	0	75.75	-17.25	0	76	-17	0.05721178
GW	1026	3	0	80.125	-17	0	76	-17	0.05721178
GW	1027	7	0	68	-19	0	58.5	-19	0.05721178
GW	1028	1	0	58.5	-19	0	58.25	-18.75	0.05721178
GW	1029	1	0	58.25	-18.75	0	58.25	-18.25	0.05721178
GW	1030	1	0	58.25	-18.25	0	58.5	-18	0.05721178
GW	1031	1	0	58.5	-18	0	60	-18	0.05721178
GW	1032	1	0	60	-18	0	60.25	-17.75	0.05721178
GW	1033	1	0	60.25	-17.75	0	60.25	-17.25	0.05721178
GW	1034	1	0	60.25	-17.25	0	60	-17	0.05721178
GW	1035	3	0	60	-17	0	55.875	-17	0.05721178
GS	0	0	0.0254		' All in in.
GE	0
EK
EX	0	18	3	0	1	0
GN	-1
FR	0	1	0	0	473	0
RP 0 1 10 1510 90. 0. 0. 20. 0. 0.

 

[300ohm]

Had all parameters open for the optimizer and it turned it to:

Wow, the optimizer did a number on that, heh.

which makes me think that I should try this

Yeah, try that. I think the key for getting the gain dip out is to have more wire in the NAROD, yet still having it resonate in the vhf hi range within the element stubs. I was going to try a 1 turn helix loop in the middle, with still enough straight wire over the elements stubs.
On the otherhand, the channel 32 - 38 1 db or so dip in the gain curve isnt going to affect those people who dont have ch 32 - 38 or who have decent ch 32 - 38 signals.

 

[300ohm]

Very nice, thats less difference than what I had expected. I forgot JEDs GH10 gain curve was dipping in the middle anyway. http://www.jedsoft.org/fun/antennas/dtv/gh.html

Your vhf-hi gains do seem to be a good 1 dbi better than the straight NAROD setup, so the extra amount of wire helps.

For people who dont know, 9.33 dBi is super for vhf-hi gain, and puts it in the Winegard YA-1713 (a dedicated ch 7 - 13 antenna) class in terms of Vhf-Hi Net Gain. Net gain for Uhf is also at the top for channels 14 - 51.
http://www.hdtvprimer.com/ANTENNAS/comparing.html

Ive found that NARODs scale up the same way as typical antennas do on stacking, so another 2.5 dBi is possible on a double bay version.

 

[300ohm]

Those are off center NAROD reflectors.

 

[300ohm]

He has 2 Top Hat type NARODs and 3 NAROD reflectors.

NAROD stands for Not A Reflector Or Director and its an unconnected wire floating in space.

 

[300ohm]

Looks good. One question because of the downward gain pattern, are you optimizing the NARODs just for channel 7 and 8 or for 174 to 216 mhz ?

Also, just to keep all the graphs identical, can you put in the numbers for the original GH6 here :
http://www.digitalhome.ca/ota/superantenna/design.htm
optimizing the original GH6 with your top hat narods and 3 narod reflectors, but use a 89mm feedpoint instead of the 44mm one ?

JEDs GHs suffer from being very tall and large when stacked. With the original GH6, a double bay version should be less than 6 ft tall.

 

[300ohm]

Hmm, just knocking the top and bottom pairs of uhf reflectors off the GH6 above, making it an unoptimized GH4, looks pretty darn good, and the uhf net gain very close to the GH4 optimized, vhf-hi about the same as above. A DBGH of it would be about 75 inches tall.

 

[300ohm]

Not being careful enough I was optimizing for 174-210, but I'll change it to 174-216 from now on.

Never mind, its perfect as is. I did a longer frequency sweep and I see whats going on. It naturally falls that way if you want the entire vhf-high band (and SWR is starting to rise on the high channels now). Optimizing for the high channels would send the SWR sky high for the low channels. You have the best compromise for the entire vhf-high band as is now.

Are you asking me to do with the original GH6 the same thing I did with the jed's models?
Just change the feed point?
I could do that.

That would be great if you would. The original GH6 has the reflector rods only as high as the stubs, making it more compact than JEDs models. A DBGH version of that would be about 70 inches tall, with a uhf gain of 16.5+ dbi and a vhf-hi gain of about 12 dbi net, if all goes well.

The vhf-hi gain on all 3 of your models above has been very consistant. The GH10 actually has the lowest vhf-hi gain of the bunch.

 

[300ohm]

A long time ago, it was determined the wider feed point in the 80 - 110 mm range gave a bit better gain on that model. Since the distance across one of my tees is 89mm, that makes a very convenient stop for the edge of the driven element. While maybe an even wider gap would give a tiny bit more gain, the tiny increase in gain isnt worth sacrificing the great benefit of that stop point. Its always a compromise, heh.

 

[300ohm]

Yeah, thats what it always did. A lot of commercial antennas have SWR in the 3+ range.

The Jeds GH4 is also on my pipeline. It too should be stackable to something not too big.

Yeah that would be in the 75" range and with 2 less pairs of co-linear rod reflectors, an easier build. Co-linear rod reflectors are more of a pain to build than a straight rod.

 

[300ohm]

Looks good, looks like I expected, and the dip is minimized.

It will be interesting to see how much less JEDs GH4 version will produce. The GH4 would be the easier build and still about 75 inches tall by 38 inches wide in the double bay version.

On another note, I replaced the 3 NAROD reflectors of the model in post #19 with a 32 X 36 inch, 2" X 4" mesh thinking that if 3 reflectors are better than 2, then 4 are better than 3 etc and mesh should be best, heh.


CM model segmentation is derived from autosegmentation 22 at 800Mhz
CM for VHF AGT of 1 set the radius multiplier of the souce wire to 1
CE
GW 1 23 0 -2.9724409 0 0 -8.0948031 5.12237008 0.125
GW 2 25 0 -8.0948031 5.12237008 0 -2.3878346 10.8293622 0.125
GW 3 21 0 -2.3878346 10.8293622 0 -7.1483071 15.5898268 0.125
GW 4 15 0 -7.1483071 15.5898268 0 -12.030197 15.5898268 0.125
GW 5 39 -2.952756 0.8661417 3.3464567 -2.952756 13.543307 3.3464567 0.125
GW 6 39 -2.952756 1.4173228 11.771654 -2.952756 14.330709 11.771654 0.125
GW 7 37 -2.952756 1.9488189 23.228346 -2.952756 14.232283 23.228346 0.125
GW 11 7 0 -7.8949606 18.1244488 0 -7.8949606 15.9773622 0.125
GW 14 15 0 -7.8949606 15.9773622 0 -12.93937 15.9773622 0.125
GW 21 23 0 2.97244094 0 0 8.09480315 5.12237008 0.125
GW 22 25 0 8.09480315 5.12237008 0 2.38783465 10.8293622 0.125
GW 23 21 0 2.38783465 10.8293622 0 7.14830709 15.5898268 0.125
GW 24 15 0 7.14830709 15.5898268 0 12.0301969 15.5898268 0.125
GW 25 39 -2.952756 -0.866142 3.3464567 -2.952756 -13.54331 3.3464567 0.125
GW 26 39 -2.952756 -1.417323 11.771654 -2.952756 -14.33071 11.771654 0.125
GW 27 37 -2.952756 -1.948819 23.228346 -2.952756 -14.23228 23.228346 0.125
GW 31 7 0 7.89496063 18.1244488 0 7.89496063 15.9773622 0.125
GW 34 15 0 7.89496063 15.9773622 0 12.9393701 15.9773622 0.125
GW 10 51 0 7.89496063 18.1244488 0 -7.8949606 18.1244488 0.125
GW 41 23 0 -2.9724409 0 0 -8.0948031 -5.1223701 0.125
GW 42 25 0 -8.0948031 -5.1223701 0 -2.3878346 -10.829362 0.125
GW 43 21 0 -2.3878346 -10.829362 0 -7.1483071 -15.589827 0.125
GW 44 15 0 -7.1483071 -15.589827 0 -12.030197 -15.589827 0.125
GW 45 39 -2.952756 0.8661417 -3.346457 -2.952756 13.543307 -3.346457 0.125
GW 46 39 -2.952756 1.4173228 -11.77165 -2.952756 14.330709 -11.77165 0.125
GW 47 37 -2.952756 1.9488189 -23.22835 -2.952756 14.232283 -23.22835 0.125
GW 51 7 0 -7.8949606 -18.124449 0 -7.8949606 -15.977362 0.125
GW 54 15 0 -7.8949606 -15.977362 0 -12.93937 -15.977362 0.125
GW 61 23 0 2.97244094 0 0 8.09480315 -5.1223701 0.125
GW 62 25 0 8.09480315 -5.1223701 0 2.38783465 -10.829362 0.125
GW 63 21 0 2.38783465 -10.829362 0 7.14830709 -15.589827 0.125
GW 64 15 0 7.14830709 -15.589827 0 12.0301969 -15.589827 0.125
GW 65 39 -2.952756 -0.866142 -3.346457 -2.952756 -13.54331 -3.346457 0.125
GW 66 39 -2.952756 -1.417323 -11.77165 -2.952756 -14.33071 -11.77165 0.125
GW 67 37 -2.952756 -1.948819 -23.22835 -2.952756 -14.23228 -23.22835 0.125
GW 71 7 0 7.89496063 -18.124449 0 7.89496063 -15.977362 0.125
GW 74 15 0 7.89496063 -15.977362 0 12.9393701 -15.977362 0.125
GW 50 51 0 7.89496063 -18.124449 0 -7.8949606 -18.124449 0.125
GW 100 17 0 -2.9724409 0 0 2.97244094 0 0.10843701
GW 101 13 -12 -16 18 -12 -12 18 0.05094856
GW 102 13 -12 -12 18 -12 -8 18 0.05094856
GW 103 13 -12 -8 18 -12 -4 18 0.05094856
GW 104 13 -12 -4 18 -12 0 18 0.05094856
GW 105 13 -12 0 18 -12 4 18 0.05094856
GW 106 13 -12 4 18 -12 8 18 0.05094856
GW 107 13 -12 8 18 -12 12 18 0.05094856
GW 108 13 -12 12 18 -12 16 18 0.05094856
GW 109 7 -12 -16 18 -12 -16 16 0.05094856
GW 110 7 -12 -12 18 -12 -12 16 0.05094856
GW 111 7 -12 -8 18 -12 -8 16 0.05094856
GW 112 7 -12 -4 18 -12 -4 16 0.05094856
GW 113 7 -12 0 18 -12 0 16 0.05094856
GW 114 7 -12 4 18 -12 4 16 0.05094856
GW 115 7 -12 8 18 -12 8 16 0.05094856
GW 116 7 -12 12 18 -12 12 16 0.05094856
GW 117 7 -12 16 18 -12 16 16 0.05094856
GW 118 13 -12 -16 16 -12 -12 16 0.05094856
GW 119 13 -12 -12 16 -12 -8 16 0.05094856
GW 120 13 -12 -8 16 -12 -4 16 0.05094856
GW 121 13 -12 -4 16 -12 0 16 0.05094856
GW 122 13 -12 0 16 -12 4 16 0.05094856
GW 123 13 -12 4 16 -12 8 16 0.05094856
GW 124 13 -12 8 16 -12 12 16 0.05094856
GW 125 13 -12 12 16 -12 16 16 0.05094856
GW 126 7 -12 -16 16 -12 -16 14 0.05094856
GW 127 7 -12 -12 16 -12 -12 14 0.05094856
GW 128 7 -12 -8 16 -12 -8 14 0.05094856
GW 129 7 -12 -4 16 -12 -4 14 0.05094856
GW 130 7 -12 0 16 -12 0 14 0.05094856
GW 131 7 -12 4 16 -12 4 14 0.05094856
GW 132 7 -12 8 16 -12 8 14 0.05094856
GW 133 7 -12 12 16 -12 12 14 0.05094856
GW 134 7 -12 16 16 -12 16 14 0.05094856
GW 135 13 -12 -16 14 -12 -12 14 0.05094856
GW 136 13 -12 -12 14 -12 -8 14 0.05094856
GW 137 13 -12 -8 14 -12 -4 14 0.05094856
GW 138 13 -12 -4 14 -12 0 14 0.05094856
GW 139 13 -12 0 14 -12 4 14 0.05094856
GW 140 13 -12 4 14 -12 8 14 0.05094856
GW 141 13 -12 8 14 -12 12 14 0.05094856
GW 142 13 -12 12 14 -12 16 14 0.05094856
GW 143 7 -12 -16 14 -12 -16 12 0.05094856
GW 144 7 -12 -12 14 -12 -12 12 0.05094856
GW 145 7 -12 -8 14 -12 -8 12 0.05094856
GW 146 7 -12 -4 14 -12 -4 12 0.05094856
GW 147 7 -12 0 14 -12 0 12 0.05094856
GW 148 7 -12 4 14 -12 4 12 0.05094856
GW 149 7 -12 8 14 -12 8 12 0.05094856
GW 150 7 -12 12 14 -12 12 12 0.05094856
GW 151 7 -12 16 14 -12 16 12 0.05094856
GW 152 13 -12 -16 12 -12 -12 12 0.05094856
GW 153 13 -12 -12 12 -12 -8 12 0.05094856
GW 154 13 -12 -8 12 -12 -4 12 0.05094856
GW 155 13 -12 -4 12 -12 0 12 0.05094856
GW 156 13 -12 0 12 -12 4 12 0.05094856
GW 157 13 -12 4 12 -12 8 12 0.05094856
GW 158 13 -12 8 12 -12 12 12 0.05094856
GW 159 13 -12 12 12 -12 16 12 0.05094856
GW 160 7 -12 -16 12 -12 -16 10 0.05094856
GW 161 7 -12 -12 12 -12 -12 10 0.05094856
GW 162 7 -12 -8 12 -12 -8 10 0.05094856
GW 163 7 -12 -4 12 -12 -4 10 0.05094856
GW 164 7 -12 0 12 -12 0 10 0.05094856
GW 165 7 -12 4 12 -12 4 10 0.05094856
GW 166 7 -12 8 12 -12 8 10 0.05094856
GW 167 7 -12 12 12 -12 12 10 0.05094856
GW 168 7 -12 16 12 -12 16 10 0.05094856
GW 169 13 -12 -16 10 -12 -12 10 0.05094856
GW 170 13 -12 -12 10 -12 -8 10 0.05094856
GW 171 13 -12 -8 10 -12 -4 10 0.05094856
GW 172 13 -12 -4 10 -12 0 10 0.05094856
GW 173 13 -12 0 10 -12 4 10 0.05094856
GW 174 13 -12 4 10 -12 8 10 0.05094856
GW 175 13 -12 8 10 -12 12 10 0.05094856
GW 176 13 -12 12 10 -12 16 10 0.05094856
GW 177 7 -12 -16 10 -12 -16 8 0.05094856
GW 178 7 -12 -12 10 -12 -12 8 0.05094856
GW 179 7 -12 -8 10 -12 -8 8 0.05094856
GW 180 7 -12 -4 10 -12 -4 8 0.05094856
GW 181 7 -12 0 10 -12 0 8 0.05094856
GW 182 7 -12 4 10 -12 4 8 0.05094856
GW 183 7 -12 8 10 -12 8 8 0.05094856
GW 184 7 -12 12 10 -12 12 8 0.05094856
GW 185 7 -12 16 10 -12 16 8 0.05094856
GW 186 13 -12 -16 8 -12 -12 8 0.05094856
GW 187 13 -12 -12 8 -12 -8 8 0.05094856
GW 188 13 -12 -8 8 -12 -4 8 0.05094856
GW 189 13 -12 -4 8 -12 0 8 0.05094856
GW 190 13 -12 0 8 -12 4 8 0.05094856
GW 191 13 -12 4 8 -12 8 8 0.05094856
GW 192 13 -12 8 8 -12 12 8 0.05094856
GW 193 13 -12 12 8 -12 16 8 0.05094856
GW 194 7 -12 -16 8 -12 -16 6 0.05094856
GW 195 7 -12 -12 8 -12 -12 6 0.05094856
GW 196 7 -12 -8 8 -12 -8 6 0.05094856
GW 197 7 -12 -4 8 -12 -4 6 0.05094856
GW 198 7 -12 0 8 -12 0 6 0.05094856
GW 199 7 -12 4 8 -12 4 6 0.05094856
GW 200 7 -12 8 8 -12 8 6 0.05094856
GW 201 7 -12 12 8 -12 12 6 0.05094856
GW 202 7 -12 16 8 -12 16 6 0.05094856
GW 203 13 -12 -16 6 -12 -12 6 0.05094856
GW 204 13 -12 -12 6 -12 -8 6 0.05094856
GW 205 13 -12 -8 6 -12 -4 6 0.05094856
GW 206 13 -12 -4 6 -12 0 6 0.05094856
GW 207 13 -12 0 6 -12 4 6 0.05094856
GW 208 13 -12 4 6 -12 8 6 0.05094856
GW 209 13 -12 8 6 -12 12 6 0.05094856
GW 210 13 -12 12 6 -12 16 6 0.05094856
GW 211 7 -12 -16 6 -12 -16 4 0.05094856
GW 212 7 -12 -12 6 -12 -12 4 0.05094856
GW 213 7 -12 -8 6 -12 -8 4 0.05094856
GW 214 7 -12 -4 6 -12 -4 4 0.05094856
GW 215 7 -12 0 6 -12 0 4 0.05094856
GW 216 7 -12 4 6 -12 4 4 0.05094856
GW 217 7 -12 8 6 -12 8 4 0.05094856
GW 218 7 -12 12 6 -12 12 4 0.05094856
GW 219 7 -12 16 6 -12 16 4 0.05094856
GW 220 13 -12 -16 4 -12 -12 4 0.05094856
GW 221 13 -12 -12 4 -12 -8 4 0.05094856
GW 222 13 -12 -8 4 -12 -4 4 0.05094856
GW 223 13 -12 -4 4 -12 0 4 0.05094856
GW 224 13 -12 0 4 -12 4 4 0.05094856
GW 225 13 -12 4 4 -12 8 4 0.05094856
GW 226 13 -12 8 4 -12 12 4 0.05094856
GW 227 13 -12 12 4 -12 16 4 0.05094856
GW 228 7 -12 -16 4 -12 -16 2 0.05094856
GW 229 7 -12 -12 4 -12 -12 2 0.05094856
GW 230 7 -12 -8 4 -12 -8 2 0.05094856
GW 231 7 -12 -4 4 -12 -4 2 0.05094856
GW 232 7 -12 0 4 -12 0 2 0.05094856
GW 233 7 -12 4 4 -12 4 2 0.05094856
GW 234 7 -12 8 4 -12 8 2 0.05094856
GW 235 7 -12 12 4 -12 12 2 0.05094856
GW 236 7 -12 16 4 -12 16 2 0.05094856
GW 237 13 -12 -16 2 -12 -12 2 0.05094856
GW 238 13 -12 -12 2 -12 -8 2 0.05094856
GW 239 13 -12 -8 2 -12 -4 2 0.05094856
GW 240 13 -12 -4 2 -12 0 2 0.05094856
GW 241 13 -12 0 2 -12 4 2 0.05094856
GW 242 13 -12 4 2 -12 8 2 0.05094856
GW 243 13 -12 8 2 -12 12 2 0.05094856
GW 244 13 -12 12 2 -12 16 2 0.05094856
GW 245 7 -12 -16 2 -12 -16 -1.311e-14 0.05094856
GW 246 7 -12 -12 2 -12 -12 -1.311e-14 0.05094856
GW 247 7 -12 -8 2 -12 -8 -1.311e-14 0.05094856
GW 248 7 -12 -4 2 -12 -4 -1.311e-14 0.05094856
GW 249 7 -12 0 2 -12 0 -1.311e-14 0.05094856
GW 250 7 -12 4 2 -12 4 -1.311e-14 0.05094856
GW 251 7 -12 8 2 -12 8 -1.311e-14 0.05094856
GW 252 7 -12 12 2 -12 12 -1.311e-14 0.05094856
GW 253 7 -12 16 2 -12 16 -1.311e-14 0.05094856
GW 254 13 -12 -16 -1.311e-14 -12 -12 -1.311e-14 0.05094856
GW 255 13 -12 -12 -1.311e-14 -12 -8 -1.311e-14 0.05094856
GW 256 13 -12 -8 -1.311e-14 -12 -4 -1.311e-14 0.05094856
GW 257 13 -12 -4 -1.311e-14 -12 0 -1.311e-14 0.05094856
GW 258 13 -12 0 -1.311e-14 -12 4 -1.311e-14 0.05094856
GW 259 13 -12 4 -1.311e-14 -12 8 -1.311e-14 0.05094856
GW 260 13 -12 8 -1.311e-14 -12 12 -1.311e-14 0.05094856
GW 261 13 -12 12 -1.311e-14 -12 16 -1.311e-14 0.05094856
GW 262 7 -12 -16 -1.311e-14 -12 -16 -2 0.05094856
GW 263 7 -12 -12 -1.311e-14 -12 -12 -2 0.05094856
GW 264 7 -12 -8 -1.311e-14 -12 -8 -2 0.05094856
GW 265 7 -12 -4 -1.311e-14 -12 -4 -2 0.05094856
GW 266 7 -12 0 -1.311e-14 -12 0 -2 0.05094856
GW 267 7 -12 4 -1.311e-14 -12 4 -2 0.05094856
GW 268 7 -12 8 -1.311e-14 -12 8 -2 0.05094856
GW 269 7 -12 12 -1.311e-14 -12 12 -2 0.05094856
GW 270 7 -12 16 -1.311e-14 -12 16 -2 0.05094856
GW 271 13 -12 -16 -2 -12 -12 -2 0.05094856
GW 272 13 -12 -12 -2 -12 -8 -2 0.05094856
GW 273 13 -12 -8 -2 -12 -4 -2 0.05094856
GW 274 13 -12 -4 -2 -12 0 -2 0.05094856
GW 275 13 -12 0 -2 -12 4 -2 0.05094856
GW 276 13 -12 4 -2 -12 8 -2 0.05094856
GW 277 13 -12 8 -2 -12 12 -2 0.05094856
GW 278 13 -12 12 -2 -12 16 -2 0.05094856
GW 279 7 -12 -16 -2 -12 -16 -4 0.05094856
GW 280 7 -12 -12 -2 -12 -12 -4 0.05094856
GW 281 7 -12 -8 -2 -12 -8 -4 0.05094856
GW 282 7 -12 -4 -2 -12 -4 -4 0.05094856
GW 283 7 -12 0 -2 -12 0 -4 0.05094856
GW 284 7 -12 4 -2 -12 4 -4 0.05094856
GW 285 7 -12 8 -2 -12 8 -4 0.05094856
GW 286 7 -12 12 -2 -12 12 -4 0.05094856
GW 287 7 -12 16 -2 -12 16 -4 0.05094856
GW 288 13 -12 -16 -4 -12 -12 -4 0.05094856
GW 289 13 -12 -12 -4 -12 -8 -4 0.05094856
GW 290 13 -12 -8 -4 -12 -4 -4 0.05094856
GW 291 13 -12 -4 -4 -12 0 -4 0.05094856
GW 292 13 -12 0 -4 -12 4 -4 0.05094856
GW 293 13 -12 4 -4 -12 8 -4 0.05094856
GW 294 13 -12 8 -4 -12 12 -4 0.05094856
GW 295 13 -12 12 -4 -12 16 -4 0.05094856
GW 296 7 -12 -16 -4 -12 -16 -6 0.05094856
GW 297 7 -12 -12 -4 -12 -12 -6 0.05094856
GW 298 7 -12 -8 -4 -12 -8 -6 0.05094856
GW 299 7 -12 -4 -4 -12 -4 -6 0.05094856
GW 300 7 -12 0 -4 -12 0 -6 0.05094856
GW 301 7 -12 4 -4 -12 4 -6 0.05094856
GW 302 7 -12 8 -4 -12 8 -6 0.05094856
GW 303 7 -12 12 -4 -12 12 -6 0.05094856
GW 304 7 -12 16 -4 -12 16 -6 0.05094856
GW 305 13 -12 -16 -6 -12 -12 -6 0.05094856
GW 306 13 -12 -12 -6 -12 -8 -6 0.05094856
GW 307 13 -12 -8 -6 -12 -4 -6 0.05094856
GW 308 13 -12 -4 -6 -12 0 -6 0.05094856
GW 309 13 -12 0 -6 -12 4 -6 0.05094856
GW 310 13 -12 4 -6 -12 8 -6 0.05094856
GW 311 13 -12 8 -6 -12 12 -6 0.05094856
GW 312 13 -12 12 -6 -12 16 -6 0.05094856
GW 313 7 -12 -16 -6 -12 -16 -8 0.05094856
GW 314 7 -12 -12 -6 -12 -12 -8 0.05094856
GW 315 7 -12 -8 -6 -12 -8 -8 0.05094856
GW 316 7 -12 -4 -6 -12 -4 -8 0.05094856
GW 317 7 -12 0 -6 -12 0 -8 0.05094856
GW 318 7 -12 4 -6 -12 4 -8 0.05094856
GW 319 7 -12 8 -6 -12 8 -8 0.05094856
GW 320 7 -12 12 -6 -12 12 -8 0.05094856
GW 321 7 -12 16 -6 -12 16 -8 0.05094856
GW 322 13 -12 -16 -8 -12 -12 -8 0.05094856
GW 323 13 -12 -12 -8 -12 -8 -8 0.05094856
GW 324 13 -12 -8 -8 -12 -4 -8 0.05094856
GW 325 13 -12 -4 -8 -12 0 -8 0.05094856
GW 326 13 -12 0 -8 -12 4 -8 0.05094856
GW 327 13 -12 4 -8 -12 8 -8 0.05094856
GW 328 13 -12 8 -8 -12 12 -8 0.05094856
GW 329 13 -12 12 -8 -12 16 -8 0.05094856
GW 330 7 -12 -16 -8 -12 -16 -10 0.05094856
GW 331 7 -12 -12 -8 -12 -12 -10 0.05094856
GW 332 7 -12 -8 -8 -12 -8 -10 0.05094856
GW 333 7 -12 -4 -8 -12 -4 -10 0.05094856
GW 334 7 -12 0 -8 -12 0 -10 0.05094856
GW 335 7 -12 4 -8 -12 4 -10 0.05094856
GW 336 7 -12 8 -8 -12 8 -10 0.05094856
GW 337 7 -12 12 -8 -12 12 -10 0.05094856
GW 338 7 -12 16 -8 -12 16 -10 0.05094856
GW 339 13 -12 -16 -10 -12 -12 -10 0.05094856
GW 340 13 -12 -12 -10 -12 -8 -10 0.05094856
GW 341 13 -12 -8 -10 -12 -4 -10 0.05094856
GW 342 13 -12 -4 -10 -12 0 -10 0.05094856
GW 343 13 -12 0 -10 -12 4 -10 0.05094856
GW 344 13 -12 4 -10 -12 8 -10 0.05094856
GW 345 13 -12 8 -10 -12 12 -10 0.05094856
GW 346 13 -12 12 -10 -12 16 -10 0.05094856
GW 347 7 -12 -16 -10 -12 -16 -12 0.05094856
GW 348 7 -12 -12 -10 -12 -12 -12 0.05094856
GW 349 7 -12 -8 -10 -12 -8 -12 0.05094856
GW 350 7 -12 -4 -10 -12 -4 -12 0.05094856
GW 351 7 -12 0 -10 -12 0 -12 0.05094856
GW 352 7 -12 4 -10 -12 4 -12 0.05094856
GW 353 7 -12 8 -10 -12 8 -12 0.05094856
GW 354 7 -12 12 -10 -12 12 -12 0.05094856
GW 355 7 -12 16 -10 -12 16 -12 0.05094856
GW 356 13 -12 -16 -12 -12 -12 -12 0.05094856
GW 357 13 -12 -12 -12 -12 -8 -12 0.05094856
GW 358 13 -12 -8 -12 -12 -4 -12 0.05094856
GW 359 13 -12 -4 -12 -12 0 -12 0.05094856
GW 360 13 -12 0 -12 -12 4 -12 0.05094856
GW 361 13 -12 4 -12 -12 8 -12 0.05094856
GW 362 13 -12 8 -12 -12 12 -12 0.05094856
GW 363 13 -12 12 -12 -12 16 -12 0.05094856
GW 364 7 -12 -16 -12 -12 -16 -14 0.05094856
GW 365 7 -12 -12 -12 -12 -12 -14 0.05094856
GW 366 7 -12 -8 -12 -12 -8 -14 0.05094856
GW 367 7 -12 -4 -12 -12 -4 -14 0.05094856
GW 368 7 -12 0 -12 -12 0 -14 0.05094856
GW 369 7 -12 4 -12 -12 4 -14 0.05094856
GW 370 7 -12 8 -12 -12 8 -14 0.05094856
GW 371 7 -12 12 -12 -12 12 -14 0.05094856
GW 372 7 -12 16 -12 -12 16 -14 0.05094856
GW 373 13 -12 -16 -14 -12 -12 -14 0.05094856
GW 374 13 -12 -12 -14 -12 -8 -14 0.05094856
GW 375 13 -12 -8 -14 -12 -4 -14 0.05094856
GW 376 13 -12 -4 -14 -12 0 -14 0.05094856
GW 377 13 -12 0 -14 -12 4 -14 0.05094856
GW 378 13 -12 4 -14 -12 8 -14 0.05094856
GW 379 13 -12 8 -14 -12 12 -14 0.05094856
GW 380 13 -12 12 -14 -12 16 -14 0.05094856
GW 381 7 -12 -16 -14 -12 -16 -16 0.05094856
GW 382 7 -12 -12 -14 -12 -12 -16 0.05094856
GW 383 7 -12 -8 -14 -12 -8 -16 0.05094856
GW 384 7 -12 -4 -14 -12 -4 -16 0.05094856
GW 385 7 -12 0 -14 -12 0 -16 0.05094856
GW 386 7 -12 4 -14 -12 4 -16 0.05094856
GW 387 7 -12 8 -14 -12 8 -16 0.05094856
GW 388 7 -12 12 -14 -12 12 -16 0.05094856
GW 389 7 -12 16 -14 -12 16 -16 0.05094856
GW 390 13 -12 -16 -16 -12 -12 -16 0.05094856
GW 391 13 -12 -12 -16 -12 -8 -16 0.05094856
GW 392 13 -12 -8 -16 -12 -4 -16 0.05094856
GW 393 13 -12 -4 -16 -12 0 -16 0.05094856
GW 394 13 -12 0 -16 -12 4 -16 0.05094856
GW 395 13 -12 4 -16 -12 8 -16 0.05094856
GW 396 13 -12 8 -16 -12 12 -16 0.05094856
GW 397 13 -12 12 -16 -12 16 -16 0.05094856
GW 398 7 -12 -16 -16 -12 -16 -18 0.05094856
GW 399 7 -12 -12 -16 -12 -12 -18 0.05094856
GW 400 7 -12 -8 -16 -12 -8 -18 0.05094856
GW 401 7 -12 -4 -16 -12 -4 -18 0.05094856
GW 402 7 -12 0 -16 -12 0 -18 0.05094856
GW 403 7 -12 4 -16 -12 4 -18 0.05094856
GW 404 7 -12 8 -16 -12 8 -18 0.05094856
GW 405 7 -12 12 -16 -12 12 -18 0.05094856
GW 406 7 -12 16 -16 -12 16 -18 0.05094856
GW 407 13 -12 -16 -18 -12 -12 -18 0.05094856
GW 408 13 -12 -12 -18 -12 -8 -18 0.05094856
GW 409 13 -12 -8 -18 -12 -4 -18 0.05094856
GW 410 13 -12 -4 -18 -12 0 -18 0.05094856
GW 411 13 -12 0 -18 -12 4 -18 0.05094856
GW 412 13 -12 4 -18 -12 8 -18 0.05094856
GW 413 13 -12 8 -18 -12 12 -18 0.05094856
GW 414 13 -12 12 -18 -12 16 -18 0.05094856
GS 0 0 0.0254 ' All in in.
GE 0
EK
LD 5 0 0 0 2.49e7 0
EX 0 100 9 0 1 0
GN -1
FR 0 1 0 0 800 0
RP 0 60 73 1001 0 0 3 5

Bottom line, not good.
While VHF-Hi wasnt hurt too badly, it did a real number on UHF.

Rods are definately best for this application, heh.

 

[300ohm]

Ill need to do more work on the double bay version of the orig GH6 with top hat NARODs and 6 NAROD reflectors. So far, Ive only gotten it to peak at 11.59 dbi with a SWR of 2.23. Not an improvement in peak gain over what I originally had here on post #20: http://www.digitalhome.ca/forum/showthread.php?t=99907&page=2
I was hoping for more with the 2 extra NAROD reflectors because the single bay version looked so promising.
The law of marginal utility of NAROD reflectors kicking in ??

The gain and SWR curves are smoother though, and the channel 13 gain is up about a db.

 

[300ohm]

The comment note in your nec file of post #16 states:
CM model segmentation is derived from autosegmentation 22 at 800Mhz
CM for VHF AGT of 1 set the radius multiplier of the souce wire to 1
I am somewhat puzzled as to why you set the auto-seg for 800Mhz, when the upper freq of the design objective for UHF is 698 mHz (a difference of 102mHz above the upper design limit)

Yes, thats 102 mhz too high IMO too. Those are nikiml's comments and I just left things alone for a straight comparison of a failed experiment with the mesh for a NAROD reflector, heh. (except I have my auto-segmentation set at 21, close enough. IIRC, 10 to 16 are the magic numbers to avoid)

For AGT tests, I always follow Ken Nist's advice when running AGT and run it at the mid freq of the desired bandwidth. For this design, the desired bandwidth is Ch 14-51 and the mid-freq is 584 mHz.

Yep, same here, 585 mhz and then one at 470 and 698 mhz.

I don't use auto-seg, partly because Arie Voors previously had bugs with that code in the past

Interesting, I didnt know the history. We certainly ran into it when different people got different results with the same NEC file, heh.

I suspect that you would see a better UHF gain-freq response if you eliminated the UHF collinear reflectors. I think you mesh screen is causing severe disruption to the normal gain pattern that the coliinears normally provide.

True, but I suspect Ill lose uhf gain, as the mesh is 12" behind the elements. Like I said, its just a failed experiment that shows rods are the way to go with NARODs.


Ah ha, I found the auto-segmentation controversy ! Before and after Snowman53 post #42 here:
http://www.digitalhome.ca/forum/showthread.php?t=83772&highlight=auto+segmentation&page=29
If its a bug, I think its a NEC engine bug, not just 4nec2.

 

[300ohm]

A modeler gives up control of his model to this auto-segmentation algorithm that Arie has coded for 4nec2. I'm from the old school, where you manually set the segmentation.

Thats true and I also like manual segmentation. I noted in the discussions, that sometimes I have no other choice but to use manual segmentation or else violate some other NEC rule and get NEC error messages, especially when modeling commercial antennas. I like to model them as I see them.

But I can also now see a problem arising where I manually segment something X, someone else has auto-segmentation on or uses/changes a different manual segmentation, and we get results that differ on the order of a couple of db. So then were left trying to figure which is the correct number, and we look at mini-nec. It seems to be fairly accurate, segmentation has to be above about 18, so most set to 21 or 22. This of course presents other problems with high segment count antennas like the 91XG or CM-4251 parabola.

 

[300ohm]

I can tell you that I find a difference of a couple of dB, very surprising for a model with the min of 10segs per half wavelength vs say 22 segs per half-wavelength.

OK, 1 1/4 dbi, I exaggerated a bit,heh.

 

[300ohm]

I have simple step by step instructions for getting measurements from NEC data here:

http://www.digitalhome.ca/forum/showthread.php?t=107457


With the multitude of antenna models on this site, it becomes an impossibility to do CAD drawings of all of them. And 4nec2 already has a pretty nice way of displaying the models.

 

[300ohm]

This modification is being touted as the latest and greatest, but it doesn't look like it's ready for prime time. Or is it?

The single bay versions above with the 3 NAROD reflectors and the Top Hat NARODs are. Those will give superior single bay vhf-hi and uhf performance.

The double bay versions still need to be worked out. Keep in mind, the double bay versions are just 2 single bay versions with a phasing line. Youre quite safe in building a single bay version now and turning it into a double bay later.

 

[300ohm]

I propose this Modeling Challenge:
Take the GH6.3-Narod_with Screen model by 300Ohm in post #31 of this thread and make a manual segment version using the design freq of 584mHz with 10 segments per 1/2 wave. You can use a smaller segmentation density for modeling the mesh screen reflector. If you are really keen, you could show the effect of varying the segmentation of the mesh screen from a very small density up to 10 segments per 1/2 wave.

I think its best to use Snowman53s original NEC file (Area 51 post 847) instead of the failed mesh experiment above. Mesh and manual segmentation dont mix well, heh. And we want to keep the graphs and data equal.
Snowman53 did present a good argrument.

I also think its best to get more modelers into this discussion , rather than just you and me alone. holl_ands will probably be back, and maybe Snowman53 too. mclapp, since he's very good with EZNEC can provide some insight too. And maybe we can get some more Mana_gal modelers into the discussion. And maybe Arie Voors too. Hes posted on this website in your absence, and likes us too. So has Dr. Natan Cohen, the Fractal Guy, the originator of the fractal antenna.

In the meanwhile, its not as important as you finishing your website for example. For now, Ill stick with the convienent and safe auto-segmentation of 21 or 22 except for antennas of very high segmentation, like the 91XG or CM4251, DBGH Mesh or Quad or modeling vhf oddballs like stampeders CM1111 or my CM1221, heh.

 

[300ohm]

The top hat is mounted at 12mm distance form the active element's legs.

Just so everyone is clear about that, thats 12mm center of wire to center of wire distance. That applies to all NEC spacing measurements.