[Antennaware] Antennaware Digest, Vol 74, Issue 7

Sun Feb 28 12:06:07 PST 2010

Moxon 40m to low, 6.8 kHz?
Try simulate with in calculated s.c. "Skin eff"; 
Look at Moxonantennaproject some of my 40m Mox files. For copper in PVC wire need calculate resonance on 7.240 for 7.050 on mast in any program.  
  ----- Original Message ----- 
  From: antennaware-request at contesting.com 
  To: antennaware at contesting.com 
  Sent: Sunday, February 28, 2010 9:00 PM
  Subject: Antennaware Digest, Vol 74, Issue 7

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  Today's Topics:

     1. Simulating the W6NL 40M moxon variant (knormoyle at surfnetusa.com)
     2. Ideas on how to mount 6 M j-pole? (Shon Edwards)

  ----------------------------------------------------------------------

  Message: 1
  Date: Thu, 25 Feb 2010 13:51:59 -0800
  From: "knormoyle at surfnetusa.com" <knormoyle at surfnetusa.com>
  Subject: [Antennaware] Simulating the W6NL 40M moxon variant
  To: antennaware at contesting.com
  Message-ID:
  <f208740f4c1f41d7918cfbc536cef498.knormoyle at surfnetusa.com>
  Content-Type: text/plain; charset=utf-8

  My problem: I'm working on a simulation for a M2 40M2L (shorty-forty, linear 
  loading) conversion to a moxon. I'm using the W6NL 40M moxon-like design as a 
  benchmark for SWR bw, and gain/fb. (trying to get similar results, but not the 
  same design)

  W6NL provided an AO .ant file so his can be easily simulated.

  here:
  http://www.kkn.net/dayton2004/
  (3 links there)

  I use 4nec2x, so I used it to convert the .ant to a .nec. There were some minor 
  issues that I hand-corrected. (for instance, using ' in a symbol name in the 
  ant)

  The simulation of the W6NL moxon looks good in 4nec2x. The visual is right for 
  the antenna, the gain/fb and swr bandwidth is right (very wide swr bandwidth).

  BUT: the swr min is centered too low I think..it's around 6.8Mhz..I would have 
  expected it to be centered around 7.05 or 7.1, based on W6NL's presentation 
  curves.

  I experimented a little. I played with different grounds. The simulation is at 
  70 ft. The taper schedule is done with explicit wires of different radiuses, but 
  it seems fine.

  I'd be surprised if nec-2 is simulating this wrong, compared to AO...

  So I'm assuming something is just wrong, but I can't figure out what.
  It's like it's shifted down in frequency for some reason. 

  If there was someone out there would could run the .ANT file exactly as W6NL 
  posted it above, and say what freq they see for a SWR min, that would be really 
  useful for me? I also could put my converted .nec somewhere if there was some 
  other simulator that could use the .nec? (or people can recommend something I 
  could use without retyping in a model?)

  I'm a little worried, because I have the design for my 40M2L conversion done, 
  and I think it's pretty good (got the wide bw I wanted).  nNot that much less 
  than the W6NL, but has just the typical moxon look (less aluminum) and on a 
  shorter boom (19-1/2') feet....But now I'm wondering if that simulation is 
  accurate..

  I don't know if there are other simulators that could use the .nec, but I could 
  provide that also (both the W6NL and mine) if anyone was interested in seeing 
  what they get for me.

  thoughts?

  thanks
  kevin
  AD6Z

  ------------------------------

  Message: 2
  Date: Sat, 27 Feb 2010 11:04:18 -0700
  From: Shon Edwards <sre.1966 at gmail.com>
  Subject: [Antennaware] Ideas on how to mount 6 M j-pole?
  To: antennaware at contesting.com
  Message-ID:
  <74b45fe11002271004j48a5afc1r33a9ccd760f831a5 at mail.gmail.com>
  Content-Type: text/plain; charset=UTF-8

  Does anyone have any ideas on how to mount a j-pole on the edge of a roof,
  which is for the 6-m band?  It is absolutely huge (somewhere between 13 and
  14 feet high, I believe).  The wind seems to be able to move it around more
  than I thought it would before getting the antenna.

  Very nice antenna, though, for a j-pole (dipole), and with it on the ground
  have been able to hit repeaters as far away as 50 miles with mountains
  inbetween.  (That knife-edge has always been wonderful to me.  To digress a
  moment, I was able once to talk with my wife on simplex 30 miles apart, with
  each of us on opposite sides of a 11,000 foot high mountain, with full
  quieting.)

  Thanks in advance,

  73 de Shon, KO3U

  -- 
  Shon R. Edwards,
  Amateur Call:  KO3U
  Commercial radio licenses:
  GROL:  PG00016801
  GMDSS/O/M:  DB00000391
  GMRS:  WQKW341
  2nd class radiotelephone:  T2GB064388
  Accredited VE:  W5YI, ARRL
  ARRL Instructor
  1039 N 2575 W
  Layton, UT, 84041-7709
  USA
  e-mail:  sre.1966 at gmail.com
  phone:  (801) 444-3445
  cell:  (801) 336-7635

  ------------------------------

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  End of Antennaware Digest, Vol 74, Issue 7
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