High Q Double-Ring Complementary Split Ring Resonator to Detect Ammoniacal Nitrogen for Water Quality Applications

The sensitivity of double-ring complementary split ring resonators (CSRR) in detecting ammoniacal nitrogen (NH
3
-N) was investigated in this work. In water quality applications, it is crucial to detect NH
3
-N at low concentrations, therefore, high sensitivity NH
3
-N sensor is necessary. A comparison study on the performance of single-ring and double-ring CSRR was carried out. They are designed on FR-4 substrate which has a relative permittivity of 4.4 and a dielectric constant of 4.3. The S-parameters response of both CSRR are measured when they are unloaded and loaded with NH
3
-N. The most obvious finding to emerge from this study is that the double-ring CSRR has a higher Q-factor than the single-ring, resulting in higher sensitivity in detecting NH
3
-N. Further investigation and experimentation in enhancing the sensitivity of the CSRR sensor would be interesting to detect the NH
3
-N at lower concentrations, which is necessary for water quality applications.