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Plans for a 20 Meter Mono-Band Beam?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by AB9RN, Jun 27, 2008.

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  1. AB9RN

    AB9RN QRZ Member

    Anyone have a link to a plan for a 20 meter mono-bander? I would like to build one and my google searches haven't turned up what i'm looking for.

    Thanks
     
  2. VE6WTF

    VE6WTF Ham Member

  3. WB3BEL

    WB3BEL Ham Member

    You should elaborate a bit more about what exactly you are looking for.

    Are you interested in some kind of mini-beam or some kind of elephant gun?

    Anyway there is a lot of information on LB cebiks W4RNL (SK) site:

    http://cebik.com/

    you have to register but it is a treasure trove...

    73,
    Harry WB3BEL
     
  4. N2RJ

    N2RJ Ham Member

    The ARRL antenna book has plans for optimized mono band yagis.
     
  5. W1VT

    W1VT Ham Member

  6. W9GB

    W9GB Ham Member

    Kevin -

    There are several sources for DIY designs and tools for mono-band HF yagi antennas.
    The ARRL Antenna Handbook (or ARRL Handbook) is a good book source, that should be available at the Wheaton library.

    The ARRL web site is a good source for Antenna Project articles and Internet links.
    http://www.arrl.org/tis/info/antproj.html
    http://www.arrl.org/tis/info/yagi-hf.html

    ARRL also has a good tutorial on antenna modeling that was written by L.B. Cebik, W4RNL (recent SK) :-(
    http://www.arrl.org/tis/info/HTML/antenna-modeling/index.html

    EZNEC is a modeling tool that you can also use.
    http://www.eznec.com/

    Another source is actually looking at the assembly and installation instructions for commerical yagi antennas,
    such as the Cushcraft 20-meter Skywalker 4 element mono-band yagi:
    http://www.cushcraft.com/support/pdf/951354.pdf

    Aluminum tubing and stainless steel fasteners are the key materials for construction
    (but you can substitute with other RF conductive and weatherproof materials).
    You are fortunate that your QTH is within a few miles of Penninger Radio with their large stock of aluminum masts, tubing and accessories.
    Penninger also recently purchased a wire and cable supplier.
    http://www.penningerradio.com/

    Other parts sources in the western Chicago suburbs are:

    WestMarine (Lombard) for stainless steel, rope and some fixtures
    Ace Hardware (Addison store very good) larger operations have aluminum tubing in a variety of sizes
    (industrial sizes as well as Reynolds DIY in screen door departments).

    DX Engineering (Ohio) and Texas Towers (Plano, TX) are 2 very good sources for antenna building supplies (tubing, etc.)
    http://www.dxengineering.com/
    http://www.texastowers.com/aluminum.htm

    Never forget that the restoration of an older weathered HF tri-band yagi can often be a cheaper entrance --
    the amount of work is more focused on restoration of the mfg. design.

    w9gb
     
    Last edited: Jun 28, 2008
  7. K9STH

    K9STH Ham Member

    The Beam Antenna Handbook by Bill Orr, W6SAI, has some very good designs for yagi antennas. His 3-element 20 meter design on a 20 foot boom is an excellent performing antenna. I have had one of these in the air for well over 30 years and it is still working great.

    Glen, K9STH
     
  8. AB9RN

    AB9RN QRZ Member

    Thanks everyone for the suggestions. I hadn't really settled in on more specific design criteria, other then to say it didn't need to be portable. This would go on a tripod (hopefully) on my roof. It would also be preferrable if the required materials were readily accessible.

    Having just gotten into HF and digitial modes, I've found 20 Meters to be a blast. An antenna with some gain and directionality over my G5RV is what I'm seeking.

    By the way, I did look extensively at the links on DXZone. For this topic many of them appeared to be dead links.

    Thanks for all the help.
     
  9. W9GB

    W9GB Ham Member

    Kevin -

    What are you doing this weekend?

    The York Radio Club has their Field Day operational setup Saturday morning -- we will have a
    variety of antennas (TH3JR yagi, R-5 vertical, etc.) and my old Novice W2AU 80/40 trap dipole antenna (still works well).
    We might have some openings for some late Saturday night / Sunday morning operational shifts !

    w9gb
     
    Last edited: Jun 28, 2008
  10. WY6K

    WY6K Ham Member

    W9GB, thanks for the links and the work involved in posting them.
     
  11. AB9RN

    AB9RN QRZ Member

    This is exactly what i was looking for, thanks! However, I also read up on the20 Meter 3-Element Yagi design specs in the ARRL Antenna Book. When I compare the two designs I noticed that boom length was different.... by 11" which seems like a lot (element spacing along the boom was different too).

    I appreciate the differences between the two, primarily being the book design is assuming tapered AL tubing and the lightweight article using wire. That factor contributes to the electrical lengths of the 3 elements, but wouldn't see that effecting boom length and spacing?!

    Has anyone actually built the lightweight version? In the article, the author mentions it was a scalled up version from that of a working 2M yagi design. With the cost i'm looking at to build this it would be helpful to hear others feedback?

    Thanks!
     
  12. AB9RN

    AB9RN QRZ Member

    Has anyone actually built the lightweight design as referenced in the ARRL article? I'm curious how much money it cost to complete? By my estimate it will cost me close to $280 which seems high for what it is?

    6 - 20' fishing poles $120 (Bass Pro Shop)
    18 Feet of rectangular tubing $125 (Metal Supermarket)
    plus various odds and ends

    For a wire beam is this worth it (compared to purchasing a antenna)?
     
  13. W9GB

    W9GB Ham Member

    You have realized that purchasing materials brand new and then assembling is often not much cheaper than the commerical antennas.
    There is some truth in that realization.

    1. The process is educational and provides you 'hands on" experience.
    2. Some amateur have access to surplus materials (scrap) that are free or inexpensive -- reducing their costs.

    w9gb
     
  14. WB3BEL

    WB3BEL Ham Member

    If you build it like a spiderbeam then you will only need 4 poles and skip the boom.

    http://www.spiderbeam.net/sb/home/index.php

    Sure the gain will be a bit lower, but it may be more in line with your budget.

    You can get poles that are stronger than those fishing rods at maxgain :

    http://www.mgs4u.com/index.html

    Or you could get some shorter fishing rods (Black Widow) at a cheaper price at Cabelas

    http://www.cabelas.com

    Or you could buy the kit from spiderbeam and have a multibander that has better performance than most commercial 3 ele tribanders
     
  15. W8NSI

    W8NSI Ham Member

    Another possible antenna

    I noticed that no one mentioned the Hex Beam, and NO you do not have to buy it from Traffie Tech.

    The design is floating all over the net and many have been constructed around the world.

    W1GQL's Homebrew Hexbeam page

    Another roll your own version.

    Hexbeam.com The commercial version from Traffie

    These are mostly multiband but can just as easily be built as a single band antenna.

    There are other antennas [such as the moxon] out there too. The wire beams have the advantage of being light and easy for one person to install if your friends are all busy.
     
    Last edited: Jul 7, 2008
  16. K4EEZ

    K4EEZ Ham Member

    good link if your a member, Not so Good if your NOT!

    The server www.arrl.org at ARRL Members Only requires a username and password.
    _________________________________________________________________

     
  17. AB9RN

    AB9RN QRZ Member

    Thanks for the additional suggestions... some of those look like good "next antenna" projects but i would like to get a standard mono band yagi under my belt first.

    Let me rephrase my question... Do folks believe i'm sourcing the materials for this antenna project in a way that gets me in the ballpark for a cost of $275 or am i way over where i should be? I haven't built any antennas beyond a simple dipole or G5RV and am unfamiliar with typical costs.
     
    Last edited: Jul 7, 2008
  18. WB3BEL

    WB3BEL Ham Member

    Well,
    Here are the reasons that I thought you might want to consider a spiderbeam or moxon rectangle or hex beam.

    Here is some additional information on the moxon. Not everything on this site is solid engineering. But the basic design is solid. Steer clear of any design using coaxial cable as the antenna element as it is dubious.
    http://www.moxonantennaproject.com/design.htm

    1. You can make a monoband version for a lot less cash than $250. The fishing rod moxon will likely be the cheapest. I am fairly sure that it could be built for around $100-150. The hexbeam will be a bit more but will be easier to convert to multiple bands later if you decide to go this route. The spiderbeam will likely be the highest cost option of these three and will also support conversion to multiband.

    2. You indicate in previous post that you will put this on roof tripod or small roof tower. So a full size 3ele 20 meter antenna will be pretty big and will likely require you to add some roof strengthening by putting wood bracing across the trusses. A little tripod won't cut it and a roof tower is a lot more expensive than the antennna you are contemplating. It may require some sort of guy wire system to stabilize. These alternative antennas are smaller and lighter and won't require the same amount of civil engineering. It will also be less of a shock to your neighbors which might be an issue in some locations. If you have to install it yourself or with limited helpers the smaller antenna on the roof is a lot easier and safer to manage.

    3. A three element full size yagi will need a good size antenna rotor. This will also add to the project cost. The antennas I recommended can be turned with a much smaller rotor. They have less weight and less wind load area.

    4. The two element designs are simpler so for an early stage project they might be more satisfying.

    5. If the antenna height is low like many roof mounted systems are, you probably won't notice that big of a difference in performance between 2 and 3 elements. If the tradeoff is a higher two ele beam vs a lower 3 ele beam, you probably would be better off with the higher two element.

    I hope that you have fun with your project.

    73,
    Harry WB3BEL
     
    Last edited: Jul 8, 2008
  19. W9GB

    W9GB Ham Member

    Last edited: Jul 12, 2008
  20. AB9RN

    AB9RN QRZ Member

    Thanks for the smaller yagi plan and also to the others for their additional antenna plans. I've got a month before i get started with this project and appreciate all the helpful suggestions.
     
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