This work proposes the development of a novel sensor comprising a rectangular microstrip antenna enclosed within a small cubic container made of acrylonitrile-butadiene-styrene (ABS). A complementary split ring resonator (CSRR) has been incorporated into the antenna, endowing it with two resonance frequencies within the desired range. The sensor is designed to determine the soil water content (SWC) of various soil types. The operational principle relies on the modulation of two resonance frequencies of the antenna due to changes in the relative permittivity of the material under test (MUT). The sensor’s sensitivity was thoroughly examined and compared with various sensors documented in the literature. Additionally, an electric field analysis was conducted, revealing that optimizing the dimensions of the CSRR can enhance its sensitivity. Consequently, the proposed sensor exhibited superior sensitivity compared to other sensors reported in the literature. Display omitted •Sensitivity analysis of the proposed Compact CSRR-Based sensor.•The optimization of the sensor based in the electromagnetic fields’ analysis.•The analysis of dielectric properties of two different types of soil.•Determination of soil water content with the proposed sensor and fitted equations.•Improvement of the sensitivity compared with the other systems presented.