@article{HarzheimMuehmelHeuermann2021,
  author    = {Harzheim, Thomas and M{\"u}hmel, Marc and Heuermann, Holger},
  title     = {A SFCW harmonic radar system for maritime search and rescue using passive and active tags},
  series = {International Journal of Microwave and Wireless Technologies},
  volume    = {13},
  journal   = {International Journal of Microwave and Wireless Technologies},
  number    = {Special Issue 7},
  publisher = {Cambridge University Press},
  address   = {Cambridge},
  doi       = {10.1017/S1759078721000520},
  pages     = {691 -- 707},
  year      = {2021},
  abstract  = {This paper introduces a new maritime search and rescue system based on S-band illumination harmonic radar (HR). Passive and active tags have been developed and tested while attached to life jackets and a small boat. In this demonstration test carried out on the Baltic Sea, the system was able to detect and range the active tags up to a distance of 5800 m using an illumination signal transmit-power of 100 W. Special attention is given to the development, performance, and conceptual differences between passive and active tags used in the system. Guidelines for achieving a high HR dynamic range, including a system components description, are given and a comparison with other HR systems is performed. System integration with a commercial maritime X-band navigation radar is shown to demonstrate a solution for rapid search and rescue response and quick localization.},
  language  = {en}
}
@article{HeuermannHarzheimCronenbroeck2021,
  author    = {Heuermann, Holger and Harzheim, Thomas and Cronenbroeck, Tobias},
  title     = {First SIMO harmonic radar based on the SFCW concept and the HR transfer function},
  series = {Remote sensing},
  volume    = {13},
  journal   = {Remote sensing},
  number    = {24},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2072-4292},
  doi       = {10.3390/rs13245088},
  pages     = {23 Seiten},
  year      = {2021},
  abstract  = {This paper presents a new SIMO radar system based on a harmonic radar (HR) stepped frequency continuous wave (SFCW) architecture. Simple tags that can be electronically individually activated and deactivated via a DC control voltage were developed and combined to form an MO array field. This HR operates in the entire 2.45 GHz ISM band for transmitting the illumination signal and receives at twice the stimulus frequency and bandwidth centered around 4.9 GHz. This paper presents the development, the basic theory of a HR system for the characterization of objects placed into the propagation path in-between the radar and the reflectors (similar to a free-space measurement with a network analyzer) as well as first measurements performed by the system. Further detailed measurement series will be made available later on to other researchers to develop AI and machine learning based signal processing routines or synthetic aperture radar algorithms for imaging, object recognition, and feature extraction. For this purpose, the necessary information is published in this paper. It is explained in detail why this SIMO-HR can be an attractive solution augmenting or replacing existing systems for radar measurements in production technology for material under test measurements and as a simplified MIMO system. The novel HR transfer function, which is a basis for researchers and developers for material characterization or imaging algorithms, is introduced and metrologically verified in a well traceable coaxial setup.},
  language  = {en}
}
@article{HoffmannUhlCeblinetal.2022,
  author    = {Hoffmann, Andreas and Uhl, Matthias and Ceblin, Maximilian and Rohrbach, Felix and Bansmann, Joachim and Mallah, Marcel and Heuermann, Holger and Jacob, Timo and Kuehne, Alexander J.C.},
  title     = {Atmospheric pressure plasma-jet treatment of PAN-nonwovens—carbonization of nanofiber electrodes},
  series = {C - Journal of Carbon Research},
  volume    = {8},
  journal   = {C - Journal of Carbon Research},
  number    = {3},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2311-5629},
  doi       = {10.3390/c8030033},
  pages     = {8 Seiten},
  year      = {2022},
  abstract  = {Carbon nanofibers are produced from dielectric polymer precursors such as polyacrylonitrile (PAN). Carbonized nanofiber nonwovens show high surface area and good electrical conductivity, rendering these fiber materials interesting for application as electrodes in batteries, fuel cells, and supercapacitors. However, thermal processing is slow and costly, which is why new processing techniques have been explored for carbon fiber tows. Alternatives for the conversion of PAN-precursors into carbon fiber nonwovens are scarce. Here, we utilize an atmospheric pressure plasma jet to conduct carbonization of stabilized PAN nanofiber nonwovens. We explore the influence of various processing parameters on the conductivity and degree of carbonization of the converted nanofiber material. The precursor fibers are converted by plasma-jet treatment to carbon fiber nonwovens within seconds, by which they develop a rough surface making subsequent surface activation processes obsolete. The resulting carbon nanofiber nonwovens are applied as supercapacitor electrodes and examined by cyclic voltammetry and impedance spectroscopy. Nonwovens that are carbonized within 60 s show capacitances of up to 5 F g⁻¹.},
  language  = {en}
}