Its length greater than a half-wave creates multiple lobes and increased gain in selected directions.
Antennas · F1SYH
Double Zepp
The Double Zepp is a long wire antenna generally made of two legs near five eighths wavelength each.
HF
Double Zepp
Gain filaire
Operating principle
Main characteristics
Typical gain
Supérieur au dipôle sur bande prévue
Impedance
Élevée et variable
Polarization
Horizontale
Difficulty
Intermédiaire
Dimensions and design
A common version is about 1.25 wavelengths overall and is normally balanced-line fed.
Construction and tuning
Step 1
Select the main operating band.
Step 2
Calculate two legs near 5/8 wavelength.
Step 3
Install a central balanced line.
Step 4
Mount the antenna sufficiently high.
Step 5
Use a balanced tuner.
Advantages
- More gain than a dipole on the design band.
- High efficiency.
- No concentrated loading components.
- Can be matched on several bands.
Limitations
- Very long span.
- Multilobe radiation pattern.
- High impedance.
- Demanding installation.
History and origin
The Zepp name comes from wire antennas used on Zeppelin airships and fed at the end with parallel line.
Safety
The antenna and line contain high RF voltage regions.