Malyhe Jalilvand

A Compact Double-Layer On-Body Matched Bowtie Antenna for Medical Diagnosis

A compact double-layer Bowtie antenna optimized for medical diagnosis is presented in this paper. This on-body antenna is matched to the human body to allow more energy to be radiated into the human body to obtain stronger reflections for image processing. By using a Bowtie antenna with double layers as well as a folded structure and meandered microstrip lines at the bottom of the antenna, a small size of 30 × 30 mm2 with a size reduction of 40% is achieved, compared to the reference antenna of 50 × 50 mm2 within the same operational frequency range. After the optimization of the antenna parameters, the antenna is characterized from 0.5 to 2 GHz, where the low frequencies enable a high penetration into human body and the large frequency range contributes to a high bandwidth and hence a fine range resolution. The simulated and measured results are shown with respect to the impedance matching, near-field pattern, gain and SAR distributions. With features such as a very small size, very low operational frequency, high front-to-back ratio, this design shows a high potential for use in medical diagnosis of stroke, breast cancer and water accumulation detection in the human body.

Realization Limits of Impulse-Based Localization System for Large-Scale Indoor Applications

In this paper, a 3D indoor localization demonstrator on the basis of impulse-radio ultrawideband (UWB) technology and time-difference-of-arrival (TDOA) principle is developed and analyzed. The parameters of the transmitter and receiver hardware components are investigated to determine their influence on the localization performance. The signal detection method based on a comparator and the precise time measurement unit was examined. Two effects, namely the threshold-trigger offset and the TDOA variance errors, were quantified. Corrections methods of both these phenomena have been proposed, which delivered very good results in the experiments. With the identified and modeled inaccuracies, the Cramer-Rao lower bound for a 3D TDOA localization system is derived for the first time and verified by measurements, performed in a large-scale industrial environment. The results obtained from measurements follow closely the variance predicted by the CRLB. Moreover, the comparison with the literature published up to date proves the excellent performance of the system presented here.

UWB synthetic aperture-based radar system for hemorrhagic head-stroke detection

In this paper, a synthetic aperture based ultra wideband imaging system with semi-adaptive signal processing is proposed for hemorrhagic stroke detection in a simulated head model. The 3D spherical model consists of four dispersive layers representing different parts of the head. In a bistatic configuration, two ultra wideband Vivaldi antennas sweep a semi-spherical synthetic array conformal to the model. As for image reconstruction algorithm, conventional delay and sum together with coherence weighting is applied to the backscattered signals. Through achieved simulation results, it is shown that ultra wideband radar concept has the potential of being an alternative imaging technique for stroke detection.

Design and near-field characterization of a planar on-body UWB slot-antenna for stroke detection

A planar UWB slot-antenna with a size of 35×35mm2 is proposed for stroke detection. The antenna is optimized for operation directly on human skin in the frequency range from 1 to 9 GHz. A sector-like slot is applied to the design to enhance the bandwidth regarding the current distribution. The near-field performance of the antenna is characterized and verified by the measurements. Benefiting from a symmetrical structure and differential feeding technique the antenna owns a very stable radiation behavior in the whole frequency range and a very high front-to-back ratio which would improve the stroke detection capability of the brain imaging system with robust performance.

Synthetic aperture-based UWB imaging system for detection of urine accumulation in human bladder

This paper presents a synthetic aperture-based UWB radar imaging system. The goal is to detect the urine accumulation in the human bladder. To verify this radar concept a bladder model with various human tissues including realistic dielectric properties is simulated. Two scan configurations with different antenna positions are used to investigate the influence of the synthetic aperture length and position number in the microwave images. To generate the imaging results, Delay and Sum algorithm together with coherent weighting is applied. The achieved imaging results demonstrate the possibility of detecting the position and volume of urine in the human bladder and therefore the potential application of this radar imaging system in the clinics for diagnosis purposes.

A multiband slotted Bowtie antenna for stroke detection

For stroke detection, low frequencies are required due to the increasing signal attenuation in human tissues with the frequency. In this paper a multiband slotted Bowtie antenna is proposed, which can be operated directly on or near to the skin. The antenna has a very small size of 26×34 mm2. Moreover, the operating bands are from 0.5 to 0.7 GHz and 1.3 to 4 GHz. The antenna is optimized in the simulation and verified through the measurements. The results show that the antenna provides a high potential for medical diagnostics such as human stroke detection.