A six-band microstrip sensor, based on a pair of electrically coupled resonators (ECRs), is proposed to perform multifrequency dielectric characterization of liquids. A pocket is milled through the substrate bottom of the sensor to contain the fluid sample, avoiding the need for a sample holder. The pocket has been designed to achieve a higher electric field magnitude in the sensing region and a mechanism to separate the resonant frequencies, which helps to ensure a high span between the first and the last resonant frequency. The microstrip sensor is implemented on a 1.905-mm-thick substrate with $\varepsilon ^{\prime }_{r} = 12.2$ and $\tan \delta = 0.0019$ . The sensor’s six resonance frequencies span the range between 1 and 3.5 GHz. Experimental tests show that the sensor can measure a wide range of $\varepsilon ^{\prime }_{r}$ values between 2 and 79 resulting in close similarities to the dielectric constants published in previous works.