Where to Feed 75-Meter Vertical Open Loop

Discussion in 'Technical' started by W5HRO, Jun 7, 2014.

  1. W5HRO

    W5HRO Administrator

    The antenna below is what I'm considering putting up soon, but the question is where's the best place to feed it for use on 75-meters?

    Bottom corner like in the pic below or in the top corner above that?

    80_Meter_Vertical_Loop.png
     
  2. KF7JAF

    KF7JAF Member

    I'd feed it where the open wire line has the clearest shot back to the shack, that is, away from other objects. I know in a square or round loop the feedpoint affects the polarization, whether it's vertical or horizontal, I'm thinking it won't matter in this case because you're rectangle is mostly horizontal.
     
  3. W5HRO

    W5HRO Administrator

    It probably wont that much on 75-meters, but it may when used on the higher bands. I probably should have worded my question differently.

    The bottom corner in the pic will give me the OWL length that I need which is an 1/8 wavelength on 75. The top corner will probably be ok too. The question is which corner, bottom or top? I'm mainly concerned with 40 and 15-meters and could care less about 20 meters.

    I think I need to make the vertical sections 11' instead of 12' though. Bellow is an update.

    75-Meter_Vertical_Open_Loop_1.png
     
  4. W5HRO

    W5HRO Administrator

    I ordered a 40' Rohn push-up mast yesterday to support the other side of my new antenna. The problem is if I put up this loop the bottom part is only going to be a couple of feet from the roof.

    I'm still not sure this antenna is what I want, but whatever I do put up will only be about 30' to 40' up in the air. That's about the only thing I can do right now so it is what it is.
     
  5. W5HRO

    W5HRO Administrator

    I've decided to just put up a 1/2-wave 75-meter dipole fed with coax. I still have the 100' of RG8-X with the hefty radio works B1-5K+ 1:1 balun I bought over a year ago and never used. I'm just going to put it up as high as I can and work 75 and 10-meters this winter. I still have the 3-element 10-meter mono band Yagi on the tower. Seems like 75-meter AM here in California is really hot right now. The other bands can just wait until next year.

    balun&coax.jpg