Each section reverses or delays phase so that radiating currents add in the horizontal plane.
Antennas · F1SYH
Coaxial collinear
A coaxial collinear uses alternating coaxial sections to create several phased radiating elements.
VHF
UHF
Coaxial
Operating principle
Main characteristics
Typical gain
Variable selon sections
Impedance
Proche de 50 Ω après adaptation
Polarization
Verticale
Difficulty
Avancée
Dimensions and design
Section length depends critically on the actual velocity factor of the coaxial cable.
Construction and tuning
Step 1
Determine the velocity factor.
Step 2
Cut sections accurately.
Step 3
Alternate centre and shield connections correctly.
Step 4
Protect every joint.
Step 5
Install inside a non-conductive tube.
Advantages
- Readily available materials.
- Omnidirectional gain.
- Protected internal construction.
- Compatible with a PVC radome.
Limitations
- Coaxial losses.
- Very accurate cutting required on UHF.
- Many joints.
- Results depend on cable type.
History and origin
The coaxial collinear became popular as an inexpensive amateur VHF and UHF construction.
Safety
Do not surround the antenna with conductive tubing and weatherproof all joints.