A rabbit ears antenna is what is known as a half-wave dipole antenna. The electromagnetic field that propagates the transmitted RF (Radio Frequency) signal induces a standing wave into the antenna. The magnitude of the standing wave (seen as signal strength) is dependent on many factors, one of which is the point at which the standing wave is coupled to the receiver.

The peak magnitude of the standing wave occurs at the one-quarter wavelength point on the antenna. Because the antenna total length is one-half wavelength, this means the exact center of the antenna is the best place to couple the signal from. If the antenna "ear" lengths are not equal, this shifts the coupling point away from the center of the antenna.