Walking-stick Antenna for 2m, and 70cm

Discussion in 'Communications' started by fachento, Oct 26, 2008.

  1. fachento

    fachento Member

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    I thought this might be of general interest to Ham Radio operators (and future Ham Radio Operators!)

    I built a couple of antennas designed for use on the 2m and 70cm bands, using 300 ohm twin-lead (that old TV antenna stuff) in a j-pole design - and was able to use some pvc and some pvc-fittings to make 'walking-sticks' into which the antenna fit.

    Here's the fun part -- the second one I build was CAVERNOUS inside... the 300ohm twin-lead just rattled around inside everywhere I walked... and at first I just put packing peanuts inside around the antenna to keep it still...

    But then it occurred to me that you could fill it with other useful things, and make it into a useful carrier of equipment should you be called out as an emergency responder, or simply to "bug out."

    I've got the plans to build the antenna, and some photos of the results I got. Both the ones that I built worked really well, and would make great additions to a more extensive "Go Bag." :cool:

    If you are interested in either or both, please email me. Also, FYI, the photos are on the Yahoo Group for the Yaesu VX-5, in the photos section.

    73 (regards),

    Fachento
    KD5VEZ
     
  2. Old Sarge

    Old Sarge Member

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    Walking Stick Antenna

    Hey I'd be interested in seeing what you made with the PVC pipe. I made one of those antennaes, from the 300 ohm TV cable. Have used it numerous times, when we were RVing, with the top end clothes pinned to the motorhome awning, and the other end to the Yaesu VX5. Works wonders. I don't see your e-mail address. kd5yxw @ arrl.net
     

  3. fachento

    fachento Member

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    Parts List / Cost estimate

    I thought it might also be helpful to provide a short parts list and a rough cost estimate - assuming you already have the hard-ware to solder.

    Parts:
    1 chassis-mount BNC connector (Radio Shack)
    1 ft. RG-58 Coaxial Cable
    5 ft. 300 Ohm Twinlead - to allow for mistakes/practice (Lowes)
    5 ft. PVC pipe
    2 male-threaded end-caps
    2 female-threaded end-caps

    $20


    [optional]
    3 inches of shrink-wrap to cover coax-to-twin lead solder joint
    RTV or Silicone-based glue to water-proof BNC connection on inside of end-cap.
    $7

    I'd be happy to send out photos and plans!

    Regards,

    Fachento
    KD5VEZ
     
  4. JeepHammer

    JeepHammer Well-Known Member

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    I'd like to see the photos and plans!
    If you don't know how to post the pictures, post the links and I'll make them show up here for you!
     
  5. fachento

    fachento Member

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    Pictures!

    If you want me to email you the plans and photos just send me an email -- fachento @ gmail.com

    I'll try and post some of the images here...

    Here's the "prototype" -- the experimental one.

    [​IMG]
    [​IMG]

    Here's of the second try -- the "production model" if you well, after having worked out a few kinks.

    [​IMG]
    [​IMG]

    I cleaned up the solder joints on the second model, and covered them in shrink-wrap that I got from radio shack, to protect them from getting knocked loose. The second one is pretty big inside -- lots of room for other gear!

    Regards,

    Fachento
    KD5VEZ
     
  6. northernontario

    northernontario Well-Known Member

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    What'd you use to tune the antenna? What frequency did you try to target for lowest SWR?

    I've been getting into antenna building, playing with j-poles, and picked up an MFJ-249 antenna analyzer on ebay.

    [​IMG]

    Had pretty good luck with my first j-pole I made... some 450ohm ladderline twinlead... hang it off a tree... huge improvement over any duckbill.

    I still need to spend time messing around to find the relation between lengths from feedpoints and affect on SWR.

    I still haven't found out if there should be dimensional differences between using 450ohm and 300ohm twin-lead.

    How do you support your antenna when transmitting?
     
  7. fachento

    fachento Member

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    I just used the dimensions provided in the design that I found for it -- it seems to work perfectly on both 2m and 70cm - so I guess I can't complain! You can supposedly decrease the tendency to have "lobes" of reception by putting a small iron-ferrite core/bead around the coax, but I haven't tried it yet.

    I haven't "tuned" the antenna really... the design seems to make things work out well enough!

    If I'm just walking around, I'll hold up the antenna with my hand. If I'm going to be parked for a while, I'll either drive in a T-Post and zip-tie the antenna to it, or hang it from a tree. I bought a BNC adapter for my VX-5, and a small coax line to connect the radio and the antenna, and it works out pretty nicely!

    I haven't tried it with 450 ohm ladder-line... not sure what differences in dimensions there would need to be. I only found plans for 300ohm twin-lead... but that is getting harder to find in stores these days.

    Fachento
    KD5VEZ
     
  8. northernontario

    northernontario Well-Known Member

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    One thing to consider... they sort of mention it in the article... is 'velocity factor'.

    You can make a j-pole in free air (nothing around it) and tune it to a perfect 1:1 SWR.

    Now stick that j-pole into a PVC pipe, and it'll throw off the SWF. The PVC has a specific velocity factor that changes how well the antenna radiates. If you do get the opportunity to tune the antenna, make sure it's done with the wire inside the PVC.


    Another example of PVC j-poles..
    http://hometown.aol.com/alonestaryank/selfj.html

    And his version that collapses down, fits inside a larger PVC pipe, and includes a telescoping pole for more antenna height.
    http://hometown.aol.com/alonestaryank/VHFDeploy.html
     
  9. BlueRidgeYJ

    BlueRidgeYJ New Member

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    I'd recommend having a look at the ARRL's big Antenna Book. That thing has an amazing wealth of information about antenna design, proper radiation, etc. If you know a few Hams, ask around and see if you can borrow a copy.
     
  10. fachento

    fachento Member

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    Reference Materials / Books that are worthy of note

    I own a copy of it ... it's being mailed up to me as we speak. It's been pretty useful, and I expect to make better use of it as I'm preparing to upgrade license classes.

    I've got the line-up of books from the ARRL - the 2002 editions, and they've been handy references. The Antenna Book, the Handbook, the Operating Manual,

    I've got several books that my be of interest to Ham Radio operators in the forum:

    Stealth Amateur Radio
    Independent Energy Guide
    ARRL's Low Power Communication


    They've got quite a few projects listed that are downright useful as well! I just wish I had a garage to do projects out of these days. :eek:

    -Fachento
    KD5VEZ
     
  11. N8EPE

    N8EPE Member

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    Field Antenna Handbook

    For anyone wanting a crash course on antennas, especially field portable antennas, propagation, selecting an antenna and frequency for the task at hand. I have not seen a better handbook than this one, and I have ARRL Handbooks and reference materials going back to the 1930s.

    The ARRL is a treasure trove of radio, antenna, and electronic reference materials. Their manuals and books are the 'Bibles' for those subjects, as far as I'm concerned. The only problem with them is they can be so in depth, that they can be intimidating to people trying to get their feet wet and get their arms around a concept and get a foothold.

    The Marine Corps Field Antenna Handbook is a crash course.. a 'just the facts Ma'am' of what works, how it works, how to make it work, when it comes to what comes in and out of that radio, how to get it from the radio to the antenna, and how to do it in the field, under less than ideal conditions.

    The Handbook is free, and it's available as a PDF file that you can save.

    http://www.armymars.net/ArmyMARS/Antennas/Resources/usmc-antenna-hb.pdf

    This is a really good reference to have.

    Doug
     
  12. fachento

    fachento Member

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    Files / Plans / Photos

    I've had a few people contact me in the last few months, asking if I still have plans / photos of what I have been able to do.

    The answer is: YES. I still have the plans, and would be happy to send them out.

    I've actually thought it might be worthwhile to spruce up the visuals on it for another rendition -- I'll publish the final result, when I get around to it, here.

    - Fachento

    KD5VEZ
     
  13. DKRinAK

    DKRinAK As smart as

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  14. LincTex

    LincTex Jack of all trades?

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    This needs to come back to the top :D
     
  15. LincTex

    LincTex Jack of all trades?

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  16. jsriley5

    jsriley5 Well-Known Member

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    I wonder if this anttenae walking stick couldnt be made a bit stronger by using a cut down fiberglass shovel or other tool handle. makes me think about looking to see what kind of fiberglass heavy wall tubes I can find. PVC doen'st like sunlight and it gets brittle in the cold. Just thinking out loud mostly but it may cause a brain storm. I really got to get those lil radioes back out and play with them some more and maybe even get my test studies done so I can actually tx with em :p I"m a terrible procrastinator lately.
     
  17. Shammua

    Shammua No Effort No Rewards, Big Effort Big Rewards

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    Id like a copy of this please.