Multiport calibration for microwave tomography systems

Zimmermanns, Marc; Rolfes, Ilona; Mallach, Malte; Gebhardt, Patrik; Musch, Thomas

doi:10.1109/gemic.2016.7461565

Cited by 4 publications

(3 citation statements)

References 5 publications

(11 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The installation method for antennas and connections to VNA follows the same configurations presented in Section 3.2 (e.g. [30,[39][40][41][42][43] and others) and we used the same data set that was used in [14].…”

Section: Experimental Results For a Large Grain Binmentioning

confidence: 99%

Single Data Set Calibration and Imaging with Uncooperative Electromagnetic Inversion Systems

Kim

LoVetri

Jeffrey

et al. 2021

2021 15th European Conference on Antennas and Propagation (EuCAP)

View full text Add to dashboard Cite

After the production process, various types of grains are stored in storage facilities for years, and it is important to maintain humidity and temperature at values that ensure safe storage. Recently, Electromagnetic Imaging (EMI) systems for grain storage monitoring have been developed as an alternative method to monitor moisture content and temperature in grains while providing more sensitivity than other approaches. EMI systems use a large number of co-resident antennas usually connected to a Vector Network Analyzer via a switch. A numerical model is used to model the physical electromagnetic problem and an inversion algorithm is used to invert the collected data to produce an image of the target. However, before the computer model can be used, the raw VNA measurements must be calibrated to bridge the computational model and the true system physics. Traditional calibration approaches usually require two data sets: a data set measured from a known target for calibration purposes and a data set measured for the unknown target. We introduce and evaluate a new calibration method to calibrate and image using a single S-parameter measurement of the unknown target only. We apply this method to EMI inside of grain bins. This proposed calibration workflow: (1) estimates the bulk contents of the grain bin using a parametric inversion method and(2) uses the bulk results to subsequently estimate per-channel calibration coefficients for both the transmit and receive paths to each antenna. The novel calibration procedure is demonstrated via both synthetic and experimental results. The single-data set calibration can provide similar quality results as traditional two-data set calibration for a lab-scale experiment setup, but the technique could not produce acceptable images on the larger experiment. i ContributionsThe main contribution of this thesis is to show that, in the domain of Electromagnetic Imaging, both calibration and imaging with single data set is possible. In some sense, this could be called calibration of a measurement system without reference measurements. In grain bins, like many other electromagnetic imaging systems in other application areas, it is common practise to use two (or more) sets of measurements with a known and unknown target to calibrate the system. To the authors knowledge, calibration and imaging with only a single set of measurements has not been completed previously.This thesis is based on the work published in the following papers: [

show abstract

Section: Experimental Results For a Large Grain Binmentioning

confidence: 99%

Single Data Set Calibration and Imaging with Uncooperative Electromagnetic Inversion Systems

Kim

LoVetri

Jeffrey

et al. 2021

2021 15th European Conference on Antennas and Propagation (EuCAP)

View full text Add to dashboard Cite

show abstract

“…From ( 15), ( 20), (21) and Appendix IV, the kth element of the gradient vector of the cost function r 1 (α α α) can be written as…”

Section: B Computing Approximated Gradientmentioning

confidence: 99%

Joint Calibration and Tomographic Reconstruction for Time-of-Flight Sensor Systems

bhuvana¹,

Och²,

Schuster³

2022

Preprint

View full text Add to dashboard Cite

<p>A typical time-of-flight (ToF) tomography method requires accurate information about the system’s calibration parameters in order to reconstruct the features of interest within a region of interest (RoI). This paper proposes a constrained joint calibration and tomography (CJCT) method based on a separable least squares (SLS) approach for ToF tomographic systems. Contrary to the existing offline and online calibration methods, the proposed method utilizes prior information about the calibration parameters in the form of constraints. The imposed constraints allow for an efficient search for the minimum of the inherent SLS cost function by reducing the system and measurement ambiguities. Thus, the proposed CJCT method can find the optimum values for both tomography and calibration parameters more efficiently compared to unconstrained methods. The general applicability of the proposed method is demonstrated by evaluating it on two applications: tomographic reconstruction of the permittivity distribution in a RoI using ToF measurements from a high resolution millimeter-wave radar system, and the temperature distribution inside an industrial blast furnace using measured and simulated acoustic ToF values. The simulation and experimental results show that the proposed method performs significantly better in terms of tomographic reconstruction accuracy compared to unconstrained methods.</p>

show abstract

“…This two-data set process is the same for many other types of inversion algorithm and applications (e.g. [6], [7], [8], [9], [10], [11] and others).…”

Section: Introductionmentioning

confidence: 99%

Imaging and Calibration of Electromagnetic Inversion Data With a Single Data Set

Kim

Mohammadi

Asefi³

et al. 2022

IEEE Open J. Antennas Propag.

View full text Add to dashboard Cite

Electromagnetic Imaging (EMI) systems use a large number of co-resident antennas usually connected to a Vector Network Analyzer via a switch. A numerical model is used to model the physical electromagnetic problem and an inversion algorithm is used to invert the collected data to produce an image of the target. However, before the computer model can be used, the raw VNA measurements must be calibrated to bridge the computational model and the true system physics. Traditional calibration approaches usually require two data sets: a data set measured from a known target for calibration purposes and a data set measured for the unknown target. In this paper, we introduce a new calibration method to calibrate and image using a single S-parameter measurement of the unknown target only. We apply this method to EMI inside of grain bins. This proposed calibration workflow:(1) estimates the bulk contents of the grain bin using a parametric inversion and (2) uses the bulk results to subsequently estimate per-channel calibration coefficients for both the transmit and receive paths to each antenna. The novel calibration procedure is demonstrated via both synthetic and experimental results, showing that single-data set calibration can provide similar quality results as traditional two-data set calibration.

show abstract

Multiport calibration for microwave tomography systems

Cited by 4 publications

References 5 publications

Single Data Set Calibration and Imaging with Uncooperative Electromagnetic Inversion Systems

Single Data Set Calibration and Imaging with Uncooperative Electromagnetic Inversion Systems

Joint Calibration and Tomographic Reconstruction for Time-of-Flight Sensor Systems

Imaging and Calibration of Electromagnetic Inversion Data With a Single Data Set

Contact Info

Product

Resources

About