Kosmic Antennas: SuperQuad 4 Bay Bowtie

Kosmic Antennas: SuperQuad 4 Bay Bowtie


This is a discussion on Kosmic Antennas: SuperQuad 4 Bay Bowtie within the DTV | HDTV Reception and Antenna Discussion forums, part of the Over-the-Air (Antenna TV) category.

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    Kosmic Antennas: SuperQuad 4 Bay Bowtie




    Introducing the Brand New SuperQuad from Kosmic Antennas!

    These antennas are identical. One is marketed towards the DIYer experimenter, and the other to the general market or those that have no interest in the tunability of this antenna...but are interested in its as delivered high gain, high performance, high quality.

    Price: $59.95



    Search eBay for Kosmic SuperQuad

    Hope you like it. Please ask questions... Complete discription on the eBay link. Joining the forum is easy and only takes a minute.





    Here is a diagram naming the parts of the antenna...




    Here is the recommended balun attachment method for a permanent mast roof/tower mount....the coax should be electrical taped to the mast farther down....and dont forget the weather boot as well. This gives you a solid rigid connection which wont blow around in the wind. It is also beneficial to connect the balun leading away perpendicular to the feed lines of the antenna, to reduce interference between the 2. However a quick and dirty connection just hanging straight down works good for testing purposes.

    EDIT:

    We were discussing baluns the other day, and it came to my attention that the balun attachment method that I have recommended may not be optimum.

    Here is the thread where baluns are discussed, and about page 2 we start discussing the Kosmic SuperQuad Tune-A-Tenna balun attachment method.

    Preferred antenna balun?



    Why is the Kosmic SuperQuad Tune-a-Tenna better than commercially available 8 bays?

    Let us count the ways!

    Seriously, lets talk about how this antenna is superior to the 8 bays and other differences. It seems too good to be true....but it is true!

    The 8 bays all have shorter length whiskers or elements which are designed for gain over a larger UHF frequency spectrum, ch. 14-69. They still sell them this way because Mexico and Canada continue to have television broadcasts on channels 51-69, so they want to cover the North American market. The longer elements on the Kosmic SuperQuad Tune-A-Tenna maximize gain on the smaller ch. 14-51 television band used in the United States, post digital transition. This results in superior gain and SWR numbers on UHF ch. 14-51....as well as superior performance on the lower UHF channels, especially.

    Also the longer elements are superior for VHF High performance. While the 8 bays have more elements they arent as good at those frequencies.

    Furthermore the 8 bays with multi-piece screens are not as good on VHF High nor on Lower UHF. You want one solid reflector back there...so that it resonants nicely at those frequencies and reinforces the elements at those frequencies. It just so happens that these lengths are pretty good 3/2 wave resonant antennas at mid to lower UHF ch. 14-51, as well...so you miss that reinforcement and resulting gain increase with a partitioned antenna screen. The curved reflector also compresses the clover pattern of a 3/2 wave antenna at UHF frequencies and directs them back towards your antenna elements.

    Next up! Uniform illumination of the elements. The 4 bowties of the Kosmic SuperQuad Tune-A-Tenna present a smaller antenna area than the 8 bays dual 4 bay configuration. This means that you are likely to get more uniform illumination of the elements...which is good for integrating each element into the same transmission wire. Integrating different current levels and voltages degrades possible potential performance of the antenna. This situation is less likely to occur in the 4 bay Kosmic SuperQuad Tune-A-Tenna.

    Then there is the necessity of creating phased feedline integration between the 2 4 bays in an 8 bay. Many are poorly designed and defeat the potential gain increase of ganging 2 4 bays together.

    The Kosmic SuperQuad Tune-A-Tenna also has a wider beamwidth than the 8 bays (which typically run about 25 to 30 degrees on UHF). The Tune-A-Tenna on UHF is about 55 degrees +/- 5 degrees depending on frequency. This can be extremely beneficial for those with television transmissions off axis by up to 75 degrees (but you could also favor the tighter beamwidth depending on your situation)....but in that case you may want to go for an xg91 or similar Corner Reflector Yagi.

    The Kosmic SuperQuad Tune-A-Tenna also has a smaller profile for those Home Owner Association battles.

    Hope you found the above informative.


    EV

    Some good analysis with successful users TVFool charts starting on page 9 of this thread...

    Independent Testimonials

    I bought two [Tune-A-Tennas] and love them. They are doing a fantastic job. In my opinion, they are the best on the market, so much so that I disconnected my satellite service permanently that I have had since 1996 with dish network. I could not ask for any better reception. I personally want one more, that way I can pick up Fort Wayne, South Bend, and Indianapolis. My dad was so impressed that he wants to buy two of them for his house. I thank you very much for the two that I already have.

    Andrews, Indiana
    I just received the “Tune-A-Tenna” yesterday so I have not yet had enough time to do a full evaluation. However, based upon my results so far, this antenna is very good. My receiving situation is that I have a very weak and distant (52 miles) UHF station on the high end of the scale (real channel 41) and I also have a low power VHF station (real channel 7) and a distant VHF station (real channel 9 which is 47 miles away). This antenna is able to pick up all of these stations with a solid lock and good signal strength. I am impressed and pleased with its performance.

    ...

    Now that I’ve had the time to do a more comprehensive evaluation of the 4 Bay SuperQuad (aka “Tune-A-Tenna”), I’ve concluded that this is best 4 bay antenna for the US market. It’s tuned for the current US television broadcast frequencies (7 thru 51) and it delivers. This is, after all, a UHF antenna and it pulls in all UHF stations from 14 through 51 perfectly. The real surprise with this antenna is that is does so well on VHF high band as well.

    I’m using the stock reflector since I have as yet been unable to find a source for 1” x 2” galvanized fencing in my area. However, considering the great performance I‘ve experienced with this antenna on VHF high, I really don’t need to enlarge the reflector. More than anything, I was just curious to see how much better the VHF high band reception could be with a larger screen.

    Also, I live along the gulf coast in an area subject to high winds and salty air. I have no doubt that this antenna will stand up to weather conditions in my area and provide many years of service. It's built like a tank.

    I have an XG-91 that I use for UHF reception. In direct comparisons I've found that the SuperQuad 4 Bay equals the XG-91 on the high end of the UHF television spectrum and exceeds the XG-91 in receiving UHF signals on the low end of the spectrum (14-30).

    I'm very pleased with this antenna and feel it was well worth the price.

    Gulf Breeze, Florida

  2. #2
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    Looks like a winner, EV.

    The last line of the Image #4 description has a misspelled word.
    " They sung down very tightly."

    What are the dimensions of the screen?
    Is the screen removable?

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    Cool! That's not a bad price either.

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    The screen dimensions are 36" tall by 28" wide.

    I had a larger screen dimension of 44" x 36" but shipping was outrageous....so I had to shrink the size. However the size is still in good territory for VHF performance.

    Yes the screen is very easily removed and or replaced.

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    Has anyone tested that antenna to see if it has better front to side than say the classic 4221A ?


    PS: You can Tuna Antenna, but you can't Tuna Fish!
    The more I understand, the less I know.

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

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    Only a bit.

    The end caps should actually be bent back. Originally, I had them bent forward but on a wider spacing from the bowties (36").

    Bending them back out (they have to be bent to fit in the box) slightly improves VHF performance and also significantly decreases interference with the end of bowtie elements...as antennas.

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    Quote Originally Posted by EscapeVelocity View Post
    Only a bit.

    The end caps should actually be bent back. Originally, I had them bent forward but on a wider spacing from the bowties (36").

    Bending them back out (they have to be bent to fit in the box) improved VHF performance ..
    So, if the screen is bent completely flat, it will work better for highband VHF? I ask because we have VHFs on channels 9 & 10 and plan on recommending this antenna to some folks if it has sufficient gain on those channels, and if changing the shape of the screen will improve VHF gain even more. Do the instructions mention this?

    I do have a question/comment about the ebay listing:
    Although the description starts out by saying it is definitely a highband VHF & UHF antenna, it goes on to say:

    " ...pretuned to maximize gain across the entire post transition digital television spectrum."

    Isn't that sentence a bit ambiguous and misleading? The post-transition DTV spectrum is still channels 2 thru 51.

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    Yes, if the screen is not "kinked" at the outside edges then it will increase VHF Hi band performance because it lengthens or widens the reflector horizontally. It will also be better for the UHF performance.

    Yes, the instructions mention this.

    You can also increase performance on VHF High Band (and especially the lower side of VHF High Band) by removing the screen and adding your own, at 36" wide....which also slightly increases forward gain and F/B ratio on UHF, increasing its height also improve F/B ratio and Forward Gain on UHF.

    On VHF High, its a bi-directional pattern as well.

    Im available here to help people that have questions or need help with the antenna.

    I guess that sentence is a bit ambiguous. Ill see if I can clean it up.

    Thanks for the recommendation.

    These improvements for Gain are all in the territory of a 1 dB or less. Not insignificant, but also not gigantic either.

    The 36" width screen with the indented ends gives you an effective length of 32" (plus wire lengthening effects) which is better on the low end of VHF High Band. Its a better solution overall, because its slightly worse on upper VHF High Band and so evens out the gain across the VHF High Band. Either way, upper VHF Hi gain is better than lower VHF Hi gain.

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    Quote Originally Posted by EscapeVelocity View Post
    Yes, if the screen is not "kinked" at the outside edges then it will increase VHF Hi band performance. It will also be better for the UHF performance.

    Yes, the instructions mention this.

    You can also increase performance on VHF High Band (and especially the lower side of VHF High Band) by removing the screen and adding your own, at 36" wide....which also slightly increases forward gain and F/B ratio on UHF, increasing its height also improve F/B ratio and Forward Gain on UHF.

    On VHF High, its a bi-directional pattern as well.
    Thanks. All great info.

    These improvements for Gain are all in the territory of a 1 dB. Not insignificant, but also not gigantic either...
    Not insignificant around here, where we take all the gain we can get

    A friend used an old-school CM 4221+7777 to get stations almost 70 miles away, including channel 10. It worked amazingly well, considering there's a 1300' hill 1/2 mile directly in front of his house in the path of the distant transmitters. TVFool & antennaweb both show "no reception" at his address. He did have to walk the roof, but he found a hot spot.

    Yours seems to be a very well designed 4-bay like the old CM, but tweaked for the current UHF channel band and improvements to high VHF. Much better than the cheap crap now being imported from asia.

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    Yours seems to be a very well designed 4-bay like the old CM, but tweaked for the current UHF channel band and improvements to high VHF. Much better than the cheap crap now being imported from asia. --- Eureka
    That was the design objective. Its also easily tweaked....for those interested in that aspect.

    Screen is easily replaced and flip-able for increased beamwidth or keep the curve forward for tighter beamwidth and slightly increased forward gain.

    The whiskers are fairly easily bent to sweep forward or backwards in conjuction with the screen, for similar effects. While still being strong and resistant to bending.

    The whiskers can be trimmed and the inter-bowtie spacing easily adjusted for impedence and phase matching....with the length of the whiskers. Trimmed whiskers improve the upper UHF gain, but at a cost to lower UHF and VHF Hi. But that could be beneficial giving a particular situation. Also keep in mind upper UHF cable run attenuation loses are greater than those down lower.

    You can also replace the screen with a larger one. Which improves F/B Ratio, and Forward Gain on UHF. Plus increased gain on VHF Hi, especially the lower channels of VHF High.

    The longer whiskers of this design as compared to the CM 4221 improve gain across in the newly created smaller UHF Television Band.

    The thick 9 gauge whiskers improve bandwidth and SWR characteristics of the antenna.

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    Hi EV,

    Good idea! Your antenna appears to be a good option for someone that does not have the inclination or time to build their own DIY antenna. As you know from another forum, I have built several mclapp antennas and have compared a mclapp 4-bay to the EZ HD antenna. A few questions for you:

    1) What is your spacing between bays?
    2) Do you provide guidance to the buyer when he/she should perhaps consider altering the bay spacing and whisker length?
    3) The user can reduce bay spacing but not increase it. Are you stressing that the user must maintain identical length between the two phase lines? Don't ask me how I know the negative effects of varying phase line lengths....
    4) Did you measure gain in dBd for your antenna or is this a modeled number?
    5) Do you have data that thicker phase lines improves gain and reduces SWR? There have been posts at AVS where phase line diameter did not alter antenna gain... I'd like to see your data! If there is enough of a difference, I am willing to change my phase line diameter.
    6) Interesting comments on effect of reflector edges on VHF gain. Do you have some data on this as well? On AVS, wider reflectors are typically used (mine is 36 x 36 and 1 x 2 hardware cloth).

    Thanks!

    Rick

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    Hello IDRick

    1. The current inter bowtie spacing center to center is 9.5 inches. The whiskers are 9.75 inches or there abouts. Its 9.75 inches from the inside of the washer to the end of the whisker.

    2. Yes, Im here to help.

    3. You could theoretically increase bay spacing, however you really wouldnt want to do that. You could want to decrease it to 9 inches and trim the whiskers a 1/2 inch or quarter inch. Or to 8.5 inches and trim the whiskers 1 inch or 3/4 of an inch. Basically you want to keep the inter bowtie spacing at or just below the length of the whiskers....measuring from the inside of the washer to the end of the whisker and from center to center on the bowties. This is to keep phasing and impedence within good parameters. A quarter inch is better than a 1/2 inch....but measurement is crucial, youd rather err shorter on the inter bowtie spacing to the whisker length. This setup allows easy adjustment of the interbowtie spacing and accurate measurement. Just loosen the brackets and slide along the mast, when you have your desired measurement, tighten back down. You can do this more than once, but remember you cant make the whiskers longer, if you want to go back.

    4. Modeled number. Im thinking about having it tested at Georgia Techs fascilities.

    5. Phase line diameter are not as critical as whisker diameter. I use the same wire for reasons not related to performance.

    6. Antenna theory...backed by modeling. The bends were more for show than function originally on the antenna with 44" x 36" 1x2" screen. They are now necessary to squeeze a 28" wide screen into a 24" box. They should be bent back out (which is fairly easy) to increase performance on VHF High and as is, they interfere somewhat with the whiskers being to close to the ends. However UPS dimensional weight kicks in on a larger box. Its a compromise solution, but it is what it is. A larger box with the original screen dimension makes shipping to West Coast $60+ dollars. With the reduced screen size I can ship this anywhere in the continental US for $20 or less.

    36" is better for channels 7 and 8, though this size is still good for upper VHF High (and VHF High is still better than lower VHF).
    32" is a good compromise....thus the bends in the original design.
    28" is better for channels 10 and above, but still effective for lower VHF High.

    Off resonance (1/2 wave) impedence and SWR are what you are dealing with with regards to reflector screen size and VHF High performance.

    Hope that helps.

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    Thanks for the detailed reply EV! I've been primarily using 10 inch whiskers and 9.5 inch bay spacing, and 1-1/4 inch spacing between phase lines. Over Memorial Day weekend, I compared three different DIY antennas. I saw no performance change with 9.5 inch whiskers and 9 inch bay spacing nor with 11 inch whiskers and 9.5 inch bay spacing.

    I'm currently playing with a 2-bay which compares favorably with the 4-bay. It has about 3 dB less gain but would work well in an urban environment. I'm building this for my son who has two high VHF channels (ch 7 and 10) and several UHF channels 12 miles away. I'll report the results here when I've completed testing in early October.

    All the best,

    Rick

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    Its better to err on the long side of VHF High 1/2 wave(for the screen), as SWR tails up at a relatively gently sloped curve off resonance towards higher frequencies in the VHF High band. And they skyrocket at some point below the resonant frequency.


    As regards the bowtie, its a variation on a simple dipole antenna. Increase the diameter of the dipole elements and you increase bandwidth by reducing off resonant SWR. You can take this to ludicrous proportions.

    You can also do this by having a conical element with the larger part of the cone on the outside.

    Or more simply a fan of whiskers. Three and 5 whisker fans were common.

    Simplified even more, just 2 whiskers in the fan.

    So the bowtie itself is a bandwidth increasing design....but it still applies that increasing the diameter of the whiskers helps increase bandwidth and reduce off resonant SWR.

    Hope that makes sense.


    A 2 bay with a large screen should work well. It weird that the Winegard HD 1080 is so half arsed on VHF High. The design is promising, just poorly executed.

    Ive been studying antenna theory, big time, of late. Lots and lots of books. Can you tell?

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    LOL! Yes, I can tell!!!! Good job! This 2-bay may have some application in your indoor antenna thread. I'll keep you posted.

    Best,

    Rick

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    Quote Originally Posted by EscapeVelocity View Post
    Yes, if the screen is not "kinked" at the outside edges then it will increase VHF Hi band performance. It will also be better for the UHF performance.

    Yes, the instructions mention this.

    You can also increase performance on VHF High Band (and especially the lower side of VHF High Band) by removing the screen and adding your own, at 36" wide....which also slightly increases forward gain and F/B ratio on UHF, increasing its height also improve F/B ratio and Forward Gain on UHF.

    On VHF High, its a bi-directional pattern as well.

    Im available here to help people that have questions or need help with the antenna.

    I guess that sentence is a bit ambiguous. Ill see if I can clean it up.

    Thanks for the recommendation.

    These improvements for Gain are all in the territory of a 1 dB. Not insignificant, but also not gigantic either.

    The 36" width screen with the indented ends gives you an effective length of 32" (plus wire lengthening effects) which is better on the low end of VHF High Band. Its a better solution overall, because its slightly worse on upper VHF High Band and so evens out the gain across the VHF High Band. Either way, upper VHF Hi gain is better than lower VHF Hi gain.
    Absolutely true, it was proven time after time over the last 3 years by those that have equipment and posted in the AVS UHF Antenna thread if the screen is 32 to 36 inches wide. This is why a factory 8 bay works much better on VHF than a 4 bay. It goes back to you can't cheat on element length to receive. It's not a great VHF antenna, but someone with 50 NM signals can get away with using a bow tie with a 34 inch screen as a VHF antenna.

    It's simple, the reflector is the right size horizontally to be a dipole on VHF. It couples some of that energy into the driven elements.
    The more I understand, the less I know.

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

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    Good Luck with your experiments IDRick. Looking forward to hearing about them.

    2 points to consider. The screen distance from the whiskers effects gain and impedence. The closer you get up to about .15 of wavelength the higher the gain, but also the higher the impedence.

    With the 2 bay design, you have about 150 ohm theoretically at the center feedpoint, IIRC. So you would want to increase that to 300 ohm (or reduce it to 75 ohm).

    You can also increase impedence by shortening the inter bowtie spacing (I believe)...in relation to the whisker length. However, i think working the screen distance is better because you get Gain increases as well. Say about 3 1/2 or 4 inches. This impedence is frequency dependent as well....and you dont want to get too close for the upper frequencies...because past .15 wavelength you start getting into negative gain effects because the parasitic elements (screen in this instance) are too close.

    My 2 cents.

    Ill check on that figure of .15, it might be .10. I have a reference here somewhere.

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    Thanks EV! My prototype build has a 4-1/2" spacing between the reflector and whisker elements. I'm not familiar with wavelength for varying high vhf channels. What is the wavelength for channel 8? Once I know the wavelength, I then multiply by 0.15 to determine spacing between elements and reflector?

    All the best,

    Rick

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    Let me check my references, before I get back to you. I have to clear something up, I may have given you incorrect information there.

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    Quote Originally Posted by IDRick View Post
    Thanks EV! My prototype build has a 4-1/2" spacing between the reflector and whisker elements. I'm not familiar with wavelength for varying high vhf channels. What is the wavelength for channel 8? Once I know the wavelength, I then multiply by 0.15 to determine spacing between elements and reflector?

    All the best,

    Rick
    180 to 186 MHz, with the ATSC carrier on 181.31

    But with ATSC you really can't go on carrier to tune like AM or FM type modulation, so you are better turning to the center of the channel or 183 MHz.

    In free space it's 82 cm for a half wave length, if it's a wire dipole it's 78 cm due to end effect.
    The more I understand, the less I know.

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

 
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