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ZR-3

Low Profile, High Efficiency Antenna for 20-15-10 Meters

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The ZR-3 is a Z-axis, low profile, triple band doublet antenna. The term "Z-axis" means the antenna is oriented vertically in relation to the ground. There are no traps, loading coils, toroids, or radials. The ZR-3 is designed for the amateur bands and is patterned after our commercial, proprietary ZR models. ZR antennas are more than 93% efficient.

The ZR-3 is only 5'4" tall and is designed to be mounted 18-24" above the ground. The ZR-3 is fully 1/2 wavelength long on each band (a real vertical dipole on 20, 15 & 10 mtrs). The 1/2 wavelength on each band is accomplished using "end linear loading". The ZR-3 is rated at 2,500 watts CW.

The vertical portion is the center radiator and is the feed point for the ZR-3. It is fed at the center (high current point), just like a regular, efficient dipole. The square structures on the top and bottom of the center radiator are not capacity hats. They are a continuation of the center radiator and comprise the end linear loading for the antenna. They are made into the square shape for compactness. If measured, the total length of the center radiator, horizontal bars and squares will be slightly longer than a 1/2 wavelength on each band. The largest squares are for 20 mtrs and are only 48" across. The ZR-3 is a combination of welded and swaged aluminum construction. Sections are secured with stainless screws for easy assembly and disassembly with a minimum of tools: a screwdriver and crescent wrench!

Both the upper and lower portions of the ZR-3 are equal, making the antenna balanced. There is no need for a radial or counterpoise system. Since the ZR-3 is a vertical dipole, the pattern is omni-directional (like a doughnut), with a take-off angle of between 14-22 degrees above the horizon when mounted over typical ground. The take-off angle will be lower when mounted over salt water. The ZR-3 is perfect for phased or parasitic vertical arrays.

The ZR-3 is designed to be mounted 1 or 2 feet above ground. It can also be elevated, such as on a roof or balcony, or in an attic or garage, or mobile. The ZR-3 weighs about 24 pounds. A convenient ground mounting is a 5 gallon bucket with a single sack of quick-drying concrete holding the mount! The ZR-3 can be painted (as in the photo).

ZR-3 operating bandwidth (2:1 VSWR points) at the end of 50' of feedline is about 300 kHz on 20 meters, 400 kHz on 15 meters and 600-800 kHz on 10 meters. Each band is easily tunable. The preferred feed is at right angles to the center radiator using the supplied Force 12 B-1 balun, which has been convenient for most installations. Optional feed is from the bottom, up through the center radiator.