How (and why) it works
In a quarter-wave antenna, the voltage maximum is at the end. By
loading the antenna (by touching it) we reduce the voltage at that
point. Obviously the greatest effect on received signal strength
will occur if we load the point of maximum voltage on the antenna.
Conversely, if we observe the greatest effect on received signal
strength at a given point, it follows that that point must be the
point of maximum voltage on the antenna, i.e. one quarter wavelength
along the antenna.
Fig 1.3 Current and voltage in a half-wave antenna. A ground plane
antenna such as this is effectively a vertical half-wave dipole.
Bending the radials downwards at a 45º angle alters the
impedance of the antenna towards 50 ohms.
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