Current distribution on the rectangular frame creates a directional pattern perpendicular to its plane. Feed position adjusts impedance.
Antennas · F1SYH
Hentenna
The Hentenna is a rectangular open or folded antenna mainly used on VHF and UHF.
VHF
UHF
Boucle rectangulaire
Operating principle
Main characteristics
Typical gain
Environ 3 à 6 dBi
Impedance
Réglable par position du point d’alimentation
Polarization
Selon orientation
Difficulty
Intermédiaire
Dimensions and design
Classic proportions are related to wavelength, although several variants exist. Width and height require accurate construction.
Construction and tuning
Step 1
Calculate the frame for the selected frequency.
Step 2
Use rigid conductor.
Step 3
Maintain right angles.
Step 4
Move the feed point to tune impedance.
Step 5
Install a common-mode choke.
Step 6
Measure front and rear response.
Advantages
- Simple construction.
- Useful gain.
- Compact on VHF/UHF.
- Adjustable matching.
Limitations
- Mechanical geometry is important.
- Feed point is sensitive.
- Documentation varies between versions.
- Metal supports disturb the pattern.
History and origin
The Hentenna was developed and popularized by Japanese radio amateurs. Its name roughly refers to a strange antenna.
Safety
The frame must be securely mounted and kept away from people during transmission.