A Modified Minimum-Coherence Sampling for Fast Spherical Near-Field Measurements

A modified compressed sampling based on minimal mutual coherence for spherical near-field measurements is proposed. After defining the sampling points for minimal coherence, more sampling points along the positioner mechanical path are added following the principles of equiangular sampling. Since the number or length of positioner movements is not increased, the measurement speed stays the same while the acquired information is increased. Exploiting the sparsity of the Spherical Mode Coefficients (SMC), the SMC vector is reconstructed using compressed-sensing techniques. This scheme is applied to measured data. Using the SMC calculated from a measurement using equiangular sampling, the data at the given sampling points is calculated. From these data, the SMC are reconstructed using basis pursuit. The reconstruction error is evaluated for schemes with a different number of sampling points. It is shown that the proposed sampling strategy allows for faster measurements for a given error level.