-=> On 09-25-97  10:27, Jeff Edmonson said to Mark Magill,<=-
-=>"About High Gain Antennas for 14...,"<=-
 
Hi, Jeff;
 
 JE> For that matter, has anyone ever thought of lining up
 JE> several J-poles and mounting them on a mast in a Yagi
 JE> configuration?
 
 MM>         Interesting idea. What do you guess is typical
 MM> gain for a 5/8 J-pole?
 
 JE> 6 or 7db, typically.
 
Compared to what?  Compared to an isotropic, perhaps, but not to any REAL
PHYSICAL antenna.  Compared to a dipole, it's about 3 dB.  Of course, the
antenna manufacturers usually compare their products to an isotropic
because having a gain less than unity, that's the standard which makes
their jun...er... products look the best.   ,-}
 
 JE> Phasing three or more might prove a challenge...
 
Yes, it could prove to be a very interesting challange to get such an
array peaked.
 
 JE> For example, would
 JE> there need to be a shorting bar across the resonant point of the "J"
 JE> connection for the  directors?
 
That's an interesting question.  Perhaps a 50 Ohm resistor?  (Like
terminating a rhombic - the terminating resister has to absorb one half
of the transmitted power, but it's presence controls the directional
characteristics of the antenna.)
 
OTOH, say if you are using 2-element colinear 5/8 wave J-poles in an
array, wouldn't simple 5/8 wave elements, (insulated?), + 5% for
reflectors, and - 5% for directors be effective?  I would think that
complete J-pole assemblies for directors and reflectors would be
unnecessary and wasteful of time and materials.  It would be interesting
to see what kind of insulators would be used between elements if it's a
horizontal array!  (Don't say, "Wooden dowls!")   :-}
 
73 DE KB9QPM
   Ivy
 
 
 
... Can't sleep? Problem. Are you a Ham? NO PROBLEM!!!! CQ-CQ-CQ... ;-{}
 
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