16 results
Filters
Settings
Now showing1 - 10 of 16
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Simulation framework for the evaluation of the radar channel transfer function in the near field of electrically large targets(Cambridge University Press, 2026-10-05); ; ; ; A simulation framework to evaluate the radar channel transfer function in the near field of electrically large targets is presented in this article. The framework is based on the concepts known from physical optics adapted to the near-field conditions. The impact of the radar antenna characteristics on the scattering, which is non-negligible in the target near field, is incorporated by means of the antenna’s far-field radiation patterns. The inputs of the simulation framework are an STL-file-based model of the target and the gain and phase patterns of the antenna. The required sampling density of the target surface is examined in the context of convergence. The framework accounts for absorption effects due to dielectric or ohmic losses. Because the framework relies on direct evaluations without the need to solve equations, it exhibits a low computational effort, leading to fast computations. The applicability of the simulation framework is validated by measurements with different antennas at 24 and 61 GHz.Publicationtype: Journal Article36 173 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Multilayer substrate integrated waveguide six-port junctions with embedded resistive filmsThis article deals with multilayer substrate integrated waveguide (SIW) six-port junctions with embedded carbon resistive films. SIW six-ports usually employ reactive power dividers, which degrade the amplitude and phase balance when the six-port is terminated with mismatched power detectors. The associated impairments are studied and two SIW six-port junctions with improved isolation and output matching are designed for K-/Ka-band applications to overcome these limitations. The proposed designs differ with respect to the configuration of the output ports making the underlying six-port topology applicable for different layout requirements. Measurements of the fabricated components validate the concept. The six-ports are compact, fully shielded and can be integrated in multilayer printed circuit boards.Publicationtype: Journal Article56 23 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Miniaturization of folded circular SIW cavity filters(2023-05-05); ; ; This contribution presents miniaturization techniques for folded circular substrate integrated waveguide (FCSIW) cavity filters. The cavities support dual-mode operation. Two of these cavities are combined to form a fourth-order filter. Two filter designs are implemented. The first one serves as a reference and exhibits good manufacturability. For the second one, the cavity is modified, which leads to 50% more compactness. The designs are experimentally verified with 10 GHz bandpass filters. Even though the achieved level of compactness requires higher technological effort, the measurements validate the miniaturization concept. The out-of-band rejection exceeds 40 dB between 11.2 and 30 GHz for the reference filter and between 11.3 and 33 GHz for the miniaturized one. The implemented components are compared with state-of-the-art filters.Publicationtype: Journal ArticleScopus© Citations 1 108 45 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A new class of spatial harmonic magnetrons with potentials for CW and sub-THz operation(Cambridge University Press (CUP), 2023-02-22); ; A strictly physically based design theory of a new class of Spatial Harmonic Magnetrons (SHM) is thoroughly derived which leads to analytically evaluable expressions. Thus two advantages are obtained: (1) The design parameters appear grouped into two separate categories - one just containing geometrical and material parameters, the other one exclusively containing beam current-related ones, which are in product-form determining performance. The influence of each parameter can thus easily be discovered and investigated. (2) Numerical efforts for any new design will be reduced by at least one order of magnitude. Subsequently and based on feature (1) it is derived that loading the anode structure by a suitably selected meta-material will increase output power and efficiency, will pave the way to CW operation, and can extend oscillation frequency well into the sub-THz range. Finally, it is shown that the Rising Sun Magnetron is a first step toward a meta-material loaded SHM offering the same but quantitatively reduced features and less stringent requirements to fabrication technology.Publicationtype: Journal Article40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A compact low-noise frontend for interleaved Rx/Tx arrays at K-/Ka-Band(2021-07); ; This contribution deals with a frontend for interleaved receive (Rx)-/transmit (Tx)-integrated phased arrays at K-/Ka-band. The circuit is realized in printed circuit board technology and feeds dual-band Rx/Tx- and single-band Tx-antenna elements. The dual-band element feed is composed of a substrate-integrated waveguide (SIW) diplexer with low insertion loss, a low-noise amplifier (LNA), a bandpass filter, and several passive transitions. The compression properties of the LNA are identified through two-tone measurements. The results dictate the maximum allowable output power of the power amplifier. The single band feed consists of a SIW with several transitions. Simulation and measurement results of the individual components are presented. The frontend is assembled and measured. It exhibits an Rx noise figure of 2 dB, a Tx insertion loss of ~ 2.9 dB, and an Rx/Tx-isolation of 70 dB. The setup represents the unit cell of a full array and thus complies with the required half-wave spacing at both Rx and Tx.Publicationtype: Journal Article85 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Evaluation of a robust correlation-based true-speed-over-ground measurement system employing a FMCW radarThis paper presents a novel approach for the determination of True-Speed-Over-Ground for trains. Speed determination is accomplished by correlating the received signals of two side-looking radar sensors. The theoretically achievable precision is derived. Test measurements are done in two different scenarios to give a proof of concept. Thereafter a series of field measurements is performed to rate the practical suitability of the approach. The results of the measurements are thoroughly evaluated. The test and field measurements are carried out using a 24 GHz frequency modulated continuous wave radar.Publicationtype: Journal Article195 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Compact low-cost substrate integrated waveguide fed antenna for 122 GHz radar applicationsThis paper describes the design and characterization of a compact substrate integrated waveguide (SIW) fed antenna for the 122 GHz industrial, scientific, and medical band. The use of a single RO4350B substrate layer and the SIW feeding ensure a low-cost fabrication. Two versions of the antenna are presented differing in antenna gain and size. For measurement purpose, a transition from rectangular waveguide to SIW is introduced. Measurements of the radiation pattern have been performed and show good agreement with the numerical results for both antennas and an antenna gain up to 7.14 dBi.Publicationtype: Journal Article81 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Comparative study of envelope models for hybrid time- and frequency-domain simulation of traveling-wave tubes(2018-06); ; ; A selection of hybrid frequency-and time-domain approaches is evaluated with respect to their suitability for predicting the multi-tone behavior of a reference Ku-band helix traveling-wave tube. For this, a frequency-domain code is extended by a selection of frequency-dependent and frequency-independent envelope models and compared to a number of simulated and measured responses to two-tone signal excitation with varying frequency spacing. The selected envelope methods are investigated both in the hybrid approach and based on measured TWT characteristics. Output levels and classical multi-tone metrics, such as intermodulation products and phase transfer factors, are considered. By reducing a modulation scenario to a number of significant sequences, a comparison to full physics-based frequency-domain simulation is presented to show the potential of the proposed approach.Publicationtype: Journal Article153 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , K/Ka-band dual-polarized SIW-fed lens antennas for Rx/Tx integration(2018-04-03); ; This contribution deals with array elements for K/Ka-band satellite communication terminals. It proposes an end-fire design realized in substrate integrated waveguide technology and featuring dual-band functionality, and dual circular polarization. The latter is achieved by means of a dual-band orthomode transducer. An extended hemispherical dielectric lens ensures good matching and radiation properties. The feed structure is composed of a multilayer printed circuit board and tapered superstrates. The design procedure of the components is explained in detail and three different variants of the antenna are compared. The measured scattering and far-field parameters validate the concept.Publicationtype: Journal Article187 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Ka-band antenna arrays with dual-frequency and dual-polarized patch elementsIn this contribution a dual-band, dual-polarized microstrip antenna element for array applications is presented. The patch antenna is designed to operate simultaneously at around 30 and 20 GHz, the up-and downlink frequencies of modern Ka-band satellite communication systems. The antenna is smaller than half the freespace wavelength at 30 GHz to enable its utilization as array element of dual-band ground terminals. Integrating transmitter and receiver circuits allows, in turn, for a very compact active terminal solution. To minimize production cost, the design is carried out in standard multilayer printed circuit board technology. The antenna features two distinct polarization ports suitable for either dual linear or dual circular polarization if both ports are excited in quadrature. The single antenna design process is described in detail and simulation and measurement results are presented. Finally, different arrays based on this patch antenna are evaluated by simulation and measurements.Publicationtype: Journal Article133