Design a "Hentenna" type of antenna, a rectangular asymmetrical double-loop supported by a single main support, and fed at two points along its'
vertical sections: it's a good DX antenna. This type of antenna is designed for one principal amateur HF or VHF band, for a maximum wavelength of 15 meters - for longer
wavelengths, the antenna becomes too large for practical portable use. By altering slightly the position of the feed-points on the vertical
sections, the VSWR resonant frequency can be adjusted to be close to the design frequency. If the antenna is supported only by the supporting pole,
the beam direction can be changed simply by rotating the pole. The feed-point impedance is generally 60 to 65 ohms, so a fair match to a 50 ohm system.
The "Hentenna" antenna - sometimes known as the "Japanese miracle" - was originally developed by a group of Japanese 6-meter operators in the
1970s - the "Hen" (meaning interesting, unusual, strange, etc.) in "Hentenna" was chosen to reflect the curious fact that, when vertically-
oriented, the antenna has horizontal polarization, and vice-versa.
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"Hentenna" antenna designer
Antenna feed-point: ⬥
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Here you can generate plots of radiation patterns, VSWR chart, antenna currents diagram and Smith chart for your antenna over a
choice of ground types. By changing the physical dimensions of the antenna, and refreshing these plots, you can learn a lot about
how such antennas will perform in the field.
Please note that
radiation patterns are here modelled over flat ground -
when the antenna is erected on a hill-top or mountain summit, the surrounding sloping ground will generally cause angles in
the elevation radiation pattern to be lowered in the direction of the
slope: the steeper the slope, the lower the effective elevation take-off angle will be, and the better the chances of making
long-distance contacts.
Choose ground type of
land in the vicinity of the antenna: |
Conductivity:
S/m
Dielectric const.:
F/m
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View radiation patterns: |
Set elevation angle for azimuth plot:
Set azimuth angle for elevation plot: |
View VSWR chart: | |
Impedance curves scales: | |
Effect of coax on VSWR: | Coax length: Type: |
View currents diagram: | |
View Smith chart: | |
Antenna gains at 0° elevation: |
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Antenna impedance: | |
Frequency range: | |