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Antennas / Re: Double Bazooka antenna plans
« Last post by K3DAV on July 13, 2013, 09:57:40 PM »I have built several Bazooka antennas in my past, and I have to honestly say that every one I built out performed the basic wire dipole it replaced. A lot of how they perform depends on the materials used in the construction. ie type of coax, type of wire used for the tails, and even down to the kind of solder used on the connections. And one big mistake that many guys make when building a Bazooka is the exact measurements on each side of the feedpoint.
Too many times, guys just do a rough measurement and one side turns out to be a few inches longer than the other. They do the same with the tails when trimming for SWR. This makes it impossible to get a good low SWR across the band. You have to make the measurements exactly the same on each side of the main element and on the tail trimmings. It is how you get the best impedance balance over the entire length. If these aspects are paid close attention to, a Bazooka will outperform a dipole every time. And yes it is possible to get a 1.1 SWR in the band center and as low as 1.4 SWR at the band edges. I have proven it time after time.
Another mistake is the type of coax used to make the antenna. Using any kind of coax with a double shield or a foil lining around the center conductor, actually lowers the performance. A Bazooka is designed to work best with leaky type coax. The only 2 coax types that should ever be used to make a Bazooka are RG-8X and RG-8U. Basic RG-8X (Mini) works very well on almost any HF band. But the basic standard RG-8U coax works better. The main reason is due to the larger diameter of the RG-8U shield wire. The larger diameter wire provides a wider bandwidth for better SWR at the band edges.
I built a Bazooka with RG-8X for a friend to use on 60 meters. I cut it to the center frequency of the 5 channel spectrum. The SWR does not go above 1.2 at the edges and a 1.1 in the middle. He has had great contacts around the country and into Europe and Asia with it. Build the the right way and they will work the right way.
I have an article on my website that explains the details a lot better than I could do here. Anyone wishing to read my article can CLICK HERE
Too many times, guys just do a rough measurement and one side turns out to be a few inches longer than the other. They do the same with the tails when trimming for SWR. This makes it impossible to get a good low SWR across the band. You have to make the measurements exactly the same on each side of the main element and on the tail trimmings. It is how you get the best impedance balance over the entire length. If these aspects are paid close attention to, a Bazooka will outperform a dipole every time. And yes it is possible to get a 1.1 SWR in the band center and as low as 1.4 SWR at the band edges. I have proven it time after time.
Another mistake is the type of coax used to make the antenna. Using any kind of coax with a double shield or a foil lining around the center conductor, actually lowers the performance. A Bazooka is designed to work best with leaky type coax. The only 2 coax types that should ever be used to make a Bazooka are RG-8X and RG-8U. Basic RG-8X (Mini) works very well on almost any HF band. But the basic standard RG-8U coax works better. The main reason is due to the larger diameter of the RG-8U shield wire. The larger diameter wire provides a wider bandwidth for better SWR at the band edges.
I built a Bazooka with RG-8X for a friend to use on 60 meters. I cut it to the center frequency of the 5 channel spectrum. The SWR does not go above 1.2 at the edges and a 1.1 in the middle. He has had great contacts around the country and into Europe and Asia with it. Build the the right way and they will work the right way.
I have an article on my website that explains the details a lot better than I could do here. Anyone wishing to read my article can CLICK HERE