Using a Fan or Bowtie Dipole to Cover 75/80 Meters

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W5JD, Jan 7, 2019.

ad: L-HROutlet
ad: l-rl
ad: Left-2
ad: Subscribe
ad: L-MFJ
ad: MessiPaoloni-1
  1. W5JD

    W5JD Ham Member QRZ Page

    What do you think about combining the broadband Bowtie and the matching scheme?

    Side note...I had a Maule M7-235 and my daughter and I have been bow hunting for Mule Deer with relatives in Prescott.
     
  2. W5JD

    W5JD Ham Member QRZ Page

    WA7ARK, does this look familiar?

    [​IMG]

    [​IMG]
     
    K0UO likes this.
  3. WA7ARK

    WA7ARK Ham Member QRZ Page

    The Maule is familar, but what is the green stuff underneath it?

    Was the hunting pix taken looking north-west from somewhere near the Perkinsville Rd loop?
     
  4. W5JD

    W5JD Ham Member QRZ Page

    The Maule is on my 1300 feet Bermuda Grass strip that I built behind my house when I owned the Maule.

    Not sure where we were hunting with our cousins during the hunting picture, but remember something about a mountain nearby that was a sanctuary for panthers.
     
  5. N3DT

    N3DT Ham Member QRZ Page

    I have a standard 80M dipole resonant at about 3600. I use 30 some feet of RG11 or even RG9 TV cable in the shack and add it to the end of my 130' long or so 50Ω feed line. I get under 2:1 across the band and it seems to work just fine. Even the AL80B loves it. I get more power out with the RG11 transformer, but it might be even better to add the RG11 transformer right at the antenna because otherwise it depends on how long your feed line is. It won't work for all lengths if added later. In my case it was sure easier than redesigning/rebuilding the antenna. I think the procedure is in one of the articles mentioned earlier.

    I actually found it by mistake when I started playing around with the SWR trace of my AA600 of the 80M dipole. I just started adding RG11 for fun and whoa, all of a sudden the whole band became low SWR. You can watch the Smith trace rotate around in the AA600 software as you add different types of cable (transformers) and the SWR chart just smoothes out. Of course I had to try it and it did work. Cheap and easy, I like that part.
     
  6. K8JD

    K8JD Ham Member QRZ Page

    I recall, back in the 60's there were some local guys who liked both CW and AM and several had 80 M bow ties up, they were shorter than a halfwave, 55 ft each side comes to mind, depending on the spread angle , you could get below 1.5:1 SWR on 75 and 80 M extremes. The bowtie makes the dipole look fatter and widens out the bandwidth,
    Bow tie antennas for UHF TV had a very wide frequency bandwidth for receiving 500 to 750 MHz !
     
  7. N3DT

    N3DT Ham Member QRZ Page

    I made a half bow tie, or rather a vertical bow tie ground plane on 440 once just for drill. I had to shorten the thing like crazy from the normal 7" but with a 45° vertical section, the thing had some bandwidth. It must have covered 50 MHz or so. I think I still have it around here somewhere.
     
  8. WA7PRC

    WA7PRC Ham Member QRZ Page

    My 4-wire cage inverted vee w/ apex at 70' covers 3.5 - 4.0 MHz no worse than 2:1 VSWR:
    [​IMG]
    I used a FREE design program on smeter.net (http://www.smeter.net/antennas/wire-cage-dipole.php) and initially made it a few feet long, assuming I'd need to prune it. As it turns out, it's good enough as-is, and I don't spend much time in the top of the band anyway; I didn't bother changing the length.

    Later, with about 85' of feedline, I surmised it might function as a vertical w/ top-hat on 160m. I removed the common-mode choke at the apex, and added a SPDT vacuum relay at the bottom end of the feedline. My rig's ATU is able to drive it against several radials.

    Bryan WA7PRC
    http://tinyurl.com/wa7prc-80m-160m
     
    N2EY likes this.
  9. KM1H

    KM1H Ham Member QRZ Page

    The combination of the correct lengths of 50 and 75 Ohm coax as also resurfaced by Mike sounds to be an ideal solution to the bandwidth problem.
    BUT what are the VSWR losses on the coax? Pure Instinct (WAG) says they have to be high but at 80M the losses may be tolerable??? Usually there is no free lunch.

    Ive been using 75 and 80M parallel dipoles since I moved here 30 years ago to cover 3500-3900 at 2:1 or less. Never tried to extend to 4000 since nothing of interest is up there even tho the amp loads fine:D With them at almost 90 degrees apart the radiation pattern appears to show no substantial nulls as they have worked over 350 DXCC and all 40 Zones plus contributed well to the DX and WPX contest scores which included several #1 USA.

    Ive mentioned several times on here over the years that I had a 80M cage vertical at a prior home in the 80's and cant imagine using one as a dipole here unless it was down under the trees and out of the high winds. What an unwieldy monster it would be even in a snow storm much less an ice load!!:eek: No thanks!

    Carl
     
  10. K5VWZ

    K5VWZ Ham Member QRZ Page

    You might look at a cage dipole, mine covers 75/80 with out a tuner.
     

Share This Page