3 or 4 element Yagi for VHF SOTA?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N1RBD, Aug 22, 2019.

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  1. N1RBD

    N1RBD Ham Member QRZ Page

    What are the pros/cons of a 4 element Yagi vs a 3 element, other then the obvious weight difference? Looking at one of the Arrow Antenna 2m Yagis for hiking. 146.520MHz will be used almost exclusively.

    Thanks!
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Probably no difference you'd notice.

    The whole advantage of "SOTA" ops on VHF is they're from mountaintops.:)

    Hundreds of them take place around here, and I work SOTA ops on 146.52 very often -- probably nearly every day, more so on weekends. Some of those ops are 120+ miles away and using a whip antenna (no beam), with a 5W handheld, but they're up 10,000 feet. They hear so many callers that even if they're "S9" here, I have difficulty getting through, or I should say "waiting my turn" while they're working stations 120 miles in the other direction who I cannot hear.
     
  3. W1VT

    W1VT Ham Member QRZ Page

    I built a tiny 2 element Yagi for hiking. 2 elements gives a lot of gain for the weight and bulk. I've done 83 miles with 2M FM and the stock rubber duck antenna.
     
  4. AI3V

    AI3V Ham Member QRZ Page

    The gain of a Yagi-Uda is directly proportional to the boom length, NOT the number of elements.

    https://duckduckgo.com/?q=gain+vs+boomlength+yagi&t=fpas&iax=images&ia=images

    [​IMG]

    For a true line of sight (optical) path there will be no difference.

    It has been my experience that a troposcatter path will see a doubling of range for every 10 db increase in radiated power.

    Rege
     
    Last edited: Aug 23, 2019
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  5. N1RBD

    N1RBD Ham Member QRZ Page

    Thanks for the info. The 3 Element is 37.5". 4 Element is 48"
     
  6. AI3V

    AI3V Ham Member QRZ Page

    Those 2 are so similar it will be hard to even measure the difference.

    Co$t and mechanical construction would be what I would look at.

    Rege

    P.S. the Wife and I hike to summits here in the Pisgah National Forest , last week was "Big Butt"

    https://www.hikingupward.com/PNF/BigButtTrail/

    I was thinking about SOTA when we found the U.S.G.S marker , here's hoping Santa brings me a rig :)
     
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  7. N1RBD

    N1RBD Ham Member QRZ Page

    Cost is the same. Looking at the Arrow 146-3 and 146-4, both with 3 piece boom. The 4 element is 5oz more.

    I want to come up and do Mount Mitchell once it gets just a wee bit cooler. That looks like a great hike!
     
  8. NH7RO

    NH7RO Ham Member QRZ Page

    If I had mountains like that to hike I'd be all over DIYing a super-lightweight fiberglass and wire long boom Yagi---maybe a featherweight version of the two models that that M2 makes for 6m (both 3 el)---the first director is way out in front of the other two elements (giving the most forward gain at the expense of other parameters) and I see no reason not to do something similar for 2m work if you're really into it.

    Just my take on it; it's easy to buy off the shelf and get going but is often more satisfying and educational over the long run by building something on your own,

    Remember, most of us are in this for the long haul, and I don't just mean dx...
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Depends where you start.:)

    There's a paved road to nearly the summit, and the "hike" from the parking lot to the actual summit is only 980' long. Whew.:p

    If you ever get out west, the hike up Mt. San Gorgonio, the highest point in southern California (11,503 feet above sea level), is a bit more strenuous as there's no road. We've done that one three times; when you summit that hill, you're overlooking an area that includes a population of 20 million people and line of sight to all of that, so a SOTA activation there (and they happen about every week!) on 2 meter FM can be real fun. It's "they never stop calling" until your batteries run dry.:D
     
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  10. AI3V

    AI3V Ham Member QRZ Page

    Indeed, from the parking lot to the observation deck on the summit of Mt Mitchell there is a paved asphalt walking path 10 feet wide.

    And a snack stand at the parking lot.

    Now Mt Pisgah, and Big Butt....

    BTW ,on a weekday, when the woods are relatively empty, there is about a 20% chance you will encounter a black bear, Asheville and the surrounding forrest is crawling with them.

    http://www.brnnetwork.org/2018/01/1...lle-urban-suburban-bear-study-on-february-20/

    Rege
     
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