Microwave sensing provides a non-contact method for characterizing semiconductor materials through their interaction with electromagnetic fields. Unlike conventional four-point probe, Hall-effect, and contact-profiling techniques, microwave methods can evaluate conductivity, carrier concentration, dielectric properties, and material uniformity without electrical contacts or surface preparation. This paper reviews the operating principles, sensing architectures, electromagnetic models, calibration procedures, and practical limitations of microwave semiconductor characterization. A resonant-cavity sensing approach is analyzed as a representative system. The relationship between the measured resonant-frequency shift, quality-factor variation, complex permittivity, and semiconductor conductivity is presented. Illustrative simulation results demonstrate that increasing carrier concentration produces greater microwave absorption and a reduction in resonator quality factor. The results indicate that microwave sensing is suitable for rapid wafer inspection, thin-film evaluation, process monitoring, and characterization of temperature-sensitive or fragile semiconductor structures.