Tom, W8JI, makes a good point about directivity for receiving.
I often listen on my Beverages on 40M rather than the beam or
Delta Loop because the Beverage is quieter. When running
weak Europeans, it is a toss up between having enough signal
to copy the guys with incredibly poor antennas and being able
to copy the signal through the noise. I guess phased Beverages
is the next step for the SERIOUS contester who wants to hear
those puny signals that are 40 db or more below the average
100W and dipole guys. Fortunately, there are enough DX
stations with moderately good antenna systems to allow DXers
to work all the active countries on 40M using modest antenna
systems.
Tom N4KG
On Tue, 13 Nov 2001 09:39:42 -0500 "Tom Rauch" <w8ji@akorn.net> writes:
>
> > Since I'm planning an antenna installation I did some modeling of
> a
> > Cushcraft D-40 (half a 402CD) at 60 feet over poor ground (Diel
> Const
> > = 10, Cond = 2 ... sandy Florida soil) vs a four square with 60
> on/in
> > ground radials per element. The loaded dipole was about 2 dB
> better
> > (at the same take off angle) than the four square (and a full size
> > dipole would have been even better).
> >
> > The difference is enough for me to decide the four square isn't
> worth
> > the effort on 40. One of the common loaded/shortened two element
> > yagis looks the winner unless one is on an ocean beach.
>
> Assuming the model is reliable, that is true for transmitting. I
> tend
> to believe that would be true in many cases on 40 meters and
> above, but not on 80 meters and lower where it seems modelling
> programs I have tried over-estimate Fresnel zone losses (at least in
>
> every case I have tried).
>
> For receiving at HF, it is only *directivity* that matters. The four
>
> square will likely be much better for receiving, and that alone may
> make it worth while!
>
> It is common but very incorrect folklore that "gain helps" on
> receiving. You see that in magazine articles, like those that say a
> 5dB gain antenna improves receive 5 dB. That is not true.
>
> Directivity is important thing...not gain. An antenna that is -20 dB
>
> gain can have 15 dB of directivity, and be better for receiving than
> a
> 5dB gain antenna.
> 73, Tom W8JI
> W8JI@contesting.com
>
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