Design Of High-performance Filters Research Articles

Electrospun Polymer Composite Membrane with Superior Thermal Stability and Excellent Chemical Resistance for High-Efficiency PM2.5 Capture.

To address the challenge of high-temperature air filtration, a novel electreted polysulfonamide/polyacrylonitrile-boehmite (PSA/PAN-B) composite nanofiber based filter was developed via electrospinning for effective high-temperature dust removal. In this study, the spinnability of PSA was greatly improved by adding a small amount of PAN as an auxiliary polymer, and the introduction of a boehmite electret further significantly reinforced the properties of PSA fibers. As a result, the PSA/PAN-B membrane exhibited a high filtration efficiency (up to 99.52 ± 0.32%), low pressure drop (45.16 ± 1.39 Pa), excellent flexibility, good mechanical properties, high thermal stability (up to approximately 300 °C), and superior chemical resistance. Through data analysis and 3D simulation, the important benefits of the boehmite electret in the optimization of the PSA fibrous membrane performance were determined: it increases the charge storage capacity, constructs a rough surface morphology, improves the specific surface area, and enhances the mechanical properties. More importantly, the PSA/PAN-B film possessed a robust PM2.5 purification capacity, and the particulate matter removal efficiency was kept unchanged after high-temperature, acid, or alkali treatment-a performance derived from the intrinsic molecular structure of PSA. The PSA/PAN-B composite fibrous membrane, with excellent comprehensive properties, is a promising candidate for air filters, especially in harsh environments, further broadening the applications of PSA and providing new insight into the design of high-performance filters with high-temperature and corrosion resistance.

High-Order Balanced Superconducting Filter With High Selectivity, Low Insertion Loss, and Wide Stopband Range For Radio Astronomy

In this paper, a newly shunted-line stepped-impedance resonator (SLSIR) is studied and applied to realize high-order balanced filter design for radio astronomy application. The proposed SLSIR not only has more flexible control of the internal coupling between adjacent units but also provides more design freedom for the cascade connection of high-order filter. Then, the operating theory of three kinds of electrically, magnetically, and electromagnetically coupled SLSIR pairs has been discussed and utilized to high-performance filter design. Hence, fourth-order balanced filter using electromagnetically coupled SLSIR pairs is investigated and designed, which exhibits an excellent filtering performance under differential-mode (DM) operation as well as a high common-mode (CM) suppression level. In addition, the production mechanism of DM transmission zero is modeled and analyzed. Based on the analysis above, two dissimilar types of coupled SLSIR pairs with the same fundamental frequency but different harmonics are adopted to design an eighth-order balanced filter. Finally, the high-order balanced filter is fabricated on 0.5-mm-thick MgO wafer with double-sided YBCO thin films. Measured results show that the eighth-order balanced filter operates at 2.53 GHz with the corresponding in-band insertion loss of 0.1 dB. Results well verify the proposed structure with high selectivity, low insertion loss, and wide stopband performances.