Development of Yagi antenna sensors for dielectric properties analysis using Zr-substituted NdTi(0.5-x)ZrxMo0.5O4 substrate

NdTi(0.5-x)ZrMo0.5O4 ceramics were synthesized via the conventional solid-state reaction method and characterized for their microwave dielectric properties. Phase formation and structural changes were investigated using X-ray diffraction (XRD), where the unit cell volume was found to increase with rising Zr content (x = 0 to 0.05). The Nd(Ti0.49Zr0.01Mo0.5)O4 ceramic obtained a maximum relative density of 98.7% after being kept at 1425 degrees C for 4 h. The Nd(Ti0.49Sn0.01Mo0.5)O4 ceramics were sintered for 4 h at 1425 degrees C, yielding a relative dielectric constant (epsilon r) of 18.7, a temperature coefficient of resonant frequency (TCF) of - 31.0 ppm/ degrees C, and an unloaded quality factor (Qu x f) of 33100 GHz (at 17.6 GHz). A microwave-based liquid sensor was developed by utilizing the synthesized ceramic substrate with a microstrip Yagi antenna design. The sensor exhibited distinct resonance shifts upon exposure to different liquids: 0.92 GHz for acetone and 1.51 GHz for water. These results demonstrate the antenna sensor's potential for reliable liquid characterization in environmental monitoring applications.