A self tuning electromagnetic shutter.

摘要

A self-tuning electromagnetic shutter (STEMS) is a slotted metallic surface with computer-controlled switchable shorting wires placed across the slots. By opening and closing the shorting wires, the transmissitivity of the surface may be adjusted. In particular, the surface may be placed into open and closed states, creating an electronically-controllable iris.;Since the states of the switches needed to create a selected transmissitivity depend on frequency, a binary search technique, such as a genetic algorithm, is used to find an acceptable state. A feedback signal, is used to judge whether a given state produces the desired behavior.;To investigate the feasibility of STEMS, and to study its dependence on frequency, polarization, and angle of incidence, the STEMS is used to seal the opening to a cubical box containing a monopole antenna. The monopole is used as a receiving probe to measure the coupling from an incident electric field into the box. A closed STEMS is sought by minimizing the field entering the box, while an open STEMS is sought by maximizing the received field.;Both simulation and measurement results attesting to the eeffectiveness of STEMS to create an electronically-controllable iris are presented in this thesis.