Broadband Characterization of Liquids at Millimeter Waves by Using an U-Shaped Bent Waveguide

This paper proposes an U-shaped bent waveguide for liquid characterization. Compared to straight rectangular waveguide, it is more simple for liquid sensing, without using special liquid holder. Additionally, it requires no complex de-embedding process, consequently improving characterization convenience and accuracy. Two types of liquids are put at the sensing area and then the liquid-loaded sensor is simulated by using an electromagnetic simulation software. Next, the electro-magnetic property of each liquid is extracted using the Nicolson-Ross-Weir (NRW) method over a wide frequency range. The small error range compared to the setting values indicates that the proposed sensor can accurately characterize the broadband electromagnetic features of liquids.