This paper presents a tunable selective antenna using variable-length liquid metal (LM) for frequency adaptability. The LM length is adjusted by voltage controlled movement within 3D-printed microfluidic channels, enabling frequency tuning. This compact antenna operates in the 1-3.6 GHz range, covering WiMAX, WiFi, and WLAN bands. By optimizing the LM length, we achieve six distinct, non-overlapping frequency bands from 0.9 to 3.6 GHz. We analyze the phase and amplitude using Smith charts to explain the band generation. The design’s effectiveness is confirmed through simulation and measurement, showing strong alignment and practical viability.