The University of Manitoba Microwave Imaging Repository: A Two-Dimensional Microwave Scattering Database for Testing Inversion and Calibration Algorithms [Measurements Corner]

We present a repository of multi-static, near-field microwave scattering measurements. The data are presented both raw (uncalibrated), and calibrated with a scattered-field calibration. Measurements were taken with 24 co-resident Vivaldi antennas in a single plane, inside an air-filled microwave tomography system. The antennas were linearly polarized in the vertical direction, and we intended for the two-dimensional transverse magnetic (scalar) approximation to apply. Data are presented for seven targets, both metallic and dielectric, with varying geometrical complexity. Data from simple geometric targets, useful for calibration using analytic equations, are given. The repository is available from the Web site: http://www.ece.umanitoba.ca/lovetri/EMILab/index.html.

1. Introduction

Acommon issue in the inverse-scattering community is a lack of experimental scattering data. Experimental data is required to prove that imaging algorithms, which are typically first tested on synthetic data, will provide useful images in the real world. Databases such as the Ipswich (e.g., [1]–[4]) and Fresnel (e.g., [5]–[7]) databases have partially addressed this insufficiency. The Ipswich and Fresnel data were collected with a bistatic, mechanically scanned system, with antennas located in the far field. However, there are many applications, such as biomedical imaging or nondestructive testing, for which scattering data are better collected with a mechanically static near-field system. Advantages of near-field imaging include higher resolution [8],[9], but additional complications such as antenna coupling and a complicated incident field do occur. We are aware of one repository of near-field multi-static data [10], but this dataset is available pre-calibrated, with closely coupled antennas removed, and at a single frequency.