Crazy George wrote:
"And how does that help track a non-frequency-stationary signal?"

It senses the line between the transmitter and receiver that contains
the path of the signal
by finding a null along that line.

You have a broadband antenna array in the Adcock which produces a null
simultaneously in horizontal and vertical polarizations.

You can have confidence in the null produced by the Adcock array.
Cross-polarized reception causes no error so long as the antenna remains
balanced regardless of the frequency of reception. The Adcock doesn`t
require self-resonance nor a definite spacing between elements. Its
bandwidth means the balance can be good throughout the 2-meter band if
that`s the design frequency.

The longest dimension can be about 40 inches which makes the antenna a
practical size for the 2-meter band.

Best regards, Richard Harrison, KB5WZI