A Wavefront Reconstruction Method for 3-D Cylindrical Subsurface Radar Imaging

Abstract

In recent years, the use of radar technology has been proposed in a wide range of subsurface imaging applications. Traditionally, linear scan trajectories are used to acquire data in most subsurface radar applications. However, novel applications, such as breast microwave imaging and wood inspection, require the use of nonlinear scan trajectories in order to adjust to the geometry of the scanned area. This paper proposes a novel reconstruction algorithm for subsurface radar data acquired along cylindrical scan trajectories. The spectrum of the collected data is processed in order to locate the spatial origin of the target reflections and remove the spreading of the target reflections which results from the different signal travel times along the scan trajectory. The proposed algorithm was successfully tested using experimental data collected from phantoms that mimic high contrast subsurface radar scenarios, yielding promising results. Practical considerations such as spatial resolution and sampling constraints are discussed and illustrated as well.

New horizons for microwave applications using spin caloritronics

“…Mathematically, the phase of the reflection varies according to the distance between the horn antenna, the target and the sensor following the equation Φ ¼ ωDðθÞ=c, where DðθÞ is the signal travel distance at the scan location θ. For broadband microwave measurements, the phase differences between the frequencies lead to the formation of a phase modulated signal with the form [32][33][34]:…”

“…Obviously, this time domain signal has a delay which is directly related to the signal travel time between the radiating antenna, the target and the receiving sensor. Using such reconstruction algorithms [32][33][34], the recorded data is converted to form the position of the object in space, which transfer the reflection spectra measured in the spatial-temporal domain to the spatial domain. The results of the reconstruction using the phase measured by a spin caloritronic sensor are shown in Fig.…”

A Bimodal Reconstruction Method for Breast Cancer Imaging

“…To properly assess the target dimensions and locations, the data must be reconstructed. An effective way of doing this is by using the wavefront reconstruction approach proposed in [13,27]. This method compensates the spectrum of the recorded responses by removing the effects of the scan geometry.…”

“…The result of this process is the image i p (x, y). A more detailed explanation of the cylindrical BMR holographic reconstruction technique is given in [13].…”

“…The most significant challenge that BMR imaging faces are the effects of the dense tissue structures in the breast region [6,[11][12][13]. Recent experimental studies have shown that these regions have conductivity and permittivity values that significantly limit the propagation of UWB signals used in BMR imaging [14,15].…”