Investigation On Time-Domain Characteristics Of Complex Metallic Enclosures And Antennas In The Presence Of Electromagnetic Pulses

With the miniaturization of electronic and electrical devices, systems are increasingly sensitive and susceptible to electromagnetic interference (EMI). In modern electronic countermeasures, the coupling characteristics of antenna and shielding enclosure should be understood thoroughly to ensure the protection from high-power wideband electromagnetic pulse (EMP) attack. As a time domain (TD) method, TD integral equation has additional advantages as an integral solver - more accurate and with no numerical dispersion. However, it suffers from late-time instability and computational inefficiency.At fisrt, wideband pulse responses of metallic rectangular, multi-stage cascaded enclosure with multiple rectangular apertures illuminated by a high power EMP are investigated numerically. The computation results show that metallic cascaded enclosure can be a better choice by which inner pulse response can be suppressed and shielding effectiveness can be enhanced.In the next chapter, TDIE for solving transient response of PEC objects is reviewd. Then, explicit and implict marching-on-in-order (MOT) schemes are presented. We compare their simulation results and conclude that the implicit MOT still suffers from late-time oscilation, although it is more stable. Some reasons accounting for the iteration divergence as well as some solutions are briefly given out.In the third part, to model complex geometries of practical wire antennas, we employ linear vector basis defined on cyliderical surface. At the same time, Laguerre polynomials as entire domain temporal basis are used to expand the time variables, leading to a marching-on-in-degree (MOD) scheme. We not only investigate the transient current respose of some wire antennas under high-power wideband EMP illumination, but also reveal the resonance frequency compression property and the multiband impedance matching characteristics of fractal antennas directly in time domain. Furthermore, vector bases defined on straight line and triangular patch are combined into a hybrid solver so as to evaluate the TD performance of monopoles mounted on finite PEC grounds.Finally, TD-PMCHW and TD-EFIE-PMCHW formulas are used to analyze the transient scattering of dielectric objects and PEC-dielectric composite objects, respectively. Our approach has been validated by frequency-domain results through IDFT. From computation results, we find that a PEC antenna with dielectric coating or substrate will show lower resonance frequencies.