Half-square antenna designer
Design a half-square antenna for amateur HF use which, depending on how it is fed, can function either as:
a single-band full-wave antenna fed at one upper corner (current-fed) and acting as two phased vertical antennas: in this
configuration, the feed-point impedance will be close to 50 ohms and the antenna will propagate at low elevation angles,
predominantly in vertical polarization;
- a multi-band EFHW (end-fed half-wave) antenna fed at one end (voltage-fed): in this configuration, as with all voltage-fed antennas, the
feed-point impedance will be high (around 2500 to 3000 ohms) and an unun, typically 49:1, will be required to match a 50-ohm system.
This antenna requires two support points, one of which could be a lightweight pole, the other could be a tree.
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.