[Towertalk] 40M Dipoles (Was: Need EZNEC model 402CD..)

[n4kg@juno.com]

Note that Bill's model shows a simple (full size) 40M Dipole
at 1/2 WL (70 ft high) is 2.3 dB stronger than a 4 Square,
providing further support to the notion that a 40M rotary
dipole is a good, simple, and competitive antenna alternative.

A loaded dipole will come very close to a full size dipole in
gain with reduced SWR bandwidth.  Matching the BOOM of a 
tribander or 20M beam is another good alternative for either 30M
or 40M, assuming the end elements are attached to the boom to 
provide capacitive end loading.

Tom  N4KG

On Tue, 09 Jul 2002 14:15:02 -0400 Bill Tippett <btippett@alum.mit.edu>
writes:
>         Here's a quick look using EZNEC models I had on hand, 
> all assuming EZNEC high-accuracy "Good" ground (0.005, 13):
> 
>                                      dBi  @ peak TOA
> 4-square (EZNEC's 4square.ez)        5.34 @ 25 deg
> 4-square (EZNEC's 4sqtl.ez)          5.29 @ 25 deg
> Dipole @ .5 wl                       7.63 @ 27 deg
> 2 el Yagi 16' boom @ .5 wl          11.56 @ 26 deg (+6.2 dB over 
> 4SQ)
> 
> The 16' boom model happens to be the only 40M 2 element I had but it 
> 
> should be a reasonable comparison to the 40-2CD (23' boom should 
> give 
> higher gain but probably +0.5 dB loss due to loaded elements).  The 
> above gains for the dipole and Yagi would drop at lower heights and 
> I 
> would not personally not use them at less than .5 wavelengths.
> 
>         The above is essentially what I posted previously so my
> memory did not completely fail me:
> 
>         "This should be no surprise.  Even a dipole up 1/2 
> wavelength
> will beat a 4-square.  I recall a dipole's gain is in the order of 
> 2-3 
> dB over a 4-square for equivalent grounds.  Add another 4-5 dBd for 
> a 
> 2 element Yagi and you are around 6-8 dB over a 4-square.  The only 
> place a 4-square can realistically compete with a Yagi is if you are
> over salt water."
> 
>                                                 73,  Bill  W4ZV
> 
> 
> 
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