Phased array calibration and beamforming using signal processing
Doktorsavhandling, 2007

Array antennas have a wide range of applications which includes ground and airborne radar, weather radar and anti-collision radar. In addition, equally important applications exist for communications, both on earth and to satellites in space, as well as for medical applications such as the detection and treatment of tumors. The modern trend in array design is to use digital beamforming and to integrate the antennas with the rest of the system more closely. This adds new possibilities, but also contributes to make the system expensive. To make full use of the new technology, this thesis presents a direction dependent signal processing array calibration method. The new method, called local calibration, also allows for larger array imperfections and, possibly, a lower overall array cost. In contrast to other non-parametric calibration methods, the proposed method can handle position errors and shows good performance also for sparse calibration grids, which is demonstrated by high resolution direction of arrival estimation. The local calibration has also been included in a convex beampattern optimization, which makes it possible to achieve a uniform sidelobe level also with unknown sensor position errors in the array. The embedded element pattern is included in the optimization by extracting the direction dependence of the received power from the calibration. Another application for the local calibration method is to reduce the number of necessary calibration measurements by calculating pseudo calibration data from a sparse grid of measured calibration data. Array signal processing is often performed assuming Uniform Linear Arrays (ULAs), although this model is far too simple to reveal the true behavior of array antennas. Throughout this thesis, more realistic models including mutual coupling and array imperfections are used. Specifically, the impact of mutual coupling and position errors on the adaptive beamforming performance in linear and circular arrays is studied. In the studied cases, the circular array is found to be more sensitive to neglecting the mutual coupling. Robust adaptive methods are commonly used to handle model uncertainties, such as unknown mutual coupling, but even better performance can be achieved if these methods are combined with a calibration.

mutual coupling

calibration

array imperfections

beampattern synthesis

adaptive beamforming

convex optimization.

array signal processing

Array antennas

EA, Hörsalsvägen 11, Chalmers
Opponent: Dr. Hans Steyskal, Air Force Research Lab. /SNH, Hanscom AFB, Massachusetts, USA

Författare

Maria Lanne

Chalmers, Signaler och system, Signalbehandling och medicinsk teknik, Signalbehandling

Performance analysis of beam forming using an approximate mutual coupling model

4th European Workshop on Conformal Antennas,; (2005)

Paper i proceeding

Array calibration using local models

Antenn 06, Nordic Antenna Symposium,; (2006)p. 251-256

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

T/R-module mismatch and antenna pattern characteristics

IEEE Int. Symp. Phased Array Technol.,; (2003)

Paper i proceeding

Two-step ESPRIT with compensation for modelling errors using a sparse calibration grid

ICASSP 2007, Honolulu Hawaii,; (2007)

Paper i proceeding

Calibrating an array antenna for scan dependent errors using a sparse grid

Asilomar conference on systems, signals and computers, Asilomar, CA, oct 29-nov 1,; (2006)

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

Optimized beamforming calibration in the presence of array imperfections

ICASSP 2007, Honolulu Hawaii,; (2007)

Paper i proceeding

Ämneskategorier

Elektroteknik och elektronik

ISBN

978-91-7291-948-8

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 2629

EA, Hörsalsvägen 11, Chalmers

Opponent: Dr. Hans Steyskal, Air Force Research Lab. /SNH, Hanscom AFB, Massachusetts, USA