*** Quoting Alex Draper to All dated 11-09-96 ***
>   I've been looking at different antenna installations and noticed most
> are this design.  My question is why?  Does the mast being so must
> higher act like a lightning rod?  If so, could this design help protect
> my radios during a lightning storm?
>                                          Alex...
> # <-- mast
> #
> #     _
> #    ( )
> #####I I <-- folded dipole
> #    (_)
> #     _
> #    ( )
> #####I I <-- folded dipole
> #    (_)
The mast is part of the support for the dipoles....also in the arrangement 
you showed, the mast is being used a reflector with both dipoles pointing the 
same direction...this adds 3db to the signal....SO the gain of the above 
antenna would be 6db IN the DIRECTION of the dipoles and 0 at the sides and 
-3 off the back side....
4 dipoles are placed around the mast at 90degree placements to give a 
circular pattern of 6db..
The mast DOES provide lightning protection to the antenna dipoles since it is 
taller....and of coruse it is used to support them as well...so it has 3 
functions overall..
Now, as for protecting your scanner, maybe...maybe not...the COAX connector 
on the dipole array you drew could be blown apart at the next lightning shot 
IF the mast is NOT grounded well enough to act as the better path to earth 
ground for the strike...I have seen this before on antennas mounted on 500ft 
towers where the coax was the better path because the mount or tower had 
paint on it and was therefore a higher resistance to ground path than the 
coax was..
BEST bet to protect your radio during lightning?? UNPLUG THE COAX and power 
cord!
There is NO 100% safe way with it connected to the outside world!
73
Chris
WB5ITT
--- T.A.G. 2.7c Standard
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