2M/70CM Tape Measure Beam

Discussion in 'Satellite and Space Communications' started by K6LCS, Jan 8, 2012.

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  1. K6LCS

    K6LCS Premium Subscriber QRZ Page

    For those of you who aren't yet ARRL members (or who have lent their January, 2012 issue of QST magazine to someone else), John Portune W6NBC's construction article, "A 2 Meter and 70 CM Portable Tape Measure Beam" is available on the ANTENNAS page at ...

    http://www.work-sat.com

    A "cut above" just using the 2M tape measure beam projects for the 2M/70CM FM birds. A well-researched and clean construction project. Thanks to John for the permission to reprint.

    Clint Bradford, K6LCS
     
  2. W5PFG

    W5PFG Premium Subscriber QRZ Page

    I think the tape measure beams are a nice project and a good introductory antenna but quickly it should become apparent to the user that "there's gotta be a better way."

    Honestly, I started with an Arrow, so I'm a little spoiled. Nevertheless, here are my tape-measure beam observations:
    1. It tends to be even more "sensitive" to polarity and spin of the satellite.
    2. If there is any wind, forget trying to use the antenna. Even 5mph winds can pose a problem.
    3. Using the traditional 2m tape measure beam performs very poorly on SO-50 or receiving any CubeSats with a weak downlink.
    4. On a positive note, these antennas can be folded up nicely for storage.
    5. The ones cut for 70cm are noticeably better than the ones made strictly for 2m.

    I recommended the tape measure beam approach more when we had AO-51 but the other birds tend to be more problematic with it. The ISS works well with it but it's strictly 2m anyway. There are other inexpensive antenna options available with much better performance... The CJU, ioIO, K5OE design, WA5VJB design, etc. are all simple to construct in a matter of hours...(or minutes when you get more experience.)

    If you have difficulty constructing any of these antenna designs there is a multitude of experienced hams out on the Internet who have built, tested, and used them for more than one pass.
     
    Last edited: Jan 9, 2012
  3. K6LCS

    K6LCS Premium Subscriber QRZ Page

    >> ... I think the tape measure beams are a nice project and a good introductory antenna but quickly it should become apparent to the user that "there's gotta be a better way."


    Certainly. But for less than US$20, a person can get into the world of high gain with a tape measure beam attached to their HT ...

    >> ... It tends to be even more "sensitive" to polarity and spin of the satellite ...

    Should not be a "determining factor" whether or not to build one. I have never ( and I NEVER use absolutes) experienced diminished performance during a pass that could be attributed to an FM LEO "spinning." And polarity issues? I have ONLY experienced that phenomenon on the FM LEOs during the end of passes - well after I expected to be able to access them with an HT and a Watt or two ...

    >> ... If there is any wind, forget trying to use the antenna. Even 5mph winds can pose a problem.

    How stiff are your elements ... (grin)

    >> ... Using the traditional 2m tape measure beam performs very poorly on SO-50 or receiving any CubeSats with a weak downlink.

    The traditional 2M tape measure beam - the plans that I offer on my site, a common one - performed remarkably well receiving ARISSat-1, as well as AO-51 and SO-50. Yes, I know the engineers will come back and tell me that a 2M tape measure beam won't work on 440 ... But in the real world, these are still a fun AND useful item to have on hand.

    >> ... The ones cut for 70cm are noticeably better than the ones made strictly for 2m.

    Well, my experience has been the opposite ... (grin)

    >> ... when we had AO-51 but the other birds tend to be more problematic with it ...

    YES - We WERE spoiled, indeed, with the operating characteristics of AO-51: a Watt of downlink was incredibly easy to work!

    >> ... The CJU, ioIO, K5OE design, WA5VJB design, etc. are all simple to construct in a matter of hours ... (or minutes when you get more experience.)

    All good construction projects, indeed. I tend to shy away from projects that exclaim, "Great for the LEOs ... " - but then require a pre-amp to use. I mean, if you can hear a bird well with a simple handheld tape measure beam, how "good" is an alternative that demands a pre-amp to be used (grin)?

    It's a wonderful hobby, indeed!

    Clint K6LCS
     
  4. M3ONL

    M3ONL Ham Member QRZ Page

    I've had nothing but extremely good results using the tape measure beam and also my elements have never collapsed in 5mph winds (breeze)..
     
  5. K6LCS

    K6LCS Premium Subscriber QRZ Page

    Whip out a tape measure beam at a fair or park, and it will ALWAYS stimulate conversations with folks ... a great "ham radio ice breaker."

    But whip out an Elk or Arrow, and you might receive weird looks ... or someone will call law enforcement ... (grin)

    Clint
     
  6. W5PFG

    W5PFG Premium Subscriber QRZ Page

    I always try to be discreet and pick locations that draw the least amount of attention. Somtimes you can't avoid it, such as in urban areas. Last week I was in EL29 and had lunch with a ham there. We stepped outside and worked AO-27 from our vehicles. Luckily we both use small receive-antennas and preamps, so it is not as bad a sticking a 6-7 element UHF yagi out of the car window.

    In the past I have now been stopped/inspected 3 times by US Customs & Border Patrol, questioned by state police twice, and once by a local LEO. Despite best attempts of "covert" satellite use, if you do it enough, you will get caught! :cool:
     
  7. WD9EWK

    WD9EWK Ham Member QRZ Page

    Time will tell if the tape-measure beam attracts the same attention as the other antennas. Law enforcement may be called, just because bystanders and spectators don't know what it is we are doing with these antennas. Some think animal tracking, or we're just talking to aliens.

    I've lost count of the numbers of encounters with law enforcement I have had while working satellites. Mostly for me, it has been with the US Border Patrol when near the USA/Mexico border in Arizona, California, and New Mexico. All are cordial, with some asking if I have any gear that can monitor their radio system (I don't have anything that can receive their digital-voice transmissions). I have spent more time talking about ham radio and satellites to Border Patrol agents than any other agency, and - other than sometimes cutting into a pass in progress - I don't mind it. There are times where I've driven off some state highways here in Arizona to work passes, yet still get visits by state troopers responding to someone's 911 call of a broken-down vehicle off the highway. Go figure.... sometimes, you can't win. Just know it may happen, and be ready to give an impromptu presentation. :)

    73!
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I never understood the allure of tape measure beams. They're not easier to build and certainly not more efficient than other designs, and if you're not constantly adjusting element lengths I see no reason for them to be calibrated.:eek:

    For a quick & dirty antenna that has more gain, covers three bands (just because it was possible), fold up "flat" for transport in about ten seconds, weighs much less than one pound, and will withstand being fully assembled and installed on a vehicle traveling at 75 mph (we've done it -- for hours!), this one is hard to beat: http://commfaculty.fullerton.edu/woverbeck/vhfquad.htm
     
  9. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    Making an antenna from parts many may already have at home, or purchased for not much $$$, may be part of the allure. Being inexpensive is almost always a draw for hams. Using non-rigid elements makes it more forgiving in some moments that might lead to a broken or bent element on an antenna made from something more rigid than this - another good reason. I'm not sure I would try carrying the tape-measure Yagi in a checked bag on a commercial flight, but the flexible elements would remove one big reason why it isn't advisable to carry the Arrow Yagis or Elk log periodics aboard aircraft (an element, especially a broken element, could be considered a weapon).

    It might not be easier to build than other designs, but it is a design that can be built by many at home. I'm sure I could build one of these, and I've never built a tape-measure Yagi of any sort. I don't think anyone has said "homebrew" = "easy to build". There are many hombrew items we could use with our radio gear - or the radios themselves - that would not qualify as "easy to build". At the top of the first page of the article, the antenna is referred to as an "inexpensive portable dual band handheld tape measure Yagi." No reference to the ease of assembly.

    An interesting antenna. Thanks for posting the link. Do you know if anyone has tried that - or some version of that - for satellite work?

    73!
     
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The quad design I referenced can be broken down and folded flat and packed almost anywhere including in a regular sized suitcase. It does this, or re-assembles by reversing the operation, in much less than a minute.

    Sure, I have. It can be mounted using a tilting bracket on a mast, or just extend the boom by 12" or so behind the reflector elements to hand-hold it. It's very light. But an advantage to those who want to operate portable by driving to an operating site is the antenna can be mounted on the roof of a vehicle having roof racks, completely installed and operational (and connected) and it will survive zipping down the freeway at 75 mph, as we have done with exactly that antenna. Several of us, while "roving" for VHF-UHF contest operations. In that case, the antenna is on a mast along with several others that "rotates" while mounted on the vehicle roof, and the rotator can be turned and antennas used while driving.:eek:
     
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