Search

Bandstop filters (BSFs) have many applications in suppressing interference signals and shielding specific bands. Among them, reconfigurable BSFs that cover more frequency bands by switching modes have great research value. In this paper, a novel synthesis approach for compact reconfigurable BSFs with controllable equal-ripple performance is proposed. By switching the ON/OFF state of the positive intrinsic negative (PIN) diode, the proposed reconfigurable BSF can be switched between single-BSF (S-BSF) and dual-BSF (D-BSF). Based on the synthesis approach, the equal-ripple levels of stopband and passband for S-BSF and D-BSF can be independently controlled. To verify, the equal-ripple levels of stopband and passband for S-BSF state and D-BSF state are independently controlled in four groups of examples. Finally, a reconfigurable BSF with a miniaturized size is designed and fabricated. The fabricated reconfigurable BSF behaves with 15 dB and 10 dB return loss (RL) in two different passbands of the D-BSF state, and 25 dB bandpass RL and controllable stopband rejection (SR) for the S-BSF state. The measured results are in good agreement with the electromagnetic (EM) simulation results. [ABSTRACT FROM AUTHOR]

A novel wideband dual‐band bandstop filter with multi‐transmission zeros and multi‐reflection zeros is presented. It consists of two pairs of symmetric open‐ended coupled lines at two sides and (2N − 1) pairs of coupled‐line sections with an open‐circuited stub in the middle. Through even‐ and odd‐mode analyses, general simultaneous equations for characteristic impedances are derived with the proposed algorithm. By suitably selecting all the design parameters, the proposed topology could not only provide a controllable equal‐ripple response in the passband but also control the stopband rejection, bandwidth (BW), and centre frequency ratio in the stopband flexibly. For verification, one prototype circuit is finally fabricated and measured in the experiment. Good agreement between the measured and simulated results is attained so as to successfully validate the correctness of the proposed design method. [ABSTRACT FROM AUTHOR]

Objective: We aimed to evaluate the mitral valve calcification and mitral structure detected by cardiac computed tomography (cardiac CT) and establish a scoring model based on cardiac CT and clinical factors to predict early good mitral valve repair (EGMR) and guide surgical strategy in rheumatic mitral disease (RMD)., Materials and Methods: This is a retrospective bi-center cohort study. Based on cardiac CT, mitral valve calcification and mitral structure in RMD were quantified and evaluated. The primary outcome was EGMR. A logical regression algorithm was applied to the scoring model., Results: A total of 579 patients were enrolled in our study from January 1, 2019, to August 31, 2022. Of these, 443 had baseline cardiac CT scans of adequate quality. The calcification quality score, calcification and thinnest part of the anterior leaflet clean zone, and papillary muscle symmetry were the independent CT factors of EGMR. Coronary artery disease and pulmonary artery pressure were the independent clinical factors of EGMR. Based on the above six factors, a scoring model was established. Sensitivity = 95% and specificity = 95% were presented with a cutoff value of 0.85 and 0.30 respectively. The area under the receiver operating characteristic of external validation set was 0.84 (95% confidence interval [CI] 0.73-0.93)., Conclusions: Mitral valve repair is recommended when the scoring model value > 0.85 and mitral valve replacement is prior when the scoring model value < 0.30. This model could assist in guiding surgical strategies for RMD., Clinical Relevance Statement: The model established in this study can serve as a reference indicator for surgical repair in rheumatic mitral valve disease., Key Points: • Cardiac CT can reflect the mitral structure in detail, especially for valve calcification. • A model based on cardiac CT and clinical factors for predicting early good mitral valve repair was established. • The developed model can help cardiac surgeons formulate appropriate surgical strategies., (© 2024. The Author(s), under exclusive licence to European Society of Radiology.)