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This paper proposes a UHF-band microwave sensor for solid material detection based on a tweaking electric field coupled (ELC) resonator. The microwave sensor operates at a low resonant frequency of 0.82 GHz to characterize solid materials with a permittivity range of 1–9.8. The location of the sensing area is determined based on the surface of the resonator with the highest electric field. The permittivity of the sample is determined based on perturbation theory by observing the frequency shift relative to changes in the permittivity of the sample placed in the sensing area of the proposed sensor. From the measurement process, the proposed sensor has a normalized sensitivity (NS) of 1.49%, frequency detection resolution (FDR) of 0.012 GHz, and an average accuracy of 96.72%. This work has a significant contribution and can be recommended for several applications including the pharmaceutical, biomedical, and materials industries.