Author Topic: The BIG STICK , Half wave , 2 Meter antenna  (Read 12082 times)

Offline Carl

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The BIG STICK , Half wave , 2 Meter antenna
« on: August 31, 2010, 04:51:42 PM »
This is an antenna that I have made about 50 of ,for local Hams. It is easy to build ,but really should be double-checked for good SWR with an SWR meter or analyzer as proper tuning can be less than 1/8" of a measurement away. If you read my directions,it is hard to go wrong,the photos show the building of one with a bit of ladder line and some hook-up wire . I suggest Mini 8 coax , but most any coax will do . Test runs show about 16 mile range between two antennas with 2 hand held radios at low power ,about 1 watt each with the antennas about 30 feet up a tree ,hung by rope. Getting your antenna to a high point is the secret to talking distance with VHF radios, or UHF also ...This antenna does work well in the 440-450 mhz range ,though it is best as a 2 meter antenna. I can give cut lengths for other VHF frequencies as MURs ,Marine,Aviation as I have provided this antenna for some local agencies. Enough ,here is the link to the DOC file.    http://www.mediafire.com/file/49i4vvod3lyxivv/The%20BIG%20STICK.doc

http://www.mediafire.com/file/49i4vvod3lyxivv/The%20BIG%20STICK.doc

Not real good at this,Hope one of the methods was right.

Offline Mr. Bill

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #1 on: March 03, 2011, 08:49:59 AM »
A belated thanks for posting that, Carl.  Nice write-up.

[moderator]
Summary of the two snarky posts I just deleted:
  • The file is on a free hosting site that has a lot of pop-up ads.
  • Recent browsers have pop-up blockers that can be set to avoid most pop-ups.
[/moderator]

Offline Carl

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #2 on: April 28, 2017, 12:47:37 PM »
  I finally got around to editing the Big Stick instructions to make it less confusing and easier to deal with,also included measurements for a non-PVC roll-up version for you people who want one for your travel or GO kits.

https://drive.google.com/file/d/0B5ZIZLZV4AwIdVdqaTh2cFMyOTg/view?usp=sharing

Offline Alan Georges

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #3 on: April 28, 2017, 06:29:08 PM »
Carl, thanks for posting and then updating this.  I'd built something similar a while back out of 1/2" cpvc and 300ohm twin lead, but it has turned out not to be sufficiently rugged for trail use.  The 1/2" pipe is too floppy and 300ohm is downright fragile.  1" shed 40 & 450ohm are much more robust.  Rainy weekend in store... might get this one knocked out in record time.

Offline Carl

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #4 on: April 29, 2017, 02:00:45 AM »
Carl, thanks for posting and then updating this.  I'd built something similar a while back out of 1/2" cpvc and 300ohm twin lead, but it has turned out not to be sufficiently rugged for trail use.  The 1/2" pipe is too floppy and 300ohm is downright fragile.  1" shed 40 & 450ohm are much more robust.  Rainy weekend in store... might get this one knocked out in record time.

  I started the earliest test versions of this antenna with 300 ohm TV twin lead and 1/2" sched 40 PVC but they also were difficult to work with and got 'floppy' in the sun and weather,just not tough enough.

  I have some Big Sticks in the air for over 8 years now ,one I made special due to the cost of a commercial antenna for Civil Air Patrol being so high and it proved to be the first antenna that CAP was able to communicate with our international airport here in Shreveport.I have run in excess of 500 watts VHF through a Big Stick with only slight discoloration of the PVC after several months...I did this for a TEST...as I don't use an amplifier on FM...only for SSB.

  I will post a roll-up version of the Big Stick soon as dimensions are slightly different.(58" and 17 1/2" were the final dimensions, If you want an early start on one)

Offline Carl

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #5 on: April 29, 2017, 06:54:32 AM »
MURS/GMRS Big Stick now available,the rough tough antenna is now available for non-Hams.Great as a SCANNER ANTENNA too!

http://thesurvivalpodcast.com/forum/index.php?topic=60317.msg715627#msg715627

Offline Carl

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #6 on: April 30, 2017, 08:32:35 AM »
So much for having made 50 of them ,my log shows 174 made now and Jeff is headed this way to make some more today.

Offline FreeLancer

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #7 on: April 30, 2017, 05:47:25 PM »
[Moderator Note:  iam4liberty's HF antenna post has been split off into its own thread]

http://thesurvivalpodcast.com/forum/index.php?topic=60330.0

Offline Carl

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #8 on: April 30, 2017, 06:22:15 PM »
Jeff,my new Minion (or student) can by today and build TWO Big Stick antennas with one a special needs antenna as we put a large eye bolt on the top and included a length of 550 Para-cord to hang the antenna with about 25 feet of knotted every 5 feet paracord extending below the antenna to provide support for the coax to avoid damage from flexing and weight stretching the cable. Taking advantage of his surroundings and a tall tree,Jeff can now talk on VHF and UHF from an area so far out that even mobile radios with high power fail as HEIGHT IS ALL IMPORTANT for using VHF/UHF at distance as he and I talked from 'no man's land' with him now only needing FIVE WATTS.

1  Height is very important for range
2  Support you coax
3   Use high quality coax or feed line as it improves your signal at low cost
4  Carry a Big Stick

Offline backwoods_engineer

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #9 on: May 29, 2017, 08:19:52 PM »
Thanks for this, Carl.  I just posted the Big Stick instructions on our Montgomery (AL) Amateur Radio Club Facebook page.  It's getting good feedback as we speak.  I'm gonna build one for the BOL, I think.

Offline Alan Georges

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #10 on: May 29, 2017, 08:32:13 PM »
Rainy weekend in store... might get this one knocked out in record time.
Finally finished it today, a month after my optimistic estimate.  So much for "record time."  ::)

Minor modifications... instead of 1" Sched 40, I went with 3/4" SDR 21.  It has a thinner wall, and 450 ohm window line just fits inside.  Makes for a lighter antenna that's less suited for base applications, more suited to hiking, etc.  Not "better," just "different application."

Naturally this difference in PVC wall thickness changed up all of the dimensions.  Freely adapting Carl's numbers and cross-checking with several online j-pole dimension calculators, after tuning the final numbers are:
450 ohm line length: 17.3"
feed line tap (from end of 450 ohm line): 2.2"
total length: 54.3" (+1" extra to turn over at the end)

There's maybe 4' of extra PVC below the window line section.  I cut off about 2' from the original 10' length to make it a less unwieldy, less floppy.  The length's not critical, but whatever you're planning on attaching it to, leave enough PVC below the ladder line section so things don't interfere.  Especially if you're attaching it to any kind of metal pole, frame, etc.

Used 12 gauge wire because it's what I had on hand.  It's definitely overkill.  Instead of Carl's crimped-on lug at the end, I turned over 1" of the end and zip-tied it down with a piece of bank line in the crook; the bank line slips under the PVC cap and holds things up.  If you have an antenna analyzer, cut it about 3" long and trim back to tune; otherwise, just go with the numbers above.  Didn't cinch down the zip-tie until everything was tuned up.  The coax just hangs out the bottom, then it's looped back up and zip-tied on the outside to give strain relief.

SWR is < 2:1 from 144 to 151 MHz, bottoming out at 1.2 around 147-148 MHz.  Frankly, I cut it about 1" too short, but this is good enough.  What can I say, storm was closing in and I was in a hurry.

Carl, much thanks for the inspiration and for the original design.

Offline Carl

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #11 on: May 30, 2017, 05:40:27 AM »
  Thanks Alan for the report,The antenna is consistent (in 1" schedule 40 PVC)and 52 " overall length with 17 and 3/8" on the short leg. It is the same ratio I use now for an HF antenna of 51 feet and 17 feet with a 4 to 1 balun as feed point to aide matching.Your choice of lighter/smaller PVC and the need to alter wire lengths illustrates how the PVC pipe actually is part of the radiator and conducts at RF frequencies.

  Good work as many may prefer a thinner lighter antenna. I used a pull up whip for a camper version and only PVC long enough to contain the matcher and support the whip...about 30 inches long...tied to a pack frame,and great results. A good SWR meter of ANALYZER is really needed
when deviating from the original....Great work.

Offline Alan Georges

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #12 on: May 30, 2017, 06:46:16 AM »
Thanks Carl.  Yeah, it's plausible that the numbers for thinner PVC should fall somewhere between those for thick Sched 40 pipe and for no pipe at all.  I'm sure these final dimensions could be iterated down to give a slightly better SWR, but this is backyard engineering and the current result is good.

Other projects await – not all of them radio-related.  For one thing, opening day of hurricane season is this week and I still haven't picked up my license.

Offline Carl

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #13 on: May 30, 2017, 11:14:16 AM »
Thanks Carl.  Yeah, it's plausible that the numbers for thinner PVC should fall somewhere between those for thick Sched 40 pipe and for no pipe at all.  I'm sure these final dimensions could be iterated down to give a slightly better SWR, but this is backyard engineering and the current result is good.

Other projects await – not all of them radio-related.  For one thing, opening day of hurricane season is this week and I still haven't picked up my license.

It's been so long ago that I forget how to dress out one of them Hurricanes.

Offline Alan Georges

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Re: The BIG STICK , Half wave , 2 Meter antenna
« Reply #14 on: May 30, 2017, 05:27:21 PM »
It's been so long ago that I forget how to dress out one of them Hurricanes.
;D