OptiBeam OB1‑40 40 Meter Rotatable Dipole

The OptiBeam OB1‑40 is a purpose-built rotatable dipole antenna designed exclusively for the 40‑meter amateur radio band (7 MHz). Featuring a single aluminum element measuring 48.2 ft. (14.7 m), it provides a simple, dependable, and effective solution for operators seeking strong performance on this anchor HF band.

Physical Design and Installation

• Element Length:

  48.2 ft. (14.7 m)

• Turning Radius:

  24.1 ft. (7.35 m)

• Weight:

  24.25 lbs. (11 kg)

The compact turning radius of the OB1‑40, with highly efficient coil-loading, make this antenna suitable for installations where tower space or nearby obstacles are a concern. Despite its low weight, the antenna is built from high‑quality materials engineered to withstand harsh environmental conditions. Its wind area of only 3.33 sq. ft. (0.31 sq. m), and wind load rating of 250 N, ensures reliable performance in challenging weather.

The antenna uses a single 50‑ohm coaxial feedline to minimize complexity and reduce potential failure points.

Electrical Performance

Electrically, the OB1‑40 performs as a full‑size dipole with 0 dBd gain. When installed at approximately 20 meters above ground, ground reflection increases effective gain to about 7.0 dBi, consistent with typical elevated dipole behavior.

The antenna exhibits the classic dipole figure‑eight radiation pattern, featuring strong broadside lobes and reduced radiation off the element ends. This pattern offers excellent coverage for many domestic and DX directions depending on antennas orientation.

SWR and Bandwidth

The OB1‑40 can be optimized for either U.S. or European 40‑meter allocations:

U.S. Tuning 7.000–7.300 MHz

• SWR remains below 1.7:1 at band edges

• Supports CW, Digital and SSB modes across the entire U.S. band

European Tuning (7.000–7.200 MHz)

• SWR typically 1.2:1 to 1.7:1

• Ideal for CW, Digital and DX Phone operation within the narrower range.

Both tuning options provide broad usable bandwidth and efficient power transfer across the target segment.

Summary

The OptiBeam OB1‑40 is a mechanically robust and electrically dependable rotary dipole for the 40‑meter band. Its full‑size element, wide SWR bandwidth, durable construction, and straightforward single‑feed design make it an excellent choice for amateur radio operators who want a reliable, efficient, and low‑maintenance HF antenna.

OptiBeam OB1-40 Single Element 40 meter Rotatable Dipole

OptiBeam Antenna Technology has achieved directional antennas with extraordinary electrical properties, including the highest efficiency, optimum band coverage, nearly constant gain and unchanging radiation pattern across the band, and low SWR. These antennas maintain consistent electrical characteristics under all weather-conditions and include a high power balun with UHF female connector for your 50 Ohm coaxial cable. OptiBeam Antennas are distinguished by their advanced mechanical qualities. Specially configured, stable and properly shaped element holders, robust square and round booms with effective and very solidly-built element transitions are OptiBeam exclusives. They provide advanced physical properties, including proper balance and the highest stability of the entire system. Elements are perfectly aligned and secured against torsion with minimal sag for a visually pleasing appearance.

OptiBeams antennas are made for those who understand the true value of investing in proven electrical performance and unequalled mechanical quality for the ultimate in reliability. They are built to withstand the harshest conditions using the very best materials, including high quality aluminum alloys, UV stable synthetic parts and stainless steel hardware. OptiBeam antennas are designed to be easier to build than others, arriving in subassemblies with every part carefully sorted, clearly labeled, and extremely well packed for worry-free shipment and straightforward installation.

For enthusiastic operators of all pursuits, OptiBeam provides the advantage of pure performance. Proven in the field and confirmed by the most demanding hams around the world. Choose OptiBeam for your station.