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Field decompositions and the EM potentials
Published in Edward J. Rothwell, Michael J. Cloud, Electromagnetics, 2018
Edward J. Rothwell, Michael J. Cloud
A classic application for a biconical transmission line is the bicone antenna. The cones are made identical with θ2=π-θ1 $ \theta _2=\pi -\theta _1 $ and are fed at the apex by a two-wire transmission line (or a coaxial cable with a balun). Assuming the cones reside in free space, find the cone angle that makes the characteristic impedance of the biconical transmission line 300 Ω $ \Omega $ .
Ultra-Wideband Antenna Technology
Published in James D. Taylor, Introduction to Ultra-Wideband Radar Systems, 2020
P. R. Foster, J. Doss Halsey, Malek G. M. Hussain
The bicone has a radiation pattern which is rotationally symmetric around the axis of the bicone. The radiation pattern in the orthogonal plane is related to the vertical aperture of the bicone and quite narrow patterns can be achieved (Figure 5.19). The elevation beamwidth and the peak antenna gain are therefore a function of frequency and are related approximately by () Beamwidth (elevation)=65⋅λDdegrees
The effect of silica nanoparticles on the stability of aqueous foams
Published in Journal of Dispersion Science and Technology, 2019
The same rheometer was used for interfacial shear rheology. A bicone (diameter =68.28 mm, cone angle =0.087 rad) and a measuring cell (diameter =80 mm, height =90 mm) were used.[56] First, the measuring cell was half-filled with the dispersion of the silica nanoparticles in the aqueous HTAB solution, and then left for 15 min to ensure that the surfactant-laden particles formed a film at the air–water interface. The contact of the tip of the bicone with the interface was ensured by measuring the normal force. Then the bicone was slowly lowered up to its positioning height, which was calculated from the point of contact and the geometry of bicone. This positioned the bicone on the air–water interface. Thereafter, interfacial shear viscosity was measured as a function of shear rate, which was varied from 0.01 to 10 s−1. Nonlinear viscoelastic behavior of the air–water interface was studied by the elastic and viscous Lissajous–Bowditch curves at five strain amplitudes (i.e. 1, 6.4, 10, 21, and 45%) and two angular frequencies (i.e. 0.1 and 1 rad s−1). The minimum surface viscosity that could be measured by the rheometer was 10−5 Pa s m. When the rheometer was operated in the direct strain oscillation mode, it could detect 0.02 μN m of torque with 0.001 μN m resolution. The moment of inertia of the disk was 0.02379 mN m s−2. At low shear rates, it was assumed that the interfacial flow was decoupled from the bulk phase flow. This is because of the high Boussinesq number (which represents the ratio of surface and sub-phase viscosities). At a higher shear rate, however, the Boussinesq number becomes less than 1, and hence, the bulk flow influences the interfacial flow. Therefore, we did not performed experiments above 10 s−1 shear rate. A Peltier device was used to keep an isothermal condition at 298 K during each experiment.
Study of surfactant-polymer system containing a novel ternary sulfonated polyacrylamide on the oil-water interface properties
Published in Journal of Dispersion Science and Technology, 2018
Feng Li, Wenxi Zhu, Hua Song, Keliang Wang, Wei Li
All of the rheological measurements were carried out using an interfacial rheology system consisting of a commercial rheometer (DHR-2, TA America) with an interfacial rheology cell based on bicone geometry. The resonance frequency was 0.01-10 Hz and the resonance frequency was 30 rad/s. The temperature was controlled to 45°C, and the aqueous phase was the above simulated brine containing surfactant and polyacrylamide.