Wideband End-Fed for 75/80 m band? It seems quite feasible…

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by SP3L, Jul 9, 2020.

ad: L-HROutlet
ad: l-rl
ad: Subscribe
ad: L-MFJ
ad: FBNews-1
ad: Left-2
ad: Left-3
  1. SP3L

    SP3L Ham Member QRZ Page

    It seems that you can construct a relatively simple end-fed antenna having awesome bandwidth if only you can spare a little more wire for it than for a classic dipole.

    The drawings below show the antenna model and its dimensions.
    upload_2020-7-9_9-40-47.png
    upload_2020-7-9_9-41-3.png


    The SWR plots when modeled in free space and over the average real ground at various heights:

    upload_2020-7-9_9-41-41.png


    The antenna has the same gain and radiation pattern but has substantially wider bandwidth than a center-fed dipole. Its feed point impedance equals 200 ohms, so it requires a 4:1 balun. Due to 19 m long „counterpoise” (the middle wire between the top and bottom wires) the antenna is partially balanced by itself and I do not expect big problems with the common-mode current flowing on the coax shield as you normally have with classic end-feds. But you should use a current (Guanella) 4:1 balun to minimize the risk.

    The simulator calculated very low Average Gain Test and it means the model is very accurate.

    I can not hang that long antenna in my QTH and the 80 m band is not that wide here in Europe either, so I am not going to spend more time on this design. However, I am attaching the antenna model files in various formats (see the zip file) for those of you who would like to tweak this design further and perhaps build a real thing.

    73
    Jacek
     

    Attached Files:

    N0TZU, AG5DB, KK4NSF and 1 other person like this.
  2. AI3V

    AI3V Ham Member QRZ Page

    Your computer is lying to you.

    In 5 minutes all the "end fedz" shills will be along to sell $200 wires to people who "allways wanted to get into ham"

    Rege
     
    K7JOE, AJ5J and AG5CK like this.
  3. WR2E

    WR2E Ham Member QRZ Page

    Fixed it for ya Rege.
     
    K2XT, K7JOE, AJ5J and 1 other person like this.
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    Jacek,

    Ignore Rege. His rants are motivated by his lack of understanding of antennas and physics. If he cant comprehend it, he tears it down.

    I really enjoyed the articles you recently had published in QST and QEX. Really innovative.
     
    KK4NSF likes this.
  5. KK4NSF

    KK4NSF Ham Member QRZ Page

    that's why I keep him on ignore nowadays.
     
  6. WR2E

    WR2E Ham Member QRZ Page

    I don't. He amuses me.
    [​IMG]
     
    KK4NSF likes this.
  7. WA7ARK

    WA7ARK Ham Member QRZ Page

    Jacek, I ran the .ez file at 15m agl. I tried both a 1:4 and 1:9 balun. The 1:9 makes it look more like a dipole.
     
  8. KK4NSF

    KK4NSF Ham Member QRZ Page

    too bad I don't have a long enough place to put it. It looks interesting
     
    WR2E likes this.
  9. WR2E

    WR2E Ham Member QRZ Page

    Can you post the radiation patterns?
     
  10. K8JD

    K8JD Ham Member QRZ Page

    End fed needs some kind of cunterpoise to work with. Or the coax shileld is part of the antenna.
     

Share This Page

ad: elecraft