Recovering scattering obstacles by multi-frequency phaseless far-field data
For inverse scattering problems, this provides a method to recover both location and shape from phaseless data, overcoming a fundamental limitation of single-frequency single-plane-wave setups.
The paper breaks the translation invariance of phaseless far-field data by using superpositions of two plane waves across multiple frequencies, enabling simultaneous recovery of both location and shape of scattering obstacles. A recursive Newton-type algorithm is developed and validated with numerical examples.
It is well known that the modulus of the far-field pattern (or phaseless far-field pattern) is invariant under translations of the scattering obstacle if only one plane wave is used as the incident field, so the shape but not the location of the obstacle can be recovered from the phaseless far-field data. In this paper, it is proved that the translation invariance property of the phaseless far-field pattern can be broken if superpositions of two plane waves are used as the incident fields for all wave numbers in a finite interval. Based on this, a recursive Newton-type iteration algorithm in frequencies is then developed to recover both the location and the shape of the obstacle simultaneously from multi-frequency phaseless far-field data. Numerical examples are also carried out to illustrate the validity of the approach and the effectiveness of the inversion algorithm.