Bandwidth Limitations on Linearly Polarized Microstrip Antennas

The Bode-Fano integral can be used as an objective tool for assessing the bandwidth of antennas, and especially schemes for bandwidth improvement. Results for U-slot and E-slot dual resonant patch antennas suggest that the Fano integral is invariantly related to the overall volume. The Bode-Fano and Youla theories of broadband matching have been applied to the narrowband and wideband lumped equivalent circuit of microstrip antennas to calculate the maximum achievable return loss-bandwidth product of linearly polarized microstrip antennas. Curves are presented showing the relation between the antenna bandwidth, maximum achievable return loss, and parameters of the equivalent circuit. It has been shown that creating parallel slots on the patch despite all potential advantages, may reduce the potential bandwidth of patch antennas.      

Sustained release of CIP from TiO2-PVDF/starch nanocomposite mats with potential application in wound dressing

Electrospinning is an economical and alluring method to fabricate wound dressing mats from a variety of natural and synthetic materials. In this study, polyvinylidene fluoride (PVDF) and starch composite mats containing ciprofloxacin (CIP) loaded on titanium dioxide nanoparticles (TiO₂) were prepared. Fourier Transform Infrared spectra of CIP, synthesized TiO₂ NPs, TiO₂/CIP, and PVDF/starch composite mats are analyzed. Scanning electron microscopy images revealed that the fiber diameter of PVDF nanofibers thickens by increasing starch, which varies between 180 nm and 550 nm. Strain at break of PVDF, starch, PVDF/starch (2:1 w:w; P2S1), PVDF/starch (1:1 w:w; P1S1), PVDF/starch (1:2 w:w; P1S2), and nanofibers were 103 ± 11, 3 ± 0.6, 27 ± 4, 52 ± 5.2, 7.7 ± 1%, respectively. Based on strain at break and young modulus, P2S1 was selected as a suitable candidate for wound dressing to which load TiO₂/CIP as a bioactive agent. The release rate of CIP showed that about 40% of the drug is released in the first 2 days. Furthermore, the antibacterial activity of dressings was investigated using Escherichia coli and Staphylococcus aureus microorganisms and zones of clearance were obvious around the specimen on the agar plate. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48916.