In this letter, design of compact size rat-race coupler (RRC), based on impedance-controlled simple transmission line structure is proposed for predetermined harmonic suppression. The present approach has the advantage that within the fabrication limit of high-impedance lines, a large number of harmonics are suppressed. Design guidelines are provided. Theoretical predictions are verified by implementing a prototype microstrip RRC, with up to twelfth harmonic of the operating frequency suppressed along with 75% size reduction compared with the conventional RRC.
展开▼
