Miniaturized ultra wideband microstrip antenna based on a modified koch snowflake geometry for wireless applications

This paper presents a compact micro-strip patch antenna for ultra wideband (UWB) applications using a Koch Snowflake fractal radiating antenna. The antenna supports two ultra widebands. For the lower band, a good impedance bandwidth of 6.55GHz has been achieved from 3.4892GHz to 10.0392GHz. While the upper band covers 5.4976GHz (from 10.9013GHz to 16.3989GHz). It is fed by a 50? micro-strip transmission line with an overall size of 30x27 mm. The simulation was performed by Computer Simulation Technology (CST) MICROWAVE STUDIO software, and compared with High Frequency Structural Simulator (HFSS) software. The results show that the proposed antenna has interesting characteristics for UWB applications

Experimental Analysis on Effectiveness of Confocal Algorithm for Radar Based Breast Cancer Detection

Breast cancer is one of the most commonly diagnosed cancers in females in UK [1]. Early breast cancer detection which has recently been gaining a lot of consideration within the research community and the most important for a quick and effective treatment of the cancer is early detection. UWB radar based microwave imaging for early breast cancer detection is one of the most promising and attractive screening techniques currently under research. This technique offers several advantages such as low cost, better patient comfort, non-ionising and non-invasive radiation compared to X-Ray mammography. In this technique the breast is illuminated from various points with short UWB microwave pulse(s) and the collected backscattered energy is then processed to identify the presence and location of the tumour. In this thesis experimental measurement of the reflection coefficient in complex frequency domain is obtained from Vector Network Analyzer (VNA E5071) when the antenna is exposed to the environment and when the antenna is exposed to breast phantom. The tumor is simulated with different materials to investigate the effectiveness of the Confocal Microwave Imaging Algorithm for breast cancer detection. In addition, we used the materials at different depths to determine the effect of antenna distance to that of the tumor response. The Confocal Microwave Imaging (CMI) Algorithm for breast cancer detection is an easy and robust technique for tumor detection, which is used to approximate the precise location of the tumor. CMI is based on illuminating the breast with the UWB pulse from different antenna locations. The relative arrival times & amplitudes of the backscatter signals is used to estimate the location of the tumor. We applied the Confocal Algorithm in this study to the numerical data generated with the VNA and analyzed the results with different material(s) as tumor at different depth to verify its ability to estimate a tumor response

Parallel delay multiply and sum algorithm for microwave medical imaging using spark big data framework

Microwave imaging systems are currently being investigated for breast cancer, brain stroke and neurodegenerative disease detection due to their low cost, portable and wearable nature. At present, commonly used radar-based algorithms for microwave imaging are based on the delay and sum algorithm. These algorithms use ultra-wideband signals to reconstruct a 2D image of the targeted object or region. Delay multiply and sum is an extended version of the delay and sum algorithm. However, it is computationally expensive and time-consuming. In this paper, the delay multiply and sum algorithm is parallelised using a big data framework. The algorithm uses the Spark MapReduce programming model to improve its efficiency. The most computational part of the algorithm is pixel value calculation, where signals need to be multiplied in pairs and summed. The proposed algorithm broadcasts the input data and executes it in parallel in a distributed manner. The Spark-based parallel algorithm is compared with sequential and Python multiprocessing library implementation. The experimental results on both a standalone machine and a high-performance cluster show that Spark significantly accelerates the image reconstruction process without affecting its accuracy

FMCW Signals for Radar Imaging and Channel Sounding

A linear / stepped frequency modulated continuous wave (FMCW) signal has for a long time been used in radar and channel sounding. A novel FMCW waveform known as “Gated FMCW” signal is proposed in this thesis for the suppression of strong undesired signals in microwave radar applications, such as: through-the-wall, ground penetrating, and medical imaging radar. In these applications the crosstalk signal between antennas and the reflections form the early interface (wall, ground surface, or skin respectively) are much stronger in magnitude compared to the backscattered signal from the target. Consequently, if not suppressed they overshadow the target’s return making detection a difficult task. Moreover, these strong unwanted reflections limit the radar’s dynamic range and might saturate or block the receiver causing the reflection from actual targets (especially targets with low radar cross section) to appear as noise. The effectiveness of the proposed waveform as a suppression technique was investigated in various radar scenarios, through numerical simulations and experiments. Comparisons of the radar images obtained for the radar system operating with the standard linear FMCW signal and with the proposed Gated FMCW waveform are also made. In addition to the radar work the application of FMCW signals to radio propagation measurements and channel characterisation in the 60 GHz and 2-6 GHz frequency bands in indoor and outdoor environments is described. The data are used to predict the bit error rate performance of the in-house built measurement based channel simulator and the results are compared with the theoretical multipath channel simulator available in Matlab

Microwave Breast Imaging Techniques and Measurement Systems

Electromagnetic waves at microwave frequencies allow penetration into many optically non-transparent mediums such as biological tissues. Over the past 30 years, researchers have extensively investigated microwave imaging (MI) approaches including imaging algorithms, measurement systems and applications in biomedical fields, such as breast tumor detection, brain stroke detection, heart imaging and bone imaging. Successful clinical trials of MI for breast imaging brought worldwide excitation, and this achievement further confirmed that the MI has potential to become a low-risk and cost-effective alternative to existing medical imaging tools such as X-ray mammography for early breast cancer detection. This chapter offers comprehensive descriptions of the most important MI approaches for early breast cancer detection, including reconstruction procedures and measurement systems as well as apparatus

Application-Specific Broadband Antennas for Microwave Medical Imaging

The goal of this work is the introduction of efficient antenna structures on the basis of the requirement of different microwave imaging methods; i.e. quantitative and qualitative microwave imaging techniques. Several criteria are proposed for the evaluation of single element antenna structures for application in microwave imaging systems. The performance of the proposed antennas are evaluated in simulation and measurement scenarios

Quantitative interpretation of UWB radar images for non-invasive tissue temperature estimation during hyperthermia

The knowledge of temperature distribution inside the tissue to be treated is essential for patient safety, workflow and clinical outcomes of thermal therapies. Microwave imaging represents a promising approach for non-invasive tissue temperature monitoring during hyperthermia treatment. In the present paper, a methodology for quantitative non-invasive tissue temperature estimation based on ultra-wideband (UWB) radar imaging in the microwave frequency range is described. The capabilities of the proposed method are demonstrated by experiments with liquid phantoms and three-dimensional (3D) Delay-and-Sum beamforming algorithms. The results of our investigation show that the methodology can be applied for detection and estimation of the temperature induced dielectric properties change