The analysis of materials plays a critical role in ensuring product quality, driving innovation, improving cost-effectiveness, and maintaining safety standards across a wide range of industries. An effective method for material characterization involves evaluating permittivity using sensors based on metamaterials, which are renowned for their ability to provide fast and accurate results. A new sensor, the dual-band octagonal Complementary Split Ring Resonator, has been developed using metamaterial technology to measure the dielectric properties of materials. This sensor is fabricated on an affordable FR4 substrate with a 50 Ω microstrip line and has undergone testing with various materials to improve its quality factor and sensitivity. Noteworthy is the sensor’s consistent performance even when analyzing materials that slightly exceed the designated measurement threshold. The unloaded S21 response shows depths of −25 dB for the first notch and −38 dB for the following notch. Furthermore, the research also presents findings from various configurations of the measurement under test under different load conditions.