• HD Blade HDBLADE100 Antenna Comparison Tests



    SolidSignal sent me both the signal finder SL 1000 from King Controls
    King Controls SureLock SL1000 Digital TV Signal Finder (SL-1000) from Solid Signal
    and the HDBLADE100 antenna
    Solid Signal HD-BLADE Indoor Digital Flat Indoor TV Antenna (HDBLADE) from Solid Signal
    to test and see how they worked and to see if I could use them for any future attempts at testing various antennas, either purchased or built.

    In this blog I'll look at the HD Blade antenna. For those who don't know anything about this antenna, it is a flat, floppy antenna embedded in a floppy two-color mat that is made for mounting to a wall or simply laying flat on a table or other flat surface. You can read about it and see some photos by searching for "blade" on the SolidSignal site.

    When I first looked at this antenna and read some of the comments about it, I thought that it might be some kind of design that exhibited some minor gain over a standard wide-element bowtie dipole antenna (BT, BTA) that has long been in use for UHF TV. If we look at the design, which can be seen in the photos taken of the light-colored side of the antenna mat, we see: (1) A standard wide-element BT and (2) a pair of loop antennas that are vertically stacked (which one might assume should lead to some kind of gain) and (3) there are four "tails," for lack of any better description, which come off of the loop sections, two per loop.

    I asked for, and received, the gain plots for this antenna. The plots and gain figures seem to be consistent with those of a single element dipole antenna whose center design frequency is around 651 MHz, UHF Channel #44 (UHFC#44). The maximum gain was ~ 2.2 dBi (a dipole has a free space theoretical gain of 2.15 dBi) and then the gain decreased. All other frequencies showed lower gain than the gain at 651 MHz.

    The gain figures fluctuated with different frequencies, also as expected. How this would actually compare to a single element BT, I don't know, but I wouldn't be surprised to find that they are pretty much the same, with differences only in which frequencies exhibit the various peaks and valleys on the gain figures. The plots also showed the gain of the antenna in the VHF TV section and these were, across the board, very poor indeed, Again, this is expected of any UHF antenna being used in the VHF range, so no surprises there.

    From the online description comes this simple statement: "Latest technology allows silver elements to be printed onto a thin plastic sheet, giving you the strength of a bow-tie antenna squished in a flat, easy-to-mount package" So, by their own advertising, you are buying a fancy looking BT and paying about two to three times what one would pay for the single element BT, if they were still available. As far as being "squashed flat," the mat it actually thicker than a standard BT made out of 16 gauge wire would be, so I'm not sure what they're trying to say. Yes, the silver elements are much flatter than the wire used in a standard UHF BT antenna, but that is neither an advantage nor a disadvantage because the wide elements in the BT design are used to increase the bandwidth of the antenna far more than the diameter of the wire, or the flat, but wider-printed, element.

    Yes, it is cute, and it looks much nicer than the wire BT elements, but if we're talking about hiding the antenna behind a TV or picture, then I'll simply say that (1) the BT antenna will fit behind anything the Blade will fit behind, but conversely the Blade will not fit behind everything the BT might fit behind. (2) Neither antenna should be placed behind any electronic piece of equipment such as a TV, since TVs are RF emitters and digital TVs are probably worse and will probably interfere with the antenna's ability to receive the TV stations of interest, especially in the direction of the TV screen. Here you're asking the TV signal to go through the TV - which has wires and circuits in it - to get to the antenna - not a good idea.

    So, on the surface and by their own advertising, the Blade is simply a BT antenna. Is it any better given that it is a BT with a little something extra added?

    I did some quick and simple tests of the HD-BLADE TV Antenna (HDBLADE006) and my homebrew BT. I ran three very basic tests: 1. Each antenna was connected to the SL 1000 Signal Finder 2. Each antenna was connected to my Alinco Wide Band Receiver (WBR) to check a few stations. 3. Both antennas were connected to a portable DTV and a few channels were checked. The results of this comparison of the two antennas using the three signal receivers was:

    1. The SL 1000 Signal Finder results were identical. No channel information is available from the SL1000.

    2. The results from the Alinco WBR on all stations checked were as close to the same, for both antennas, as I was able to tell.

    3. The TV test between the two antennas was pretty much the same. I think the BLADE was a bit more difficult to test than the BT since it was more difficult to attach to the mast and put up, but I suspect that if I had been able to do that, then the results would have been identical as well.

    I did conclude that the Blade was too floppy to use for comparison testing of other antennas which would be mounted onto a mast. Also, since it was similar to the BT - and all tests I ran confirmed this - I figured that the bowtie would work better as the "standard" antenna against which to test and compare all other antennas.

    The bottom line is this: My homebrew BTA will be used as the reference antenna for all further tests. Since it costs almost nothing but a little time to make, it's also lighter on the wallet. If you want to make one of your own, you can use my diagram/photo to make one out of a couple of old clothes hangers, a few screws, a small plastic or wood rectangle to hold the two bowtie elements in a dipole configuration, and some twinlead or coax as the feed line attached to each half of the antenna. I also mounted mine on an old broom handle so it is much easier to use in testing situations when the antenna needs to be rotated. It gives good, broad directional results.

    As for the Blade antenna, I have to admit that I was looking for a bit of gain over a standard UHF bowtie and I did not find that either in my brief experiments or in the literature. Still, if you live in an area where a bowtie antenna would work the Blade will do just as well and it sure looks nicer.

    Until next time, happy viewing!
    Phil K

    All my blog articles are listed at: Karras' Corner
    or
    Karras' Corner Article Links on my KE3FL web site.


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    Comments 22 Comments
    1. VOS's Avatar
      VOS -
      I use the diagnostic menu in my TV, as it shows the SNR for the channel tuned to.

      I made up a bt matching your photos.

      I then ran tests between it and the HDBlade:
      VHF:
      7 21 dB SNR, but nothing with the bowtie
      12 +5 dB better with the HDBlade.

      UHF:
      19 +8 dB
      29 +4 dB
      30 +3 dB
      36 -5 dB < bt was better
      38 +1 dB
      42 +4 dB
      44 -1 dB < bt but not by much
      45 +2 dB
      50 -2 dB < bt is better
      I ran the tests twice for each, starting and ending with the HDBlade.

      Channel 36 & 50 are 51 off axis, while the others were 43 the other direction
    1. PhilK's Avatar
      PhilK -
      Thanks VOS! Glad to see that the Blade is a bit better most of the time. I suspect that if we change the dimensions of the bowtie the improvements will change channels but that's probably all it will do.

      Unfortunately, the portable DTV I have does NOT have any kind of signal meter, SNR, or BER (Bit Error Rate) which would be an even better indication of DTV signal usability. I haven't seen any DTV with BER.

      My Vizio DTV has a simple signal level meter even in the set up menu, no SNR as far as I've been able to find.

      I should add the photo of my original lab book when I built the first antenna. Just to be sure, you did connect the feed line to the edge of each bowtie half & not to just one point, in other words each bowtie half is a complete wire loop with no breaks in it.

      Even if I had your situation I doubt my present setup would have been able to see a 3dB change, I hope something I have will be able to see at least that. I'll know better when I test out the DTV, SL1000 and my DJ-X10 using a good signal and a good antenna with the attenuators. Still, I'll only be able to tell 3dB steps since I only have 3, 6, and 12dB attenuators for
      steps: 3, 6, 9, 12, 15, 18, & 21. My plan is to see when the signal cuts out when using the attenuators for the BT, the 4ETBT, and the DTV. With the DJ-X10 I'll see if I can actually see the signal levels change on the meter, and last for the SL1000 I'll see if I can find what dB step there is between each LED, assuming I can actually find a four LED signal which I can knock down using the built in attenuator.

      In any event, my next article will be on the SL1000 so I hope this test setup works well.
    1. VOS's Avatar
      VOS -
      Quote Originally Posted by PhilK View Post
      Thanks VOS! Glad to see that the Blade is a bit better most of the time. I suspect that if we change the dimensions of the bowtie the improvements will change channels but that's probably all it will do.
      Just to be sure, you did connect the feed line to the edge of each bowtie half & not to just one point, in other words each bowtie half is a complete wire loop with no breaks in it
      yeah, this isn't my first rodeo, so the 5 dB "bump" for channel 36 had me wondering.

      I noticed in your photo that you used twin lead.
      I'd mounted the balun on the bt, so the coax from the HDBlade could be swapped over for comparison.
      I added a 28" length of twin lead between the bt and balun and retested.

      Not surprising it changed the results by:


      The twin lead being part of the antenna removes the channel 36 "bump" and improves the low end, but the antenna is now 14" x 33".

      What you referred to as "tabs" in the HDBlade, look like strip line tuning stubs, allowing the HDBlade to have a smaller footprint and averages 2 to 3dB more than the bowtie for all my tests here for channels 7 through 51.
    1. PhilK's Avatar
      PhilK -
      Vos,

      Thanks again. Please explain the graph, is this BT dB Gain vs Real Channel or BT dB reference the Blade vs Real Channel or BT S/N ratio vs Real Channel?

      Try again without the balun, this is a dipole design and thus already has a ~73 Ohm impedance so no 300-75 Ohm balun needed to feed a 75 Ohm TV input. you can try removing all 300 Ohm twin lead & simply connect some 75 Ohm feed line directly at the feed points. Or, do as I do and use twin lead and an empty balun case - no transformer is present inside since I've removed it.

      A big Ouch at Ch 36, that's Washington's Fox 5 station, but then I get a Baltimore Fox and ABC Baltimore id Channel 2 (Ch 38 UHF) and I don't need much gain there since it is los. The 30's stations 33, 34, 35, 36, 38 are W/WHUT, W/ION, W/MyN 20, & B/ABC. If I'm exhibiting the same loss as you in that section that would explain why getting WHUT is difficult. I'll have to see about the others since I thought I was getting ION & MyN from Washington.
    1. VOS's Avatar
      VOS -
      Quote Originally Posted by PhilK View Post
      Vos,

      Thanks again. Please explain the graph, is this BT dB Gain vs Real Channel or BT dB reference the Blade vs Real Channel or BT S/N ratio vs Real Channel?
      These are "real channels". This graph is the difference of SNR from the bt with 28" of twin lead added [vertically] between it and the balun, to show how the twin lead becomes part of the antenna.
      Try again without the balun, this is a dipole design and thus already has a ~73 Ohm impedance so no 300-75 Ohm balun needed to feed a 75 Ohm TV input. you can try removing all 300 Ohm twin lead & simply connect some 75 Ohm feed line directly at the feed points. Or, do as I do and use twin lead and an empty balun case - no transformer is present inside since I've removed it.
      Besides the impedance change, the balun changes from a balanced line to unbalanced line. If a coax were connected directly, the shield is still going to have a voltage and be part of the antenna.
      In one of my tests, I used a crappy balun on the bt and many channels would increase their SNR by 2 dB when I touched the coax.
      A big Ouch at Ch 36, that's Washington's Fox 5 station, but then I get a Baltimore Fox and ABC Baltimore id Channel 2 (Ch 38 UHF) and I don't need much gain there since it is los. The 30's stations 33, 34, 35, 36, 38 are W/WHUT, W/ION, W/MyN 20, & B/ABC. If I'm exhibiting the same loss as you in that section that would explain why getting WHUT is difficult. I'll have to see about the others since I thought I was getting ION & MyN from Washington.
      Here's a comparison to the HDBlade, zero reference line, [which averages a SNR of 22.6 dB] to the SNR of the bt and the bt with 28" of twin lead before a good balun.
      I'd call these "real world" results as they're what I get, but they're off axis by a good 45, because the towers are 100 apart from my location and the wall the antennas were mounted on is halfway between.
      28" of twin lead was "picked" only because it was the first piece of twin lead I came across.


      On axis results will vary along with changes to the length of the twin lead.

      As we know, building an antenna for one frequency is pretty straight forward. Building one for a wide frequency range gets a lot harder as there are tradeoffs, which the graph shows.
    1. PhilK's Avatar
      PhilK -
      Thanks again Vos, good work!

      I understand/agree that the channels are "real" channels meaning the originally designated frequency bandwidth at which you are receiving signals. I'll standardize on that as well rather than having to say "Ch 26/27 real" or something similar all the time. It will save time & space.

      Perhaps a better graph would be the Blade normalized to 1 (made into the "0"-line) then plot the above results on that center line. So, if at Ch 12 the Blade was only 18 SNR the red & blue lines would move up 4.6 dB to 2.6 dB & ~1.6dB. This would give us the best idea of how the BT antenna compares to the Blade or to anything else for that matter.

      I'll have to measure the twin lead length so we can at least have those match up as well. If you can remove the impedance matching transformer from one balun & simply attach the coax to that we'll have exactly the same test set-up. I will NOT use a 300-75 Ohm balun on a bowtie antenna since I get consistently better results without it. A 1-1 balun could be made. We could wind the same number of loops of wire for both sides around the core removed & we could try that as well.

      Unfortunately from my location I'd only receive one TV station if I mounted these on a wall. That wouldn't help us characterize the antenna except at that one frequency. I have to wait for time & conditions to be able to test outside.

      When I Looked at the Blade's gain figures I would not have expected the SNR to be 22.6 for all stations and since the gain was all over the place, as expected for a wide-bandwidth design, an average would NOT be a good thing to use. The bottom line is that the average SNR has little to do with the actual SNR.

      We need to understand that SNR also has to do with the strength of the station at that frequency, its distance, and interference factors in between. Unfortunately neither of us has an antenna range to be able to compare apples to apples.

      If you can normalize the graph let's see what that looks like. Eventually we'll want to put the "standard" BT as the normalized center line & plot the Blade against that to see how much and where it is better than the BT. Then we'll also have something "simple" to compare all other antennas to.
    1. VOS's Avatar
      VOS -
      Phil,
      I have to say I just don't share your interest in this bt.
      Since you'd compared it to the HDBlade, which I have one of, I was curious, but it has since faded because of results like this:

      Attachment 678

      I started to run the tests of the bt on axis with a coax connection, and then removing the bt showed the TV was still getting a signal with the open coax.
      Without a balun, it's hard to separate the antenna from the line connecting it.
    1. PhilK's Avatar
      PhilK -
      Wouldn't the open coax cause the same issues with the Blade? I see no balun on the Blade, do you? If we want the coax out of the picture we need a one-to-one balun so we don't introduce losses due to a 300-to-75 balun/matching network which is NOT needed, at least for the BT and I suspect they worked on the Blade to produce as close to 75 Ohm impedance throughout the freq. range as possible.

      I understand your loss of interest since you have a Blade, I do not and I don't want to cause others to have to buy it IF there are any others interested in these tests. A simple BT can be made & it can be mounted on a stick/pipe whatever very easily, unlike the Blade. So as a Standard antenna I will stick with the BT. I'm also pleased to see that the Blade does exhibit some gain over the BT at least in some places, more places than not.

      I placed an order for a DTV USB stick that also comes with free software for measuring BER and I believe SNR and perhaps signal level. With that I'll pick as good a location on my property, or perhaps on the Mt. Airy Ridge, where I can run tests against the BT and any other antenna. The disadvantage is that I have to have a laptop to run the tests. But, it will be interesting to simply first run the tests with the antennas I have as they are mounted in winter and then in the summer.

      Thanks for your help.

      Oh, do you have any clip on ferrite cores you could clip onto the coax? They should eliminate RF on the outside of the coax. In this case they would need to be put close to the TV antenna input. Unlike a transmitter when they would be most useful close to the antenna.

      If you do, you might try adding them to the Blade to see if it changes the Blade-coax response.
    1. VOS's Avatar
      VOS -
      no ferrite cores here.

      This comes from an earlier article on the Blade:


      Seems like the Blade is using a transformer in their balun.

      Given the Blade is an indoor antenna, I don't see the need for it to be mounted on a pole, and its design blends in much better on my wall. I've read that it has been painted to match the wall with little degradation too.

      The bt by itself doesn't work for me because I have two networks using VHF and as the plot above shows, the bt doesn't pick up VHF, where the blade does.

      I'm sort of surprised your bt hasn't evolved into this:
    1. PhilK's Avatar
      PhilK -
      You're getting ahead of where I'm going Vos. Yes, the BT has gone there and more: reference my recent article in Popular Communications: February 2013 pages 10 - 16.

      Popular Communications Current Issue

      Click on the title, "An Omnidirectional DV Antenna - With Gain!"

      You'll get the pdf of the first two pages of the article and on the first page is the photo of my antenna. BUT, no 300-75 Ohm transformer is used I removed it from the case & simply use the case to connect the antenna phasing harness to the coax.

      I also built one like the image you posted for a friend but I mounted it on PVC pipe for outside use here in MD.

      The gain on this antenna was 3X the Blade or the BT as measured by the SL1000, SureLock Digital TV Signal Finder, three LEDs vs one LED for both the BT & Blade. Also, by the TV where the number of viewable stations for this antenna increased well over what the BT or Blade could view in my area.

      You'll have to see the full article for the details. I will be doing a similar article for this blog, when I hopefully have a way to measure at least the BER and the signal level & perhaps the SNR.
    1. PhilK's Avatar
      PhilK -
      Given the Blade is an indoor antenna, I don't see the need for it to be mounted on a pole, and its design blends in much better on my wall. I've read that it has been painted to match the wall with little degradation too.
      Absolutely on all counts! But since I'm in a fringe area, indoor use shows nothing to one station so I have to test these outside. We wanted to use the blade since it is what I'd call the basic antenna. Everything else should show gain above it and would be used outside, well almost. The image of the antenna you show was actually designed for use inside but has been used outside, by the editor of Popular Communications, in his area and myself. Here in MD if I were to put out an antennna made of unprotected coat hanger wire, parts the of the antenna would rust away and the antenna would fall apart within about 10 years. Been there, done that.

      You are very lucky to be able to use a good basic antenna like the Blade inside and be able to receive as many signals as you do.

      I'm simply too far from all stations and over the hill from the stations I want to get from Washington, two - one edge depending on antenna height. To get clear of the last edge for Washington my antenna would have to be at least 50' up! Then about half of the Washington stations are clear of the last edge, to get them all clear I'd have to go even higher. But at this height I would have cleared both WHUT and WETA-TV both Public stations I like from Washington D.C.

      Reference: TVFool.com
    1. VOS's Avatar
      VOS -
      Quote Originally Posted by PhilK View Post
      You're getting ahead of where I'm going Vos.
      I don't know who's ahead or behind here.
      I've shown the cable connected to the bt will change the performance.

      I also don't know why you seem to go "against the grain" of every antenna manufacture over the balun.
      Since theoretically there is close to a 2 dB gain with a better impedance match, one might think the antenna manufacturers would know this.

      Maybe a good project for you is to build a 1:1 balun and use it for testing instead of just gutting one for the connectors.
    1. PhilK's Avatar
      PhilK -
      I go against the grain because of my experience and education. I have degrees in physics and I've been a ham radio operator for over 20 years. I have designed and built antennas for radio and TV. Some of which I've written about and have had published in various radio magazines. I am mostly a seat-of-the-pants experimenter, using some knowledge from my education as well as the writings of others on antennas to come up with ideas to try.

      BUT, the most important is that I've tried it and it works better, WHEN the antenna is a 73 Ohm antenna. (Which matches the theory and has been used by hams for more years than I am old.) When I designed and tested this same idea on a 300-Ohm full wave loop for TV it worked better with the 300-75 Ohm transformer, also according to the theory.

      The theory says that if the feed line impedance matches the receiver input impedance and the antenna impedance then no matching transformer is needed. If you're using coax then IF you don't want the coax to add anything (or as a ham you don't want it to transmit anything) then a number of loops of coax or some slip-on or clip-on ferrite cores will keep the RF off the outside of the shield. I'm not stopping you from doing just that but in my location I need all the help I can get so unless it improves the signal, which it clearly doesn't, I'm not using a matching transformer which I don't need for this kind of antenna because it wasn't designed for this kind of an antenna and I won't recommend it to anyone else either.

      The 300-75 Ohm matching transformer was designed for the log-periodic antenna which seems to have been designed to have a 300-Ohm impedance and that's why 300-Ohm twin-lead was used to go to the TVs of old, NO matching transformer was needed at the antenna. When the TV's started having 75 Ohm inputs because people wanted to use coax, for some good reasons, of which better transmission of the signal to the TV was not one of them, the 300-75 Ohm transformer was needed to match the impedance of the antenna to the feed-line & TV.

      It is my belief that since the manufacturers used this transformer for the TV antennas they simply started putting them on every antenna whether it needed it or not because it was needed to make it easy to attach coax to an antenna that had only screw-on antenna connectors.

      So, I ask you, why do you insist that the manufacturers are right when they are obviously wrong when they use a 300-75 Ohm matching transformer for a 73 Ohm antenna?

      There is a time and place for all things, using a 300-75 Ohm transformer on a 73 Ohm antenna fed by 75 Ohm feed line going to a 75 Ohm TV antenna input is simply not one of them.

      Using a 300-75 Ohm transformer on a 300 Ohm log-periodic, or full-wave-loop, antenna, both of which can have 300 Ohm impedance if designed correctly, IS one of them.

      Also, as a former practicing scientist I know that theories are based on real-life experience or put another way, the supporting experimental data accumulated over the years. There are many very good test equipment manufacturers and a few reputable antenna manufacturers who know the theories and build their equipment and antennas based on the best scientific evidence and then only claim what is theoretically possible or what they have experimental data to support.

      Unfortunately, just in case you didn't know it, many antenna manufacturers are notorious for over stating the facts about the antennas they build. All you have to do to understand that is to read some of the articles by Kurt N. Sterba who simply loves to disprove many of the antenna claims of the manufacturers.

      The bottom line is that I run tests and if it works better with or without this or that, then I use it or not as the experimental evidence proves out.

      Using ferrite cores or looping the coax will keep the RF off the outside of the coax shield. The time to be concerned about that is when transmitting many watts of RF which may come back on the outside of the shield IF the impedances do not match at the antenna. This could destroy the transmitter or give the operator one nasty RF burn. Since the TV is NOT transmitting there's no reason to be concerned with any RF getting onto the outside of the shield from the TV stations. The RF on the outside of the shield may not help the signal to the TV but it surely won't hurt the TV & is of little concern in my opinion.

      I hope that clarifies my position on why I do what I do where antennas and impedance matching transformers are concerned. They are to be used when and only when impedances need to be matched.
    1. VOS's Avatar
      VOS -
      My interest here is not to have some contest of measurement of male parts.
      20 years in electronic warfare has given me some experience too.
      Impedance [matching] of a transmitting antenna is fairly easy to measure and determine.
      A receiving antenna isn't quite as easy.
      You don't care what affect the transmission line has, but when you are comparing one antenna to another, shouldn't it either be defined or eliminated?

      I guess I ruffled some of your feathers by suggesting for you to build a 1:1 balun.
      It would seem like a good test to see which impedance had the higher gain.

      I've suggested you contact Winegard before as they publish specs for most of their products, and they look to be professional [enough to me] to be meaningful.
      All the outdoor Winegard antennas I've seen in the past 10 years, have coax connectors and at least a balun. Whether they have a 1:1 or 4:1 transformer, I don't know, "but would guess" they're using what has a higher gain, as it's in their best interest to.
    1. PhilK's Avatar
      PhilK -
      My interest here is not to have some contest of measurement of male parts.
      20 years in electronic warfare has given me some experience too.

      Impedance [matching] of a transmitting antenna is fairly easy to measure and determine.

      A receiving antenna isn't quite as easy.

      You don't care what affect the transmission line has, but when you are comparing one antenna to another, shouldn't it either be defined or eliminated?

      I guess I ruffled some of your feathers by suggesting for you to build a 1:1 balun. It would seem like a good test to see which impedance had the higher gain.

      I've suggested you contact Winegard before as they publish specs for most of their products, and they look to be professional [enough to me] to be meaningful.

      All the outdoor Winegard antennas I've seen in the past 10 years, have coax connectors and at least a balun. Whether they have a 1:1 or 4:1 transformer, I don't know, "but would guess" they're using what has a higher gain, as it's in their best interest to.

      -----
      My interest here is not to have some contest of measurement of male parts. 20 years in electronic warfare has given me some experience too.
      Me either, but I did want it known I have some experience here. And thanks for letting me know where you're coming from.

      Impedance [matching] of a transmitting antenna is fairly easy to measure and determine.

      A receiving antenna isn't quite as easy.
      True, but here is where my experience says while it may not be as easy for the receiving antenna, it also seems to not be nearly as important. I've simply used the try-it-and-see method to prove to myself that using 300-Ohm twin-lead to feed even a 73 Ohm antenna is better than using coax. Then simply feeding it into the TV using wire to wire connections works much better than the 300-74 Ohm impedance transformers.

      You don't care what affect the transmission line has, but when you are comparing one antenna to another, shouldn't it either be defined or eliminated?
      You are correct, but again, I use 300 Ohm balanced feed-line to a balanced antenna so it should have little effect on the pattern. Perhaps not in your area where you were able to actually receive stations with just coax, I can't even receive stations with the Blade or Bowtie inside my house, so once inside the house I can convert to coax and have probably no effect whatsoever on the antenna pattern.

      I guess I ruffled some of your feathers by suggesting for you to build a 1:1 balun. It would seem like a good test to see which impedance had the higher gain.
      No, I would like to do that but I haven't enough time for most things when I get home. I have saved the parts I've taken out and will get around to it.

      Another reason it is not that important to me is that for all my TV antennas I use 300 Ohm balanced twin-lead. So, going from a balanced antenna using balanced feed-line should be no problem. I did this at first because it was always done that way, later I experimented and found that even using a 73 Ohm antenna the twin-lead worked better than the coax did in getting signals to the TV in my fringe area, so I continue to use it. Simple experiments with very noticeable results.

      The antenna I put up over the kitchen comes into the house using 300 Ohm twin lead & then gets converted right at the wall plate to a 75 Ohm connector, but no balun. It works very well getting all Baltimore stations and some Washington stations and even sometimes the stations I am interested in from Washington.

      Unfortunately I'd have to get that antenna up 50' to be in the los zone for the stations of interest and it simply isn't going to happen. The best I can hope for is to adjust the height to get the antenna into a peak of the diffracted signal pattern.

      All the outdoor Winegard antennas I've seen in the past 10 years, have coax connectors and at least a balun. Whether they have a 1:1 or 4:1 transformer, I don't know, "but would guess" they're using what has a higher gain, as it's in their best interest to.
      Sounds good, and as time permits I'll try to remember to do just that. I should be able to ask what the impedance is of the antenna and the matching circuit. I now have a WINEGARD technical contact.
    1. VOS's Avatar
      VOS -
      I understand why you do what you're doing.
      It's been so long since I cared about twin lead, that I had to google it to find its loss at 500 MHz takes RG11 to equal.
      The "downside" of being unshielded is interference, but this can be "a plus" for a TV antenna, as when I used a 28" length on the bt and improved the VHF levels.

      Let me try to bring this to a close by saying I understand how you came to your conclusions, but with my background, see variables that affected the results. Without quantifying these variables, it's hard for me to come to the same conclusions.
      Finding something works better can be easy, but finding out why it does may take a lot more effort.
    1. PhilK's Avatar
      PhilK -
      I have to admit that after re-reading my response to you I really did vent a bit and I must apologize for that.

      The fact is I was hoping for people like you with different experiences so you could share your ideas and insights. I'm no expert here, far from it, I just enjoy experimenting and seeing what can be done and with what. The more people like you who respond with ideas, questions, and insights the better.

      I hope to find time to learn more, especially with the antenna modeling programs available, but also from others who know things I don't.

      The "downside" of being unshielded is interference, but this can be "a plus" for a TV antenna, as when I used a 28" length on the BT and improved the VHF levels.
      The interference problem used to be a big problem back in the 1950's, 60's, etc. with cars causing the entire TV sound and picture to be wiped out, picture being AM would go first. As I said, there were good reasons to go to coax, etc. Today the cars are so much better and I haven't once had any problems using twin-lead and now that TV is digital it's less susceptible to AM generated noise, though I would think that this still might cause the BER to go up & the signal to then drop out.

      Finding something works better can be easy, but finding out why it does may take a lot more effort.
      Isn't that the truth. To help in the characterization of things I picked up a USB WinTV-HVR-950Q stick and the free software for looking at the signal levels and the BER.

      Perhaps with that in hand, once I learn to use it, I can get some good information from my location.

      You're going to hate me, but I was thinking of trying different BTs with just the V shape at different lengths to see what effect that has on things. Once I get the WinTV & software working I think that may be interesting.
    1. VOS's Avatar
      VOS -
      Quote Originally Posted by PhilK View Post
      You're going to hate me, but I was thinking of trying different BTs with just the V shape at different lengths to see what effect that has on things. Once I get the WinTV & software working I think that may be interesting.
      Nope, you like to play with things like this. I was there too when I lived behind a mountain and played to find how to get any reception with a NM of about 1 dB.

      I looked at a couple of baluns mounted back to back and found their insertion loss can be close to the gain of the correct impedance, which may make this moot.

      The HDBlade is what it is and for those that don't want to spend the time to make their own, might be a good choice.
    1. PhilK's Avatar
      PhilK -
      The HDBlade is what it is and for those that don't want to spend the time to make their own, might be a good choice.
      I agree with that. It seems to be about as good or better than the old standard bowtie and it sure looks alot better!

      Next up is a short evaluation of the SL1000, SureLock Digital TV Signal Finder.

      Then I may have something to say about the HVR-950Q and the free signal level, SNR/BER software and a different Bowtie.

      I like the idea of making interchangable elements for the bowtie, perhaps a small board with screws where either twin lead or coax can be attached as well as the different sizes of BT elements.

      Attachment 680
    1. PhilK's Avatar
      PhilK -
      Oh but it has, and more... see: http://www.popular-communications.co...dv_antenna.pdf - my article on how to build the Turnstile-Bowtie version of the above quad bowtie version.

      If I remember my antenna phasing stuff correctly the impedance of the quad bowtie antenna shown above is 1/4th that of a single bowtie. That means it is ~ 18.25 Ohms, now, if we could reverse the connections of the attached balun, which I'm assuming is a 300 to 75 Ohm transformer/balun or a 4:1 balun it would be correctly attached. But, if it is attached as a 300:75 Ohm / 4:1 balun then we have 18 Ohms going to the 300 Ohm section of the transformer which then tries to convert that back down to 75 Ohm so it divides the input impedance by 4 giving us ~ 9 Ohms coming out of the 4:1 transformer. This probably causes more losses than if we simply left it off.. On the other hand if we use it as a 1:4 transformer by attaching the 18 Ohms of the antenna to the 75 Ohm section of the transformer we get it multiplied 18.25 X 4 up to 73 Ohms and this ends up being very close to the 75 Ohm, TV input. I've got to try that! I'll see if I can take one apart & reverse the wiring.

      Perhaps this is why my results are better without it than with it?