Range-angle coupling and near-field effects of very large arrays in mm-wave imaging radars
Wissenschaftlicher Artikel
Authors
Dürr, André
Schneele, Benedikt
Schwarz, Dominik
Waldschmidt, Christian
Faculties
Fakultät für Ingenieurwissenschaften, Informatik und PsychologieInstitutions
Institut für MikrowellentechnikPublished in
IEEE Transactions on Microwave Theory and Techniques ; 2020 (2020). - ISSN 0018-9480. - eISSN 1557-9670
Link to original publication
https://dx.doi.org/10.1109/TMTT.2020.3022938Peer review
ja
Document version
publishedVersion
Abstract
In order to improve the resolution of imaging radars, electrically large arrays and a high absolute modulation bandwidth are needed. For radar systems with simultaneously high range resolution and very large aperture, the difference in path length at the receiving antennas is a multiple of the range resolution of the radar, in particular for off-boresight angles of the incident wave. Therefore, the radar response
of a target measured at the different receiving antennas is distributed over a large number of range cells. This behavior depends on the unknown incident angle of the wave and is thus denoted as range-angle coupling. Furthermore, the far-field condition is no longer fulfilled in short-range applications. Applying conventional signal processing and radar calibration techniques leads to a significant reduction of the resolution capabilities of the array. In this article, the key aspects of radar imaging are discussed when radars with both a large aperture size and a high absolute bandwidth are employed in short-range applications. Based on an initial mathematical formulation of the physical effects, a correction method and an efficient signal processing chain are proposed, which compensate for errors that occur with conventional beamforming techniques. It is shown by measurements that with an appropriate error correction an improvement of the angular resolution up to a factor of 2.5 is achieved, resulting in an angular resolution below 0.4° with an overall aperture size of nearly 200 \lambda.
Funding information
Hochauflösende binokulare MIMO-Millimeterwellen-Radare (binoMIMO) / DFG [317632307]
Subject Headings
Eichen [GND]MIMO [GND]
Radar [GND]
Calibration [LCSH]
Imaging systems [LCSH]
MIMO systems [LCSH]
Keywords
direction-of-arrival (DoA) estimation; far-field condition; imaging radar; large array; millimeter-wave radar; short-range radarDewey Decimal Group
DDC 620 / Engineering & allied operationsMetadata
Show full item recordCitation example
Dürr, André et al. (2020): Range-angle coupling and near-field effects of very large arrays in mm-wave imaging radars. Open Access Repositorium der Universität Ulm. http://dx.doi.org/10.18725/OPARU-33862