Computational and experimental analysis of the scattering by rotating fans

Abstract

The electromagnetic scattering of rotating blades is investigated both theoretically and experimentally. We have developed an analytical method based on physical optics (PO) and the method of equivalent currents (MEC), in conjunction with the quasi-stationary method. We have predicted the bistatic field scattered by a multiple skew-plated rotating fan. Comparisons with a numerical calculation based on the method of moments and with measurements have given very satisfactory results. A comparison with previously published results has also been carried out. Physical interpretations are given both in time and frequency domains. Our analytical model correctly predicts the spreading and magnitude of the frequency response as a function of the scatterer's skew angles, its rotation frequency, and the directions of incidence and scattering.

Blocking and desensitization in bipolar and MOSFET differential amplifiers

“…In contrast with the results obtained in [1] through (8) one can see that the gain of the desired small signal is dependent on its normalized amplitude X 1 . For sufficiently small values of X 1 and X 2 the Bessel functions can be approximated by J1(z) = z 2 (9) and Jo(z) = 1 0 z 2 2 (10) and (8) …”

“…1 shows the bipolar and MOSFET differential amplifiers. The dc characteristic of an asymmetrical bipolar differential amplifier can be expressed as [8] …”

“…An alternative way to calculate the voltage induced in a conductor at the earth's surface is to use the electric field determined from the magnetotelluric relation involving the horizontal magnetic field Bx and the surface impedance Z [8], [9] 0Ey = Z 0…”