Specials - "Hentenna" antenna designer

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.

Get started  » » »

  1. Use the controls on the left-hand side to configure your antenna - set the design frequency, antenna element lengths and angles, wire diameter, wire insulation if required, support height, etc.
  2. When you are happy with your configuration, press the "Show antenna" button to display your antenna in interactive 3D graphics mode in the area on the right-hand side. Each time you change your configuration, you should press the "Show antenna" button to register the changes to the app.
  3. After you have configured your antenna, you can then use the controls further down in the page to generate charts and diagrams to evaluate the antenna's performance - you will need to to access these controls.
    You can choose to view any combination of the available charts and diagrams: these include four radiation pattern types: azimuth, elevation, 3D and polarization patterns; other options include VSWR charts, an antenna currents diagram, and a Smith chart.

Set antenna color:    

Principal band
Band:
Frequency: kHz    Info
Nominal λ: m     Corrected length:   m
Antenna wire
Wire core: mm  diameter
Insulation: thickness   
Ins. type:   Corr. factor:
Support pole
Height: m  (At support point)
Antenna main dimensions
Width: m
Height: m
Antenna vertical sections
Lengths ratio: % Info
Short sec.: m
Long sec.: m
Antenna overview
Support
point
height 		Antenna
height 		Antenna
width 		Long vert.
section
length 		Short vert.
section
length 		Feed-pt.
position,
Δλ
 
 "Hentenna" antenna designer
  1. Use the controls on the left-hand side to configure your antenna.
  2. When you are happy with your configuration, press the "Show antenna" button to display your antenna in interactive 3D graphics mode in this area.
  3. After you have configured your antenna, you can then use the controls further down in the page to generate charts and diagrams to evaluate the antenna's performance ...
Antenna feed-point: ⬥
 

Antenna performance

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
 
View radiation patterns:    Set elevation angle for azimuth plot:     Info
  Set azimuth angle for elevation plot:     Info

Info
View VSWR chart:
Impedance curves scales:   
Effect of coax on VSWR: Coax length: Type:   Info
View currents diagram:
View Smith chart:
Antenna gains
at 0° elevation:
Antenna impedance:
Frequency range: