One wavelength antenna fed at two points

A wavelength of wire offers interesting options.  Here we have one wavelength of wire fed at two different points…

Currents of two wavelength wire antennas changing only the feed position.
Figure 1 – Currents of two wavelength wire antennas changing only the feed position.

In antenna A the feed is positioned at the peak current point much like a typical center-fed dipole (half wavelength).  Antenna B moves the feed to the middle of the wire.  Both models were optimized in length to yield a zero reactance leaving a resistance of…

  • 91 ohms for antenna A,
  • 1900 ohms for antenna B.

Antenna B obviously requires a system to mate with typical feedlines.  Plenty of options exist so this just a task and not a problem.

Note how Antenna B harmonized the phases so they don’t cancel.  This is evident in this pattern plot of both antennas…

Patterns of a one wavelength wire changing only the feed position.
Figure 2 – Patterns of a one wavelength wire changing only the feed position.

Each provides options for the radio operator.  Viva la choice!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.