by Tsang, Yuk-fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 67-68). / by Tsang, Yuk-fai. / Chapter 1 --- Introduction --- p.4 / Chapter 2 --- Uniform accelerated charge radiation --- p.7 / Chapter 2.1 --- An old paradox: Radiate or not? --- p.7 / Chapter 2.2 --- Uniform Accelerating Charge(UAC) --- p.8 / Chapter 2.3 --- EM fields of UAC --- p.9 / Chapter 2.4 --- Radiation of UAC --- p.13 / Chapter 2.5 --- Energy conservation: acceleration energy --- p.14 / Chapter 3 --- Numerical calculation of EM field energy --- p.18 / Chapter 3.1 --- EM fields of UAC --- p.19 / Chapter 3.2 --- Comparison of total EM field energy --- p.23 / Chapter 3.3 --- Results --- p.28 / Chapter 4 --- Modification of the paradox --- p.30 / Chapter 4.1 --- Uniformly accelerated frame (UAF) --- p.30 / Chapter 4.2 --- Radiation in UAF --- p.32 / Chapter 4.3 --- The paradox in another situation --- p.34 / Chapter 5 --- The rotating frame --- p.37 / Chapter 5.1 --- The reference frames --- p.37 / Chapter 5.2 --- Geometric properties of co-rotating frame --- p.38 / Chapter 5.3 --- Maxwell equations in non-inertial frame --- p.41 / Chapter 6 --- Transformation of radiation fields to rotating frame --- p.42 / Chapter 6.1 --- EM fields of a moving charge --- p.43 / Chapter 6.2 --- Dipole radiation --- p.44 / Chapter 6.3 --- Dipole radiation of a rotating charge --- p.45 / Chapter 7 --- Tr ansformation of the complete fields to rotating frame --- p.49 / Chapter 7.1 --- Lienard-Wiechert Fields --- p.49 / Chapter 7.2 --- Determination of R --- p.54 / Chapter 7.3 --- Radiation is a frame-dependent phenomenon --- p.58 / Chapter 7.4 --- Transformation of static field --- p.59 / Chapter 8 --- Conclusions --- p.62 / Chapter 8.1 --- Comparison of the transformation of EM fields / Chapter 8.2 --- Radiation is a frame-dependent phenomenon --- p.64 / Chapter 8.3 --- The concept of photon --- p.65 / Chapter 8.4 --- Problems left --- p.65 / Reference --- p.67

Absorber lined chambers (ALC's) or anechoic type enclosures operated under degraded conditions are introduced. Results of measurements inside scaled model ALC's are reported to demonstrate the feasibility of their use as environment simulators for electromagnetic susceptibility (E.M.S.) measurements over an extremely wide frequency range. The hardware and software of the automated microprocessor based facility developed for the measurement of amplitude and phase of e.m. fields in a volume of space, are described. / A geometrical optic (GO) technique and an 'idealized' material model to predict ALC fields is developed. Computed results are presented for a range of cases including some whose measurement would not be practicable. Using measured and computed data, criteria and guidelines for economic ALC design are established. / An experimental investigation of near-region scattering by various absorbers was carried out to seek the possibility of improving the material model with the objective of improving field prediction using the geometrical theory of diffraction (GTD).

Thesis (PhD)--University of South Australia, 2000

Thesis (PhD)--University of South Australia, 2000

Thesis (PhD)--University of South Australia, 2000

Thesis (M.Sc.) -- University of Adelaide, Mawson Institute for Antarctic Research, 1976.

No description available.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017. / This research project focuses on the implementation of a Reverberation Chamber (RC) by the transformation of an existing electromagnetically shielded room. The reverberation chamber is a kind of shielded room designed to create a statistically random internal electromagnetic environment. The reverberating environment makes it possible to obtain high field strengths from a relatively low input power. The electric fields in the chamber have to be stirred to achieve a statistically uniform field. The first part of this thesis presents an overview of reverberation chamber principles and preliminary calculations are done: the lowest usable frequency is estimated to be close to 300 MHz from empirical criteria. Modelling of the statistical environment is then presented, where electromagnetic quantities are characterised by probability density functions (Gaussian, Rayleigh and exponential); correlation issues are also presented. Measurements are performed in the frequency range of 800 MHz – 4 GHz, dictated by the antennas available for this research study. An investigation of cable losses is conducted, followed by a discussion on measurement accuracy. Mechanical stirrers are designed and manufactured. Electromechanical components are selected based on the literature study. Measurements are obtained through an automated setup using MATLAB®. To verify that the RC, with its in-house designed mechanical stirrers, is well-operated, the stirring ratio is experimentally determined. After this first test, an exhaustive investigation of probability density functions is conducted, taking into account correlation issues. Measurements show that the quality factor of the chamber is close to 2000 at 3 GHz, and that 60 independent stirrer positions at 4 GHz can be used for statistical analyses. Finally, the uniformity test is performed with an improved accuracy using frequency stirring. In conclusion, the CPUT RC passes the validation procedure according to the IEC 61000-4-21 standard by generating the required field uniformity within the accepted uncertainty level.

The formulation and calculation of the electromagnetic fields scattered from, and the natural resonances of, a thin, perfectly conducting circular strip mounted on a perfectly conducting ground plane is presented. The fields are excited by an axial electric dipole, oriented normal to the surface of the ground plane. An electric field integral equation is formulated in terms of the induced surface current and solved in closed form in the quasi-static limit as an expansion of Chebyshev polynomials. In addition, the integral equation is solved for the general case by the method of moments (MOM). Numerical results are given which show the excellent agreement between the quasi-static and method of moments solutions. The MOM currents are used to determine the field scattered from the circular strip, in both the frequency and time domains. The frequency domain analysis is applied to the problem of fencing small vertical broadcast antennas. We find that appropriately designed fencing can enhance the ground wave of the antenna, while decreasing the sky wave. In addition, we determine that the radiation efficiency of the dipole is sensitive to the size of the circular strip, and that the radiation efficiency displays resonant behavior when the frequency of operation is near a natural resonance of the circular strip. We, also, calculate the time domain transient scattered fields for different circular strip geometries, using the MOM currents and GTD. By deemphasizing the low frequencies in the transient pulse spectrum, we obtain good agreement between the GTD early time scattering and the transient scattering determined from the MOM formulation. Using the MOM formulation, we determine the natural resonances of the circular strip. These resonances are divided into two classes: the exterior resonances and interior resonances. We show the pole trajectories for the first layer of exterior resonances for a wide range of strip height-to-radius ratios. In addition, we locate strong interior resonances which correspond to TM₀(pq) circular cavity modes. Included in these interior resonances are weakly damped resonances which correspond to the TM₀(p)₀ cavity modes. This is the first known report of these TM₀(p)₀ interior resonances for the circular strip geometry. We find that these resonances dominate the scattering in our problem. Using the transient scattered fields calculated from the MOM formulation as input and output data for a single input, single output identification algorithm, we identify the dominant poles in the scattered fields. We show that these dominant poles are those associated with the TM₀(p)₀ interior resonances of the circular strip. In addition, we show that by using intelligent filtering and source selection, a few resonances with higher damping can also be identified.

No description available.