In high speed indoor communication, ultra-wideband (UWB) plays a crucial role. UWB contains several other narrow band systems, which give interference. In order to reject these narrow bands present in UWB system, a novel multilayer step via electromagnetic band gap (MS-EBG) structure to vary the band-notch of UWB monopole printed antenna is presented in this work. The proposed EBG consists of grooved substrate with step via arrangement. These grooved substrate allow for the deposition of the liquids with different dielectric constants to achieve the variations in band gap center frequency of EBG. The microstrip line based model with equivalent circuit diagram of MS-EBG is developed with experimental results using suspended micro strip line (SML) method, with different liquids like kerosene, sea water, mineral oil, without grooved substrate, etc. The simulated and experimental results show liquid sensing ability of the proposed MS-EBG structure. The application of MS-EBG to vary the band notch in UWB hexagonal monopole antenna (HMA) is also demonstrated. Simulated and experimental results show noticeable variation in the band notch center frequency with different liquids deposited in the grooved substrate. The proposed method required only liquid change arrangement to get desired band notch in UWB monopole antenna. Compared to electrical and mechanical method to get band notch in UWB monopole antenna, the proposed method works without any power supply, active devices and additional complex arrangement.