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Location estimation of a wireless capsule endoscope at 400 MHz MICS band is implemented here using both RSSI and TOA-based techniques and their performance investigated. To improve the RSSI-based location estimation, a maximum likelihood (ML) estimation method is employed. For the TOA-based localization, FDTD coupled with continuous wavelet transform (CWT) is used to estimate the time of arrival and...
Microwave imaging performance deteriorates with increasing clutter and heterogeneity in the imaging medium. Breast cancer detection becomes increasingly challenging with increasing breast density. Decomposition of the time reversal operator (DORT) uses signal subspace of the multistatic matrix which is perturbed in highly heterogeneous medium. To overcome the problem we propose coherent processing...
An implantable miniaturized planar inverted-F antenna (PIFA) that can operate over 2.45 GHz Industrial, Scientific, and Medical (ISM) band which occupies a small volume of 92 mm3 is proposed. The impedance characteristics of the proposed antenna are measured using experimental tissue mimicking phantoms. The proposed compact PIFA has a size of 8.1×7.1×1.6 mm3 which is tested using both numerical and...
In this study we consider coherent processing for time reversal microwave imaging for breast cancer detection. We derive coherent time reversal standard Capon beamformer (C-TR-SCB) and coherent time reversal robust Capon beamformer (C-TR-RCB) and compare their imaging performances for breast cancer detection in anatomically realistic heterogeneous 3-D breast phantoms.
We consider maximum likelihood based beamspace time reversal beamforming for breast cancer localization. We reduce the computational burden of maximum likelihood estimation through reduced dimensional beamspace processing. Beamspace processing also provides additional beamspace gain which contributes to suppress strong clutter effects. We collect multistatic scattering fields through FDTD simulation...
This paper presents a novel G-shaped compact monopole UWB antenna printed on FR4 substrate with coplanar waveguide (CPW) feeding. The proposed antenna operates over the frequency band between 3 and 11 GHz offering a fractional impedance bandwidth of around 110 %. The antenna is designed by analysing the modal currents calculated using the characteristic mode theory. Experimental results on reflection...
This paper presents the design of a triple-band implantable miniaturised slot PIFA antenna for Medical Implant Communication Service (MICS) band at 433MHz, Wireless Medical Telemetry Service (WMTS) band at 1430 MHz and Industrial, Scientific, and Medical (ISM) band at 2.4GHz. Simulations based on homogeneous and inhomogeneous phantoms are employed to design the proposed small antenna suitable for...
The time reversal (TR) based minimum variance beamforming, both the standard capon beamforming (SCB) and robust capon beamforming (RCB) techniques for microwave imaging of breast for early stage breast cancer detection is considered in this paper. The performance of coherent signal subspace processing for TR-SCB and TR-RCB techniques is investigated. We have used anatomically realistic numerical breast...
In this paper we investigate the detection of breast cancer using two-dimensional slices of realistic numerical phantoms employing time reversal microwave imaging. We used maximum-likelihood estimation coupled with time reversal technique to detect and estimate the location of tumor using FDTD based breast phantoms that contain dense fibroglandular tissue clutter. We show that time reversal maximum-likelihood...
This paper presents an implantable miniaturised printed E-shaped PIFA antenna for biomedical applications at 2.4 GHz. The design and measured results for the proposed antenna suitable for implanting either in the arm or under the chest are presented. Simulations are conducted using both homogeneous and inhomogeneous phantoms to help to design the proposed antenna. The measured results are obtained...
In this paper, we present a two-step convolutional perfectly matched layer (CPML) absorbing boundary condition for implicit locally 1-D finite difference time domain (LOD-FDTD) method for analysing 3-D microwave structures. We also derive a modified two-step LOD-FDTD algorithm which we will denote as C-LOD-FDTD. A comparison with the standard FDTD demonstrates the advantages of the proposed C-LOD-FDTD...
In this paper we investigate the localization of breast cancer in 3-D numerical breast phantoms using time reversal beamspace processing. FDTD method is employed to compute the scattered field inside an anatomically realistic numerical breast phantom. The beamspace processing is applied prior to the back propagation which obtains superior performance when compared to conventional time reversal imaging...
We consider electromagnetic inverse scattering using time reversal for microwave imaging for early stage breast cancer detection. Assuming that the malignant tissue inside the breast to be the strongest scatterer, we localize it by employing subspace based time reversal techniques viz., decomposition of the time reversal operator (DORT) and time reversal MUSIC. In denser breasts, the fibroglandular...
This paper investigates techniques of calibration of complex natural resonances (CNR) of dielectric targets embedded in inhomogeneous breast models used for early stage breast cancer detection. We apply two step procedure viz., calibration of CNRs in free space and half space dielectric medium, and compare with corresponding embedded conducting objects. We demonstrate that the CNRs related to the...
This paper describes a novel HF RFID multi loop bridge reader antenna for improved positioning and localization. Bridge configuration is employed to split reader recognition area and to obtain error signals for positioning. The proposed approach reduces uncertainties for HF-RFID reader based positioning even under sparse floor tag infrastructure. Simulation results highlight the usefulness of the...
Here we propose novel beamspace processing techniques to enhance the existing time reversal imaging techniques and demonstrate their capability for the detection of early stage breast cancer. Performance of the proposed imaging technique for the detection of malignant lesions has been investigated using the FDTD breast model that contains dense breast tissues that have differing composition of fibroglandular...
Structures with rotational symmetry (RS) are commonly encountered in many wireless systems that involve antennas and microwave filters. Such rotationally symmetric structures have body of revolution (BOR) symmetry which allows one to analytically extract the known azimuthal behaviour of the fields around the axis of symmetry, and to project the original three-dimensional problem to a numerically solvable...
Breast cancer is a common type of cancer among women all over the world. Successful treatment and prevention of death greatly depends on early detection. Mammography is so far the gold standard for screening breast cancer. But mammogram has high false positive rates for early stage detection and especially not highly reliable for younger women since their breasts are composed of dense breast tissues...
The radar based UWB microwave imaging techniques have shown great potential for the localization of embedded dielectric targets in breast phantoms [1], [2]. In practical UWB microwave imaging systems, antennas play a key role in determining the characteristics of the received signals. The antennas behave as spatial-temporal filters as they have to radiate narrow pulses and thus the radiated signal...
In this paper, the electromagnetic scattering from two-dimensional conducting and dielectric bodies is investigated by using locally one dimensional FDTD (LOD-FDTD) method. The scattered field formulation is presented for solving 2D TMz electromagnetic scattering problems. The computational domain of the scatterers is bounded by the convolutional perfectly matched layer (CPML) absorbing boundary condition...
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