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CQ Magazine Review

You've never heard of a Double Bazooka antenna? I'm not surprised. The Double Bazooka had its origin in the 1940's as a broad-band, half-wave antenna for use in radar installations. It subsequently was introduced in the amateur community in the 1950s.

The antenna never gained widespread use in the amateur world because of difficulties in construction. Rarely could an amateur build a Double Bazooka that could and would withstand the harsh wind and ice loading that we encounter in our everyday environments. I believe that the construction problem has been solved in this antenna.

The antenna construction begins with a length of 50 ohm coax. The shield is split in the middle, but the center conductor and its insulation are left intact. The shield becomes the radiating element of the dipole. The 50 ohm feed line is attached to the center braid of the coax through a proprietary design connector. This connector has an eye hook for mounting the antenna in an inverted-Vee configuration. It also has an SO-239 coax connector and the entire center connector is enclosed in high-shear, UV-resistant potting compound.

At the ends of the coax, the center conductor is shortened to the braid, and this end is extended through industrial-grade 300 ohm twin lead. The coax is bonded to the twin lead with mil-spec heat-shrink tubing. This assembly technique ensures a high-strength, UV-resistant antenna.

The antenna has no exposed metal wire. This feature should reduce static buildup on the antenna. Those of you who have antennas that suffer from rain and snow static can appreciate this advantage.

The antenna will handle the full legal limit. The company recommends that the antenna be mounted in an inverted-Vee configuration. I have tested the antenna in the inverted-Vee and horizontal configurations. Measurements were made using an MFJ 259 SWR analyzer at the end of approximately 90 feet of RG8x coax.

I first installed the antenna as a horizontal dipole at a height of about 55 feet.

Antenna Layout Out of Box

This is how the antenna looks when you take it out of the box prior to putting it up.

The SWR was 1.4 to 1 at resonance, and it rose to about 1.6 to 1 at the band edges. I next installed the antenna as an inverted Vee (the recommended installation) with the center at about 35 feet. With this installation the SWR was 1 to 1 at resonance and about 1.4 to 1 at the band edges. In either case, the antenna produced many solid contacts even when I was running QRP.

For those of you who may want more gain from your antenna system, the company offers an option for phasing two of these antennas. They predict a forward gain of approximately 5.5 dB and a front-to-back ratio of about 20 dB.

The company offers antennas for 17, 20, 40, and 80 meters. The price of the 40 meter antenna is $115. For more information, contact International Antenna Corporation, P.O. Box 121430, Clermont, FL 34712 USA
(407-380-6270).

Configuration of Broad-Band Dipole
Fig. 1 The basic configuration of a broad-band dipole, once commonly called a "double bazooka." The original antenna used open wire or ladder line at the ends. In the International Antenna Corp. version the ladder line has been replaced with an industrial-grade 300 ohm twin lead. This increases the bandwidth on 80 and 160 meters and at the same time increased mechanical strength.

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