On the Impact of Channel Imbalance on MIMO Radar Performance

Grove, Ricard L.; Dall, Jørgen

doi:10.1109/eurad48048.2021.00091

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…However, for an SMA MIMO system, the impact of mutual coupling on the end-elements of the full array will repeat itself periodically N S times through the virtual array. The resulting sidelobes will have their power concentrated in N S equidistant peaks in the angular frequency domain as described in [31]. Naturally, the effect also decreases with an increasing number of elements, since the percentage of virtual elements affected decreases assuming N F = N S .…”

Section: B Embedded Radiation Patternmentioning

confidence: 98%

Mutual Coupling and Channel Imbalance Calibration of Colocated MIMO Radars

Grove

Dall

Leth-Espensen

2022

IEEE Open J. Antennas Propag.

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The Multiple-Input Multiple-Output (MIMO) radar combines the signals from multiple transmit and receive elements separately to form a virtual array. Consequently, system imperfections in the MIMO radar caused by channel imbalance and mutual coupling are repeatedly present in the virtual array, affecting the beamforming performance. In this paper, the beam pattern deviations caused by these imperfections are described mathematically in relation to a single point target. Furthermore, a nonparametric calibration technique to estimate and compensate for these effects at different angles is presented by exploiting that the same imperfections are present multiple times in the virtual array. The proposed calibration method is applied to measurements with an 8 × 8 colocated X-band MIMO radar, and the peak sidelobe level (PSL) and the integrated sidelobe level (ISL) are used as performance parameters. The calibration technique is found to improve both the PSL and the ISL by approximately 15 dB within the whole field-of-view (FOV) for antennas that are not minimum scatterers. For angles above ±30 • from the antenna boresight, the performance of the proposed calibration method is found to surpass other calibration methods. This is advantageous for MIMO radars as they typically cover a wide FOV.

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Section: B Embedded Radiation Patternmentioning

confidence: 98%

Mutual Coupling and Channel Imbalance Calibration of Colocated MIMO Radars

Grove

Dall

Leth-Espensen

2022

IEEE Open J. Antennas Propag.

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“…The MIMO radar virtual array structure plays a significant role when investigating the system imperfection effects on the system performance, as each physical element is represented repeatedly. As a consequence, if channel imbalances occur due to, for instance, differences from the RF components or signal path length, they are repeated across the virtual array as documented in [9], [10]. Interactions between the antenna elements, i.e., mutual coupling, result in the embedded radiation pattern causing angle-dependent imperfection effects.…”

Section: Introductionmentioning

confidence: 99%

Efficient Calibration of Colocated MIMO Radar

Grove,

Dall

2023

IEEE Open J. Antennas Propag.

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Measurement-based calibration with a complete MIMO radar system is beneficial due to all imperfections being considered simultaneously. However, if high performance is needed, the number of required calibration measurements escalates with an increasing number of antenna elements. This paper presents a calibration technique that reduces the number of measurements required to obtain adequate calibration coefficients, compensating for all system imperfections that can be described in matrix form. This includes channel imbalance and mutual coupling under the assumption of minimum scattering antennas. The proposed technique estimates the calibration matrix for the transmit and receive array separately, by canceling out the element radiation pattern and effects from the other array through normalization. In this way, the computational complexity and the risk of local convergence is reduced. Using prior knowledge of the expected mutual coupling, the number of equations in the nonlinear leastsquares can be further reduced without affecting the calibration performance. Besides validation with a simulated model, the calibration technique is applied to an eight-by-eight MIMO radar system.INDEX TERMS Colocated multiple-input multiple-output (MIMO) radar, array calibration, channel imbalance, mutual coupling, digital beamforming.

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Impact of channel imbalances on beamforming performance in Automotive MIMO Radar

Eschbaumer

2022

2021 18th European Radar Conference (EuRAD)

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On the Impact of Channel Imbalance on MIMO Radar Performance

Cited by 3 publications

References 8 publications

Mutual Coupling and Channel Imbalance Calibration of Colocated MIMO Radars

Mutual Coupling and Channel Imbalance Calibration of Colocated MIMO Radars

Efficient Calibration of Colocated MIMO Radar

Impact of channel imbalances on beamforming performance in Automotive MIMO Radar

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