Fred,

   I have a double Bazooka for 20, 40 and 80 meters and they work fine! 
There is a formula for them on the coaxial dipole site.  Mine are home made. 
We just cut the Coax a little long for the antenna and that way you can tune 
them by folding the ends back until you get the S W R where you want it. The 
feed line is cut from the same run of coax which helps keep the valocity 
factor the same for the whole antenna.    I have had mine up for going on 5 
years and they are still less than 1 to 2 S W Rs.  The 80 is good  from 4000 
to 3600 with out a tuner.

KF5UB Richard