Analysis and optimization of the unpredictable transmission zero in X-band filter design

Abstract

This article focuses on the common problem of uncontrollable transmission zero (TZ) in X‐band filter design. Using uniform impedance rectangular resonator (UIRR) to design an X‐band filter always results in an unpredictable TZ on the low‐frequency side of the passband, which greatly deteriorates the frequency selectivity of the filter performance. Electromagnetic coupling polarity analysis of the UIRR shows that the magnetic crosscoupling between nonadjacent resonators which is opposite to the main coupling plays a major role in the unpredictable TZ. By optimizing the UIRR from the loop structure with a small opening to the folded one, weak couplings between resonators are obtained. A high‐temperature superconducting filter at X‐band using folded UIRR resonator was designed and fabricated with a center frequency of 10.01 GHz and a bandwidth of 58 MHz, and the uncontrollable TZ has been removed successfully from the low‐frequency side of passband. The measured insertion loss is less than 0.4 dB and the return loss is greater than 15 dB.

Mode shape-based damage identification for a reinforced concrete beam using wavelet coefficient differences and multiresolution analysis

“…Through multiscale analysis, the locations of cracks are detected from the modulus line and the angle line of wavelet coefficients. By comparison, the singularity is much more apparent from the angle line of complex CWT . A neuro‐wavelet technique was proposed for damage identification of cantilever structure.…”

“…By comparison, the singularity is much more apparent from the angle line of complex CWT. [25] A neuro-wavelet technique was proposed for damage identification of cantilever structure. Damage indicators and damage locations were selected as input parameters for the neural networks to quantify damage.…”