Document Type


Publication Date



Department of Mechanical Engineering-Engineering Mechanics


Modern diesels employ a particulate filter (DPF) to reduce soot emissions. Additionally, the selective catalytic reduction (SCR) of NOx by NH3 stored on the SCR catalyst reduces NOx emissions. In some vehicles the functions of these aftertreatment components are combined in the SDPF, a DPF having a SCR washcoat. The RF resonant method has been shown to be an alternative tool for measuring the DPF's soot loading and the SCR's NH3 loading. For both applications, the transmitted electromagnetic signal between antennae placed on either side of the catalyst change with loading. Here we report the influence of the RF signal on both soot and NH3 loadings on a SDPF segment. We show that the attenuation of the RF signal by soot is much larger than that caused by saturating it with 400 ppm NH3. By taking the mean RF signal amplitude measured over a wide range of frequencies, we demonstrate a method for determination of the soot loading even in the presence of stored NH3. For "light"soot loadings, before the RF attenuation by soot cause the resonant modes to disappear in the spectra, we demonstrate a method for the simultaneous determination of both the soot and NH3 loadings.

Publisher's Statement

© 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. Publisher’s version of record:

Publication Title

Journal of the Electrochemical Society

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Publisher's PDF



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.