A driven loop is combined with a reflector loop and sometimes directors. Coupling between loops creates a forward lobe.
Antennas · F1SYH
Cubical Quad
The Cubical Quad uses one or more full-wave loops, usually square or diamond shaped, to form a directional antenna.
HF
VHF
Directive
Operating principle
Main characteristics
Typical gain
≈ 6 à 9 dBi selon éléments
Impedance
Variable selon géométrie
Polarization
Selon alimentation
Difficulty
Avancée
Dimensions and design
Each loop perimeter is near one wavelength, with different corrections for reflector, driven element and directors.
Construction and tuning
Step 1
Build strong insulated spreaders.
Step 2
Form loops with low-stretch wire.
Step 3
Respect perimeter and element spacing.
Step 4
Select feed point for the required polarization.
Step 5
Install matching and a choke.
Advantages
- Good gain with a relatively short boom.
- Closed loops without open high-voltage ends.
- Selectable polarization.
- Useful on HF and VHF.
Limitations
- Large structure.
- High wind loading.
- Mechanical construction is demanding.
- Complex multiband dimensions.
History and origin
Clarence C. Moore, W9LZX, developed the Cubical Quad during the 1940s to solve high-voltage discharge problems in high-power antennas.
Safety
The structure must resist torsion, wind and the weight of wet or iced wires.