Hi Jon,
In a message dated 96-03-19 14:27:59 EST, you write:
>Hi Tom....when are you going to publish your phased-loop setup so we can all
>hear as well as you (OK, then it wouldn't be your secret weapon!)
Well someone has offered to help, so I need to send my file to him like I
promised, hi.
>>>A 3 or 4-wavelength beverage (1800-2400 feet on 160) gives you a low
SNIP
>>I wonder if that data is from NEC models?
>Yes
SNIP
NEC does not agree with real world currents in antennas I've actually
*measured*. If the current is "off", so are calculated patterns.
I don't have UN's book, but Roy Lewallen modeled one of my Beverages on
NEC-4. The current calculated by NEC had significantly LESS taper than the
real world antenna. Incorrect losses would cause an error making the longer
Beverage model much better than a real world antenna would actually work.
To verify accuracy, I'd be sure the currrent distribution and loss in the
model matched the current distribution and loss in my real world antenna.
That's a simple and relatively failproof test of the model.
Personally, I do not trust NEC-2 or 4 when modeling low horizontal wires
(including elevated radials). NEC seems to estmate less loss than actually
occurs in real world systems.
>>What did Wild Willy notice?
>Sometimes signals were better on the shorter wires. (I've found similar
>differences between a 700-ft beverage 10 ft high and a "shortie" 136-ft
>wire 1 ft high, which models with a higher-angle lobe).>
In Cleveland Ohio I had 500 ft and 1000 ft Beverages on Eu in an empty flat
field a mile from the house and TX antennas. Only on very rare occasions was
the longer wire better, and only then for very short periods of time. I
attributed that to space diversity fading, rather than wave angle. But who
knows for sure? Anyway, at the end of a 1000 ft Beverage the remaining
current was only ~20% of the feedpoint current!
>>Ernie, K1PBW all but abandoned Beverages when he had TWO verticals phased.
>>He said they were much better than the Beverage. SNIP
>Interesting...my recollection was he missed the bevs when he was at a BC
>station using two towers in phase in Western Mass. (and used them regularly
>when he had his own place with the two phased towers, until someone stole
>all his radials for scrap!) But while he was saying this he was running
>Europeans that I couldn't tell were there, and I was using a 300-400 ft
>beverage in Connecticut, so maybe the reality was the 2-el was that much
>better!
I'm sure of my comment, because Ernie and I were good friends and discussed
antennas quite often at great length. Ernie did install at least one
temporary Beverage at the BC location, and told me he NEVER found the
Beverage better than the phased towers.
> I know more recently K1ZM Jeff has commented that his 4-square
>outhears the beverages regularly because of the better f/b ratio.
I believe that! Beverages and other long wire arrays have very poor directive
gain when compared to a two element end fire arrays, even if the Beverage's
current taper (from ground losses) isn't included in the model! The four
square should be better, unless it's near a noise source!
But Beverages are cheap and very easy to install, not everyone has phased
antennas or very high dipoles. They are very good antennas for the effort
required.
73 Tom
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