Usually, the higher frequencies already show satisfactory results without the use of these techniques, but the low-frequency gain
and axial ratio of the spiral antenna remain unsatisfactory.
 used the frequency filter to change low-frequency gain adaptively, and the adaptive linear device had a simple circuit structure, but the frequency information shaped by the rectifier was inaccurate, and the stability still needed to be optimized.
Jeong, "A 0.18-[micro]m CMOS 3.5-gb/s continuous-time adaptive cable equalizer using enhanced low-frequency gain control method," IEEE Journal of Solid-State Circuits, vol.
The differential voltage range with this probe expands up to 8,000 Vpk before saturation when capturing short-duration overshoots." They added that the low-frequency gain
accuracy remains 1%.
The noncompensated directional setting does not adjust for the low-frequency gain reduction and thus results in less low-frequency amplification.
On average, less low-frequency gain was achieved in the directional mode for the more severe losses because of the inherent reduction of low-frequency energy with directional systems.
However, we speculate that, given the potential limitations of full-time use of the directional mode, preferences in individual listeners may have resulted from each unique subject's listening environments, low-frequency gain differences, and the frequency of directional benefits and decrements.