1. In celebration of the launch of the new redesigned site, we just gave away a FREE antenna! Click Here to See Who Won!

tophats and such on top of antennas

Discussion in 'CB Antennas' started by BOOTY MONSTER, Jan 11, 2010.

  1. theres varying claims on tophats and ball tops and stuff on top of cb antennas and and how effective they are . i was wondering what yalls experiences are with them ? from what i can tell most cb antenna builders claims about them lowering TOA and such are , guestionable , because theyre just too small to have the effect they claim on their antennas . i have read that they can be helpful to make an antenna less attractive for a lightning stike because they spread the elevated attracting charge out over a larger surface area so its not a such a little hot spot up there .



    anyhow , whats your experiences , thoughts and knowledge on them on or around 27 MHz. ?
     
    #1
  2. hookedon6

    hookedon6 W9WDX Amateur Radio Club Member

    Joined:
    Jun 21, 2008
    Messages:
    1,483
    Likes Received:
    234
    a cap hat can be useful on the LOW bands (not 27 Mhz). they give the antenna more bandwidth.

    the claims by the manuf's you repeated above are pretty far fetched:whistle:

    Antenna Cap Hats

    the little ball on the tip of an antenna is somewhat effective is reducing static noise
     
    #2
  3. ROC1

    ROC1 Active Member

    Joined:
    Apr 5, 2008
    Messages:
    112
    Likes Received:
    7
    [​IMG]
     
    #3
  4. Marconi

    Marconi Supporting Member

    Joined:
    Oct 23, 2005
    Messages:
    4,028
    Likes Received:
    275
    Hookedon6, I might agree with you that the use of a top hat can increase the bandwidth in cases where its structure is a modest to significant portion of the elements wavelength. I don't make any claims about the info in the link you provided us, however both quotes below can be read to disagree with your claim---unless I misunderstand your words about "LOW BANDS."


    I also agree with Booty Monsters comment about the use of top hats and balls on the top of vertical radiators being useful in helping to reduce the chances of lightning strikes.
     
    #4
  5. "Adding a lot of insult, is the typical low Q of the loading coils, and short lengths. Fact is, few amateurs really understand just how inefficient an HF mobile antenna system is. In the worst of cases, efficiencies are less than 1% (80 meters), and in the best of cases, about 80% (10 meters)."


    how fortunate for us chicken banders that our little peice of the sky is right nextdoor to 10 meters :) .
     
    #5
  6. hookedon6

    hookedon6 W9WDX Amateur Radio Club Member

    Joined:
    Jun 21, 2008
    Messages:
    1,483
    Likes Received:
    234
     
    #6
  7. HiDef

    HiDef Active Member

    Joined:
    Aug 16, 2008
    Messages:
    543
    Likes Received:
    5
    Top gizmos are 98% gimmick on chickenbander base station sticks.

    Mo-bile ants benefit anytime a loading coil's resistive loss can be reduced. Top loading does this by lowering the inductance necessary for resonance.

    You have arrived when your 75 meter mobile stick is resonant and you can't get it to work at 50 ohms without some type of network at the feedpoint.
     
    #7
  8. CDX-007

    CDX-007 Transducer Fanatic

    Joined:
    Jan 26, 2006
    Messages:
    707
    Likes Received:
    6
    Years ago I helped a friend rebuild a Penetrator. It came with mostly unusable top hat radials due to being bent or broken.

    Instead of making new ones he asked if they weren't just ornamental because he had a SigmaII a decade earlier and remembered it having nothing on top, and at that time we were running identical radios and lived only blocks apart (I was using a Penetrator) and we were always neck-n-neck.

    So I told him that I thought we could get away without them but the radiator would require increased length.

    We simply lengthened it and it worked perfectly.

    A year later I decided to remove mine just to see if it would make any difference at all.

    Static did not increase, signal remained the same except for maybe a needle width of increased receive from having 10" more height / vertical capture area.

    Now I rebuild them w/o the top hat, just like the SigmaIV, SigmaII, Old Vector 4000, LW-150, etc...
     
    #8
    Last edited: Jan 12, 2010
  9. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,834
    Likes Received:
    726
    Another little tid-bit that might be handy to know, is that anything 'pointy' is more susceptible to arcing, or static discharge, or corrona, or the rest of that stuff than something that's 'blunt'. The 'radial' looking thingys do work, but they ar not as efficient as the 'wheels', or 'clover-leaf' looking thingy top-hats.
    If an antenna is loaded, getting that top-hat as far above that coil/load as possible is also a very good thing to do. Putting it at the top of the 'stinger' is nice, but it also introduces more 'wind loading' and 'bending' in that stinger. Take the best compromise you can get, sort of.
    I also wouldn't get too 'thankful' about that efficiency thingy at 10 or 11 meters. That quoted "80%" is the -best-, not the typical efficiency, and is also dependent on how much the thing was shortened to start with. A LOT of things affect efficiency, that top-hat is just one of them. Unless you really need to shorten an antenna a bunch, adding a top-hat isn't going to be much of an advantage at all. If it were, you'd see a lot more of them.
    - 'Doc
     
    #9
  10. im interested in base antenna use . i know i want to add horozontal ground elements to my antenna later and im thinking of trying something different with the top to just play around with . i remember the pointy stuff attracting noise , i actually filed some of the parts on my antenna to smooth them .

    it sounds like that if theres any effect to be had from them that they need to be rather large and rounded/connected around the perimeter . how about the lid off a big frying pan ? drill holes in it or skeletonize the inside kinda like rims on a vehicle so wind doesnt grab it as strongly ? or how about the front wire blade guard off of a broke table fan ? that should have minimal wind load ???

    ive got an idea about putting a pressure treated 6x6 about 3 or 4 feet into the ground with some concrete and having 5 or 6 feet above ground with a hinged plate at the bottom a mast would connect to and som sort of locking/securing thingy at the top . have it hinged at the bottom for easy one person raising and lowering for easy testing . getting a 19ish feet feedpoint on antennas above it will get it above the surrounding homes and such .

    anyhow , kinda rambling .............................
     
    #10
  11. HiDef

    HiDef Active Member

    Joined:
    Aug 16, 2008
    Messages:
    543
    Likes Received:
    5
    Experimenting is great.

    Don't let anyone including me convince you more than 3 radials is a waste of time and material.

    I wouldn't listen to me either.
     
    #11
  12. W5LZ

    W5LZ Crotchety Old Bastard

    Joined:
    Apr 8, 2005
    Messages:
    6,834
    Likes Received:
    726
    Mast/pole.

    View attachment 1707

    Wood, metal, whatever, it works.

    Top-hats.

    "they need to be rather large and rounded/connected around the perimeter", that would certainly sort of summarize it. An iron skillet lid would be kind'a much, but how about a trashcan lid, bicycle wheel, umbrella? Circle made from some kind of mesh? Or just round, like two 20 gallon bowls fit together? Okay, 5 gallon bowls, maybe? Metal frisbee (the one under the couch? empty it first.)?
    Let your imagination be your guide...
    - 'Doc


    (Attach 10 gallon beer keg at bottom of tilt over pole. Water faucet in top and bottom of keg. Attach hoses to faucets. Fill keg with water to raise it, empty to lower it. Add anti-freeze as necessary.)
     
    #12
    Last edited: Apr 26, 2014
  13. hidef , four radials seem to be popular with the more respected antennas of today and from the old school days so ill stick with that .
    plus it copying the wolf 64's attachment of ground radials doesnt look difficult to copy
    [​IMG]

    hey 5 , 8 through 23 inches what do you recomend ??? hahahahahaha

    Commercial aluminum pizza pans for restaurant use
     
    #13
  14. HiDef

    HiDef Active Member

    Joined:
    Aug 16, 2008
    Messages:
    543
    Likes Received:
    5
    In this case 4 are easier to implement than 3. Like I said, I wouldn't listen to me either.

    Been there with the radials myself. I even tried connecting the ends about 34 years ago.
     
    #14
  15. Marconi

    Marconi Supporting Member

    Joined:
    Oct 23, 2005
    Messages:
    4,028
    Likes Received:
    275
    For me, back in the 70's - 34 years ago, all I had on my mind was my lady, my car, and my job. I had a radio with some wire in the air, but I hardly knew what a commercial CB vertical antenna was and I sure couldn't afford one until later on in the 80' when the CB craze started.

    Talking about top hats on verticals, one of the best antennas I have is the AstroPlane. It has a 50% top hat and I think it is very effective at being able to work a shortened radiator. I tend to believe that the device has to be large relative to the wavelength in order to really make a really noticeable difference though. In fact I made a full 1/4 wave radiator for my old Top One antenna and I see a difference. It's not a lot of difference, but it says a lot---to be so short and work as good or better than the full length 1/4 wave radiator.

    I wish I had two of the old style AP's and I would try and compare them side by side. I can't tell you it will perform as good or better as some of the more popular CB verticals around today, but if you can get it up as high to the tip as those others, then you might be surprised at how strong of a signal it can make.

    Don't just tease us with "I dids" HiDef. Tell us how & what you did and the results your had. Give us some of your experience within this interesting topic.
     
    #15
    Last edited: Jan 14, 2010

Share This Page