Area 51 for Antenna Modelers & Builders (See Post #1)

[RamKat]

Unless people complain, I'm going to continue posting parametrized NEC

Please continue firimari, I am getting a lot of ideas from your approach. Just did my first parametized antenna (or at least my version of it) last night. Still have figure out how to use the optimizer.

[RamKat]

That's respectably flat gain and SWR on the X-011

Any idea what is a typical bandwidth is that one could realisticly expect to get in this regard? I am currently trying to cover both the FM Radio and VUHF-LO bands (54 Mhz to 108Mhz) with a single reflectorless hentenna based design, not having much success - VUHF LO alone or FM Radio alone appears to be more possible with a few added ons

[astupidoldman]

Sorry I haven't posted much. This is what I was working on before the NAROD development and I have been doing a bit of fly fishing. I was playing with the reflector lengths and was trying to dial it in for just the few channels I wanted for my area here. Now I am trying the NAROD system of elements with it, but for the sake of simplicity, I may just build as is from my 217 zigzag series. My favs are still the 179 zigzag series, but this 217 seemed to work for me. I believe I could have benefited figuring out the optimizer. I think the NORAD’s are pure genius. Perhaps you could link me to the use of the optimizer? Thanks again gentlemen, will post later.

CM
CE
GW 1 3 0 -0.0475 -0.05 0 0 -0.05 3.3e-3
GW 5 10 0 0.1771921 -0.3526735 0 0.2626921 -0.3526735 3.5e-3
GW 6 9 0 0.02375 -0.813 0 0.17719215 -0.9664422 3.5e-3
GW 7 9 0 0.17719215 -0.9664422 0 0.02374994 -1.1198843 3.5e-3
GW 8 9 0 0.02374994 -1.1198843 0 0.17719208 -1.2733265 3.5e-3
GW 9 10 0 0.17719208 -1.2733265 0 0.26269208 -1.2733265 3.5e-3
GW 13 10 0 -0.2246922 -0.3526735 0 -0.3101922 -0.3526735 3.5e-3
GW 14 9 0 -0.07125 -0.813 0 -0.2246922 -0.9664422 3.5e-3
GW 15 9 0 -0.2246922 -0.9664422 0 -0.07125 -1.1198843 3.5e-3
GW 16 9 0 -0.07125 -1.1198843 0 -0.2246922 -1.2733264 3.5e-3
GW 17 10 0 -0.2246922 -1.2733264 0 -0.3101922 -1.2733264 3.5e-3
GW 92 9 0 -0.2246922 -0.3526735 0 -0.0712501 -0.5061157 3.5e-3
GW 93 9 0 -0.0712501 -0.5061157 0 -0.2246922 -0.6595579 3.5e-3
GW 94 9 0 -0.2246922 -0.6595579 0 -0.07125 -0.813 3.5e-3
GW 95 9 0 0.17719215 -0.6595578 0 0.02375 -0.813 3.5e-3
GW 96 9 0 0.02374995 -0.5061157 0 0.17719215 -0.6595578 3.5e-3
GW 97 9 0 0.1771921 -0.3526735 0 0.02374995 -0.5061157 3.5e-3
GW 112 18 -0.0855 0.35825 -0.1050892 -0.0855 1.25e-3 -0.1050892 3.5e-3
GW 113 15 -0.0855 -0.40575 -0.1050892 -0.0855 -0.04875 -0.1050892 3.5e-3
GW 114 18 -0.0855 0.35825 -0.4190446 -0.0855 1.25e-3 -0.4190446 3.5e-3
GW 115 15 -0.0855 -0.40575 -0.4190446 -0.0855 -0.04875 -0.4190446 3.5e-3
GW 116 18 -0.0855 0.35825 -0.733 -0.0855 1.25e-3 -0.733 3.5e-3
GW 117 15 -0.0855 -0.40575 -0.733 -0.0855 -0.04875 -0.733 3.5e-3
GW 122 15 -0.0855 0.36825 -0.2620669 -0.0855 1.25e-3 -0.2620669 3.5e-3
GW 123 15 -0.0855 -0.04875 -0.2620669 -0.0855 -0.41575 -0.2620669 3.5e-3
GW 124 15 -0.0855 0.36825 -0.5760223 -0.0855 1.25e-3 -0.5760223 3.5e-3
GW 125 15 -0.0855 -0.04875 -0.5760223 -0.0855 -0.41575 -0.5760223 3.5e-3
GW 128 18 -0.0855 -0.40525 -1.2069554 -0.0855 -0.04825 -1.2069554 3.5e-3
GW 129 15 -0.0855 0.35875 -1.2069554 -0.0855 1.75e-3 -1.2069554 3.5e-3
GW 130 18 -0.0855 -0.40525 -0.893 -0.0855 -0.04825 -0.893 3.5e-3
GW 131 15 -0.0855 0.35875 -0.893 -0.0855 1.75e-3 -0.893 3.5e-3
GW 134 15 -0.0855 -0.41525 -1.0499777 -0.0855 -0.04825 -1.0499777 3.5e-3
GW 135 15 -0.0855 1.75e-3 -1.0499777 -0.0855 0.36875 -1.0499777 3.5e-3
GW 136 1 0 -0.07125 -0.813 0 -0.0475 -0.813 3.5e-3
GW 137 58 0 -0.0475 -0.813 0 -0.0475 -0.05 3.5e-3
GW 139 2 0 0 -0.813 0 0.02375 -0.813 3.5e-3
GW 140 58 0 0 -0.813 0 0 -0.05 3.5e-3
GW 141 10 0 -0.2246922 0.25267355 0 -0.3101922 0.25267355 3.5e-3
GW 142 9 0 -0.07125 0.713 0 -0.2246922 0.86644217 3.5e-3
GW 143 9 0 -0.2246922 0.86644217 0 -0.0712499 1.01988429 3.5e-3
GW 144 9 0 -0.0712499 1.01988429 0 -0.2246921 1.17332651 3.5e-3
GW 145 10 0 -0.2246921 1.17332651 0 -0.3101921 1.17332651 3.5e-3
GW 146 10 0 0.17719218 0.25267349 0 0.26269218 0.25267349 3.5e-3
GW 147 9 0 0.02375 0.713 0 0.17719217 0.86644217 3.5e-3
GW 148 9 0 0.17719217 0.86644217 0 0.02374995 1.01988429 3.5e-3
GW 149 9 0 0.02374995 1.01988429 0 0.17719217 1.17332641 3.5e-3
GW 150 10 0 0.17719217 1.17332641 0 0.26269217 1.17332641 3.5e-3
GW 151 9 0 0.17719218 0.25267349 0 0.02375003 0.40611568 3.5e-3
GW 152 9 0 0.02375003 0.40611568 0 0.1771922 0.55955785 3.5e-3
GW 153 9 0 0.1771922 0.55955785 0 0.02375 0.713 3.5e-3
GW 154 9 0 -0.2246922 0.55955785 0 -0.07125 0.713 3.5e-3
GW 155 9 0 -0.07125 0.4061157 0 -0.2246922 0.55955785 3.5e-3
GW 156 9 0 -0.2246922 0.25267355 0 -0.07125 0.4061157 3.5e-3
GW 157 18 -0.0855 -0.40575 5.0892e-3 -0.0855 -0.04875 5.0892e-3 3.5e-3
GW 158 15 -0.0855 0.35825 5.0892e-3 -0.0855 1.25e-3 5.0892e-3 3.5e-3
GW 159 18 -0.0855 -0.40575 0.3190446 -0.0855 -0.04875 0.3190446 3.5e-3
GW 160 15 -0.0855 0.35825 0.3190446 -0.0855 1.25e-3 0.3190446 3.5e-3
GW 161 18 -0.0855 -0.40575 0.633 -0.0855 -0.04875 0.633 3.5e-3
GW 162 15 -0.0855 0.35825 0.633 -0.0855 1.25e-3 0.633 3.5e-3
GW 163 15 -0.0855 -0.41575 0.1620669 -0.0855 -0.04875 0.1620669 3.5e-3
GW 164 15 -0.0855 1.25e-3 0.1620669 -0.0855 0.36825 0.1620669 3.5e-3
GW 165 15 -0.0855 -0.41575 0.4760223 -0.0855 -0.04875 0.4760223 3.5e-3
GW 166 15 -0.0855 1.25e-3 0.4760223 -0.0855 0.36825 0.4760223 3.5e-3
GW 169 18 -0.0855 0.35775 1.1069554 -0.0855 7.5e-4 1.1069554 3.5e-3
GW 170 15 -0.0855 -0.40625 1.1069554 -0.0855 -0.04925 1.1069554 3.5e-3
GW 171 18 -0.0855 0.35775 0.793 -0.0855 7.5e-4 0.793 3.5e-3
GW 172 15 -0.0855 -0.40625 0.793 -0.0855 -0.04925 0.793 3.5e-3
GW 175 15 -0.0855 0.36775 0.9499777 -0.0855 7.5e-4 0.9499777 3.5e-3
GW 176 15 -0.0855 -0.04925 0.9499777 -0.0855 -0.41625 0.9499777 3.5e-3
GW 177 1 0 0.02375 0.713 0 0 0.713 3.5e-3
GW 178 58 0 0 0.713 0 0 -0.05 3.5e-3
GW 179 2 0 -0.0475 0.713 0 -0.07125 0.713 3.5e-3
GW 180 58 0 -0.0475 0.713 0 -0.0475 -0.05 3.5e-3
GW 188 13 -0.0855 0.311 1.18349 -0.0855 2.e-3 1.18349 3.5e-3
GW 189 13 -0.0855 -0.357 1.18349 -0.0855 -0.048 1.18349 3.5e-3
GW 190 13 -0.0855 0.309 0.87 -0.0855 0 0.87 3.5e-3
GW 191 13 -0.0855 -0.359 0.87 -0.0855 -0.05 0.87 3.5e-3
GW 194 13 -0.0855 0.309 0.55751115 -0.0855 0 0.55751115 3.5e-3
GW 195 13 -0.0855 -0.359 0.55751115 -0.0855 -0.05 0.55751115 3.5e-3
GW 198 13 -0.0855 0.308 0.24251115 -0.0855 -1.e-3 0.24251115 3.5e-3
GW 199 13 -0.0855 -0.36 0.24251115 -0.0855 -0.051 0.24251115 3.5e-3
GW 200 13 -0.0855 0.31 -0.341 -0.0855 1.e-3 -0.341 3.5e-3
GW 201 13 -0.0855 -0.358 -0.341 -0.0855 -0.049 -0.341 3.5e-3
GW 204 13 -0.0855 0.309 -0.656 -0.0855 0 -0.656 3.5e-3
GW 205 13 -0.0855 -0.359 -0.656 -0.0855 -0.05 -0.656 3.5e-3
GW 208 13 -0.0855 0.309 -0.9684889 -0.0855 0 -0.9684889 3.5e-3
GW 209 13 -0.0855 -0.359 -0.9684889 -0.0855 -0.05 -0.9684889 3.5e-3
GW 212 13 -0.0855 0.308 -1.2834889 -0.0855 -1.e-3 -1.2834889 3.5e-3
GW 213 13 -0.0855 -0.36 -1.2834889 -0.0855 -0.051 -1.2834889 3.5e-3
GW 214 26 -0.0855 0.413 1.028 -0.0855 2.e-3 1.028 3.5e-3
GW 215 26 -0.0855 -0.459 1.028 -0.0855 -0.048 1.028 3.5e-3
GW 216 26 -0.0855 0.412 0.40051115 -0.0855 1.e-3 0.40051115 3.5e-3
GW 217 26 -0.0855 -0.46 0.40051115 -0.0855 -0.049 0.40051115 3.5e-3
GW 218 26 -0.0855 0.411 0.08551115 -0.0855 0 0.08551115 3.5e-3
GW 219 26 -0.0855 -0.461 0.08551115 -0.0855 -0.05 0.08551115 3.5e-3
GW 220 26 -0.0855 0.412 0.713 -0.0855 1.e-3 0.713 3.5e-3
GW 221 26 -0.0855 -0.46 0.713 -0.0855 -0.049 0.713 3.5e-3
GW 222 26 -0.0855 0.415 -0.184 -0.0855 4.e-3 -0.184 3.5e-3
GW 223 26 -0.0855 -0.457 -0.184 -0.0855 -0.046 -0.184 3.5e-3
GW 224 26 -0.0855 0.414 -0.499 -0.0855 3.e-3 -0.499 3.5e-3
GW 225 26 -0.0855 -0.458 -0.499 -0.0855 -0.047 -0.499 3.5e-3
GW 226 26 -0.0855 0.413 -1.1264889 -0.0855 2.e-3 -1.1264889 3.5e-3
GW 227 26 -0.0855 -0.459 -1.1264889 -0.0855 -0.048 -1.1264889 3.5e-3
GW 230 26 -0.0855 0.413 -0.814 -0.0855 2.e-3 -0.814 3.5e-3
GW 231 26 -0.0855 -0.459 -0.814 -0.0855 -0.048 -0.814 3.5e-3
GE 0
LD 5 0 0 0 24900000
GN -1
EK
EX 0 1 2 0 1 0
FR 0 0 0 0 585 0
EN

[300ohm]

I am currently trying to cover both the FM Radio and VUHF-LO bands (54 Mhz to 108Mhz) with a single reflectorless hentenna based design, not having much success - VUHF LO alone or FM Radio alone appears to be more possible with a few added ons

A huge bowtie, ie 3 to 4 foot legs, that used to be very common when I was a kid should do you nicely if you dont want anything too fancy. Bowties have very wide bandwidths.

[300ohm]

I think the NORAD’s are pure genius.

That and a lot of black magic, heh.

Perhaps you could link me to the use of the optimizer?

F1 - help > index > optimize, its all in there.

[300ohm]

I googled, but couldnt find a radiation pattern for the Fracarro P54.

Found it !. Its here http://www.fracarro.com/internationa...97&&Itemid=250

It does have a wide radiation pattern. They changed the model numbering scheme to the "PU" series, heh.

[firimari]

I don't know if anyone noticed, but I didn't put new values in for the parameters in X-010 vs X-008

SY gap=0.047743
SY segment_0_length=0.238629
SY segment_1_length=0.115095
SY tail_length=0.156403

should be

SY gap=0.052535
SY segment_0_length=0.233646
SY segment_1_length=0.102343
SY tail_length=0.141824

I only noticed because I'm starting the copper bending tonight and double checked.

[RamKat]

huge bowtie, ie 3 to 4 foot legs, that used to be very common when I was a kid should do you nicely if you dont want anything too fancy. Bowties have very wide bandwidths

Did a quick 4nec2 model and set the whisker length, angle and gap between the whiskers as the optimization parameters. Optimized atr 88Mhz and optimized for max horizontal gain, Impedance of 300 ohm, low SWR (my first optimization)

Results are whisker length = 91.82 inches , whisker angle = 12.44 deg and gap between whiskers 4.22 inches - sounds a tad big but shows some very interesting patterns in the FM Radio band.

[300ohm]

Results are whisker length = 91.82 inches , whisker angle = 12.44 deg and gap between whiskers 4.22 inches - sounds a tad big but shows some very interesting patterns in the FM Radio band.

It does sound a bit big and at around almost 3/2 wavelength. The old vhf/fm bowties were around 1/2 wavelength wide (I dont think each whisker was more than 40 to 48 inches IIRC), which is about 69 1/2 inches at channel 6, so each whisker would be half that. The angle IIRC, was around 30 degrees. And a lot of them had a shorter horizontal dipole in the middle of the whiskers, which I believe was 1/4 wavelength of like the highest channel 13.

The max optimized version may be nice, but not practical for the additional gain, heh. Try optimizing from around 1/4 to 3/4 wavelength, the gain difference may not be that significant to the 3/2 wavelength version.

I think there may be pictures of the old vhf-hi bowtie posted somewhere on this forum.

Here ya go, step one on the Alliance Rotor instructions has a drawing of one.

[RamKat]

Thanks 300 Ohm. I started it at 45 inches and it ended up at

Whisker Length 41.34 inches,
Angle 13.9 deg and
the gap of 2.54 inches

which is closer to what you have stated at the beginning.

This one I may be able to fit into the attic. . The angle is the half angle (from the horizontal) so the full angle is close to 30 degrees as per your estimate. I may play a bit more to see if I improve the SWR at 54Mhz (9.4) and impedance (33 Ohm). (and add the shorter dipole in the middle) Thanks again

[300ohm]

I may play a bit more to see if I improve the SWR at 54Mhz (9.4) and impedance (33 Ohm). (and add the shorter dipole in the middle) Thanks again

On a single bowtie, you can change the impedance a lot, hence the SWR, by changing the feedpoint gap. What kind of gain are you getting with it ?

(and add the shorter dipole in the middle)

Yeah, I would make the center dipole either the top freq youre after or the lowest freq. Then the vee pairs would be at the lowest freq or the highest freq, if you get my drift.

Heres what the head, the feedpoint, on one of those old vhf bowties looked like :



Ill see if I can dig it out again and get some measurements.

[stampeder]

Please put the model number into all of your posts either in the title or else just something like RE: X-008 at the top of the text area.

The reason is that we will definitely be getting overlapping discussions in here and I know from deep diving in old threads that it can get very confusing.

For the sake of humanity I beg you to save our future generations! You're our only hope.

cheers

[300ohm]

Yeah, firimani and I have. Its all astupidoldmans fault !!! heh, heh. (been saving that one up, heh)

[RamKat]

Please put the model number into all of your posts either in the title or else just something like RE: X-008 at the top of the text area.

Yes yes I am guilty Sooorry! Did not consider a single bowtie worth naming in a bleeding edge section

What kind of gain are you getting with it ?

The unnammed bowtie mentioned in Post 23 peaked at 6.55 dBi @81Mhz SWR 3.9 R120

The smaller version (Post 25) about 3dBi lower at the same frequency (but the Raw gain sloped up towards 4 dBi at 108 MHz (should get that screen capture software so that I could paste the graphs)

[300ohm]

Did not consider a single bowtie worth naming in a bleeding edge section

Its still bleeding edge 1940's technology, which is still good, heh. With your above figures, that gives it about a 4.63 net gain on channel 5, which is better than all the other antennas found here http://www.hdtvprimer.com/ANTENNAS/comparing.html, with the exception of Winegard YA-1026 Wideband Yagi for VHF 2-6 and Channel Master 3671B VHF/UHF combo. And youre not done tweaking yet !

Back view picture of the head I have :


Top view picture:


The feedpoint gap is 1 24/64 inches (1 3/8 inches). The forward swept angle is 100 degrees total on the top view picture. The looking at the back view, the spread angle is about 45 degrees total. And thats a 3/4 inch square boom piece.

We had the typical double bay version of the vhf-bowtie when I was a kid and had no trouble pulling in stations that were 80 miles away consistantly and relatively snow free with the antenna only mounted about 20 ft high.

One of the amazing things about the bowtie is, from the link holl_ands found, is that the bowtie was patented in 1898, and has been "discovered" again at least few times since then, heh.