DOUBLE BAZOOKA antenna is an extremely broad banded Half Wave Antenna which can operate efficiently across an entire Ham band with little change to the SWR. The DOUBLE BAZOOKA antenna design was first conceived as a radar antenna in the early 1940's for use by the U.S. Government. It was modified for amateur radio use in the 1950's.
Antenna construction centers around 50 Ohm coax
The coax elements are sealed in this molding, which exhibits high adhesion to the PVC jacket.
This unique design eliminates the need for antenna matching baluns and can be fed directly with 50 Ohm coax. The DOUBLE BAZOOKA is 98% efficient and typically provides S.W.R. readings of less than 2:1 over the entire amateur band.
It tunes and radiates like normal like a half-wave dipole; it works as flat-top, V, inverted-V, sloper, NVIS configuration.
Since this antenna has no exposed metal wire static charges can not build up thus reducing noise by 6dB over antennas constructed of exposed wire.Some additional 'quietness' may partially attributed to the vinyl covering on the coax.
Using covered wire on double bazooka antennas helps reduce corona and precipitation static.
Antenna works without a tuner and no balun is required... easy field trip antenna or base antenna.
-The low SWR comes thru losses in the end stubs lenght adjustment.
-These are a single band antennas tuned to the band in question.
These antennas are hand made and 100% tested on bench equipment and in the field.
Antennas are tested SWR LOWER THEN 1.5 TO 1 .
Power handeling 1.5 Kw ssb at 50 ohms
Antenna has waterproof juction box
Heavy duty Marine Stainless fittings used
plastic end insulators
connecton is PL 239
RG58 C/U coax used.
The dipole antenna is said by many to be the perfect antenna for a specific frequency. For the most part, this is true. If you want to use a dipole for a band of frequencies, you cut it to the center frequency on that band, and hope it has a low enough SWR at each end of the band. A dipole is very simple to build. It is 2 long wires, each cut to 1/4 wave of the frequency. One wire gets connected to the center conductor of the coaxial feedline, and the other wire gets connected to the shield of the coaxial feedline.
Dipoles are usually strung up horizontally so it beams the signal in 2 horizontal directions. So it is important to have the antenna facing in the 2 directions you most want to transmit in. The signal emits off the long sides. The signals emitting off the ends of the dipole are greatly reduced.
A dipole can also be strung up in an “Inverted Vee” configuration. This means the center of the dipole is mounted on a mast or tower several feet up, and each side of the antenna from the center are angled downward on a 45 degree angle (Give or take a few degrees). It looks like an upside-down (Inverted) letter “V”. Hence the term Inverted Vee. An inverted Vee is still somewhat directional in the same 2 horizontal directions, but it now has more of an omnidirectional pattern. This is due to the wires being sloped downward on each side. The signal can now radiate off the wire in partly a vertical, and partly a horizontal polarization. It actually works better in more directions with stations using both vertical and horizontal antennas.
Dipoles have a narrow bandwidth due to the simple 2 wire design. There are no loading coils and no DC ground. They are also subject to noise and static. There is a way to help both the bandwidth and static problems. It’s not a cure for those problems, but it really helps.
It’s Called A “Double Bazooka”
The Double Bazooka is a unique design alternative to a dipole. It is made of coax cable, instead of a single strand of copper wire. The braided copper shield of the coax is the actual RF radiator, and the center conductor acts like a balun or matching transformer to provide a DC ground. The larger diameter of the shield-braid acting as the actual elements, gives the Bazooka a wider bandwidth, and reduced noise over the old wire dipole. So it covers a wider range of frequencies on each band with lower SWR. As with the dipole, the feedline can be either 50 ohm coax or 400 ohm ladder line. Every comparison has shown the Bazooka to outperform a standard dipole. Now I am going to show you just how simple this antenna is to build.
The Double Bazooka is a very popular antenna. But the following design is my slightly modified version from the original. The main difference is in the tails. The original uses an added piece of twinlead or solid copper wire. My version uses an extended unshielded portion of the center conductor for added strength, and easier SWR tuning.
First, Some Important Notes Before You Begin
Before we get into the instructions, it is very important that all measurements are checked and checked again to be sure that everything is correct. I can not stress this fact strong enough. To many guys make a quick measurement and starting cutting and slodering. Then the antenna does not perform correctly. The reason is they made a big mistake in the measurements.
If the length of the main covered section on one side of the feedpoint is longer or shorter than the same section on the opposite side of the feedpoint, the antenna will not perform at it’s best. You will not be able to get a low SWR and the broadbanding will be poor. So be extra carefull to make sure that the main covered elements on each side of the center feedpoint are exactly the same. This is a crucial point to making the Bazooka live up to it’s claim.
ALSO Very Very Very Important To Know
Do NOT use any coax that has a foil shield wrapping. It will work, but the Bazooka was designed to work best with a leaky type of coax. A foil shield wrap will defeat this concept and the antenna will not perform as well.
Another thing about foil shield coax is the center feedpoint. The instructions for the Bazooka will describe how to separate the shield wire in the center to make 2 separate elements. The foil shield is also part of the braided shield line. The foil shield must also be cut and removed in the center. If this is not done, the 2 main elements will be directly shorted at the feedpoint.
Do not use thin RG-58 coax. It won’t be any better than a basic 2 wire dipole. The severe thinness of the braided shield of RG-58 will allow the Bazooka to perform no better than a basic straight wire dipole.
And DO NOT worry about the Velocity Factor of the coax you use to build this antenna. It does not matter and will have no effect on the length calculating formulae. Check out this article about Velocity Factors of coax.
50 ~vs~ 75 Ohm Coax
The Bazooka was originally designed to work with a 50 ohm coax that is a little leaky, and a foil wrap defeats that idea. The 2 most popular coax types are typical RG-8 or RG-8X (Mini). The RG-8 is the best for this design. RG-8 is a larger diameter radiator which makes the antenna a little more broadbanded. But the RG-8X (Mini) is a good second choice but slightly less broadbanded.
If you decide you want to use a 75 ohm type of coax to build your Bazooka, just consider these facts before you make the decision. 75 ohm coax will not make the Bazooka perform better. Using the low grade 75 ohm RG-59 coax will not perform as well as a basic wire dipole. In fact, the wire dipole will work better. A 75 ohm RG-11 type coax will work fairly well as long as it is the type that does NOT have a foil shield wraped around the center wire.
You Must Convert The Decimal Point To True Inches.
One last detail that is crucial to making your measurements and calculations. There have been many Bazooka antennas built that just did not work right. They could not get a low SWR. It was not broadbanded…..etc..
The reason in many cases is the builder did not convert the number in the calculator that is after the decimal point. A final calculation of 12.5 feet does NOT mean 12 feet and 5 inches. 12.5 feet really means 12 feet 6 inches.
If a foot was just 10 inches long, we would not have this problem. That’s because a calculator thinks in multiples of 10, so it would be a perfect calculation. But a foot is NOT 10 inches, it has 12 inches. That means the number after the decimal point does not mean real inches. It represents a fraction of 12 inches and must be converted. For example, .5 of a foot means half of a foot which is 6 inches. And .75 of a foot means 3/4 of a foot which is 9 inches.
Don’t worry, there is a simple way to fix this and get the correct measurement. Re-enter only the number after the decimal into the calculator. You must use the decimal point followed by the number after the decimal. For example… If the answer is 12 .8473 feet, it means 12 feet plus .8473 of a foot. Here is the simple way to figure it out.
Enter the .8473 then multiply times 12 (for 12 inches). 10.1676 is the answer. This means 10.1676 inches. After you convert the number to the correct inches, just round up to the next inch after the decimal point. This fraction of an inch will not have a noticeable impact on the antenna.
So we have determined that the original 12.8473 feet actually equals 12 feet 10 inches after converting the number after the decimal to real true inches. Failure to do this important conversion will most likely produce an incorrectly measured Bazook that will not perform well.