Fractal Antenna Worked For Me
 

I'm a newbie here also, so until I get used to the forum and rules, I won't post any links to my sources.

I live in an area that all retailers said I would also need a deep fringe antenna mounted at least 20 feet over my house. And, I would probably still have unusable reception for the 3 channels I really wanted (CBS, NBC & ABC local).

With the cost of the antenna, rotator, distribution amplifier for 3 TVs, this would have put the initial cost of well over $400.

Amplified indoor/outdoor antennas in the range of $35/$100 were very ineffective, and were quickly returned.

So, I started experimenting with building a fractal antenna, based on the "star shape" elements. My first was with 1 inch per segment. Indoor I was able to get all of the LOS channels in my area. Pwr range at my home from -10dBm to -40dBm.

Without accurate equipment, I relied on the signal strength meter on my TV. The results from my homemade antenna were about 20% higher than the amplified rabbit ear VHF/UHF. And, to top it off, the rabbit ears had a 6 foot coax lead. My homemade antenna used a 50 foot coax.

Only 1 2Edge station (was able to be picked up with the rabbit ears, but I to find the exact placement, and effectively lost signal to the other LOS stations. My homemade antenna was able to receive this station without moving the antenna.

I set my homemade antenna outside on a temporary mount from my abandoned satellite antenna, and was pleased to get decent signal from another 2Edge in the high VHF range.

My next attempt was the same design, but with a 3 inch segment star shape. Indoors, I get every LOS and 2Edge available in my area.

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

For reference, I'll focus on just one channel for comparison. Based on the Radar Map for an outside antenna mounted at 10 feet, and the signal strength meter in my TV's setup menu.

KAME - Real channel 20, distance 1.9 miles, Pwr(dBm) -10.4

Amplified Rabbit ears - signal strength = 38 - 40
1 inch segment fractal indoors - signal strength = 42 - 48
1 inch segment fractal outdoors - signal strength = 60 - 65
3 inch segment fractal indoors - signal strength = 85 - 88

And I forgot to mention, all of these were without the use of a reflector.

So, after my long winded post, if you can afford to buy less than $20 worth of material and be willing to spend an hour or so building it, this may be the way out. I was lucky enough to have enough scrap material laying around, and only had to buy a matching transformer.

Where I live (Reno area), there's a company that will come to my house and take signal readings and recommend the best antenna, with no guarantee of it actually working, for $100. Needless to say, I didn't try this option.

Given the significant differences between you situation and madvetos, I've given your post it's own thread. Feel free to cite sources.

Welcome to the forum.

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.

Thank you, GroundUrMast. The tvfool site in general, has helped me tremendously after I decided to "Cut The Cable" to satellite service.

Hi Dave.

I actually printed the diagram of the link you posted -- months ago. But, after I found that my first test with the format located at http://www.leoda.us/projects, worked so well on the 3 HI VHF stations in my area, I didn't look much further at that site.

No offense or critique intended, but the little I actually read at digitalhome was so far over my head that I didn't go much further.

However, the simple design of the William Ruckman version worked great for me. And again, I have to stress that all of the antenna retailers have had very low hopes of a working antenna system for less than $300.00.

I simply found a basic approach for testing 2 versions of this design, and found the results better than 2 commercial products. To me, that seems worthwhile sharing.

For what its worth, my first working model was made with 30 ga. buss wire, thumbtacks, and an 8 by 10 inch piece of cardboard. And according to the signal meter on my TV menu, it outperformed the ClearStream 2 on both indoor and outdoor tests, and blew the doors off the Radio Shack Amplified HDTV Indoor Antenna (Model: 15-254).

Please note that I can get reception from all of the LOS stations that are within 2 miles of my house with 12 inches of test leads clipped to the same 100 foot coax. It was the 3 - 2Edge, HI VHF stations that I really wanted. I guess that's why my 3" segment version worked so much better than my 1" version for those.

On a comical note, just this evening I found that my burr style coffee grinder, about 8 feet away from my test antenna, severely lowered signal level on the 2Edge channels when grinding coffee.

Maybe, the fractal community still has hopes. Even with old technology and designs.

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 stations.

RenoPaul, note that KAME's predicted signal level is highlighted in grey. That's a warning that it will overload just about anything. You should absolutely never, ever use a preamplifier of any sort in your system. Any professional that has recommended such should be reported for gross negligence! There is no way you will need to spend $400.

Again, to sum up the results of the digitalhome crowd's exploration of fractals:
1) when applied to existing designs, the antenna's fequency range was shifted up in frequency OR the antenna could be 30% smaller. No net change in gain.
2) Ruckman designs tended to suffer from high VSWR (poor match to the coax), meaning less net gain. No magic bullet.

Commenting on your experiences - It's no wonder all the amplified antennas had to be returned. They were all certainly overloaded by KAME. The amount of signal picked up by the CS2 probably overloaded your receiver. When active alements like amplifiers are overloaded, noise and spurious signals are generated throughout the spectrum, potentially swamping out other stations. The offending signal will be passed through, but could also be heavily distorted. The avalanche of signals will cause your receiver to turn its sensitivity way down, so surviving weaker signals aren't locked and the super strong signal will be sensed weakly.

The main reason KAME's strength went up is because your homemade antennas did not have an amplifier and, at the proper orientation, did not have much gain towards KAME and company.

Your situation is not typical. What you need is minimal UHF sensitivity to the west and modest hi-VHF sensitivity to the south-southeast. I offer two suggestions for the rest to ponder: an RCA ANT-751 or an Antennacraft HBU-22 or-33 aimed at 185 degrees. The criteria I am using are having enough forward gain for hi-VHF while having just enough off the side of the main beam to catch the locals.

In response to both of your replies:

Far be it from me to debate technical specifications, but from what little I do understand, a 3 dB gain is roughly equivilent to doubling signal strenghth. With this in mind, consider the additional 50 feet of low cost Radio Shack RG59u (2 - 25' with a connector to join them), and according to http://www.net-comber.com/cable-loss.html I've already lost 1 - 3dB over the frequency range , probably more with 10 year old, cheap cable. So, with that I figure the gain is more like 6db or more. Without proper test equipment, I really have no idea of the actual gain. Again, this is without the use of any type of amplification.

However, as far as topology goes, my house is at 4800 feet, and less than 500 feet south of me, there is a hill that is almost 5000 feet. The transmitting tower for the VHF HI channels is close to 20 miles south of me, and direcly blocking line of site to the transmitter. Hence, the 2Edge Path in the chart.

My signal strength is solely based on the "Antenna Setup - Digital) on my Sharp SB57 Series TV. and I have no idea of the relation of their "0 - 100" scale vs. dB, and/or AGC on the receiver.

What I do know, is that the ClearStream 2 mounted outdoors 20 feet above ground level, was able to get the lowest frequency, real channel 8 (KOLO. KTVN - 13 and KRNV - 7 were totally non-existant), at a maximum signal strength of 15 to 17 (totally undetectable with a channel scan), and my home made cardboard mounted "leoda" based design, sitting in my living room (farthest north part of my house) with 50 feet of cheap RG59u brought my signal meter to 52. Also, take into consideration that my house is full of EMF producing equipment; Surround receiver, appliances, cordless phones, WIFI, Bluetooth and more than 7 computers running full time, all sitting between my test antenna and the southernmost part of my house.

To make matters worse, sitting in the high desert of Nevada, we are prone to many high level wind storms. Some close to hurricane wind speeds. This makes it extremely difficult to safely mount a large antenna on my roof, or a tower. In fact, today the general area is experiencing wind gusts of over 40 mph, and at my house, I've recorded gusts of almost 60 mph.

So, in layman's terms, as it seems most of antenna questions aren't coming from engineering or technician minded people, I must restate my situation and opinion. Granted, this is in my case, but the thread title clearly implies that.

For MY situation:

1. Every retailer claims that reception is slightly possible with the best deep fringe antenna available, preferably with a stacked configuration, in order to get the 2Edge VHF HI stations.

1a. All of the LOS stations, KAME, KNPB work without any antenna, KRXI worked with simple rabbit ears (non-amplified). When using the amplified antenna, I had to turn the amplifier off for KAME. KAME also works with just exposing the F connector.

2. Weather conditions prohibit a heavy antenna without a tremendous amount of support.

3. Commercially available compact indoor/outdoor amplified antennas don't work well.

4. The William Ruckman design works pretty good both indoors and outdoors without an amplifier.

5. The leoDA version of the William Ruckman design works very well indoors (outdoor tests will be made when weather permits)

With that in mind, I honestly think that most people that can read a ruler and protractor, can afford a few feet of copper wire, a box of thumbtacks, a piece of cardboard or foamboard, 2 screws, 2 clothespins, a bit of masking tape, and a matching transformer with a short piece of coax cable, can build a quick test antenna in less than an hour. Much less expensive and less time consuming than climbing their roof with a helper, to install a large antenna.

To make matters even easier, it seems that exact measurements aren't all that critical, although I did correct the scale of the template from William Ruckman's image to match my printer. That made the need of using a ruler and protractor minimal.

Yes, I know that the techies will debate this point, but for a person to use either of these designs to see if a particular channel might work before spending a good chunk of cash on a quality commercial antenna...

A note on Dave's comment regarding "gross negligence":

My main concern was for the 3 channels in the VHF HI band, KRNV, KTVN and KOLO. And, taking into consideration of the frequent high wind conditions, the close proximity of the hill south of my house. Also, I aimed my test antenna for the best reception for KTVN, so the KAME signal level is not at its optimum.

BTW, when I purchased my home, the Antennacraft HBU33 was already mounted to the side of the house, and had zero signal for KOLO, KRNV and KTVN. Of course, there was already damage to the eaves, and the guy wire anchors in the roof that cost more to repair than the antenna was worth. It was only mounted on a 5 foot mast.

So, again in my situation, the leoDA's modification of the Ruckman design (despite any possible VSWR mismatch causing loss of gain) allowed me to receive the 3 channels that a commercial antenna couldn't.

And a side note regarding high winds at my location. The previous owner of my home told me that 3 years before I bought my home a wind storm had blown 1/3 of the roof off my house. Its very common to have wind gusts well over 100 Mph at my location.

In my case, a Magic Bullet!

Out of curiosity, how do the ClearStream 2 and the Radio Shack amplified rabbit ear antenna rate on VSWR? And, is there an inexpensive way to actually test my system's VSWR? I do remember the old CB radio days using an SWR meter to adjust for transmitting, but never saw much difference in reception with a CB antenna that was "out of tune".

A note on Dave's comment regarding my situation is not typical:

I know that I'm not the only person in the world where a mid or full-size outside commercial antenna isn't feasible or possible. And I also don't believe there are any antenna installers that will refund their labor charges if a commercial antenna doesn't work. I'd rather throw away a $10 experiment than a $50 - $150 antenna plus labor, and the cost to repair holes in my roof or siding from mounting hardware. Therefore, I do believe my situation is more typical than you suggest.

Again, I must stress that the LOS stations, less than 2 miles away, are no problem. Only the 2Edge stations that are roughly 20 miles and the geographic obstructions.

A cheap set of rabbit ears and a $10 A-B switch will easily eliminate any problems from over-driving my receiver for KAME.

The technical aspects can be debated for years, but so far, I've only spent $8.00 and have a working antenna that is capable of delivering the stations I want, and its still sitting indoors, without an amplifier.

Antennas Direct is pretty good about providing technical information for their products: http://www.antennasdirect.com/clearstream2gain.html

Radio Shack is not as forthcoming with such technical information.

I've noticed that a few commercial manufacturers are lacking in this specification.

Please correct me if I'm incorrect in my next assumption/question.

My only experience in measuring VSWR was back in the late 70's during the CB radio craze. In order to adjust VSWR, you had to actually transmit on a specific frequency, and if my memory holds, the 40 channel CB range was from 26.965 - 27.405 MHz. Ideally, you would adjust the length of the antenna to give the lowest possible ratio over that band, by changing the length of the antenna mast to match the entire system of cable and antenna to the actual wavelength. Even at this small band, adjustment was quite tedious, and at best, was never equal across the entire band.

In my experience, I noticed that an antenna's VSWR would change, sometimes drastically, if moved from 1 location to another, indicating that surrounding objects and cable length had quite an effect in this measurement.

With my nature of always being a bit on the skeptical side, I experimented testing VSWR with a dummy load (terminating resistor), finding VSWR results all over the board, and rarely even close to 1:1 on factory made cables.

So, my first real question is, how would the normal person (with limited technical knowledge) legally be able to transmit, even a very low signal, to test a homemade antenna of any sort?

My second question is, how is it possible to get a low VSWR on a VHF HI to UHF (174 to 806 MHz) across the entire range, on a receiving antenna?

And my third question is, has anyone ever tested a commercial antenna in more than 1 type of non-laboratory installation, and do the results ever match manufacturers' claims?

Log periodic dipole arrays (LPDA) have dipoles of different lengths. And only 2-4 are used by any frequency. That is as the frequency increases the active region of the antenna shifts toward the shorter dipoles.
Some large commercial TV LPDAs are sensitive to 54 MHz through 900 MHz or more with relatively good swr.
Keep in mind also swr is not as crucial to a receive only systems compared to transmitters (less than 2.7 just costs a little gain) partly because any reflected signal caused by the bad swr is reflected toward the antenna to be transmitted not back at the electronics.
All my "tests" would be on models (so grain of salt time) but I think the mfg. claims (reputable companies) are accurate to the extent it's given.
The Antennas Direct like though revelation of swr graphs of the whole band are rare. Usually you get an average which can hide excessive swr on some frequencies with good swr at most.

Easiest and cheapest way is model it. No physical build necessary.

I agree with @ghz24, SWR of a receiving antenna is not as high a priority as is a transmitting antenna. The power reflected back toward the transmitter can cause damage to the equipment at some point. Receive power levels are in the micro-watt and less range, hardly capable of damaging passive antenna components.

If measurement of SWR is needed, you'll find yourself in the market for some expensive test gear. Antennas Direct indicated they used an HP8510c to do the testing reported in their CS2 VSWR graph. (You can find one on E-Bay for less than $4000. :eek:) Given that SWR is not an indicator of antenna gain or directivity, I'm not in the market for a lab grade RF network analyzer.

For the DIY'er, side by side performance comparison is usually the most cost effective testing available. As, you have already stated in your own way, if it works for you, who cares if the home-built or store bought antenna will work for someone else. (But that it works for one, is not proof it will work for another.)

Thank you to everyone that replied.

In fact, my DIYtenna is working just fine. Even my first prototype laid out on 1/4 inch foam board, with the elements tacked down with artist's tape has survived rain, a small snowfall, and an 80+ Mph wind storm. More than I can say for the tanker truck on the highway a few miles north of me, the same day I posted about the high winds in my area.

As for modeling, I've been trying to find something to assist my own testing, in more of a graphical form. Guess that's something for the future.

For what its worth, my prototype was based on the 1" per segment Ruckman, and another one that I've been using indoors based on the same format, but with 3" segments. The larger one does work much better.

But back to modeling. On paper, an internal combustion engine can't possibly work, but take into consideration the lubricating factor, and all works quite well.

And a brief "Back to VSWR". In my experience of the CB Radio years, I found that moving a magnetic rooftop antenna to a different location on a vehicle made some drastic changes in VSWR.

No offense to the modelers, but I can't see how a firm statement of poor VSWR can hold true in all cases.

However, I will still hold to my main opinion. Before you buy a commercial antenna, try a DIY. You may just surprise yourself.

The length of the segments are chosen not by whim but are based on the wavelengths of the signals that the antenna is designed to receive.

Please don't repeat this statement to anyone who has studied thermodynamics. The automobile internal combustion engine on paper operates on the Otto cycle. It works very well.

This is to be expected. When you move the antenna, you change the ground plane.

OK, I'll take the hit on the engine analogy. That comparison didn't belong in this thread to begin with. My bad.

This is to be expected. When you move the antenna, you change the ground plane.[/QUOTE]

So, if I understand you, and rely on antenna modeling software, VSWR testing in a model can be totally different in a laboratory, and can and probably is totally different in the real world, and will vary greatly in real world installations.

Considering all of the replies regarding how badly a fractal antenna fails in modeling, then seeing a few companies (including the military) working on fractal antennas (applications including Bluetooth, cell phones, and etc.)

My final comments on this subject are:

In theory, everything is theoretical, but in application, everything is applicable. The Ruckman style Fractal TV Antenna works for me, and probably will for thousands of others.

While all the modelers decide a fractal antenna isn't worth considering, and retailers are selling products that anyone can purchase from $ 19.99 to well over $ 150, I'll be happy spending $ 6.39 plus tax on a Radio Shack matching transformer, spend less than an hour bending some scrap copper wire, and turning a few screws, and happily watch all of my local OTA stations.

Mr. Moderator, please close this thread. Thank you.

Let's not get snippy. Models are theoretical calculations. Laboratory tests are performed in controlled environments. The Real World is neither theoretical nor is it controlled. However, models and lab tests help people in the Real World optimize their antenna installations.

I have no idea where you get this from. I have seen models of fractal antennas that show spectacular results compared to conventional designs.

This is simply not true.

Nobody said otherwise. What is called into question are your statements. If something works, then your erroneous statements about it does not change the fact that it works.

MisterMe,

Sorry if I sounded "snippy", but my original post was regarding how well the fractal antenna worked for me, and for anyone that read a ruler and a protractor, and can draw a few lines, bend a bit of copper wire around some wire brads or thumbtacks, it could be a very inexpensive way to determine if buying and installing a commercial antenna was feasable.

The first reply made to my post was about "how the fractal community seemed to move on to other designs because of high VSWR. To me, in a receiving antenna, not as critical as a transmitting antenna, mainly because a transmitting antenna is generally tuned for 1 frequency, or small bandwidth.

My results were what I thought to be a sharable experience, and without pointing fingers, it seemed as if I was getting put down for bringing back a discussion on the fractal antenna.

I'm far from an engineer, but have a pretty good basic understanding of standing waves, tuning, and the application of a very few types of receiving antennas.

I also understand that I'm a newbie here, and have noticed in this thread (and many others) that replies generally are in a non-layman's realm of understanding, or seem to be promoting commercial antennas, so I was trying to use a bit of diplomacy in my comments. The last one was a bit harsh, but it surely seemed as if my opinion was being shot down because of "modeling". (see the first reply to my initial post)

I used a couple of bad examples regarding signal strength from a close station, however when a $ 150 commercial antenna mounted outdoors couldn't compare to my DIYtenna...

Well, nuf said.

Thank you for your input, and correcting my assumptions.

However, a friend of mine did try to apply the commercial about that sealing stuff in a can, used on a screen door, in a rowboat. Yup, it worked, as long as you put the sealer on the higher pressure side! Hence, in application every is applicable. And a theory is still a theory until a working model (not a computer model IMHO) is created from that theory.

What you don't seem to understand is that models of RF antennas have been tested in the Real World with the design, construction, and use of thousands of different antenna designs. The reason that models are more acceptable than controlled laboratory tests is that models have been proven to be more reliable than laboratory tests over decades. The models are based is Classical Electromagnetic Theory as represented by Maxwell's Equations. James Clerk Maxwell published A Dynamical Theory of the Electromagnetic Field in 1865. The great prediction of the theory was that electromagnetic fields propagated as waves through the vacuum at fixed speed. Here we are 147 years later and Maxwell's Classical Electromagnetic Theory works as well as it ever did.

Actually, I do understand a little of the background. Like I've said earlier, I do not have an engineering background, and honestly, most of the documents I've read are way over my head as far as the the math and the technical language used.

But for what I've noticed, its usually the non-technical person that is asking for help, and hit with terminology they can't or don't understand.

Again, I must stress that in my case, having just enough knowledge about antenna design to be dangerous <tongue in cheek> and trying a commercial product with a low profile (referring to my high wind conditions) that seemed to have very high rating, just didn't come close to what I built with scrap I had in my shed.

Aside from the technical aspects of design, the template (picture, not a modeling result) performed better.

So, with this in mind and considering my lack of higher education...

I was told (in a reply) that my version of the Ruckman design only had a 3dB gain. I'm also using 2 - 50 foot lengths of low quality RG 59 to attach my DIYantenna to my television. This same piece of RG59 has been used for more than 15 years, and at least 5 of those years outdoors. According to the chart at http://www.universal-radio.com/catal.../coaxperf.html, I've got an expected cable loss of 7.6 dB or better. So, judging by the earlier reply, I've lost more signal strength than I've gained.

In order to use what simple equipment I have to measure signal strength (the signal strength meter on my television), I used the same low-end cable to compare both my DIY, HBU33 and the ClearStream2 antennas.

The ClearStream 2 (rated as having a gain of 10.2 Dbi) was installed outdoors, and approximately 6 feet higher that my larger DIY. At best, I could only receive 1 of the 2Edge stations, reading less than 30 on my television. Totally unviewable. My HBU33 at 9+ dB gain, could only receive the UHF 2Edge stations, but none of the HI VHF stations.

My DIY, mounted on a piece of foamboard with inconsistent bends, and far from perfect straight segments, and mounted on a camera tripod, receives all 4 of the 2Edge stations with a signal strength of 55 or better, and all of the LOS stations at 88 or better. BTW, I am not using any type of amplifier.

Also, keep in mind that the DIY is located at the northeast section of my house, and the 2Edge broadcasts are coming from the southwest. Not only does the signal have to go through the interior of my house, but there is enormous amount of EMF in the way. Cordless telephone with Bluetooth connection to my cell phone, kitchen appliances, electrical panel, WIFI in my living room and other WIFI computers directly in line with my DIY, more than 7 computers running 24/7, and directly in LOS of my DIY positioning, my radio internet antenna.

Please correct me if I'm wrong. In modeling, and in practice, both the HBU33 and the ClearStream 2 would be a much better choice for me, yet neither worked. However, my DIY, which seemed to have been abandoned by "the community", as referenced by Dave's first reply to my first post, out performs 2 of the accepted commercial available antennas. I also understand that the ClearStream 2 is advertised as a UHF, not a HI VHF/UHF antenna and actually a poor choice.

And yes, I do get interference when a plane is on approach to our airport, I'm very close to the airport approach airspace. But that would be expected with just about any OTA antenna. And yes again, reception does change with weather conditions, but I also understand that would be expected with a 2Edge signal.

In the responses to my original post, the theory and modeling behind my DIY shows it shouldn't work well. However, in application it blows the doors off the commercial recommendations. (Sorry for the analogy again.)

Either my inaccurate bending of the wire elements, especially with rounded bends vs. sharp points, or my inaccurate spacing due to not having perfectly straight pieces of wire to connect the 2 pair of elements changes the model, or maybe, just maybe, there really is something to be said about the true gain of the Ruckman Style Fractal design.

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.

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.

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.

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

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
and if you do try the modeling program here's the model I used to get the figures above to get you started.
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.

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!

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

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.

I agree, this thread fits the Enthusiast's Exchange better than the Help With Reception.

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.

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.