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Optimum 6 Meter yagi height for Sporadic E

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WS4B, May 5, 2012.

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  1. WS4B

    WS4B Ham Member QRZ Page

    E-season will be here in just a few short weeks and I have made a decision to get on six this summer and try my hand at this band. I am thinking of getting a five element yagi and spending most of my time at or near 50.400. Since my intention is for e-skip, is 15 feet above ground the best height for a yagi of this size? I am looking at a boom length around 20 feet. Since I live in an HOA development with antenna restrictions, the weight of the antenna I can just put on a telescoping pole w/o a rotator at 12 pounds. Any suggestions on the best height of the antenna would be appreciated, knowing that on six meters the signal may be there one moment and gone the next! (No old buzzard transmissions I guess)
     
  2. KM1H

    KM1H Subscriber QRZ Page

    Low for close in E and high for long and double hop. Aurora is mostly high angle.

    At one time and mainly for contesting I had antennas at 20, 60, 100 and 190'. All had their good moments. Currently just have one at 60' but a quad of LFA 5 el at 190' is in the works.

    Carl
     
  3. KO6WB

    KO6WB Premium Subscriber QRZ Page

    Having the antenna that low is okay for sporadic E. Having it higher wouldn't hurt and for any terrestrial type of work it's an absolute necessity. You will still be able to make contacts though just not very far or very strong. That is if you are not living on the top of a hill.
    As Carl has already pointed out the incoming signals can vary widely on the angle of propagation. Contest operators know this and usually have antennas at different heights. The higher antenna isn't always the one with the best signal.
    The best thing to do is to put the antenna up and use it.
    73
    Gary
     
  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I'd say often "really high" for 2x and 3x hop Es.

    Best demonstration I ever saw of that was in 1987 during the June VHF QSO Party, when as a multiop group we ran WB2WIK/4 from FM27 off the coast of VA. The 6m antennas were on a crank-up tower on a tower trailer, so could go from about 25' above ground to about 75' above ground in just a minute or two

    The close-in single hop was all pretty easy with the tower nested. But when the band opened for double-hop, and then later triple-hop (we worked from VA to Alaska and Hawaii, both, via 3x Es), we could hear absolutely nothing of those stations -- not even 1 dB over the noise -- with the antennas nested. Cranking them up all the way, those signals became S9. Cranking it back down, they completely disappeared. What a graphic demonstration of height vs. angle.

    We had absolutely no obstructions in any directions, operating from an island at the beach. Nearest "hill" was probably 50 miles away.
     
  5. KM1H

    KM1H Subscriber QRZ Page

    More likely double hop E linked to F2 which is rather common for those paths at the bottom of the cycle.

    I remember during the sun peak year of 1991 I had a 6 el at 60' and another on a different tower at 170' (that tower was later extended 20'). During a F2 opening I could hear loud West Coast stations calling HI but couldnt hear them on the 60'. Switched to the 170' and the HI was loud and the West Coast was down around S2 and there was a KL7 in there also calling. Sort of created a mini uproar when the KH6 answered me on one call and the KL7 broke in to ask if I could have the KH6 listen for him. All 3 of us than chatted for a bit commenting on the strangeness of this 3 way which gave me my last 2 states and 2 new countries and I was the first NH for both. Nobody else in the area was hearing either one including other hilltoppers with 50-80' high antennas. After that I worked 3 more HI and the locals were listening and giving me a ribbing so I put the receive audio on the 2M repeater that we used for DX alerts.

    Carl
     
  6. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I know what that's like. I've operated from Mt. Pinos (el. 8831' asl and about 3000' above average terrain) working long strings of JAs on six when all the locals came on nearby repeaters to talk about me making it all up. I had to play the audio back to convince them, nobody else was hearing anything.

    In 1979 from Mt. Pinos, using N6NB's mobile station (a kW and 5L beam on a 30' crank-up on the back of his van) I made AJD (workd All Japan Districts) in two hours, and got an award from them saying I was the first U.S. station to make 50 MHz AJD.
     
  7. KM1H

    KM1H Subscriber QRZ Page

    My hilltop property is at 650' ASL but it drops to the 150-250' area in under a mile in most directions which results in lots of ground gain. The new array will give me a chance to try some EME aimed at the negative horizon which will give me several more degrees of moon time.
     
  8. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    That should be fun. Differences in terrain are really something. 650' asl here would be 200' below my patio.:eek:

    And I'm in the city!

    Of course unfortunately there are also hills 'round here that go to 11,499' asl. All in southern CA, before even heading north where they get a lot higher.
     
  9. WS4B

    WS4B Ham Member QRZ Page

    Thank you everyone for the replies. I guess height depends on type of propagation. With single hop e-Skip being the most "common", I guess I will go with a 15-20' antenna height. Again I cannot erect an actual tower due to my HOA antenna restrictions. I am hopeful that a 5 element at that height will produce good single hop results. Since I will be spending most of my time looking for AM QSOs on 50.400, I would rather have the single hop opportunities that may have a longer proprogation duration than those of multi-hop which have a smaller condx window. Thanks again everyone.
     
  10. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    That should be fun. Differences in terrain are really something. 650' asl here would be 200' below my patio.:eek:

    And I'm in the city!

    Of course unfortunately there are also hills 'round here that go to 11,499' asl. All in southern CA, before even heading north where they get a lot higher.
     
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