Hexbeam Antenna: Design and Performance
A Hexbeam is a directional, gain antenna popular among amateur radio operators, especially those with limited space. It is characterized by its unique “inverted umbrella” or hexagonal shape.
Design and Structure
The antenna typically consists of six fiberglass spreader arms radiating from a central hub. Wire elements are strung around these arms to form the driven element and the reflector for each band.
Most modern Hexbeams use the “Broadband” design (G3TXQ design), which offers better performance across a wider frequency range compared to the original “Classic” design.
Key Characteristics
- Directional Gain: It functions as a 2-element Yagi, providing forward gain and a good front-to-back ratio, which helps in rejecting interference from the rear.
- Multi-band Capability: A single Hexbeam can cover multiple bands (typically 20m, 17m, 15m, 12m, 10m, and sometimes 6m) without the use of “traps” or coils, which can reduce efficiency.
- Small Footprint: Its turning radius is significantly smaller than a full-sized Yagi for the same bands, making it suitable for suburban yards or roof mounts.
- Lightweight: Because it uses wire and fiberglass rather than heavy aluminum tubing, it has low wind loading and can often be turned by a light-duty rotator.
Performance
The Hexbeam provides a radiation pattern that is directional toward the driven element. While it may not have the high gain of a multi-element Yagi, its efficiency is high because the elements are full-length and air-insulated.
Comparison to Other Antennas
- Yagi Antennas: Traditional Yagis often provide higher gain but are much larger, heavier, and typically require more robust towers and rotators.
- Spiderbeams: These are also lightweight wire beam antennas. They often provide slightly more gain but have a larger turning radius and can be more complex to assemble.
- Verticals/Dipoles: The Hexbeam will generally outperform omnidirectional antennas like verticals or simple dipoles because it concentrates the signal in a specific direction and reduces noise from other directions.