OCFD antenna designer

Design an Off-Center-Fed Dipole (OCFD) antenna, in either flat-top or inverted-Vee form, using a single main support. This type of antenna is designed for one principal amateur HF band, usually 80 meters or 40 meters, but typically displays VSWR minima on at least two higher bands, and can therefore be a good multi-band antenna. The impedance at the feed-point of this antenna is often stated to be in the range of 200 ohms to 250 ohms, so it is most often matched using a 4:1 unun.  Read more...

Set antenna color:    

Principal band
Frequency: kHz    ?
½ λ: m(Adjusted for end-effect)
Length units
Antenna wire
Diameter: mm
Support pole
Height: m(At support point)
First antenna section
Length: % of total   = m
Angle: Angle from horizontal: °
Second antenna section
Length: % of total   = m
Angle: Angle from horizontal: °
Antenna overview
Section #1 Section #2 Est.
Pct. Length Angle Pct. Length Angle
Press the "Show antenna" button to display your antenna
configuration here in interactive 3D graphics mode
Antenna feed-point:

Antenna performance

Here you can generate plots of propagation patterns, VSWR chart, antenna currents and Smith charts 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 your antenna will perform in the field.

Choose ground type of
land in the vicinity
of the antenna:
   Conductivity: S/m    Dielectric const.: F/m
View propagation plots:
Set azimuth angle for elevation plot:  °    ?
Propagation patterns for: ?

View VSWR chart: Check on:   From:To:
Display impedance curves:   
Impedance curves scales:   
View currents diagram:
View Smith chart:
Antenna gains
at 0° elevation:
Antenna impedance:
Frequency range: