The Moxon Rectangle Beam Antenna is one of the most efficient compact directional antennas available to amateur radio operators. The attached diagram shows a classic wire Moxon configuration, illustrating the driven element, reflector, spacing geometry and structural bracing used to achieve high forward gain and excellent front-to-back ratio on the HF bands.
Unlike a traditional Yagi, the Moxon folds the element tips inward, forming a rectangular loop-like structure. This reduces overall size while preserving strong coupling between the driven and parasitic elements, resulting in impressive performance from a lightweight, easily rotatable antenna.
Understanding the Geometry in the Diagram
In the drawing, the antenna is defined by a small number of critical dimensions. The overall width (A) determines the electrical length of both elements. The vertical height (E) controls the spacing between the driven element and reflector, which directly affects gain and front-to-back ratio. The diagonal braces maintain mechanical rigidity and preserve element alignment under wind load.
The small end gap (C) at each folded tip is extremely important. Even a few millimeters of change can shift resonance and impedance. This is why the insulator spacing is carefully specified for each band.
At the center of the driven element, the coaxial feedline is connected. A current balun is typically added here to ensure symmetrical current distribution and clean radiation patterns.
The image provided outlines a classic “Spider-hub” style construction, where wires are supported by diagonal spreaders. The antenna consists of two main parts:
- The Driven Element: The section connected to the coax cable.
- The Reflector Element: The parasitic element that provides the directional gain.
The critical “magic” of the Moxon happens at the gap (Dimension C), where the tips of the driven element and the reflector face each other, separated by an insulator.
Multiband Scaling of Moxon Rectangle beam antenna
One of the strengths of the Moxon Rectangle beam antenna design is that it scales perfectly with frequency. The same proportions apply whether the antenna is built for 20 meters, 15 meters, or 10 meters. Using the formulas shown in the diagram, all dimensions are derived directly from the operating frequency.
These dimensions maintain the correct electrical phase relationship between the driven element and reflector, producing a clean unidirectional pattern.
Construction Approach
Most builders use a lightweight non-conductive frame such as fiberglass or PVC to support the rectangular outline. The elements themselves are typically copper or copper-clad wire, tensioned along the frame. Diagonal spreaders shown in the diagram prevent distortion and keep the geometry stable over time.
Insulators at the folded tips define the critical gap dimension and also isolate the element ends from the supporting structure. The feed point is located at the center of the driven element, where 50-ohm coax can be connected directly, usually through a 1:1 current balun.
Moxon Rectangle beam antenna : Key Construction Components
1. The Insulators (Dimension C)
The detail of the insulators is crucial. As shown in the diagram, these are usually made of non-conductive material like PVC or fiberglass plate. They maintain the tension between the driven element and the reflector while ensuring no electrical contact is made.
2. Feed point and Coax
The driven element is split at the center (Feed point). A 1:1 Balun is highly recommended here to prevent RF from traveling back down the outer shield of your coax cable, which helps maintain a clean radiation pattern.
3. Support Structure
The diagonal lines in the drawing represent the spreaders. For temporary or portable setups, fiberglass “crappie poles” or PVC pipes are excellent. For permanent installations, UV-resistant fiberglass tubing is the gold standard.
Moxon Rectangle beam antenna : Tuning and Optimization Tips
- Height Matters: For the best performance, mount your Moxon at least half a wavelength above the ground.
- Wire Gauge: Using thicker wire or insulated wire may slightly shift the resonant frequency. If using insulated wire, you may need to shorten the elements by 2-3%.
- SWR Check: If the SWR is high, check the gap distance (C) first, as this is the most sensitive part of the antenna design.
Radiation Pattern and On-Air Performance
Electrically, the Moxon Rectangle behaves like a two-element beam with strong forward gain and deep rear nulls. Typical performance includes around 5 to 6 dBi of forward gain and front-to-back ratios exceeding 20 dB. The beamwidth is broad enough for easy rotor control while still providing excellent signal concentration toward the desired direction. Because of its clean pattern and low rear sensitivity, the Moxon is also well known for its low noise reception, making weak-signal DX work noticeably easier.
The Moxon Rectangle is a “set it and forget it” antenna. Its rectangular shape makes it much more durable in high winds than a traditional Yagi, and its direct 50-ohm impedance makes it incredibly easy to interface with modern transceivers. Use the table above to start your build today and experience high-gain DX performance on a budget!
Related Antenna Projects
- How to Build a Reduced Size 40M Antenna – Complete DIY Guide (November 26, 2025)
- Morgain Antenna: Dual-Band Dipole that Beats Traps (November 27, 2025)
- Build Your Own Multiband G5RV Antenna: A Classic Ham Radio Project (November 22, 2025)
- Shortened Inverted V Antenna for 80 Meters (3.700 MHz) (November 26, 2025)
- Compact 40M HF Antennas: Short Dipoles & Short Verticals (October 16, 2025)
- 40m Vertical Antenna: Compact Base-Loaded Design for Powerful HF Operation (October 16, 2025)
- Build Your Own Indoor Antenna for 7 MHz HF Band (October 17, 2025)
