A new measurement technique on inherent-ring-resonance frequency using ring filters

Abstract

As an application of the ring filters, a new and simple method to determine an inherent-ring-resonance frequency and an effective loss tangent at a frequency of interest is introduced. When a certain condition is satisfied in the ring filters, a frequency, where all the excited power is reflected, exists. That is the inherent-ring-resonance frequency and the effective loss tangent from its reflection coefficient may be obtained correctly. To verify the method, two ring filters have been fabricated in microstrip lines and the measured results show good agreement with the predicted ones.