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Old 30-Jan-2012, 5:44 AM   #21
MisterMe
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Quote:
Originally Posted by RenoPaul View Post
....

I was told (in a reply) that my version of the Ruckman design only had a 3dB gain. ...
You need to go back and reread what Dave Loudin told you. He stated that the Ruckman design had a gain of 2 dB-3 dB in the Hi-VHF band. You have only two stations in the Hi-VHF band. They are WLS (RF-7) and WBBM (RF-12). WBBM is also line-of-sight, which means that it should be fairly easy to receive. The vast majority of your stations are UHF where the gain of the Ruckman design is probably more sensitive. Dave Loudin said absolutely nothing about the sensitivity of the Ruckman design in the UHF band.

The bottomline is that you spent a lot of time and effort to refute a statement that nobody made.
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Old 30-Jan-2012, 7:51 AM   #22
RenoPaul
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Quote:
Originally Posted by MisterMe View Post
You need to go back and reread what Dave Loudin told you. He stated that the Ruckman design had a gain of 2 dB-3 dB in the Hi-VHF band. You have only two stations in the Hi-VHF band. They are WLS (RF-7) and WBBM (RF-12). WBBM is also line-of-sight, which means that it should be fairly easy to receive. The vast majority of your stations are UHF where the gain of the Ruckman design is probably more sensitive. Dave Loudin said absolutely nothing about the sensitivity of the Ruckman design in the UHF band.

The bottomline is that you spent a lot of time and effort to refute a statement that nobody made.
I'm sorry for your error, but I live in Nevada. KRNV is on Channel 7 (4.1) , KOLO is on channel 8 (8.1), and KTVN is on Channel 13 (2.1). These 3 are all 2Edge according to my "radar map"

http://www.tvfool.com/?option=com_wr...67d940ad1928dc

as well as a few other UHF stations.

Bottom line is still -- My antenna works, and the better of the 2 recommended by Dave didn't.

And please understand me. I am not criticizing Dave's work, suggestiions or understanding, only try to educate myself on why an antenna works in application, but seems to be no longer feasable.

Dave's first quote was:

"There was a long thread on fractal antenna designs here at digitalhome.ca. That it hasn't been posted to for a while suggests that community has moved on to other designs."

Dave's other quote was:

"The modeling of the Ruckman fractal documented in that thread showed that it did not perform any better over the VHF and UHF bands than other designs. For hi-VHF, the gain is around 2 or 3 dB, which is good enough in your situation for reliable lock, but just barely. That's why the coffee grinder did in the VHF station."

Maybe I was a bit "snippy" on one of my previous posts, and if I didn't apologize to satisfaction, please accept my sincere apology now. But please don't insult my intelligence by assuming what channels are in my area by looking at Mark's map and not mine.

May I also suggest someone in the higher technical level actually build a version of my current antenna,

http://www.leoda.us/Fractal%20antenn...20drawing.html

and perhaps even model it, and explain to me why I get better reception, and can receive other stations a commercially, and technically accepted antenna couldn't.

Also note that my current DIY is not using a reflector, and is not mounted on a PVC frame. Its simply held in place with the same brads I used to bend the wire. By technical standards, I probably broke every rule regarding impedance by having it mounted directly on foam board, and leaving the wire brads still connected to the elements. But it works!

This antenna is not my design, and I'm also not trying to sell a version of this, only sharing my experience on using a DIY before spending $$$ on something else.

Referring back to Mark's original post, he was looking for "value". In my opinion, building an antenna for less that $15 vs. $50 - $150, and the possibility of many trips to try other antennas, leans closer to value than debating VSWR, Gain or loss of gain, or other technical aspects of a receiving antenna.

Again, my opinion. Unless Mark lives in a basement apartment, or doesn't have access to a suitable location, and given his distance from the transmitters, the same fractal design I'm using may or may not work. But, if he can bend wire and turn a screwdriver, the fractal antenna just might work for him too.

Apparently, you picked up the thread in the middle, and unfortunately didn't get the whole story.
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Old 30-Jan-2012, 8:47 AM   #23
GroundUrMast
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Quote:
... explain to me why I get better reception, and can receive other stations a commercially, and technically accepted antenna couldn't.
60 dB of attenuation (a reduction of power by a factor of one million times) inserted between a simple UHF loop antenna and your tuner would leave you with plenty of signal from KAME.

Dave Loudin's comments in post 7 & 8 of this thread speak to that. In particular, the extreme power level of the KAME signal is very likely causing your tuner to overload. An antenna with net gain in the UHF band is going to make overload still more likely.

Your situation is not typical, but I'm quite happy that you've found an inexpensive solution that apparently attenuates the powerful UHF signal while receiving sufficient signal from weaker UHF and VHF stations.

As long as the discussion remains polite, I'm not inclined to close the thread.
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Old 30-Jan-2012, 3:33 PM   #24
MisterMe
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Quote:
Originally Posted by RenoPaul View Post
I'm sorry for your error, but I live in Nevada. KRNV is on Channel 7 (4.1) , KOLO is on channel 8 (8.1), and KTVN is on Channel 13 (2.1). These 3 are all 2Edge according to my "radar map"

http://www.tvfool.com/?option=com_wr...67d940ad1928dc

as well as a few other UHF stations.

Bottom line is still -- My antenna works, and the better of the 2 recommended by Dave didn't.

...
As I said in my last two posts, the fact that your antenna works is not in dispute. The issue is why your antenna works. You started this thread with a response to a post by madvetos who receives Chicago stations and who has some issues similar to yours but without the issue of several broadcast towers so close. He has two Hi-VHF channels. You have three Hi-VHF. Your three Hi-VHF channels are all 2-Edge, but they also all have ample power at your location.

Putting GroundUrMast's explanation together with Dave Loudin, it is clear that your experience does not in any way contradict our understanding of antenna design or the accuracy of computer modeling of receiving antennas. To the contrary, your experience confirms them.
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Old 31-Jan-2012, 7:59 AM   #25
ghz24
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perhaps even model it

Don't take statements of performance wrong most of the statements are comparing it to a non-fractalized (if that's a word) similar antenna.
You seem very interested in the characteristics of this antenna so why don't you take the leap and download 4nec2 (free modeling program)
and give it a shot. (it's not that hard if you have an already built model)
Here is the antenna you made with no reflectors (gain is dBi net) UHF

Code:
max	7.0452717189		7.8089515597
min	4.6449004552		2.3223250366
			
Average	6.3864243396		3.8669560812
I'm kind of surprised you get a usable digital signal at all, SWR over ~2.7 can kill a digital signal.

with a flat reflector it's better. edit:changed gain figures to match the corrected model
Code:
			
max	10.9458221554		4.4905919223
min	8.9146671202		1.6696213956
			
Average	10.2025694137		2.3975494407
and if you do try the modeling program here's the model I used to get the figures above to get you started.
Code:
CM Ruckman Fractal 2 bay bowtie
CM by GHz 24
CM AWG Gauge 12 Copper Wire Elements 
CE
SY z=5.25
SY y=0.625
SY x=-5.5
GW	1	3	0	y	0	0	y	z	0.0404
GW	2	3	0	y	z	0	4.09807087-1.5+y	1.5+z	0.0404
GW	3	3	0	4.09807087-1.5+y	1.5+z	0	4.09807087-1.5+y	4.5+z	0.0404
GW	4	3	0	4.09807087-1.5+y	4.5+z	0	6.69615354-1.5+y	3+z	0.0404
GW	5	3	0	6.69615354-1.5+y	3+z	0	9.29422441-1.5+y	4.5+z	0.0404
GW	6	3	0	y	z	0	4.09807087-1.5+y	4.5+z-6	0.0404
GW	7	3	0	4.09807087-1.5+y	4.5+z-6	0	4.09807087-1.5+y	1.5+z-6	0.0404
GW	8	3	0	4.09807087-1.5+y	1.5+z-6	0	6.69615354-1.5+y	3+z-6	0.0404
GW	9	3	0	6.69615354-1.5+y	3+z-6	0	9.29422441-1.5+y	1.5+z-6	0.0404
GW	10	6	x	0	2	x	12	2	0.0404
GW	11	6	x	0	4	x	12	4	0.0404
GW	12	6	x	0	6	x	12	6	0.0404
GW	13	6	x	0	8	x	12	8	0.0404
GW	14	6	x	0	10	x	12	10	0.0404
GW	15	6	x	0	12	x	12	12	0.0404
GX	400	011
GW	16	12	x	-12	0	x	12	0	0.0404
GW	37	3	0	y	0	0	-y	0	0.0404
GS	0	0	0.0254		' All in in.
GE	0
EK
LD	5	0	0	0	5.8e7	0
EX	0	37	2	0	1	0
GN	-1
FR	0	1	0	0	585	0
EN
just copy and paste into a text file and save as "fractalblabla.nec"
then open it with 4nec2. The variables change the gap,separation,reflector distance.
If you get stuck you could open a thread in the antenna section or enthusiast exchange area.
Rather than discuss design in the help with reception area.

Last edited by ghz24; 31-Jan-2012 at 8:16 PM. Reason: minor fix to model model
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Old 31-Jan-2012, 8:20 AM   #26
RenoPaul
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Quote:
Originally Posted by ghz24 View Post

If you get stuck you could open a thread in the antenna section or enthusiast exchange area.
Rather than discuss design in the help with reception area.
I was surprised with my first DIY, especially when I mounted it outdoors. One of those Youtube videos that seem impossible, but surprisingly, actually did work.

I did notice you called your model "Ruckman Bowtie". Mine is based on the overlapping triangle, or star shape.

However, I do agree about moving to the other forum. I have a feeling I've overstayed my welcome in this forum <tongue in cheek>, and probably should have started there.

I"ll probably post in the Enthusiasts forum later this week.

My thanks to Dave Loudin, MisterMe, and especially GroundUrMast for not cutting my coax!
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Old 31-Jan-2012, 3:18 PM   #27
MisterMe
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Quote:
Originally Posted by RenoPaul View Post
...

I did notice you called your model "Ruckman Bowtie". Mine is based on the overlapping triangle, or star shape.

...
ghz24's characterization is appropriate. At its heart, the Ruckman design is a 2-bay bowtie antenna with modified whiskers.

Last edited by MisterMe; 1-Feb-2012 at 3:32 PM.
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Old 31-Jan-2012, 8:34 PM   #28
ghz24
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error in the model and gain figures

The model I posted had a wire not connected.
Sorry my eyes were tired when I finished it and I didn't notice until this afternoon.
The model and the gain and SWR figures have been corrected.
Bowtie /whisker: I'm pretty sure it's the model you posted links to like a stack of two wire whisker dipoles (with 3 extra bends to make it look like part of a star). All the whisker segments 3".

BTW SWR in that range makes this model exceptionally flawed.
It did alot better with one segment (accidentally) clipped off.

Last edited by ghz24; 31-Jan-2012 at 9:35 PM.
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Old 31-Jan-2012, 10:06 PM   #29
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I agree, this thread fits the Enthusiast's Exchange better than the Help With Reception.
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Old 31-Jan-2012, 11:05 PM   #30
RenoPaul
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I'll meet you all in the Enthusiast's Exchange. I'll start a thread called "Fractal Fun", and hope to keep it just that!

BTW, I did download 4nec2, and maybe with some guidance, I can actually do a model, and get a tiny bit closer to your level of expertise.

Maybe I should change my nick to TinkererPaul. Thanks again guys.
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Old 1-Feb-2012, 8:20 PM   #31
ghz24
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One more correction

This line
GW 37 3 0 y 0 0 -y 0 0.0404

is an imaginary wire used to specify the feed point with the "EX" line below it.
the last field in the line/card (0.0404) is radius in inches of 12 GA wire.
(same as all the other wires)
But models should be able to pass an AGT test (f-7 pick "far field pattern then look for the check box)
So to pass the AGT test this model needs the radius of that imaginary wire to be "0.077" At least in the TV UHF frequency range.
This also reveals another 0.6 dBi of gain.
So be careful of models you find posted (or create) as this could be used to cheat even if inadvertently done.
At the same forum dave pointed to there is a modeling thread here http://www.digitalhome.ca/forum/show...ighlight=4nec2 it's long and wanders a tad but the search function can weed out some of the less relevant stuff.

As far as this fractal 2 bay whisker model I think the elements are to long (Because the SWR decays at higher frequency >ch.44). Most whisker antennas are 9-10 inches long (for uhf) these are 12"
So the sections (not segments they are different) might be better at ~2.5"
for a total wire length 10" per whisker.

Overall applying fractals to an antenna does not increase gain/performance
(at least that Ive ever seen). It's a mater of "how little do I lose if" game.
The payoff is in smaller easier to stamp out antennas without giving up to much performance
So fractals are generally compared to the parent design as a best you can do max.
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