The Study, Based On Of Cmrc Microwave Filters And Harmonic Mixer

Microwave filter and millimeter wave sub-harmonic mixer have been used widely as passive and active components. The performances of RF system are affected by them directly. Recently, localized electromagnetic band gap structure (EBG) is a hot subject of research in the field of microwave engineering because of its remarkable slow wave effect and resonant bandgap characteristics. So, Compact microstrip resonant cell (CMRC) asl-D EBG has been focused on in this dissertation. Much attention has been paid on its electromagnetic characteristics, equivalent circuit model and application on microwave filter and millimeter sub-harmonic mixer. The main work of this dissertation mainly includes:The characteristics of CMRC have been researched including the electromagnetic band gap and slow-wave effect. An even-/odd-mode equivalent circuit model of CMRC has been developed, and the influence of physical structure dimensions on frequency response of CMRC has been investigated. All the research can be applied to the designs of microwave passive and active circuit.A novel symmetrical even-order Chebyshev band-pass filter with good performance is designed. The filter introduces two transmission poles in pass band and two transmission zeros out-of-band. Furthermore,λ/4 transmission lines in the filter are substituted by CMRC as admittance inverters. As a result, good stop-band suppression is achieved without affecting the excellent performance in pass-band (insertion loss of 0.7dB and return loss of 28.8dB). The filter exhibits deep suppression with 54dB at sideband and 40.8dB at spurious band respectively, and the suppression is better than 21dB in the whole stop-band. The application of CMRC also reduces the circuit size by 26.5%.Another application of CMRC discussed in this dissertation is microwave active circuit. Based on the performance of stop-band suppression of CMRC, an 8mm fourth sub-harmonic mixer has been designed where CMRC is applied to realize low-pass filter for IF signal and CMRC in-line stubs is applied to reflect and suppress idle frequencies. Measurement results show that the performance of the mixer has been improved obviously especially for conversion loss. The lowest conversion loss is 7.6 dB. The bandwidth of RF signal is from 30 to 39.4GHz and the IF output signal has a bandwidth of 1.5GHz. The results are very close to the ones declared in the papers abroad, and at the IF band our result is better.