[TowerTalk] quad vs. yagi @ low height

[David Robbins]

the answer is... it depends on your definition of 'height'.  now,
i don't mean to sound like a clinton answer, but here is the problem
and what i have seen after lots of modeling.

if the top of the loops are at the same height as the peak of the 
inverted v elements the inverted v beam is better.  if the loops are
around a boom such that the boom is at the same height as the top
of the loops (and therefor 1/2 of the loops is higher than the 
inverted v elements) the loop beam will be better.

note, this is for top heights generally 1/2-3/4 wavelength or below 
using real ground.  and feeding the loops for horizontal polarization.
results may vary as you get the tops much higher as the bottom part 
of the loops may start contributing more to the pattern.  most of my
models were to determine if it was worth putting the bottom half of
the loop on an 80m inverted v beam with the tops of the loops, and the
tops of the v's at 150'.... it isn't.  not only would i lose gain 
(just fractions of a db), but it makes construction much harder as 
it would require another rope, twice the wire to accumulate ice, and
fishing the bottom wire around guy wires and lower yagis.


zeitler@ibm.net wrote:
> 
> Esteemed Reflectees,
> 
> (I know this is not topband specific topic but I know it's readers are well
> versed in antenna theory hence the addition of them to this email)
> 
> I am going to put a fixed wire "beam" so I can have a more regualr schedule
> with my father, KA3IFO in Erie, PA, on 17 meter phone. My question is what
> do you all think will work better:
> 
> 1. A fixed wire yagi around 10-15 feet above the roof (actually an inverted
> vee yagi).
> 
> 2. A fixed wire quad at around the same height (actually a delta loop
> array).
> 
> I have plenty of room length wise to add up to say 7, 8 or 9 elements on a
> long boom (rope boom).
> 
> I do not want to make it so sharp that I can't get into the southern states
> or some parts of Canada. I will be firing the beam from San Diego.
> 
> Maybe make it bi-directional with a common reflector? Switch in different
> driven elements and sets of reflectors??
> 
> Comments and opinions most welcome. I prefer to stay away from a phased
> array at this time.
> 
> Topbanders thank you for the read.
> 
> Lane
> KM3G
> 
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-- 
David Robbins K1TTT (ex KY1H)
k1ttt@berkshire.net   or   robbins@berkshire.net
http://www.berkshire.net/~robbins/k1ttt.html

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