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51 result(s) for "Din, Iftikhar Ud"
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Frequency-Selective Surface-Based MIMO Antenna Array for 5G Millimeter-Wave Applications
In this paper, a radiating element consisting of a modified circular patch is proposed for MIMO arrays for 5G millimeter-wave applications. The radiating elements in the proposed 2 × 2 MIMO antenna array are orthogonally configured relative to each other to mitigate mutual coupling that would otherwise degrade the performance of the MIMO system. The MIMO array was fabricated on Rogers RT/Duroid high-frequency substrate with a dielectric constant of 2.2, a thickness of 0.8 mm, and a loss tangent of 0.0009. The individual antenna in the array has a measured impedance bandwidth of 1.6 GHz from 27.25 to 28.85 GHz for S11 ≤ −10 dB, and the MIMO array has a gain of 7.2 dBi at 28 GHz with inter radiator isolation greater than 26 dB. The gain of the MIMO array was increased by introducing frequency-selective surface (FSS) consisting of 7 × 7 array of unit cells comprising rectangular C-shaped resonators, with one embedded inside the other with a central crisscross slotted patch. With the FSS, the gain of the MIMO array increased to 8.6 dBi at 28 GHz. The radiation from the array is directional and perpendicular to the plain of the MIMO array. Owing to the low coupling between the radiating elements in the MIMO array, its Envelope Correlation Coefficient (ECC) is less than 0.002, and its diversity gain (DG) is better than 9.99 dB in the 5G operating band centered at 28 GHz between 26.5 GHz and 29.5 GHz.
Ultra-compact quintuple-band terahertz metamaterial biosensor for enhanced blood cancer diagnostics
Cancer and its diverse variations pose one of the most significant threats to human health and well-being. One of the most aggressive forms is blood cancer, originating from bone marrow cells and disrupting the production of normal blood cells. The incidence of blood cancer is steadily increasing, driven by both genetic and environmental factors. Therefore, early detection is crucial as it enhances treatment outcomes and improves success rates. However, accurate diagnosis is challenging due to the inherent similarities between normal and cancerous cells. Although various techniques are available for blood cancer identification, high-frequency imaging techniques have recently shown promise, particularly for real-time monitoring. Notably, terahertz (THz) frequencies offer unique advantages for biomedical applications. This research proposes an innovative terahertz metamaterial-based biosensor for high-efficacy blood cancer detection. The proposed structure is ultra-compact and operates across five bands within the range of 0.6 to 1.2 THz. It is constructed using a polyethylene terephthalate (PET) dielectric layer and two aluminum (Al) layers, with the top layer serving as a base for the THz-range resonator. Careful design, architectural arrangement, and optimization of the geometry parameters allow for achieving nearly perfect absorption rates (>95%) across all operating bands. The properties of the proposed sensor are extensively evaluated through full-wave electromagnetic (EM) analysis, which includes assessing the refractive index and the distribution of the electric field at individual working frequencies. The suitability for blood cancer diagnosis has been validated by integrating the sensor into a microwave imaging (MWI) system and conducting comprehensive simulation studies. These studies underscore the device’s capability to detect abnormalities, particularly in distinguishing between healthy and cancerous cells. Benchmarking against state-of-the-art biosensors in recent literature indicates that the proposed sensor is highly competitive in terms of major performance indicators while maintaining a compact size.
Design and validation of ultra-compact metamaterial-based biosensor for non-invasive cervical cancer diagnosis in terahertz regime
Cervical cancer belongs to the most dangerous types of cancers posing considerable threat to women’s survival. It is most often diagnosed in the advanced stages as precancerous lesions are often symptom-free and difficult to identify. Microwave imaging, especially in terahertz (THz) range, is a convenient and noninvasive cancer detection tool. It enables characterization of biological tissues and discrimination between healthy and malignant ones. This study presents a novel triple-band biosensor based on metamaterials (MTMs). By leveraging unique properties of MTMs, the proposed biosensor operates as a perfect absorber. It exploits resonant modes in the THz spectrum to achieve remarkable sensitivity. Meticulous selection of the sensor geometry and dimensions enables efficient miniaturization. Meanwhile, utilization of frequency-domain data to detect refractive index changes improves resolution of cancerous tissue identification. Extensive numerical investigations corroborate its ability to carry out reliable early-stage cervical cancer diagnosis. This includes identification of the spatial extent of the malignant tissue. Excellent electrical properties of the sensor are accompanied by its compact size, which is highly desirable for non-invasive and portable applications.
A Compact Four-Element Multiple-Input Multiple-Output Array with an Integrated Frequency Selective Surface for Millimeter-Wave Applications
A compact fork-shaped four-element multiple-input multiple-output (MIMO) antenna system with wide bandwidth for 5G millimeter-wave (mmWave) applications is presented. The antenna elements are arranged orthogonally to achieve a compact footprint of 20×26mm2. To enhance the gain, a frequency selective surface (FSS) is placed above the MIMO system, providing an average gain improvement of 1.5 dB across the entire operating band and achieving a peak gain of 7.5 dB at 41 GHz. The proposed design operates in the Ka-band (22–46 GHz), making it well suited for 5G communications. The antenna exhibits an isolation greater than 20 dB and radiation efficiency exceeding 80% across the band. Moreover, key MIMO performance metrics, including diversity gain (DG ≈ 10) and envelope correlation coefficient (ECC < 0.05), meet the required standards. A prototype of the proposed system was fabricated and measured, with the experimental results showing good agreement with simulations.
Improvement in the Gain of UWB Antenna for GPR Applications by Using Frequency-Selective Surface
In this article, high-gain ultra-wideband (UWB) monopole antenna is presented. The UWB monopole antenna is a semicircular-shaped antenna with a semicircular slot at the top side. The bottom plane consists of partial ground with triangular and rectangular slotted structures to improve the impedance bandwidth of the proposed antenna. In order to enhance gain, a 6×6 metallic reflector (FSS) is placed below the antenna. The performance of the offered design is validated experimentally. The simulated results show resemblance with the measured results. The antenna resonates for the UWB ranging from 3 to 11 GHz. Moreover, the integration of FSS improves the average gain by 4 dB, where peak gain obtained is 8.3 dB across the UWB. In addition, the reported unit cell having dimension of 0.11λ×0.11λ gives wide bandwidth (7.2 GHz) from 3.3 GHz to 10.5 GHz. The performance of the proposed antenna determines its suitability for the modern day wireless UWB and GPR applications.
A Novel and Compact Metamaterial‐Based Four‐Element MIMO Antenna System for Millimeter‐Wave Wireless Applications with Enhanced Isolation
A compact fork‐shaped MIMO antenna system with a 2 × 2 arrangement with four elements is presented. The MIMO elements are arranged orthogonally to achieve a small overall size of 36 × 28 mm 2 and a wide bandwidth for 5G mm‐wave applications. MIMO elements are positioned 4 mm from each corner of the substrate to achieve compact size and minimize coupling. To improve the isolation of the proposed MIMO system, a metamaterial slab is inserted in the middle of the substrate and between radiating elements of the MIMO antenna system, which improves isolation by 10 dB within the whole operating band and achieves maximum isolation of 65 dB at 34.5 GHz. The proposed MIMO system operates in the Ka‐band frequency range of 22–50 GHz with isolation greater than 30 dB and efficiency above 80% across the entire frequency spectrum for 5G communication. Additionally, the performance parameters of MIMO are examined, including diversity gain (DG) and envelope correlation coefficient (ECC), and it is found that they meet the required standards of DG approximately equal to 10 and ECC < 0.05. The proposed MIMO system has been fabricated and tested. The measured results are consistent with the design of the simulated structure using the CST Microwave Studio (CSTMWS) simulator.
How the Taliban undermined community healthcare in Swat, Pakistan
Iftikhar Ud Din, Zubia Mumtaz, and Anushka Ataullahjan examine the difficulties experienced by Pakistan’s lady health workers
Effectiveness of a brief group psychological intervention for women in a post-conflict setting in Pakistan: a single-blind, cluster, randomised controlled trial
Many women are affected by anxiety and depression after armed conflict in low-income and middle-income countries, yet few scalable options for their mental health care exist. We aimed to establish the effectiveness of a brief group psychological intervention for women in a conflict-affected setting in rural Swat, Pakistan. In a single-blind, cluster, randomised, controlled trial, 34 community clusters in two union councils of rural Swat, Pakistan, were randomised using block permutation at a 1:1 ratio to intervention (group intervention with five sessions incorporating behavioural strategies facilitated by non-specialists) or control (enhanced usual care) groups. Researchers responsible for identifying participants, obtaining consent, enrolment, and outcome assessments were masked to allocation. A community cluster was defined as neighbourhood of about 150 households covered by a lady health worker. Women aged 18–60 years who provided written informed consent, resided in the participating cluster catchment areas, scored at least 3 on the General Health Questionnaire-12, and at least 17 on the WHO Disability Assessment Schedule were recruited. The primary outcome, combined anxiety and depression symptoms, was measured 3 months after the intervention with the Hospital Anxiety and Depression Scale (HADS). Modified intention-to-treat analyses were done using mixed models adjusted for covariates and clusters defined a priori. The trial is registered with the Australian New Zealand Clinical Trials Registry, number 12616000037404, and is now closed to new participants. From 34 eligible community clusters, 306 women in the intervention group and 306 women in the enhanced usual care (EUC) group were enrolled between Jan 11, 2016, and Aug 21, 2016, and the results of 288 (94%) of 306 women in the intervention group and 290 (95%) of 306 women in the EUC group were included in the primary endpoint analysis. At 3 months, women in the intervention group had significantly lower mean total scores on the HADS than women in the control group (10·01 [SD 7·54] vs 14·75 [8·11]; adjusted mean difference [AMD] −4·53, 95% CI −7·13 to −1·92; p=0·0007). Individual HADS anxiety scores were also significantly lower in the intervention group than in the control group (5·43 [SD 4·18] vs 8·02 [4·69]; AMD −2·52, 95% CI −4·04 to −1·01), as were depression scores (4·59 [3·87] vs 6·73 [3·91]; AMD −2·04, −3·19 to −0·88). No adverse events were reported in either group. Our group psychological intervention resulted in clinically significant reductions in anxiety and depressive symptoms at 3 months, and might be a feasible and effective option for women with psychological distress in rural post-conflict settings. WHO through a grant from the Office for Foreign Disaster Assistance.
High-Isolation Array Antenna Design for 5G mm-Wave MIMO Applications
A low form-factor design of an eight-element antenna array is presented for 5G mm-wave MIMO applications. The design features modified circular patch radiators that achieve an impedance bandwidth of 2.6 GHz, covering frequencies from 37.7 to 40.3 GHz. The radiating elements are strategically arranged on opposite sides of a common substrate and interleaved to significantly reduce mutual coupling between adjacent elements. This innovative technique effectively minimizes coupling between the array’s radiators without the need of a decoupling structure. The MIMO antenna is fabricated on a low-loss Rogers-5880 substrate, with a thickness of 0.8 mm, a dielectric constant of 2.2, and a loss tangent of 0.0009, ensuring minimal signal loss and confirming the accuracy of simulation results. The inter-element isolation exceeds 25 dB, and the array provides a gain greater than 6 dBi, with a peak gain of 7.5 dBi at 39 GHz. This high gain enhances the antenna’s ability to mitigate atmospheric attenuation at higher frequencies, making it highly suitable for 5G mm-wave applications.
A Compact Frequency and Radiation Reconfigurable Antenna for 5G and Multistandard Sub-6 GHz Wireless Applications
This paper presents a reconfigurable antenna operating in three modes at different frequency bands with pattern reconfiguration. Frequency and pattern reconfigurability are achieved using four PIN diodes. In particular, two diodes are mounted in the radiating part of the hexagon shape to perform the frequency reconfiguration of the antenna. The other two PIN diodes are connected with the inverted L-shaped and CPW ground by changing the main lobe beam steering to achieve the pattern reconfiguration. An antenna has been designed, fabricated, and numerically and experimentally assessed. The prototype of the antenna is fabricated on a commercially available FR-4 substrate of thickness 1.6 mm (εr = 4.3). Thus, the proposed antenna supports several 5G sub-6 GHz bands (3.1 GHz, 4.1 GHz, and 3.8 GHz), WiFi (2.45 GHz), as well as (7.8 GHz, 9.5 GHz) X-Band Satellite applications. The obtained results are quite promising. In particular, it is observed that the measured results are in close agreement with the simulation results, and the proposed (compact) antenna prototype can be a prospective candidate for future portable devices, sensor networks, and telecommunication applications.