The nanosized lanthanum iron garnet (LIG) material was prepared by sol-gel method. The nanomaterial with ferrite structure was heat-treated at different temperatures from 700 to 1000°C. The phase identification, crystallinity, and morphology of the prepared samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). LIG ferrite nano powder was composited with polyvinylidene fluoride (PVDF) by solvent method. The magnitudes of reflection and transmission coefficients of PVDF (13 LIG) were measured using rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in X-band frequency. The results showed that with varying the thickness of the obtained LIG-polymer nanocomposite, reflection coefficient/transmission coefficient ratio can be tuned. © The Author(s) 2011.