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- ItemPulsed Electromagnetic Excitation of a Thin Wire-An Approximate Numerical Model Based on the Cagniard-DeHoop Method of Moments(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2024-02-01) Štumpf, Martin; Antonini, Giulio; Ekman, JonasAn approximate computational model of an electromagnetic pulse-excited thin-wire antenna is developed. The presented solution methodology is based on the Cagniard-DeHoop method of moments and Hallen's approximation of the thin-wire model. It is shown that the proposed time-domain solution leads to an inversion-free and efficient updating procedure that mitigates the marching-on-in-time accumulation error. An illustrative numerical example demonstrates the validity of the proposed model.
- ItemA wireless W-band 3D-printed temperature sensor based on a three-dimensional photonic crystal operating beyond 1000C(Springer Nature, 2024-09-23) Sánchez-Pastor, Jesús; Kaděra, Petr; Sakaki, Masoud; Jakoby, Rolf; Láčík, Jaroslav; Benson, Niels; Jiménez-Sáez, AlejandroIn addressing sensing in harsh and dynamic environments, there are no available millimeter-wave chipless and wireless sensors capable of continuous operation at extremely high temperatures. Here we present a fully dielectric wireless temperature sensor capable of operating beyond 1000°C. The sensor uses high-Q cavities embedded within a three-dimensional photonic crystal resonating at 83.5GHz and 85.5GHz, and a flattened Luneburg lens enhances its readout range. The sensor is additively manufactured using Lithography-based Ceramic Manufacturing in Alumina (Al2O3). Despite the clutter, its frequency-coded response remains detectable from outside the furnace at 50cm and at temperatures up to 1200°C. It is observed that the resonance frequencies shift with temperature. This shift is linked to a change in the dielectric properties of Al2O3, which are estimated up to 1200°C and show good agreement with literature values. The sensor is thus highly suitable for millimeter-wave applications in dynamic, cluttered, and high-temperature environments.
- ItemNovel Second-Order Transfer Section for Frequency-Selective Response Generation in Comb Filters(IEEE, 2025-03-07) Šotner, Roman; Semenov, Dmitrii; Andriukaitis, Darius; Svoboda, Marek; Polák, LadislavThis article introduces a novel unified second-order filtering topology for standard band-reject (sBR) and inverting band-reject filter, enabling selective response generation. It is applied in the design of special comb filters that allow attenuation as well as amplification of specific bands. The presented solution offers several advantageous features in topology, enhanced cascadability, better parameter-setting performance, and the use of readily available off-the-shelf components, all while reducing overall costs. This is a significant improvement compared to the previous solutions in this field, which relied on a very expensive CMOS process. The topology employs a combination of an operational transconductance amplifier (OTA) and a current feedback amplifier. The intended center frequencies and transfer values of the comb filter are set to 50 Hz (-20 dB), 1 kHz (+26 dB), 10 kHz (+17 dB), and 100 kHz (-30 dB). The comb filter was experimentally verified via simulations as well as laboratory measurements utilizing LT1228 devices in a fabricated prototype.
- ItemComments on "Transient Magnetic Shielding of a Planar Conductive ThinScreen via Exact Image Theory"(IEEE, 2024-05-14) Štumpf, MartinThe main result of Lovat et al. (2023) is put into context of previously published papers on the subject. Its correction is described.
- ItemCharacterizing the 80 GHz Channel in Static Scenarios: Diffuse Reflection, Scattering, and Transmission Through Trees Under Varying Weather Conditions(IEEE ACCESS, 2024-10-02) Závorka, Radek; Mikulášek, Tomáš; Vychodil, Josef; Blumenstein, Jiří; Chandra, Aniruddha; Hammoud, Hussein; Kelner, Jan M.; Ziółkowski, Cezary; Zemen, Thomas; Mecklenbräuker, Christoph; Prokeš, AlešThe deployment of wireless systems in millimeter wave relies on a thorough understanding of electromagnetic wave propagation under various weather conditions and scenarios. In this study, we characterize millimeter wave propagation effects from measurement data, utilizing channel impulse response analysis with a focus on root mean square delay spread and Rician K-factor. The obtained results highlight the significant influence of weather conditions and foliage on propagation, including diffuse reflection, scattering, and absorption. Particularly, we observed a notable increase in scattering from deciduous trees with leaves, in comparison with bare trees or ones covered by snow or ice. The attenuation of the signal propagated through a tree with foliage is 2.16 dB/m higher compared to a bare tree. Our validation measurements within a semi-anechoic chamber confirmed these observations and aided in quantifying the differences. These findings offer valuable insights into the dynamics of millimeter-wave signals that are important for advancing wireless communication technologies.