Metamaterial-inspired antenna array for application in microwave breast imaging systems for tumor detection

This paper presents a study of a planar antenna-array inspired by the metamaterial concept where the resonant elements have sub-wavelength dimensions for application in microwave medical imaging systems for detecting tumors in biological tissues. The proposed antenna consists of square-shaped concentric-rings which are connected to a central patch through a common feedline. The array structure comprises several antennas that are arranged to surround the sample breast model. One antenna at a time in the array is used in transmission-mode while others are in receive-mode. The antenna array operates over 2-12 GHz amply covering the frequency range of existing microwave imaging systems. Measured results show that compared to a standard patch antenna array the proposed array with identical dimensions exhibits an average radiation gain and efficiency improvement of 4.8 dBi and 18%, respectively. The average reflection-coefficient of the array over its operating range is better than S-11 <= -20 dB making it highly receptive to weak signals and minimizing the distortion encountered with the transmission of short duration pulse-trains. Moreover, the proposed antenna-array exhibits high-isolation on average of 30dB between radiators. This means that antennas in the array (i) can be closely spaced to accommodate more radiators to achieve higher-resolution imaging scans, and (ii) the imagining scans can be done over a wider frequency range to ascertain better contrast in electrical parameters between malignant tumor-tissue and the surrounding normal breast-tissue to facilitate the detection of breast-tumor. It is found that short wavelength gives better resolution. In this experimental study a standard biomedical breast model that mimics a real-human breast in terms of dielectric and optical properties was used to demonstrate the viability of the proposed antenna over a standard patch antenna in the detection and the localization of tumor. These results are encouraging for clinical trials and further refinement of the antenna-array

Bandwidth and gain enhancement of composite right left handed metamaterial transmission line planar antenna employing a non foster impedance matching circuit board

The paper demonstrates an effective technique to significantly enhance the bandwidth and radiation gain of an otherwise narrowband composite right/left-handed transmission-line (CRLH-TL) antenna using a non-Foster impedance matching circuit (NF-IMC) without affecting the antenna's stability. This is achieved by using the negative reactance of the NF-IMC to counteract the input capacitance of the antenna. Series capacitance of the CRLH-TL unit-cell is created by etching a dielectric spiral slot inside a rectangular microstrip patch that is grounded through a spiraled microstrip inductance. The overall size of the antenna, including the NF-IMC at its lowest operating frequency is 0.335 lambda (0)x0.137 lambda (0)x0.003 lambda (0), where lambda (0) is the free-space wavelength at 1.4 GHz. The performance of the antenna was verified through actual measurements. The stable bandwidth of the antenna for |S-11|<= -18 dB is greater than 1 GHz (1.4-2.45 GHz), which is significantly wider than the CRLH-TL antenna without the proposed impedance matching circuit. In addition, with the proposed technique the measured radiation gain and efficiency of the antenna are increased on average by 3.2 dBi and 31.5% over the operating frequency band

Breast Cancer Detection Based on Simplified Deep Learning Technique With Histopathological Image Using BreaKHis Database

Presented here are the results of an investigation conducted to determine the effectiveness of deep learning (DL)-based systems utilizing the power of transfer learning for detecting breast cancer in histopathological images. It is shown that DL models that are not specifically developed for breast cancer detection can be trained using transfer learning to effectively detect breast cancer in histopathological images. The outcome of the analysis enables the selection of the best DL architecture for detecting cancer with high accuracy. This should facilitate pathologists to achieve early diagnoses of breast cancer and administer appropriate treatment to the patient. The experimental work here used the BreaKHis database consisting of 7909 histopathological pictures from 82 clinical breast cancer patients. The strategy presented for DL training uses various image processing techniques for extracting various feature patterns. This is followed by applying transfer learning techniques in the deep convolutional networks like ResNet, ResNeXt, SENet, Dual Path Net, DenseNet, NASNet, and Wide ResNet. Comparison with recent literature shows that ResNext-50, ResNext-101, DPN131, DenseNet-169 and NASNet-A provide an accuracy of 99.8%, 99.5%, 99.675%, 99.725%, and 99.4%, respectively, and outperform previous studies

Minkowski Based Microwave Resonator for Material Detection over Sub-6 GHz 5G Spectrum

This paper describes the performance of a low-cost, high-sensitive microwave resonator for 5G modern wireless communication systems operating through sub-6GHz spectrum. Here, the proposed resonator is constructed from a Minkowski fractal open stub that is coupled to an interdigital capacitor. It is fetched to a circular spiral inductor structure with a back loop to increase the resonator quality and it operates at a frequency resonance of 524 MHz. Since the purpose of the study is to apply such technology to characterize liquid properties, the presented resonator is mounted on an FR4 substrate with a thickness of 1.6 mm and an area of 40× 60 mm2, Using CST MWS commercial software, the resulting design dimensions are optimized. The proposed design performance which is demonstrated in terms of S21 magnitude is found to vary significantly by the variations in the photo-resistor. Such a property motivated the authors to consider it for material detection as the frequency stability with a photo-resistor value change is relative to the light incidence. In such a manner, the achieved results are found to behave linearly without discrepancy due to the effects of diffraction from the resonator layers. This technology is frequently used as a strong contender for a variety of contemporary wireless technologies that may invoke optical-based interface systems

Design of Compact Flexible UWB Antenna Using Different Substrate Materials for WBAN Applications

In this paper, the design process of compact flexible ultra-wideband (UWB) antenna using various substrate materials such as FR4, Kapton, and Rogers RT5880 is discussed and experimentally investigated. The proposed antenna is structured as a flexible model that can conform to suite the human body surface to be suitable for wireless body area network (WBAN) applications. The performance parameters of the antenna have been evaluated by using CST Microwave Studio software and very similar results have been achieved by applying FR4, Kapton, and Rogers RT5880 substrates, but the latter substrate provides optimized results. Therefore, the Rogers RT5880 substrate was chosen to realize the experimental antenna to validate its performance. There was excellent agreement between the simulated and measured results. The proposed antenna is miniature having dimensions of 22×28×1.6 mm3 and operates at dual band across 4.8-5.3 GHz and 7.0-8.6 GHz. It has a high gain above 5.5 dBi at both bands and radiates omnidirectionally. Moreover, it has a simple geometry making it easy to manufacture and is therefore cost effective. This antenna is applicable for wireless body area network (WBAN)