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...

Set antenna color:    
Principal band
Frequency: kHz    ?
Total length: m  (Adjusted for end-effect)
Antenna configuration
Configure as a:
Antenna wire diameter
Wire diam. : mm
Antenna supports
Height: m (At support point)
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: m
Inductance load   - not applicable to current-fed single-bander
Value: µH    ?
Position: m above foot
Antenna overview
Antenna sections lengths Foot height Full height
#1 #2 #3 Cp. / radial
Press the "Show antenna" button to display your antenna
configuration here in interactive 3D graphics mode
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:  °    ?
Set azimuth angle for elevation plot:  °    ?
Check prop. patterns on:
View VSWR chart: Check on:   From:To:
Display impedance curves:   
Impedance curves scales:   
Effect of coax on VSWR: Coax length: Type: ?
  Show coax losses as: 
View currents diagram:
View Smith chart:
Antenna gains
at 0° elevation:
Antenna impedance:
Frequency range: