Antenna Gain - Is it the ultimate measure of a better antenna?
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Antenna Gain - Is it the ultimate measure of a better antenna?


This is a discussion on Antenna Gain - Is it the ultimate measure of a better antenna? within the Antenna R&D forums, part of the Advanced Discussion category.


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  1. #1
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    Antenna Gain - Is it the ultimate measure of a better antenna?

    Let me start with manufacturers that use mileage, that is a real joke. Simply if there is a hill in the way a 60 mile antenna is not going work any better than a 30 mile antenna pointed straight at the hill. Mileage is the worst way to judge an antenna, then add to fact those like the Chinese Ebay antenna, totally lie about 100 mile range. Sure they will do 100 miles, if the TV station is on top of a mountain, and you are on the top of a mountain and there are no mountains between you and the TV station, then yeah, probably work 100 miles.

    That myth out of the way, gain while probably the single most important aspect of measuring an antenna is not always the best nor the only factor in good reception.

    Two very good examples when pure gain is not what receives the signal in an antenna.

    1) Probably the most common problem not solved by just gain is multipath. Most multipath comes in from the sides, and most at an acute angle to the main lobe (acute angles are those less than 90 degrees). This means it comes in reflected from somewhere very near the main beam to from the sides. Though multipath can be from the rear, it's less common. So except where you need a lot of beam width and you don't have multipath concerns, an antenna with a narrow beam width will in general be a better DTV antenna.

    Probably the worst offenders though excellent antennas are the 2 and 4 bay whisker antennas. They have excellent gain, but poor front to side rejection. The antenna is just a 2 element beam with other 2 element beams stacked. There are no directors to limit the side reception. Nor are their any other driven elements stacked beside them such as the 8 bays (which I like to think of as two 4 bays stacked horizontally).

    Much better for front to side without sacrificing a lot of gain are short boom yagi's with corner reflectors. Many models are made. The beam width of them on the shortest models is close to a 4 bay. The longer they are though you do then sacrifice wide beam width for gain, in a narrower forward beam, but you gain tremendous front to side rejection.

    A good example of this is my situation. I have UHF towers are 54 degrees apart. A 4221A has beam width of 52 to 57 degrees on my channels 16-36. Seems like a match made in heaven! Well until the wind blows and leaves are full of water in spring and summer, then two of my channels constantly break up with multipath. The beam width is just too wide. I receive the signals reflecting from trees too far to the right and to the left. It was unacceptable to watch TV. I replaced it was a U-75R that has a beam width of 47 degrees. What is not told is the U-75R has much better front to side rejection. My multipath problems were solved.

    Why is this so? Better yet how can you tell from looking at antenna plots?

    First look at the 4221 overhead plot vs the 4228 overhead plot:



    Notice how much faster past the 3 db point (beam width) the gain drops off.

    Now look at the Winegard 9032:



    Notice that in both a log boom corner reflector yagi and the 8 bay, the beam lobe is "squeezed" more into a thinner "oval" where with the 4 bay it's much rounder. This is the core difference why a yagi solved my multipath problems.

    Now sure I could have put up a 4228 or a Winegard 8800 but not only are they twice the price, but many many times heavier and catch a lot more wind.

    I really think while the DTV transition took to the 4 and 8 bay antenna in a whirlwind of the ultimate solution, most people are much better served with a long boom yagi that is much easier to manage than an 8 bay on a pole.

    2) Narrowing the vertical beam width on VHF toward the horizon. This is really the same argument but with a different twist, problem and result.

    The same arguments and lessons above apply here but instead of looking as narrowing the beam width in the azimuth or horizontal side to side, this looks at narrowing it in the vertical or elevation up and down.

    If you read about unusual reception, you have probably heard about picking up UHF stations behind a hill but pointing the antenna up at the top of the hill. Yes this works. It's from the UHF signals being bent or refracted by the top edge of the hill. You will sometimes hear this called knife edge reception.

    On VHF, the bending is much more subtle due to the much longer wave length. This trick only works well if you are on relatively flat ground or your distance horizon is not blocked by a hill or mountain.

    By stacking vertically or doubling the boom length of long boom yagis (2 wavelengths or more) you will gain on paper 3 db. But what is not shown is squeezing of the beam width vertically. This places more signal reception right at the horizon, with less wasted on the open sky above or very important, fewer ground reflections from in front of the antenna or array.

    Most of the signal from stations that are not LOS are right there at the horizon, something 2m Amateurs operating the 144MHz band have known for years. Build that antenna long or stack on top of the other.

    While this doesn't help front to side rejection it's normally done with long boom yagis that already inherently have good front to side rejection.

    A very good example to look at this effect though not a VHF antenna is the 4221 (that I didn't like for UHF but makes a great example here for the vertical stacking effect).

    Compare the azimuth vs elevation plots for the 4221 antenna.



    Note since a 4 bay is actually 4 bowtie dipoles stacked on top of each other we can compare this to stacking VHF antennas. Look how much more "squeezed" the elevation plot is the azimuth plot. This is also the 4221's forte' and where it gets it's gain. However as stated in 1) above, on UHF multipath is much worse and vertical squeezing of beam width is less important in a lot of cases than horizontal tightening.

    As a practical example of how vertical stacking works on over the horizon (not LOS) signals helps.

    If I point at Gainesville, WNBW is 37 miles and LOS at 18 ft AGL at my house. My VHF stack is up 30 ft well above that, hence clear LOS to the station. When I added the second antenna, reception barely improved. This makes sense because stacking at best improves your gain by 2.5 db, hardly enough to notice. It's about enough to make drop outs on a signal on the edge a little less server, which is exactly what I happened.

    Now on a non-LOS stations like Jacksonville is from my house. LOS to them is about 400 ft AGL at my house, yet I am only up 30 ft, mainly to get 4 wavelengths above my metal roof where you get away from most effects of the roof.

    Toward WJCT in Jacksonville, I could only decode it in moderate to strong tropo on one antenna. WJXX and WTLV decoded about 50% of the time. All stations 61 miles away from 300 meter towers, so even on perfectly flat ground they are about 10 miles past LOS to a 30 ft antenna on my end. On top of that it's not level between me and Jacksonville, so it's a 2 edge path.

    But when I added the second antenna, WJCT starting decoding about 60 to 70 percent of the time, and WTLV and WJXX are now there 90% of the time. Much greater than expected from simply 2.5 db of gain. Probably the effect one would see from 6 to 8 db or more of increased gain. No it doesn't make gain from no where, it simply puts the signal reception right where most of the signal exists which really is gain, but for the situation. It's hard to tell how much was gained by reducing ground reflections as stacking also pulling the more of the pattern off the ground in front of the antenna or array.

    It's a long debate for terrestrial 144 MHz Amateur band reception is enhanced but stacking vs doubling the boom length (remember they both yield the same increase or close). From my experience stacking works better. Now if you are doing moon bounce or meter scater the longer boom seems to work better by reducing lobes cleanly in all planes, where as stacking always creates some odd side lobes. Hence this could be applied to TV reception. If the station is LOS, use a longer boom yagi, if it's over the horizon, consider stacking two antennas vertically. But don't expect this to work that well on on UHF, as there is much less UHF scattered at the horizon than at VHF when looking at a distance horizon.

    My appreciation to Ken Nist at HDTVPrimer.com for the use of his images.
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  2. #2
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    The manufactures mileage claims on any antenna can vary greatly and can vary either way. You may get less mileage or you may get significantly more.

    Take for example my antennas. I have two U4000's (4-bay type) and a Radio Shack 15-624 (2-bay). The U4000 is rated at (I think) 60 miles while the 15-624 is suppose to be good for 20 or 30 miles.

    Both styles of antennas will pickup most of the Cincinnati channels at 42 miles away and both will pick up WWHO out of Chillicothe, Ohio which is 54 miles aways.

    On the other hand neither antenna will pick up the Columbus station at 61 miles way but that could be due to my antennas being in the attic.

    Like Piggie said, there's a lot of factors involved in good reception such as terrain, multi-path interference, the tv stations transmitting power, etc, and there can be no guarantee one way or the other when it comes to reception range.
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    Mileage figures should all be taken with a grain of salt. YMMV.

    Example: I'm sitting here watching UHF channels over 71 miles away, with only this unamp'd antenna sitting on top of my monitor. Would the same antenna get you channels from that far away? It depends, but probably not. I'm on a 1400' hilltop and have LOS to the stations' towers, which are ~3,000' above mean sea level.

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    Mileage ratings on antennas need to die. They don't need to be justified or even given some degree of legitimacy by even saying mileage my vary.

    They are just simply misleading at best, and exaggerated lies in the worst cases. If they were a bigger consumer item I am sure the Interstate Commerce Commission would be all over them. But in the scheme of things there a niche retail item, flying under the radar, except by a few people that know mileage claims never ever did a single person a bit of good in choosing an antenna.

    Sorta surprising it was brought up again, as a good part of the gist (or I thought I got this idea across) was even comparing antenna by legitimately measured db gain figures was not the total answer to be solution.

    A good part of bringing back up mileage was for me to slam it back into the ground for the misleading worthless measure of antenna performance that it represents.
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    I agree with you here Piggie but there does need to be a way to let the average consumer know which antennas are better.
    It really wouldn't be anymore fair to let someone think that all tv antennas are the same.

    It's almost a given that a two bay bow tie is going to be better than a single bow tie antenna and a 4-bay will be better than a 2-bay and etc, so there needs to be some kind of rating system to reflect that for those wouldn't know better.

    IMO what there should be is a universal formula for measuring an antennas performance instead of letting each manufacturer pull some number out of the sky. Not sure how this could be done though.
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    Got to agree

    I have been playing a lot of with antennas over the years. The big antennas do pick up better with gain on the close stations. On good nites I can step a pair of rabbit ears just outside my room on the ground and pick up statoins up to 100 miles away. I can even use aluminuma foil to do the same by making it a bow tie. So antennas with a distance rating a 5 to 15 miles can sometimes be just as good as one rated 100 miles. All antenna really is, is something to that can caugh the singal that is already there if the signal is not there the antenna will not be available to caugh it even if the station is only 25 miles away. If you live in a metal buiding will not be able to get the recption that you would get if you live in a house made of wood siding or buck.

  7. #7
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    Quote Originally Posted by Tim58hsv View Post
    I agree with you here Piggie but there does need to be a way to let the average consumer know which antennas are better.
    It really wouldn't be anymore fair to let someone think that all tv antennas are the same.
    IMO what there should be is a universal formula for measuring an antennas performance instead of letting each manufacturer pull some number out of the sky. Not sure how this could be done though.
    Well they tried leading up to the transition. The color system.

    Someone covered this already. It was to take into account obstacles, hills, mountains, elevation changes. This was tied to AntennaWeb.

    Several things failed.

    1) Antenna Web was way to conservative. Some speculated this was done to sell bigger antennas. I disagree. Most people found they had to put an imaginary 100 ft antenna to just see what was probably possible at 20 to 30 ft. How many thousands didn't know this that tried to use it that gave up right there not seeing that many signals?

    2) The antenna manufactures didn't comply as well as they should have complied. And even companies like Winegard soon built their own systems to find the correct antenna.

    But the idea originally as go to AntennaWeb, then you could go online or to the store and buy the right antenna. It failed due a lack of common sense, any brains at all in my opinion, corporate ineptness and just ************ poor planning, cooperation and compliance.

    So it was tried, failed.

    Mileage was reinstated if it ever died, and we say 100 mile pieces of crap sold on E-Bay.
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    Well somehow this thread went from being about how beam width is just as or more important than raw gain figures to antennas advertised based on mileage. Based solely on the replies I am not sure anyone got my point about not just considering gain as the determination of antenna reception, much less mileage which is a totally bogus measure of an antenna.

    It really should be two threads, as I had planned a thread on antenna mileage claims.

    Should I go ahead with my mileage thread then move the mileage comments to that thread?
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    mileage versus gain !

    Quote Originally Posted by Piggie View Post

    My appreciation to Ken Nist at HDTVPrimer.com for the use of his images.

    Gain is obviously a major factor in antenna performance, and the mileage rating is just a poor reference at best for the non-antenna savvy consumer to have some type of indicator, and to possibly attempt to pick a somewhat proper antenna for their location.

    Granted it is not the best system for choosing a proper antenna on a technical level, but the minute you start talking dB, gain, rejection, beam width etc. in front of the average consumer, you can just see the confusion start to take them over and they quickly realize that they are at the mercy of someone else when selecting a proper antenna for their location.

    In my area of the country in the mountainous region of southwest Virginia, we deal with reception issues from viewers quite regularly. We have a very good area in which to test antenna theory, especially in regards to Digital reception and the multi-path problem. We broadcast to our city of license, which is essentially a big old soup bowl with mountain ranges on virtually every side.

    The transmitter is on a 4000 foot mountain, and I can literally look down on a large portion of our main city of license and it is easy to see why this area has all of the reception issues that it does. This would have been an ideal area to test and install a Distributed Transmission Network, but everyone in this area had already committed to Full Power operations, and the FCC waited way to long to approve the concept for it to be useful in the DTV transition.

    Rear and side rejection to me are the most important issues for this area, and a narrow beam width seems to also be desirable. We are also a LowV/HighV/UHf market, with one of them being trips favorite PBS station, which adds several more levels of complexity in itself. On top of that, not all of the transmitters are located in the same direction. It almost seems as if you need a dedicated mini antenna farm in this area to receive all of the stations reliably.

    The best antennas we have tried, and they are used in our signal strength field tests for viewers are the Clear Stream C series antennas. They have decent rejection, and seem to work in high echo areas where other designs don't work as well or at all. I went to one viewers home who had just erected a brand new fringe area VHF/UHF antenna, brand unknown with a 10 foot boom (100 MILE Antenna LOL ) . It was mounted on top of a two and a half story house at over 45 feet in elevation.

    This house sits deep in a hollow with mountains on 3 sides, and the only channel it would receive was Trips favorite channel PBS on 3. The Rhode & Swartz DTV spectrum analyzer showed echos out to the end of the 80 microsecond scale. We used a Clear Stream C2 at 20 feet for the first test, and all of the signals from the 4000 foot transmitter site showed up at receivable levels except for channel 3, when the 10 foot boom combo only received the channel 3 signal.

    I have proven the performance to myself of the Clear Stream C series antennas beyond a shadow of a doubt. This is just one of many stories from our last 5 to 6 weeks of field strength tests to see where all of the signals in this market are strong or weak since almost all of us have new antennas and transmitters and it also proved the performance of the C series antennas in my eyes.The C series of antennas work very well on UHF as Ghost Killers.

    All of the numbers on a spec sheet are all needed for reference, but in the trenches is where the rubber meets the road, our should that be where the F connector meets the antenna?
    Last edited by FOX TV; 09-29-2009 at 11:49 AM.

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    Antenna Web

    Quote Originally Posted by Piggie View Post
    Well they tried leading up to the transition. The color system.

    Someone covered this already. It was to take into account obstacles, hills, mountains, elevation changes. This was tied to Antenna Web.

    Several things failed.

    1) Antenna Web was way to conservative.
    It is also using a flawed database, and is inaccurate to boot. When I look up my address on Antenna Web, it does not even list our station as being receivable at my address, even though I have a LOS to the transmitter when standing on my roof. If I use my zip code only it shows up, but when I drill down to the exact address, it is totally wrong. I quit using it several years ago when I found out how inaccurate it really is.

  11. #11
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    Quote Originally Posted by FOX TV View Post
    Rear and side rejection to me are the most important issues for this area, and a narrow beam width seems to also be desirable.

    The best antennas we have tried, and they are used in our signal strength field tests for viewers are the Clear Stream C series antennas. They have decent rejection, and seem to work in high echo areas where other designs don't work as well or at all. I went to one viewers home who had just erected a brand new fringe area VHF/UHF antenna, brand unknown with a 10 foot boom (100 MILE Antenna LOL ) . It was mounted on top of a two and a half story house at over 45 feet in elevation.

    This house sits deep in a hollow with mountains on 3 sides, and the only channel it would receive was Trips favorite channel PBS on 3. The Rhode & Swartz DTV spectrum analyzer showed echos out to the end of the 80 microsecond scale. We used a Clear Stream C2 at 20 feet for the first test, and all of the signals from the 4000 foot transmitter site showed up at receivable levels except for channel 3, when the 10 foot boom combo only received the channel 3 signal.

    I have proven the performance to myself of the Clear Stream C series antennas beyond a shadow of a doubt. This is just one of many stories from our last 5 to 6 weeks of field strength tests to see where all of the signals in this market are strong or weak since almost all of us have new antennas and transmitters and it also proved the performance of the C series antennas in my eyes.The C series of antennas work very well on UHF as Ghost Killers.
    Interesting the C antennas work that well , something I would never have guessed at how many people I know that have replaced them with better results. But as you said you are in multipath heaven, or h-e-ll so to speak.

    Something I am curious, not debating your research is the relative AGL of his install vs your test with the C series. Could it be in that area, he probably never needed to be anywhere near 45 feet off the ground where he was up in the multipath? That lowering the antenna to 20 ft had some to do with less multipath? Was the antenna you used or use a C4? Since it has side by side elements which always help rejecting multipath from the sides.

    Though not practical for most home installers, I really believe in monobander antennas combined. This is very difficult in you market with 3 bands, I totally agree.

    I can say with only my TV as test equipment, that a U-75R rejected way more multipath than the 4221A I had up at my house.

    So what is it in the C series that I would assume from your results and my results works better than a whisker type antenna? I wonder if the loops in the C series which like other loops intersect the magnetic part of the EM wave give it the advantage? I have no idea how to explain that if it's even a factor. I know from experience on 10 meters that a 2 element quad has more than the theoretical gain when working e-skip signals. It was one of my "secret" weapons on field day running the 10 meter SSB station way back in the day. I tested 2 and 3 element yagis for months at my house one year against a 2 element quad before field day. The quad kept winning. It proved out when near by ground wave 10 meter stations all but accused me of "ghost talking" (making up contacts from stations they could not hear me working). Just throwing that out there.

    It just surprises the pudding out me as in the last couple years, almost everyone that replaced their C series with a good Winegard, even the 769xP dual banders had improved reception.

    But I have never argued or doubted a Rhode & Swartz DTV spectrum analyzer, so what you are seeing blows my mind.
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    Antennas antennas..ant...

    Quote Originally Posted by Piggie View Post
    Interesting the C antennas work that well , something I would never have guessed at how many people I know that have replaced them with better results. But as you said you are in multipath heaven, or h-e-ll so to speak.

    Something I am curious, not debating your research is the relative AGL of his install vs your test with the C series. Could it be in that area, he probably never needed to be anywhere near 45 feet off the ground where he was up in the multipath? That lowering the antenna to 20 ft had some to do with less multipath? Was the antenna you used or use a C4? Since it has side by side elements which always help rejecting multipath from the sides.

    Though not practical for most home installers, I really believe in monobander antennas combined. This is very difficult in you market with 3 bands, I totally agree.

    I can say with only my TV as test equipment, that a U-75R rejected way more multipath than the 4221A I had up at my house.

    So what is it in the C series that I would assume from your results and my results works better than a whisker type antenna? I wonder if the loops in the C series which like other loops intersect the magnetic part of the EM wave give it the advantage? I have no idea how to explain that if it's even a factor. I know from experience on 10 meters that a 2 element quad has more than the theoretical gain when working e-skip signals. It was one of my "secret" weapons on field day running the 10 meter SSB station way back in the day. I tested 2 and 3 element yagis for months at my house one year against a 2 element quad before field day. The quad kept winning. It proved out when near by ground wave 10 meter stations all but accused me of "ghost talking" (making up contacts from stations they could not hear me working). Just throwing that out there.

    It just surprises the pudding out me as in the last couple years, almost everyone that replaced their C series with a good Winegard, even the 769xP dual banders had improved reception.

    But I have never argued or doubted a Rhode & Swartz DTV spectrum analyzer, so what you are seeing blows my mind.
    The one thing I did not mention due to the length of my post is that we went back for a second visit, and the viewer had someone to climb for him and he toted a C4 up with him and sat it on top of the chimney only 5 feet lower than his "100 miler " and it gained almost 5 dB over the C2 we used at 20 feet on the first visit. We hooked the spec analyzer to his antenna on the first visit and saw the echos out at 80 microseconds, with the RF levels of the echos that sometimes spiked almost as strong as the main lobe.

    The C4 still showed the same time line, but the actual RF level of the echos we saw on his antenna were barely readable on the C4. I am not saying that there are not as good or better antennas, and i have no experience with Wineguard antennas which I understand to be good products. The tapered driven element design of the C series is very innovative, and In theory there should be an electrical path on the driven elements that coincides with every individual channel in the UHF band instead of a wire type element who's performance drops off above and below the design frequency.

    Your point of elevation difference is valid, and I have seen evidence of this in the past myself, but since we were using a volunteer climber, and time was limited, we did not have a chance to do all of the desired checks we would have liked. This location would be an antenna experimenters dream, but a TV viewers nightmare.

    I have built my version of the C2 that may violate the patent for the tapered loop design, but my feed point design and reflector is much different than theirs, and the Rhode & Swartz analyzer was used to tune it. My forward gain numbers are about 1/2 dB higher on average, and my reflection or rear rejection numbers are almost 2 dB better.

    I have been designing or re-designing UHF antennas for years, especially concentrating on the multi-path we see in this area. Check out this article on my Gray-Hoverman re-design in TV Technology Magazine.

    Polarized Power for TV Broadcasting, by Doug Lung

    The design Doug Lung favored was mine, and this is not to toot my horn, just to give an idea of my background regarding antenna designs for the DTV revolution.

    I won't flood this forum with posts, but I will chime in on antenna topics, for my efforts are now being aimed towards finding a way to reduce antennas physical size for high VHF, and to be able to build a reflector type antenna that works well on VHF, but is not so big that you would need a section of schedule 40 iron pipe to support it at 30 feet or higher.

    Also, quads on 10 meters are killer antennas. I used to use an old PDL2 quad on a 50 foot tower, and it would break through the ces pool of noise you hear on contests and pileups etc. The PDL 2 is an old 11 meter antenna that I re-tuned for use on 10. I also installed 1/4 wave radial ground system on the tower that included a chain link fence that was a city block long and ran through 10 backyards before ending at the next block. My wife worked 10 more than I, and she did DX century in less than a year.
    Last edited by FOX TV; 09-30-2009 at 07:03 AM. Reason: additions

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    Quote Originally Posted by FOX TV View Post
    The design Doug Lung favored was mine, and this is not to toot my horn, just to give an idea of my background regarding antenna designs for the DTV revolution.

    I won't flood this forum with posts, but I will chime in on antenna topics, for my efforts are now being aimed towards finding a way to reduce antennas physical size for high VHF, and to be able to build a reflector type antenna that works well on VHF, but is not so big that you would need a section of schedule 40 iron pipe to support it at 30 feet or higher.

    Also, quads on 10 meters are killer antennas. I used to use an old PDL2 quad on a 50 foot tower, and it would break through the ces pool of noise you hear on contests and pileups etc. The PDL 2 is an old 11 meter antenna that I re-tuned for use on 10. I also installed 1/4 wave radial ground system on the tower that included a chain link fence that was a city block long and ran through 10 backyards before ending at the next block. My wife worked 10 more than I, and she did DX century in less than a year.
    Excellent, and yes I know who Doug is. I never doubted your results, just unexpectedly surprised, because all in all I really don't like that company.

    Their idea on a tapered quad loop is a unique idea. But I think any thing short of their C4 is a waste of money, unless you have other data.

    lol, that is funny, the Quad I built was from a PDL 2 parts. Also a really good 10 meter antenna I made was from a Moonraker 4 that had fallen (the directors were trashed)and was given to me. I left the quad reflector alone, then shortened the driven elements to 10 meters and adjusted the match. It was then 2 element, dipole driven and quad reflector. That antenna did just about as well as the coverted PDL 2.

    Back before my ham license I built a 3 element 11 meter beam horizontal. I later replaced the reflector with a quad loop, imitating a moonraker. It helped a lot.

    So despite stuff I have read that the quad reflector was a joke, I disagree.

    Welcome to the forum, glad someone is here that has test equipment and years of experience so I can learn more!

    I wish I still had my spectrum analyzer, but it was too expensive to just keep after closing my pager and 2 way repair business.

    Thanks for posting and don't be shy or feel like you are displacing something I said. Please if you have any data that disputes what I say, bring it on or I will never learn more.

    Piggie
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    Quote Originally Posted by Piggie View Post
    ... all in all I really don't like that company.

    ...Their idea on a tapered quad loop is a unique idea...
    That antenna is unique. And they have another UHF-only antenna that has proven itself. However, I refuse to buy anything from a company that engages in such deceptive sales/advertising practices as the one that sells these antennas.

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    More antenna comments

    Quote Originally Posted by Piggie View Post
    Excellent, and yes I know who Doug is. I never doubted your results, just unexpectedly surprised, because all in all I really don't like that company.

    Their idea on a tapered quad loop is a unique idea. But I think any thing short of their C4 is a waste of money, unless you have other data.

    lol, that is funny, the Quad I built was from a PDL 2 parts. Also a really good 10 meter antenna I made was from a Moonraker 4 that had fallen (the directors were trashed)and was given to me. I left the quad reflector alone, then shortened the driven elements to 10 meters and adjusted the match. It was then 2 element, dipole driven and quad reflector. That antenna did just about as well as the coverted PDL 2.

    Back before my ham license I built a 3 element 11 meter beam horizontal. I later replaced the reflector with a quad loop, imitating a moonraker. It helped a lot.

    So despite stuff I have read that the quad reflector was a joke, I disagree.

    Welcome to the forum, glad someone is here that has test equipment and years of experience so I can learn more!

    I wish I still had my spectrum analyzer, but it was too expensive to just keep after closing my pager and 2 way repair business.

    Thanks for posting and don't be shy or feel like you are displacing something I said. Please if you have any data that disputes what I say, bring it on or I will never learn more.

    Piggie

    We do like the clear stream antenna, but really have not had a chance to compare it to any other brands of the "New Generation" antennas designed for UHF DTV. We did do a test a few weeks back using a C2 at 75 miles away from our 4000 feet transmitter on Rf channel 17 . We got very acceptable results using only 20 feet of mast pole. TV FOOL showed a good LOS which made it fairly easy to pick up.

    We were trying to find the cliff so we could drive off of it, but at 75 miles out we still had around -65 to -70 dBm with a LOS using 35 feet of quad shield RG6 and a C2 at 20 feet. We were 75 miles out which is about 5 to 10 miles outside our 41 dBu contour, and we never did drive off of the cliff.

    It looked as if it would have taken another 15 to 20 miles or more before we lost the signal to the noise, but it was a Friday afternoon, and we were already on volunteer overtime, so we turned around without finding the cliff on that day.

    We have driven a lot of miles in the last 6 weeks or so, and we actually use 2 different antennas, with one being a Z Technology calibrated dipole and calibrated cable at 30 feet for channel power tests, and either the C2 or C4 depending on what levels we see using the calibrated dipole for the actual simulated viewer reception test.

    Everywhere we go, we do both tests, and have found the c series antennas to perform well, but it would be nice to have some other brands and designs to compare it to. I met the owner of Clear Stream on their promotional tour, and he told me that they had a large grant from the NAB, and they were somehow financially backing the development of the C series antennas, and financed the antenna give away tour.
    Last edited by FOX TV; 10-01-2009 at 01:28 PM. Reason: spelling

  16. #16
    JER
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    What makes a good DTV antenna?

    Hi,

    First off, let me say right up front that I'm the inventor of the Clearstream antennas. I work as a consultant to Antennas Direct as well as many other companies and agencies. If you're interested you can see my website at John Ross and Associates - Electrical Engineering so that you know what I'm all about.

    Secondly, I want to say thanks to Fox TV for sharing his field testing experience with the Clearstream antennas. Antennas Direct and I appreciate the feed back and find it gratifying to see that our products being used and appreciated in your application.

    Lastly, I'd like to discuss briefly how we came up with the Clearstream tapered loop / reflector idea and what factors tended to make it a success.

    The Clearstream effort started out internally as an effort to create a very compact antenna to be integrated with a DTV converter box. We recognized that the antenna was key to such a product so we were focused on finding the most efficient, highest gain, directional antenna that we could fit in the smallest practical space and which would perform over the post 2009 UHF DTV band.

    We looked at a lot of options but one option that looked interesting was the full-wave loop in front of a reflector. This geometry has been known for at least 5 decades to produce 9 dBi if you could feed it properly. Best of all the loop could be placed close to the reflector and still retain the forward gain. Right away we knew a thick loop would be required to cover the bands and we iterated solvers (NEC and X-FDTD) to do trade offs on loop size, thickness, reflector spacing and reflector size. Eventually we found one that worked good and covered the band but it still was too big to fit our package requirements.

    My background is in UWB radar so one day I stumbled onto an IEEE paper where the authors were using tapered circular slots for pulse radiation so I tried tapering our loops and next thing you know we had better bandwidth and things really started to take shape. In backyard field tests our first single loop (C1) prototypes were performing as well as the double bowtie (DB2) but took up only 1/2 the volume so we began thinking of the antenna as something more than just part of a converter box part and went off and did the double (C2), quad (C4), and high VHF (C5). Other iterations are sure to follow.

    In looking back on this effort several things stand out insofar as what makes a good DTV antenna for the MASSES:

    1. Size - yes, size matters, the smaller the better or it won't sell

    2. Size - the smaller it is, the more likely that it will go up on the roof. This dramatically improves reception almost every time!

    3. Size - often referred to as Wife Acceptance Factor (WAF). It has to look good (aesthetics) or not be seen (better aesthetics). Ultimately it all boils down to size. See 1 & 2 above.


    Now that we have the important stuff out of the way...

    4. Impedance bandwidth - we targeted VSWR less than 3:1 across the whole band and achieved much better than that in most of it

    5. Forward gain - We took what we could get, but the gain we got (approx 8 dBi for C1) was very flat versus frequency across the band.

    6. 1/2 power Beam width (horizontal plane) - C1 has about 70 degree beam width on all UHF channels. Most antennas have beam width that decreases with frequency so the clearstreams should be easier to point.

    Note - I personally think that sometimes people get antennas that have too much gain and beams too narrow to be effective in their markets. Channel surfing - even with a single TV - is so essential that the days of a rotator are pretty much done. I believe that a moderate beamwidth - say 50 to 90 90 degrees - may be a better for most folks.

    7. Front-to-back - We took what we could get. The C1 has F/B of 12 to about 18 dB or so depending on channel. Higher channels were better.

    8. Side lobes - Clearstream side lobes were generally much lower than F/B since the peak lobe is usually the rear lobe.

    9. Forgiving structure - this is important for manufacturing and consumer installed antennas. We can have the best highly tuned antennas in the world but if we can't build them on an assembly line and have a consumer install them without needing an Agilent vector network analyzer then we've failed. The Clearstreams seem to be very forgiving to placement and since they are small we can ship them with simple (in some cases 1 bolt) assembly.

    10. Pulse fidelity - This is speculation on my part, but Clearstreams are wideband structures that that can radiate / receive band limited pulses without a lot of distortion. While log-periodic dipole arrays are also wideband they do NOT do well when radiating / receiving pulses due to what is known as phase dispersion. I have a hunch that this may be one of the reasons that the Clearstreams sometimes do better than much larger antennas on digital signals, but have yet to prove it all out in a practical test.

    Let me repeat, the above antenna considerations are for the masses, not the deep fringe enthusiast who has no problem with 80 ft towers, 10 ft booms and rotators.

    Sorry for the long first post. I hope you all find the information useful.

    Best Wishes,

    John

    PS - I too hate the rating of antennas with mileage. I'd much prefer to see all the gain charts and VSWR graphs on the box but the average Joe will have no idea how to interpret that so I fear we're stuck with miles...

  17. #17
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    Quote Originally Posted by FOX TV View Post
    We do like the clear stream antenna, but really have not had a chance to compare it to any other brands of the "New Generation" antennas designed for UHF DTV. We did do a test a few weeks back using a C2 at 75 miles away from our 4000 feet transmitter on Rf channel 17 . We got very acceptable results using only 20 feet of mast pole. TV FOOL showed a good LOS which made it fairly easy to pick up.

    We were trying to find the cliff so we could drive off of it, but at 75 miles out we still had around -65 to -70 dBm with a LOS using 35 feet of quad shield RG6 and a C2 at 20 feet. We were 75 miles out which is about 5 to 10 miles outside our 41 dBu contour, and we never did drive off of the cliff.

    It looked as if it would have taken another 15 to 20 miles or more before we lost the signal to the noise, but it was a Friday afternoon, and we were already on volunteer overtime, so we turned around without finding the cliff on that day.

    We have driven a lot of miles in the last 6 weeks or so, and we actually use 2 different antennas, with one being a Z Technology calibrated dipole and calibrated cable at 30 feet for channel power tests, and either the C2 or C4 depending on what levels we see using the calibrated dipole for the actual simulated viewer reception test.

    Everywhere we go, we do both tests, and have found the c series antennas to perform well, but it would be nice to have some other brands and designs to compare it to. I met the owner of Clear Stream on their promotional tour, and he told me that they had a large grant from the NAB, and they were somehow financially backing the development of the C series antennas, and financed the antenna give away tour.
    More than one person has come to this forum owning a C series and needed more VHF gain. I can't change my attitude toward their company based on exactly what Eureka said.

    I have never doubted the antennas work for UHF, and even Ken Nist says the C2 is the best indoor antenna in it's class. No whiskers make it safer indoors than other 2 bay except the old Radio Shack later Channel Master indoor 2 bay, that is out of production (can't remember the number).

    I would think to compare to a C4, a Winegard 7696p and AntennaCraft HBU33, should be all very close to the same class. I would guess AntennasDirect gave you the antennas? I know buying a lot of antenna just to test is about impossible to get into the budget, or it was where I worked.

    If the NAB gave them a grant to design that antenna, manufactured off shore and financed what I called their snake oil tour, to me that deepens the manure in mind. I lost some respect for the NAB during this transition.

    But my beef is with the company, and remain 100% open to results of antennas.. I no longer a fan of Channel Master, but their CM7777 still appears to be built as well as ever in China and I recommend it to deep fringe reception.

    Please don't take my comments about Antennas Direct company the least bit personal. I really love hearing your test results.
    The more I understand, the less I know.

    PORK... The Other White Meat....

  18. #18
    JER
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    Some comments on the above post:

    The Clearstream C1, C2 and C4 are designed for UHF but offer sufficient VHF reception to satisfy many people in urban areas. The vast majority of people who buy one of these antennas are happy with them.

    The C5 is designed specifically for high VHF and is ideal for folks who already have good UHF installations but need more performance on high VHF. C5 is very compact and comes with a VHF/UHF diplexer. I think you will have a hard time finding a better high VHF antenna in such a small package. Some customers are also reporting that C5 also performs well on UHF but we don't spec it for that band.

    C4 to the Winegard 7696p and AntennaCraft HBU33 is an apples to oranges comparison. The C4 is vastly smaller than either of the other two and thus aimed at a completely different customer. I've not tested or simulated them, but I'm sure the other Winegard and AntennaCraft are fine antennas for consumers that don't care about size.

    The NAB funded the Antennas Direct / Viamorph team to develop a reference design for an indoor smart antenna. We are grateful for their confidence and support in that endeavor.

    The NAB had nothing to do with the current Clearstreams or the Antennas Now tour. The Clearstream designs were done well ahead of the NAB smart antenna project and completed using internal funding. The Antennas Now tour was also financed internally, but the NAB was enthusiastic of our efforts in that regard since we were helping people rediscover free OTA TV.

    During the Antennas Now Road Tour, company president, Richard Schneider, gave away untold thousands of antennas and helped countless numbers of people learn how to save money in a recession by switching from cable or satellite to free OTA DTV. He criss-crossed the country in his bus evangelizing antennas and OTA DTV to just about anyone who would listen. He was often up in the middle of the night giving TV interviews for the morning news casts and then spent the day at a local TV station or Best Buy parking lot helping average Joe's and Joanna's figure out how to solve their reception problems. That doesn't sound like a "snake oil" tour to me?

    Antennas Direct, like most US companies these days uses off shore manufacturing. While I think most of us would prefer domestic manufacturing we all know the realities of that situation and its unlikely to change anytime soon. I recommend raising that issue with your elected representatives rather than here.

    Thanks again for reading!
    Last edited by JER; 10-01-2009 at 08:48 PM. Reason: spelling

  19. #19
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    All I know is that people in our area purchased the Clearstream antennas because they were touted as suitable for "all the DTV frequencies," which of course, is a crock. They were pss'd off after installing them, when they found out they can't get all their local channels because like most places, we also have VHF chs., which the clearstream can't receive here.

    I will not recommend a company's products when they continue to engage in deceptive and misleading advertising, no matter how good the products may be.

  20. #20
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    Quote Originally Posted by JER View Post
    Some comments on the above post:

    The Clearstream C1, C2 and C4 are designed for UHF but offer sufficient VHF reception to satisfy many people in urban areas. The vast majority of people who buy one of these antennas are happy with them.

    The C5 is designed specifically for high VHF and is ideal for folks who already have good UHF installations but need more performance on high VHF. C5 is very compact and comes with a VHF/UHF diplexer. I think you will have a hard time finding a better high VHF antenna in such a small package. Some customers are also reporting that C5 also performs well on UHF but we don't spec it for that band.

    C4 to the Winegard 7696p and AntennaCraft HBU33 is an apples to oranges comparison. The C4 is vastly smaller than either of the other two and thus aimed at a completely different customer. I've not tested or simulated them, but I'm sure the other Winegard and AntennaCraft are fine antennas for consumers that don't care about size.

    The NAB funded the Antennas Direct / Viamorph team to develop a reference design for an indoor smart antenna. We are grateful for their confidence and support in that endeavor.

    The NAB had nothing to do with the current Clearstreams or the Antennas Now tour. The Clearstream designs were done well ahead of the NAB smart antenna project and completed using internal funding. The Antennas Now tour was also financed internally, but the NAB was enthusiastic of our efforts in that regard since we were helping people rediscover free OTA TV.

    During the Antennas Now Road Tour, company president, Richard Schneider, gave away untold thousands of antennas and helped countless numbers of people learn how to save money in a recession by switching from cable or satellite to free OTA DTV. He criss-crossed the country in his bus evangelizing antennas and OTA DTV to just about anyone who would listen. He was often up in the middle of the night giving TV interviews for the morning news casts and then spent the day at a local TV station or Best Buy parking lot helping average Joe's and Joanna's figure out how to solve their reception problems. That doesn't sound like a "snake oil" tour to me?

    Antennas Direct, like most US companies these days uses off shore manufacturing. While I think most of us would prefer domestic manufacturing we all know the realities of that situation and its unlikely to change anytime soon. I recommend raising that issue with your elected representatives rather than here.

    Thanks again for reading!
    EEEKK, I never wanted to get a discussion started about a companies ethics, or in some opinions, a lack of them. I am just an ordinary broadcast engineer who works in a very difficult TV reception market that has a mixed assortment of bands and transmitter locations. We operate two transmitters located in opposite directions, along with this being a LOW V / HIGH V / UHF mixed market.

    Our field strength tests started about 3 months ago in order to compare the FCC coverage maps to the real world, and to help selected viewers with reception issues. Being a mixed band market has led me in a search for a compact VHF antenna that actually works well in a small package so that people would not object to its physical size, and not abandon the back plane reflector concept that works so well on UHF in killing ghosts.

    I had a discussion a few years ago with a viewer who wanted a Direc TV waiver, and he said that he would not have an ugly TV antenna on his house. I politely pointed out that if he had a Direc TV dish mounted on his house that he indeed already had an ugly TV antenna mounted on his house, and that it performed the same function as an OTA antenna. I told him that his dish received digitally formated TV signals that he wanted to view, and it was no different than an OTA antenna that performed the very same function.

    He did not even realize that his dish was a type of antenna. This sparked my interest in trying to reducing the size of a VHF back plane reflector type of antenna that we see in use on UHF with great success at addressing the multi-path issues we see with digital.

    We cannot avoid the fact that the vast majority of consumer goods are manufactured in CHINA. If you want to stand on a high horse and buy American built products only, you will find great disappointment by not being able to find all of the products you need or desire. I object greatly to the "China Syndrome" myself, but this is the world we live in like it or not.

    Every company in the world has some type of marketing strategy that is designed to produce maximum return on their investment, but that is where ethics come into play, and the ones who don't practice reasonable ethics at some point in time will cease to exist.

    I still think I have proven to myself that the C series of UHF antennas work very well in this problematic reception market, and would be very interested in testing their VHF antenna in this area where signals bounce around like they are part of an old pong game from the 1970's.

    We can all thank the FCC for folding to pressure and not limiting DTV to the UHF bands as was the original plan. Every time the Government has a chance to do it right, they seem to insist on screwing it up. I won't even mention health care.....
    Last edited by FOX TV; 10-02-2009 at 09:11 AM. Reason: spelling

 

 

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