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
