UWB Microwave Imaging of Objects With Canonical Shape

Abstract

A novel technique for imaging based on ultrawideband (UWB) microwave signals is introduced. Specifically, the procedure deals with the Huygens Principle (HP); using HP to forward-propagate the waves removes the need to solve inverse problems and, consequently, no matrix generation/inversion is required. Together with its simplicity, the methodology permits the capture of contrast-the extent to which different media can be discriminated in the final image. Moreover, UWB allows all the information in the frequency domain to be utilized by combining the information from the individual frequencies to construct a consistent image. It follows that the methodology can identify the presence and location of significant scatterers inside a volume. Validation of the technique through both simulations and measurements on cylinder and spheres with inclusions has been performed. Application of the proposed technique to medical imaging is envisaged

Huygens Principle Based Imaging of Multilayered Objects With Inclusions

“…In this section, we briefly recall the HP based procedure, presented in [14], inserting some parts of [14] to help the reader in following and understanding the paper. Let us consider a cylinder with a radius a 0 in free space.…”

“…is the Green's function defined in [14], (ρ, φ) ≡ ρ the observation point, k 1 the wave number for the media constituting the cylinder, and ∆ s the spatial sampling value. In (14), the string "rcstr" is used to indicate the reconstructed internal field, while the string HP indicates that a HP-based procedure will be employed.…”

“…Here, we will describe the extension of a recently introduced UWB microwave imaging technique based on the Huygens Principle [14] for treating multilayered objects with inclusions. More in detail, we will first investigate analytically the propagation phenomena of UWB signal in human-like tissues (in contrast to conventional approaches based on Finite Difference Time Domain-FDTD methods); specifically, the body will be modeled as a 3-layer eccentric cylinder of infinite length, and Maxwell's equations will be solved.…”

“…More in detail, we will first investigate analytically the propagation phenomena of UWB signal in human-like tissues (in contrast to conventional approaches based on Finite Difference Time Domain-FDTD methods); specifically, the body will be modeled as a 3-layer eccentric cylinder of infinite length, and Maxwell's equations will be solved. Next, the UWB microwave imaging method introduced in [14] will be employed using both the analytical results and measurements obtained on appropriate phantoms. As stated earlier, the method is based on the Huygens Principle; using HP to forward propagate the waves removes the need to solve inverse problems, which in turn, removes the need for matrix generation/inversion.…”

“…Previously, the authors have performed successful simulation and measurement tests to validate the HP on canonical objects with single and multiple eccentric inclusions [14][15][16]. In this paper, stratified cylinders involving at least 3 different layers are used as models in both simulations and measurements.…”