The present disclosure provides a signal conditioner, an antenna device and a manufacturing method. The signal conditioner includes: a microstrip line including a first portion and a second portion; an insulating layer including a first insulating layer covering the first portion; at least one electrode; a liquid crystal layer covering the microstrip line, the insulating layer, and the at least one electrode; and a common electrode line. A first end of the first portion is connected to a first end of the second portion. A second end of the first portion is connected to a second end of the second portion. The at least one electrode includes a first electrode on a side of the first insulating layer facing away from the first portion. The common electrode line is on a side of the liquid crystal layer facing away from the microstrip line.