A Horn-fed Frequency Scanning Holographic Antenna Based on Generalized Law of Reflection.

A new method of designing horn-fed frequency scanning holographic antenna is proposed. The artificial surface design of holographic antenna is based on generalized law of reflection. The input admittance is utilized to construct the interference pattern of the surface which is intervened by the excitation wave and the required radiation wave. The scalar admittance unit cell which is composed of sub-wavelength metallic patch on grounded dielectric substrate is implemented to design artificial surface, and the simulation results are just as expected that the antenna can scan the beam as the frequency changes. Furthermore, a cross shaped patch printed on grounded dielectric unit cells is used to reduce the designing complexity of tensor admittance surface. At last, a frequency scanning holographic antenna with tensor admittance surface with ability of changing linear polarization excitation wave to left-hand circular polarization (LCP) radiation wave is designed and fabricated. The full-wave simulation and experimental results show well agreement and confirm the method proposed.

Direct electrochemistry of hemoglobin immobilized on hydrophilic ionic liquid-chitosan-ZrO2 nanoparticles composite film with carbon ionic liquid electrode as the platform.

A stable composite film composed of 1-butyl-3-methyl-imidazolium tetrafluoroborate, chitosan, zirconia nanoparticles and the hemoglobin (Hb) was cast on the surface of an ionic liquid of an N-butylpyridinium hexafluorophosphate modified carbon paste electrode to fabricate a modified electrode. Scanning electron microscopy images of the modified electrode indicated that there was a dendritic structure on the modified electrode, and UV-Vis and FT-IR spectra showed that Hb in the composite film retained its native structure. Voltammetric experiments at the modified electrode showed that, in a pH 7.0 phosphate buffer solution, a pair of well-defined and quasi-reversible redox voltammetric peaks was obtained with the formal potential located at -0.216 V. The electrochemical parameters of Hb in the composite film were further carefully calculated: the electron-transfer rate constant was 0.52 s(-1) and the charge transfer coefficient was 0.34. The catalytic reduction peak current had a linear relationship with the concentration of trichloroacetic acid (TCA) in the range from 0.2 to 10.3 mmol/L with a detection limit of 66.7 µmol/L. Therefore, the composite film as a novel matrix opened up a possibility for further study on the design of enzymatic biosensors with potential applications.