In this paper, a complementary split-ring resonator (CSRR)-loaded patch is proposed as a microfluidic ethanol chemical sensor The primary objective of this chemical sensor is to detect ethanol's concentration First, two tightly coupled concentric CSRRs loaded on a patch are realized on a Rogers RT/Duroid 5870 substrate, and then a microfluidic channel engraved on polydimethylsiloxane (PDMS) is integrated for ethanol chemical sensor applications The resonant frequency of the structure before loading the microfluidic channel is 472 GHz After loading the microfluidic channel, the 550 MHz shift in the resonant frequency is ascribed to the dielectric perturbation phenomenon when the ethanol concentration is varied from 0% to 100% In order to assess the sensitivity range of our proposed sensor, various concentrations of ethanol are tested and analyzed Our proposed sensor exhibits repeatability and successfully detects 10% ethanol as verified by the measurement set-up It has created headway to a miniaturized, non-contact, low-cost, reliable, reusable, and easily fabricated design using extremely small liquid volumes

https://www.mdpi.com/1424-8220/16/11/1802/pdf

Complementary Split-Ring Resonator-Loaded Microfluidic Ethanol Chemical Sensor.

Globally, breast cancer is a major reason for female mortality. Due to the limitations of current clinical imaging, the researchers are encouraged to explore alternative and complementary tools to available techniques to detect the breast tumor in an earlier stage. This article outlines a new, portable, and low-cost microwave imaging (MWI) system using an iterative enhancing technique for breast imaging. A compact side slotted tapered slot antenna is designed for microwave imaging. The radiating fins of tapered slot antenna are modified by etching nine rectangular side slots. The irregular slots on the radiating fins enhance the electrical length as well as produce strong directive radiation due to the suppression of induced surface currents that radiate vertically at the outer edges of the radiating arms with end-fire direction. It has remarkable effects on efficiency and gain. With the addition of slots, the side-lobe levels are reduced, the gain of the main-lobe is increased and corrects the squint effects simultaneously, thus improving the characteristics of the radiation. For experimental validation, a heterogeneous breast phantom was developed that contains dielectric properties identical to real breast tissues with the inclusion of tumors. An alternative PC controlled and microcontroller-based mechanical MWI system is designed and developed to collect the antenna scattering signal. The radiated backscattered signals from the targeted area of the human body are analyzed to reveal the changes in dielectric properties in tissues. The dielectric constants of tumorous cells are higher than that of normal tissues due to their higher water content. The remarkable deviation of the scattered field is processed by using newly proposed Iteratively Corrected Delay and Sum (IC-DAS) algorithm and the reconstruction of the image of the phantom interior is done. The developed UWB (Ultra-Wideband) antenna based MWI has been able to perform the detection of tumorous cells in breast phantom that can pave the way to saving lives.

/pdf/a-low-cost-and-portable-microwave-imaging-system-for-breast-4tdguxwfma.pdf

A Low Cost and Portable Microwave Imaging System for Breast Tumor Detection Using UWB Directional Antenna array

A novel compact dual-band cavity-backed substrate integrated waveguide (SIW) array antenna using high-order radiation modes has been proposed in this paper. The first high-order hybrid mode (superposition of TM310 and TM130) and the second high-order mode (TM320) of K-band in the SIW cavity are excited by an inductive window for dual-band application. The operation mechanism of high-order modes is analyzed and then verified through simulations by inserting metallic vias in different positions of the resonant SIW cavity. The designed subarray antenna has the advantages of high gain, high front-to-back ratio, and low cross-polarization level. To further validate the design idea, a dual-frequency band $2 \times 2$ array antenna has been fabricated and measured including reflection coefficients, realized gains, and radiation patterns. The measured results show that the 10-dB impedance bandwidths at resonant frequencies of 21 and 26 GHz are 800 MHz (3.7%) and 700 MHz (2.6%), and the realized gains at boresight direction are around 16 and 17.4 dBi, respectively. Moreover, the proposed array antenna also possesses both advantages of metallic cavity-backed antennas and planar patch antennas, such as low cost, easy fabrication with the printed circuit board technology, and integration with other planar circuits.

Substrate Integrated Waveguide Cavity-Backed Slot Array Antenna Using High-Order Radiation Modes for Dual-Band Applications in $K$ -Band

This paper investigates the possibility of applying novel microwave sensors for crack detection in reinforced concrete structures. Initially, a microstrip patch antenna with a split ring resonator (SRR) structure was designed, simulated and fabricated. To evaluate the sensor’s performance, a series of structural tests were carried out and the sensor responses were monitored. Four reinforced concrete (RC) beam specimens, designed according to the European Standards, were tested under three-point bending. The load was applied incrementally to the beams and the static responses were monitored via the use of a load cell, displacement transducers and crack width gauges (Demec studs). In parallel, signal readings from the microwave sensors, which were employed prior to the casting of the concrete and located along the neutral axis at the mid-span of the beam, were recorded at various load increments. The microwave measurements were analysed and compared with those from crack width gauges. A strong linear relationship between the crack propagation and the electromagnetic signal across the full captured spectrum was found, demonstrating the technique’s capability and its potential for further research, offering a reliable, low-cost option for structural health monitoring (SHM).

https://www.mdpi.com/1424-8220/19/23/5175/pdf

Novel Electromagnetic Sensors Embedded in Reinforced Concrete Beams for Crack Detection

In this paper, a compact metamaterial multiband antenna is proposed for wireless local area network (WLAN), worldwide interoperability for microwave access (WiMAX) and international telecommunication union (ITU) band applications using a modified Triangular Split Ring Resonator (TSRR). In this work, we designed a modified TSRR with metamaterial property to obtain desirable negative permeability bands that help in accommodating all three frequency bands of interest in a single device. This approach leads to the considerable reduction of the device structure. The overall dimension of the proposed antenna structure has a compact size of 25.7 × 23.2 × 1.6 mm 3 and covers specific bands from the frequency spectra of 2.4/5.2/5.8, 3.5, and 8.2 GHz for WLAN, WiMAX, and ITU, respectively, with uniform radiation characteristics. The designed antenna structure is simulated using the High Frequency Structural Simulator (HFSS), and a prototype is developed and tested. The detailed analysis of the results obtained is presented. It is determined that the performance of the proposed antenna is superior to that of the existing antennas in the literature.

A compact metamaterial multiband antenna for WLAN/WiMAX/ITU band applications

A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR) and capacitance-loaded strip (CLS) unit cells is presented for Ultra wideband (UWB) microwave imaging applications. Four left-handed (LH) metamaterial (MTM) unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR) with a capacitance-loaded strip (CLS) to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm³, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4-12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.

A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications.

This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 16 mm and a dielectric constant of 46 The electrical dimensions of this antenna sensor are 020 λ × 029 λ at a lower frequency of 31 GHz This antenna sensor achieves a 1315% bandwidth (VSWR < 2) covering the frequency bands from 31 GHz to more than 15 GHz with a maximum gain of 657 dBi High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors

/pdf/a-negative-index-metamaterial-inspired-uwb-antenna-with-an-4o49f5fu5w.pdf

A Negative Index Metamaterial-Inspired UWB Antenna with an Integration of Complementary SRR and CLS Unit Cells for Microwave Imaging Sensor Applications

The dual-band operation of a microstrip patch antenna on a Duroid 5870 substrate for Ku- and K-bands is presented. The fabrication of the proposed antenna is performed with slots and a Duroid 5870 dielectric substrate and is excited by a 50 Ω microstrip transmission line. A high-frequency structural simulator (HFSS) is used which is based on the finite element method (FEM) in this research. The measured impedance bandwidth (2 : 1 VSWR) achieved is 1.07 GHz (15.93 GHz–14.86 GHz) on the lower band and 0.94 GHz (20.67–19.73 GHz) on the upper band. A stable omnidirectional radiation pattern is observed in the operating frequency band. The proposed prototype antenna behavior is discussed in terms of the comparisons of the measured and simulated results.

/pdf/dual-band-operation-of-a-microstrip-patch-antenna-on-a-52s9ctkvf2.pdf

Dual-Band Operation of a Microstrip Patch Antenna on a Duroid 5870 Substrate for Ku- and K-Bands

The design of a compact metamaterial ultra-wideband (UWB) antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. This proposed UWB antenna is made of four metamaterial unit cells, where each cell is an integration of a modified split ring resonator (SRR), capacitive loaded strip (CLS) and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A low-cost FR4 substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 1.6 mm, relative permeability of one, relative permittivity of 4.60 and loss tangent of 0.02. The overall antenna size is 19.36 mm × 27.72 mm × 1.6 mm where the electrical dimension is 0.20 λ × 0.28 λ × 0.016 λ at the 3.05 GHz lower frequency band. Voltage Standing Wave Ratio (VSWR) measurements have illustrated that this antenna exhibits an impedance bandwidth from 3.05 GHz to more than 15 GHz for VSWR < 2 with an average gain of 4.38 dBi throughout the operating frequency band. The simulations (both HFSS and computer simulation technology (CST)) and the measurements are in high agreement. A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor.

/pdf/microwave-imaging-sensor-using-compact-metamaterial-uwb-2c4ewljaua.pdf

Microwave Imaging Sensor Using Compact Metamaterial UWB Antenna with a High Correlation Factor

In this paper, an X-band microstrip patch antenna has been presented with enhanced bandwidth. The proposed antenna is designed on 40 mm×40mm printed circuit board and is excited by microstrip line. Commercially available High Frequency Structural Simulator (HFSS) is adopted in this study This antenna is composed of rectangular and circular slots to generate two resonances and to increase bandwidth in the desired band. Return loss -17.14 dB and -14.29 dB are obtained below -10 dB in the desired X-band (8GHz-12GHz). It has achieved stable radiation efficiency 78.85% with average peak gain 4.31 dBi in the operating frequency band. The proposed antenna has an impedance bandwidth 1.59 GHz. The proposed X-band patch antenna is discussed and presented in detail.

M. M. Islam

Papers

A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications.

A Negative Index Metamaterial-Inspired UWB Antenna with an Integration of Complementary SRR and CLS Unit Cells for Microwave Imaging Sensor Applications

Dual-Band Operation of a Microstrip Patch Antenna on a Duroid 5870 Substrate for Ku- and K-Bands

Microwave Imaging Sensor Using Compact Metamaterial UWB Antenna with a High Correlation Factor

Design of an X-band microstrip patch antenna with enhanced bandwidth