Investigation of field suitable microwave cavity measurement approaches

In our age of rapid advancements, many areas of engineering and science tend to optimize and revise the usage and the overall efficiency of energy usage. Considering the case of catalysis in the automotive area, oxygen sensors together with a Three-Way-Catalyst (TWC) converter still present the state of the art for exhaust gas aftertreatment, with all their pros and cons. Since a TWC in its housing acts well as a resonator, to tackle the cons of the classical approach, the present works investigates the possibilities to use reflectometry based, scalar microwave detection of the catalyst state, which has the potential to supersede the classical oxygen sensor approach. Both hardware and software have been developed and tested for speed, accuracy and repeatability in order to enable more accurate catalyst state descriptions, except the classical „full“ and „empty“ states. Furthermore, the software and hardware was tested against state of the art laboratory hardware in order to clear the first steps in the path of the possibility of a standalone, field-deployable measurement system. Finally, the systems behavior for many different scenarios was investigated, as experiments have shown that the TWC-filled resonator can produce both very high and very low resonance spectra, generating the need to test the behavior in case of very broad, shallow resonance peaks.