Building a Portable 20m Vertical Moxon Antenna by K5ACL

Discussion in 'Amateur Radio News' started by K5ACL, Apr 30, 2018.

ad: L-HROutlet
ad: l-rl
ad: Subscribe
ad: L-MFJ
ad: l-assoc
  1. K5ACL

    K5ACL Premium Subscriber QRZ Page

    Greetings hams!

    Back at it with another HF antenna - the experimenting never stops :)

    This time we're constructing a Portable Vertical Moxon Antenna for 20 Meters using simple hardware and some telescopic poles.

    You can find the associated write up here: https://www.k5acl.net/a-vertical-moxon-antenna-for-20-meters/

    This is my first Moxon attempted, I think the results are pretty decent & I can't wait to try it over salt water!

    Thanks for watching,

    73
    K5ACL



    [​IMG]
     
    AA3SO, EA4GWX, NH7RO and 2 others like this.
  2. K3LI

    K3LI Premium Subscriber QRZ Page

    intresting
     
    K5ACL likes this.
  3. KK5JY

    KK5JY Ham Member QRZ Page

    That's very cool. :cool:
     
    K5ACL likes this.
  4. VE2YTQ

    VE2YTQ Ham Member QRZ Page

    Did you check you the VDA design. It should be pretty close in performance and only require one pole (and a smaller cross member) which should make it easier to turn.
     
    K5ACL likes this.
  5. W6LDM

    W6LDM Ham Member QRZ Page

    Very interesting. I have been using a Moxon for 15M for long time and it is a vertical configuration like yours but with only one fishing pole. I had excellent results allover the world operating from a local park battery operated.



    Thank you and 73 de W6LDM
     
    K5ACL and NH7RO like this.
  6. K0PIR

    K0PIR XML Subscriber QRZ Page

    Nice antenna project, and excellent video as always.

    Best 73,
     
    K5ACL and NH7RO like this.
  7. W1YW

    W1YW Ham Member QRZ Page

    The conundrum of center fed vertical dipoles is one that few want to discuss. The fact is the coax is in the near field and (by definition) near the current max. That means, at the very least, it will distort the power pattern, and more likely radiate itself--unless it is at a right angle to vertical, and thus horizontal.

    Your one choke won't stop this.

    45 degrees for the coax orientation is a good rule of thumb, but 90 degrees, at least 1/2 wave away in extent, is better assurance that the power pattern won't distort from the presence of the coax.

    I suspect some of your 'unexpected' results come from the power pattern distortion.

    Vertical Moxons are very popular in Japan, BTW.
     
    K5ACL, NH7RO, KI4AX and 1 other person like this.
  8. KQ6XA

    KQ6XA Ham Member QRZ Page

    In addition to a really good balun at the feedpoint:
    About a dozen #31 mix ferrite beads along the coaxial cable in the near field can help a lot with that problem.
    Using a half-wavelength section of RG-174 makes it lighter weight; the ferrites can be smaller diameter and lighter.
     
    K5ACL, NH7RO, KD8GGN and 1 other person like this.
  9. K5ACL

    K5ACL Premium Subscriber QRZ Page

    Interesting! Thanks for this explanation - that would explain a bit. I'll have to figure out a way to get the coax perpendicular - which would be easy for Field day, just support the coax in a nearby tree, but might be a bit harder at other locations!

    73
     
  10. K5ACL

    K5ACL Premium Subscriber QRZ Page

    RG174 would probably work great! Great idea - I use the same on my SOTABeams link dipole with great success, would definitely alleviate a lot of the weight on the driven element pole! Thx!

    73
     

Share This Page