"Aiming" the dipoles

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N1VAU, Apr 11, 2012.

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  1. K1DNR

    K1DNR Ham Member QRZ Page

    Show me one 24 hour period in the history of radio there wasn't intercontinental propagation at least somewhere between 160m and 10m. In fact a lot of 160m folks live for solar minimums and low indices.

    Maybe there was some massive flare that knocked out radio globally, but generally - even during solar minimums there is global propagation somewhere.

    K is a prediction of atmospheric disturbance, not good propagation.

    Also, the methods of propagation are completely dependent on the frequency and time of day. Signals on 10m do not propagate the same way they propagate on 160m.

    "complications about db's and azimuth patters???" What are you talking about?

    An antenna has a pattern of radiation that is a function of frequency, height above ground, etc -

    We measure and compare the energy in one direction vs another direction using the unit of a decibel.

    The question was in regard to the direction or orientation of the dipole, height above ground and band of operation.

    The answer to his question is in the patterns generated by 4NEC2 over real average ground for a half wave dipole. It is quite accurate for this type of use.

    I also explained that the effect isn't as clear cut as "I can't work South America because my dipole is oriented for Spain".

    The patterns show the radiation off the sides relative to the radiation broadside - which the operator said he was *distressed* over.

    Again, the answer to "distress" and "confusion" is understanding through measurement.
     
    Last edited: Apr 12, 2012
  2. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Anyone here notice that "analytical" starts with "anal." Wonder if that's a coincidence., :)

    Eric
     
  3. K1DNR

    K1DNR Ham Member QRZ Page

    PS - look at my log. No propagation? Really? See the VK on 160? See Cook Island on 17m? That's just the past two days.

    I don't own a tower or a beam. Home brew antennas. One dipole, two verticals, and a receive loop made of hula hoops in my back garden. That's it. I run under a KW, 100W on 30m, 300W on 17m.

    Wouldn't have happened without knowing something about radio science...
     
  4. K1DNR

    K1DNR Ham Member QRZ Page

    I've always know you to be an analytical guy! All those QST articles. Seems the only anal behavior I see is in reaction to analysis! It seems to cause them great pain.

    I wonder what the folks at HAARP would think of that.
     
  5. KM1H

    KM1H Ham Member QRZ Page

    When I had a 40M rotary dipole at 60' many years ago there were often deep nulls off the ends, up to 20dB or so would be a good guesstimate on the fairly accurate 75A4 S meter at that time. No amount of modeling will compensate for varying propagation, polarization tumbling and multipath.

    Carl
     
  6. K1DNR

    K1DNR Ham Member QRZ Page

    Right. The 20m model at 40 feet would be a bit more like your 40m dipole at 60 feet. None the less, you could have still worked stations of the ends. So maybe you hear the guy S7 and our friend with the fixed dipole has to settle for S3. He can still work him.

    He'd work them more often and get better signal reports if he turned the antenna.

    We also haven't mentioned the fact that the *other* guy may be the one with the gain and great receiver that make the qso possible.

    When I first got back into the hobby, I only worked the powerful stations. As I started to build things out I started working more and more guys who were QRP, using dipoles vs beams, etc...

    It takes two...
     
  7. N4JTE

    N4JTE Ham Member QRZ Page

    To sum up; propagation is the overriding factor of what you can hear and where you can be heard, secondly a dipole will show some directionality at 1/2 WL and higher, more like a diminishing of signals off the ends.
    Bob
     
  8. AC0FP

    AC0FP Ham Member QRZ Page

    I agree, I have a 40' high 40 meter dipole with a little bit of inverted V slope. I hear signals from all directions! EZNEC says it is directional (3 dB) but I can't tell from listening.

    fp
     
  9. G3TXQ

    G3TXQ Ham Member QRZ Page

    That's right!

    The difference is that the OP wont be able to influence propagation, but he may have a choice which way the dipole is orientated.

    Steve G3TXQ
     
  10. G3TXQ

    G3TXQ Ham Member QRZ Page

    And the ones that did know something about radio science probably did even better!

    Steve G3TXQ
     
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