thomas.garne...@comcast.net wrote:
> As for the vertical bazooka antenna that you find the formulas for at the web 
> site given, the length for around 120 megahertz would be slightly longer than 
> five feet. It would be to long to install in the vertical stabilizer, without 
> the plastic pipe extending 15 or 16" above the rudder.
>
>   
Calculated correctly at 120MHz using RG-8 (Velocity factor =.66) (from 
the FEED POINT, which is the center of the dipole antenna) the top half 
of the antenna is 62.5 cm long (24.76") and the bottom half (the folded 
back braid which also acts as the balun) is 41.25cm (16.24").

The top half would extend into the vertical stabilizer (easily enough 
room), the bottom half is in the boat. Both sections would fit easily. 
The rest of the measurements in the article are simply how the author 
MOUNTED the antenna and can be disregarded for our purposes, as anything 
below the bottom of the braid is simply transmission line. Therefore, 
anything below the bottom of the braid  can be routed as needed to fit 
the KR2, (just so long as there are no SHARP bends in the transmission 
line). The radius of all bends in the coaxial cable  for routing should 
be approx 5  times the outer diameter of the coaxial cable used  (or 
more) to keep losses to a minimum.
The balun  helps match the antenna to the tcoaxial cable and reduces 
radiation from the cable itself, which improves both transmission AND 
reception.
RG-8 is good for use at VHF frequencies

Cable facts:
RG8 (Beldin 9913) would produce about  a 9% loss in Transmitted and 
Received signal strength at 20 foot length
RG58/u (Beldin 8240) would produce about  a 18% loss in Transmitted and 
Received signal strength at 20 foot length
LMR600 would produce about  a 4.5 % loss in Transmitted and Received 
signal strength at 20 foot length





-- 
Glenn Martin
KR2N1333A
N5PQ
13238 Hudson-Krohn Rd
Biloxi, MS, 39532
rep...@martekmississippi.com

  • KR> Bazooka antenna thomas.garne...@comcast.net
    • KR> Bazooka antenna measurements Glenn Martin

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