Half-square antenna designer

Design a half-square antenna for amateur HF use which, depending on how it is fed, can function either as:

This antenna requires two support points, one of which could be a lightweight pole, the other could be a tree.  Read more...

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  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
Nom. length: m     Corrected length:   m
Antenna configuration
Configure
antenna as:

Antenna wire
Wire core: mm  diameter
Insulation: thickness    Info
Ins. type: Corr. factor:
Antenna supports
Height: m 
Antenna foot height
Foot height: m
Vertical sections length
Length: m
Top section length (ref.)
Length: m
Counterpoise (radial)   - not applicable to current-fed single-bander
Length: λ     = m Info
Inductance load   - not applicable to current-fed single-bander
Value: µH    Info
Position: m above foot
Antenna overview
Antenna sections lengths Foot
height
Full
height
Est.
imped.
#1 #2 #3 Counterp.
/ radial
 
 Half-square 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:    Inductance load:
 

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
Check prop. patterns on:
View VSWR chart: Check on:   From:To:
Display impedance curves: Using unun   
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: