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Recent Submissions

  • Orientation Aware Intelligent 3D Cubic Antenna System with Automated Radiation Pattern Reconfigurability

    Bermudez Arboleda, Maria; Klionovski, Kirill; Su, Zhen; Shamim, Atif (IEEE Open Journal of Antennas and Propagation, IEEE, 2022-07-12) [Article]
    With the era of Internet of Things (IoT), antennas that can adapt to different radio frequency environments have become highly desirable. These reconfigurable antennas must be compact to suit the futuristic IoT devices, be low cost for implementation on billions of devices, and be robust to the presence of nearby electronics. This paper demonstrates a novel 2.4 GHz 3D Cubic Antenna System, which comprises of a cube package with six microstrip patch antennas, one on each face. The system with embedded electronics, is aware of its orientation and reconfigures its radiation pattern automatically by switching ON the appropriate patch antenna for a focused communication with a boresight receiver. Alternately, if the position of the receiver is unknown, a quasi-isotropic radiation pattern can be achieved by providing the right phase conditions to all the patches to radiate simultaneously. The ground plane of the antennas provides a shield between the radiators and the electronics. In the focused mode, 10 dB more power is received as compared to the quasi-isotropic mode, which results in an energy efficient communication. While the quasi-isotropic mode provides an all-around radiation coverage with a gain variation of 6.4 dB for the entire 3D sphere, which is one of the best reported experimental value in literature for IoT compatible antenna systems.
  • Rapid and up-scalable manufacturing of gigahertz nanogap diodes

    Loganathan, Kalaivanan; Faber, Hendrik; Yengel, Emre; Seitkhan, Akmaral; Bakytbekov, Azamat; Yarali, Emre; Adilbekova, Begimai; AlBatati, Afnan; Lin, Yuanbao; Felemban, Zainab; Yang, Shuai; Li, Weiwei; Georgiadou, Dimitra G; Shamim, Atif; Lidorikis, Elefterios; Anthopoulos, Thomas D. (Nature Communications, Springer Science and Business Media LLC, 2022-06-07) [Article]
    The massive deployment of fifth generation and internet of things technologies requires precise and high-throughput fabrication techniques for the mass production of radio frequency electronics. We use printable indium-gallium-zinc-oxide semiconductor in spontaneously formed self-aligned <10 nm nanogaps and flash-lamp annealing to demonstrate rapid manufacturing of nanogap Schottky diodes over arbitrary size substrates operating in 5 G frequencies. These diodes combine low junction capacitance with low turn-on voltage while exhibiting cut-off frequencies (intrinsic) of >100 GHz. Rectifier circuits constructed with these co-planar diodes can operate at ~47 GHz (extrinsic), making them the fastest large-area electronic devices demonstrated to date.
  • Co-Design of Dual-Purpose Heatsink Antenna for Multi-Source Ambient Energy Harvesting

    Bakytbekov, Azamat; Shamim, Atif (IEEE, 2022-05-11) [Conference Paper]
    IoT infrastructure involves billions of devices that must be self-sustainable. Using ambient energy sources to power IoT devices is a promising solution. Ambient RF and thermal energy (diurnal temperature fluctuations) harvesters have great potential since both are available continuously. Smart integration is required for these two harvesters to create synergy and collect more energy. Here, a dual-purpose triple-band heatsink antenna for multi-source ambient energy harvesting is presented. Heatsink antenna serves as a receiving antenna for the RF energy harvester and serves as a heatsink for the thermal energy harvester (TEH). Co-optimization of the heatsink antenna is performed in Ansys HFSS and Ansys Fluent simultaneously. Heatsink antenna operates at GSM900, GSM1800, 3G bands with measured gains of 3.8dB, 4dB, 5.3dB respectively. Antenna gain is doubled (~3dB) and the TEH performance is tripled (200%) when the heatsink fins are integrated, emphasizing the benefit of the co-design and smart integration via heatsink antenna.
  • A fully-screen printed, multi-layer process for bendable mm-wave antennas

    Akhter, Zubair; Li, Weiwei; Yu, Yiyang; Shamim, Atif (IEEE, 2022-05-11) [Conference Paper]
    In the era of Internet of Things (IoT) and wearable electronics; printing technique, such as screen printing, is becoming popular because of their lower costs and mass manufacturing abilities. However, most of the previous work has been done on printing metallic patterns and not the printing substrates. In this paper, we introduce a custom screen printable dielectric ink (polymer mixed with ceramics), which provides lower loss even at millimeter-wave (mm-wave) bands. With the help of dielectric ink and custom silver nanowires (AgNW) based metallic ink, a multilayer, fully screen-printed fabrication process has been developed. To demonstrate the efficacy of the proposed inks and the multilayer printing process, a stacked patch antenna with 4-parasitic patches in the superstrate is designed, fabricated, and tested for the mm-wave band (5G band). Despite a new fabrication process, the measured results show a decent antenna performance (both in flat and bent positions) where the input impedance is matched from 26.5-30 GHz and a maximum gain of 7.8 dBi has been attained.
  • A Fully-Printed 3D Antenna with 92% Quasi-Isotropic and 85% CP Coverage

    Su, Zhen; Klionovski, Kirill; Liao, Hanguang; Li, Weiwei; Shamim, Atif (IEEE Transactions on Antennas and Propagation, IEEE, 2022-04-25) [Article]
    Internet of things (IoT) applications require orientation insensitive wireless devices to maintain stable and reliable communication. For those reasons, antennas providing a wide quasi-isotropic and circular polarization (CP) coverage are very attractive. However, achieving a wide quasi-isotropic and CP coverage simultaneously is challenging. In this work, we show that properly designed sloped dipoles on a 3D structure can maximize the CP coverage (theoretically up to 100%) even with equal-phased feed to the dipole elements. We derive the conditions and present the design graphs for the optimum slope angle for the dipole elements on a 3D hexagonal-shaped package to achieve a wide quasi-isotropic and CP coverage simultaneously. Based on the proposed theory, a practical antenna has been designed and fabricated using additive manufacturing. The measured results demonstrate a 7dB-isotropy of 92% and a CP coverage of 85%, which matches well with the predicted results from the theoretical analysis and full-wave simulations.
  • Optimization of ANN -based models and its EM co-simulation for printed RF devices

    Yang, Shuai; Khusro, Ahmad; Li, Weiwei; Vaseem, Mohammad; Hashmi, Mohammad; Shamim, Atif (International Journal of RF and Microwave Computer-Aided Engineering, Wiley, 2021-11-30) [Article]
    Printed VO2 RF switch founds immense potential in RF reconfigurable applications. However, their generic electrical equivalent model is still intangible that can be further integrated in CAD tools and utilize for simulation, analysis and design of RF/microwave circuits and systems. The artificial neural network (ANN) has been gaining popularity in modeling various types of RF components. However, most of these works merely demonstrate the establishment of the ANN-based RF model in the MATLAB environment without involving significant optimization. Furthermore, the integration of such ANN-based RF models in the EM and circuit simulator as well as the co-simulation between the ANN-based model and conventional models have not been demonstrated or validated. Therefore, the earlier reported models are still one step removed from its real RF applications. In this work, by using the fully printed vanadium dioxide (VO2) RF switch as the modeling example, a systematic hyperparameter optimization process has been conducted. Compared to the non-optimized ANN model, a dramatic improvement in the model's accuracy has been observed for the ANN model with fully optimized hyperparameters. A correlation coefficient of more than 99.2% for broad frequency range demonstrates the accuracy of the modeling technique. In addition, we have also integrated the Python-backed ANN-based model into Advanced Design System (ADS), where a reconfigurable T-resonator band stop filter is used as an example to demonstrate the co-simulation between the ANN-based model and the conventional lumped-based model.
  • Hertzian Magnetic Dipoles Model of a Quasi-isotropic radiation microstrip patch based Antenna-in-Package

    Bermudez Arboleda, Maria; Klionovski, Kirill; Su, Zhen; Shamim, Atif (IEEE, 2021-08-23) [Conference Paper]
    The Internet of Things applications require small wireless sensors with quasi isotropic radiation, so that their placement is orientation insensitive. This paper shows the design steps for a microstrip patch based quasi-isotropic Antenna-in-Package (AiP). The structure proposed is a hollow cube with six microstrip patch radiators, one on each of its faces. The cubes internal walls are metallized to not only act as ground planes for the microstrip patch antennas, but also provide the necessary shielding between the radiators and the future embedded electronics. Thus, the problem in hand is to find the optimal phases to be applied to each patch so that when all six are activated simultaneously, the obtained radiation pattern is quasi-isotropic. Given the complexity of the structure, a simplified model of Hertzian magnetic dipoles was used to determine the phase each patch was to be excited to achieve the closest to an isotropic radiator as possible. A measured gain variation of 6.5 dB has been achieved for the entire 3D sphere after fabrication of a prototype.
  • Screen-Printed Depolarizing Chipless RFID Tag Based on Asymmetric Configurations

    Wang, Ruiqi; Akhter, Zubair; Li, Weiwei; Shamim, Atif (IEEE, 2021-08-08) [Conference Paper]
    A novel compact cross-polar chipless RFID tag with a ground plane is proposed in this paper. The proposed tag has multiple unbalanced resonators, i.e., the two arms of U-shaped with unequal length. These unequal arms are employed to generate the depolarizing (cross-polar) radar cross-section (RCS) response. The ground plane with the help of depolarizing identification enables this tag to be attached to highly reflective or absorptive background media such as metal or the human body. Low-cost screen printing has been adapted fabrication of the tag. The proposed tag presented in a 2 × 2 array configuration can encode 6-bits with a total size of 80 × 80 × 1 mm3.
  • CVD-Grown Monolayer Graphene-Based Geometric Diode for THz Rectennas

    Wang, Heng; Jayaswal, Gaurav; Deokar, Geetanjali; Stearns, John; Da Costa, Pedro M. F. J.; Moddel, Garret; Shamim, Atif (Nanomaterials, MDPI AG, 2021-08-02) [Article]
    For THz rectennas, ultra-fast diodes are required. While the metal–insulator–metal (MIM) diode has been investigated in recent years, it suffers from large resistance and capacitance, as well as a low cut-off frequency. Alternatively, a geometric diode can be used, which is more suitable due to its planar structure. However, there is only one report of a THz geometric diode based on a monolayer graphene. It is based on exfoliated graphene, and thus, it is not suitable for mass production. In this work, we demonstrate chemical vapor deposition (CVD)-grown monolayer graphene based geometric diodes, which are mass-producible. The diode’s performance has been studied experimentally by varying the neck widths from 250–50 nm, the latter being the smallest reported neck width for a graphene geometric diode. It was observed that by decreasing the neck widths, the diode parameters such as asymmetry, nonlinearity, zero-bias resistance, and responsivity increased within the range studied. For the 50 nm neck width diode, the asymmetry ratio was 1.40 for an applied voltage ranging from −2 V to 2 V, and the zero-bias responsivity was 0.0628 A/W. The performance of the diode was also verified through particle-in-cell Monte Carlo simulations, which showed that the simulated current-voltage characteristics were consistent with our experimental results.
  • Single feed dual-band RHCP dielectric resonator antenna for GNSS applications

    Mansoor, Saad; Shoaib, Nosherwan; Cheema, Hammad M.; Shamim, Atif (Institute of Electrical and Electronics Engineers Inc., 2021-08-01) [Conference Paper]
    A single-fed right-handed circularly polarized (RHCP) dielectric resonator antenna (DRA) with in-band filtering for Global Navigation Satellite Systems (GNSS) application is proposed. The design is implemented by placing rectangular DR material above feeding slots through which, two sets of degenerate orthogonal modes, the TE111 and higher order TE112 mode, are simultaneously excited to achieve circular polarization. The proposed antenna employed simplified structure and feed network to filter antenna radiation between 1.30 and 1.5 GHz to reject in-band interference from L-band satellite and terrestrial communication signals. An antenna prototype is fabricated and tested to validate performance of proposed design with a total antenna size of 103×87.5×50mm3. The measured -10 dB impedance and axial ratio bandwidth are approximately 11.03% (1.164 - 1.3 GHz) and 3.21% (1.559-1.61 GHz) in lower and higher band of GNSS respectively. The gain is found to be of 4 dBi within passband with maximum value of 5.5 dBi at 1.56 GHz.
  • Human tissues parameters and resolution for accurate simulations of wearable antennas

    Chen, Yiming; Kaburcuk, Fatih; Lumnitzer, Rachel; Elsherbeni, Atef Z.; Demir, Veysel; Shamim, Atif (Institute of Electrical and Electronics Engineers Inc., 2021-08-01) [Conference Paper]
    In this paper, a wearable antenna on a textile substrate is designed and the effect of a realistic human wrist model on the antenna performance is investigated at 2.4 and 5.8 GHz using the finite-difference time-domain (FDTD) method and CST. The antenna is re-tuned to mitigate the undesired effects caused by the wrist model and is optimized for on-wrist performance to operate at two frequency bands. Numerical results show that the effect of the wrist tissues on the antenna performance is less at 5.8 GHz than at 2.4 GHz and the antenna maximum gain decreases when it is placed on the wrist, but the radiation pattern is more directive. The simulation performance of the FDTD and CST are compared to show their simulation capabilities.
  • Wearable radar antenna array design on flexible PCB for visually impaired people

    Zhang, Haoran; Yang, Yiming; Shamim, Atif (Institute of Electrical and Electronics Engineers Inc., 2021-08-01) [Conference Paper]
    This paper proposes a multiple-input multiple-output (MIMO) antenna array with four RXs and three TXs designed in a certain geometry configuration to achieve obstacle detection ability in both horizontal and vertical planes for an anti-collision radar system, which can enable visually impaired people to perceive the environment better in their everyday lives. An aperture coupled wide-beam patch antenna with two parasitic patches is proposed for each channel of RXs and TXs, which is utilized on a four-layer flexible printed circuit board (PCB) to ensure its compactness and wearability. The proposed MIMO antenna array achieves well-matched impedance in the frequency range of 76-81 GHz and the realized gains of 4.2 dBi and 2.4 dBi in each RX and TX channel respectively. It also realizes a wide 3dB beamwidth of larger than 90 degrees in the horizontal plane which improves the radar system angular coverage.
  • Ultra- thin artificial magnetic conductor with metallic posts for a 94 GHz On-chip Antenna

    Yu, Yiyang; Akhter, Zubair; Shamim, Atif (Institute of Electrical and Electronics Engineers Inc., 2021-08-01) [Conference Paper]
    System-on-Chip has become an excellent solution for the high-level integration of systems. However, the primary barrier is the insufficient radiation from the on-chip antenna due to the lossy silicon substrate. In this paper, an ultra-thin artificial magnetic conductor (AMC) surface is proposed whose ground plane is on the top of the substrate to isolate it completely, and the thickness is reduced to house AMC within the oxide layer of the standard CMOS process by employing metal vias in the stack-up. The AMC structure is implanted for a 94 GHz on-chip monopole antenna and shows gain enhancement by 4.5 dBi with a radiation efficiency of 23%.
  • All Screen-Printed, Polymer-Nanowire Based Foldable Electronics for mm-Wave Applications

    Li, Weiwei; Zhang, Haoran; Kagita, Srujana; Shamim, Atif (Advanced Materials Technologies, Wiley, 2021-07-26) [Article]
    With the surge in devices for Internet of Things (IoT) applications, there is great interest in flexible electronics to be mass manufactured at lower costs. Screen-printing is well-known for mass manufacturing, however, this method has mostly focused on printing metallic patterns. Rare efforts have been devoted to print substrates for high frequency (mm-wave) electronics, which requires low dielectric loss to ensure a decent system efficiency. This paper presents a novel screen-printable composite ink comprising of acrylonitrile-butadiene-styrene and ceramic particles, through which, dielectric substrates with various thicknesses (down to few microns), lateral dimensions, and relative permittivities can be printed. A low dielectric loss of 0.0063 at 28 GHz (fifth generation (5G) communication band) makes the substrates suitable for mm-wave electronics. A custom silver nanowires based screen-printable ink is utilized for metallic printing to provide high conductivity (3.4 × 106 S m-1) and stable electrical response under bent or folded conditions. As a proof of concept for fully printed mm-wave electronics, a flexible quasi-Yagi antenna operating at 5G band (26.5–29.5 GHz) is demonstrated that exhibits decent performance in flat as well as bent conditions, confirming the suitability of the material system and printing processes for mass production of IoT and wearable electronics.
  • Extended throat venturi based flow meter for optimization of oil production process

    Karimi, Muhammad Akram; Arsalan, Muhammad; Shamim, Atif (IEEE Sensors Journal, IEEE, 2021-05-25) [Article]
    Water is mixed with the crude oil to form complex multiphase fluid during oil extraction process. Some of the traditional methods to measure the relative amount of water mixed with the crude oil (known as water-cut or WC) are intrusive, which are prone to wear and tear. Few other methods, used for WC sensing, are either unable to cover full range (0-100% WC) or require good mixing of the production fluid to be sensed accurately. This paper presents a unique and robust design of a dual spiral microwave resonator, which has been integrated on the extended throat of a venturi. Venturi measures the flow rate of the overall fluid while the microwave resonator measures the relative fraction of water in oil. Unlike existing meters, the presented design is fully non-intrusive, covers full WC range and does not require any mixing of production fluid for accurate measurement. The meter has been designed to withstand harsh field conditions of 1000 psi pressure and 125.C temperature and its performance has been validated in a commercial industrial flow loop with variable salinity conditions. “Phase inversion” phenomenon where the mixture changes from “oil continuous” to “water continuous” or vice versa, has been characterized thoroughly under varying test conditions. Microwave sensor’s resonance frequency (fo) and quality (Q) factor are used to measure WC in oil continuous and water continuous conditions respectively. The meter has been tested over wide range of flow rates and full range (0-100%) of WC. Liquid flow rate accuracy of ±3% and water cut accuracy of ±2% has been obtained from the industrial flow loop measurements.
  • Collocated MIMO Traveling wave SIW Slot Array Antennas for Millimeter Waves

    Ghalib, Asim; Sharawi, Mohammad S.; Mittra, Raj; Attia, Hussein; Shamim, Atif (IET Microwaves, Antennas & Propagation, IET, 2021-04-09) [Article]
    This paper presents, a novel 4-element collocated traveling wave substrate integrate wave guide (SIW) multiple-input-multiple-output (MIMO) antenna covering millimeter wave (mm-wave) bands (28-32 GHz). The antenna has exhibits a matching bandwidth of more than 4 GHz, and a measured gain of 15 dBi. The MIMO antenna elements are collocated, thus significantly reducing the size of the proposed design. To spatially isolate the beams (obtain lower correlation coefficient) of the MIMO antenna elements, the beams are oriented in different directions. The slots within each SIW array are designed to provide tilted beams ,thus eliminating the need for a beam switching network. Four distinct beams are formed towards±10o and ±30o. The dimensions of the 4-element MIMO SIW design is 68×30.68×0.5 mm3. The proposed antenna has high gain,more compact size, simpler feeding and enhanced MIMO capability compared to other SIW antennas proposed in the literature.
  • A Large Frequency Ratio Dual-band Microstrip Antenna with Consistent Radiation Pattern for Internet of Sea Applications

    Liao, Hanguang; Bilal, Rana Muhammad; Shamim, Atif (IEEE, 2021-03-22) [Conference Paper]
    Sensing and retrieving data from ocean to land are challenging tasks, while the Internet of Sea concept provides a realistic solution to that. A large frequency ratio dual-band microstrip antenna design working at GSM, LoRa, and BLE bands with consistent radiation pattern is proposed for Internet of Sea applications. The antenna is based on a modified Split Ring Antenna which provides two radiating modes, where the frequency ratio is close to 3. The proposed microstrip antenna is optimized for a better radiation efficiency and consistent radiation pattern at both bands. The method to control the H-plane HPBW of the proposed antenna is provided. The antenna prototype is fabricated and measured, which shows the radiation pattern at both bands are consistent and the H-plane HPBWs are 94°and 78°, at the lower and higher bands respectively.
  • Dual-mode Circular Microstrip Patch Antenna for Airborne Applications

    Akhter, Zubair; Bilal, Rana Muhammad; Shamim, Atif (IEEE, 2021-03-22) [Conference Paper]
    A dual-mode, dual-band 2.4/ 5.2 GHz circular microstrip patch antenna for airborne application is presented. Initially, a reference circular patch antenna is designed on Rogers© 5880 substrate for dual-mode (TM11 and TM01) performance with a single feed location. The bandwidth (BW) of the reference antenna is found to be 33 MHz and 155 MHz at 2.4 GHz and 5.2 GHz bands respectively. Later, the BW of the reference antenna at both the frequency band is enhanced with the help of proximity patches placed around the periphery of the reference/driven patch. It is found that the BW of the antenna at both the bands is enhanced by 2.5% at 2.4 GHz and 3.9 % at the 5.2 GHz band and similar improvements in their gains are also observed. The proposed antenna is fabricated and tested in an anechoic chamber for its impedance bandwidth and radiation pattern performance. A close match in simulated and measured performance of the antenna is achieved and an appropriate comparison of measured quantities is well illustrated in the paper.
  • Compact microwave based water-cut sensor suitable for downhole installation

    Karimi, Muhammad Akram; Arsalan, Muhammad; Shamim, Atif (Institute of Electrical and Electronics Engineers (IEEE), 2021-02-03) [Conference Paper, Presentation]
    Water is a by-product of oil extraction process whose amount needs to be determined accurately to optimize the oil production process. Almost 99.9% of the instruments used to determine water content in oil, are installed on the top surface outside an oil well. With the top surface water-fraction or watercut (WC) meters, it is impossible to locate the water producing zones inside the well because oil (and water) is produced from multiple branches inside a well. Ideally, a downhole WC sensor needs to be installed with every branch of the well for better water management. This paper presents a compact microwave based WC sensor which is compatible with an existing downhole system. Sensor consists of a λ/4 open stub based spiral resonator. The stub is printed on a dielectric core residing in the center of a metallic pipe. The stub is fed with a microstrip feedline which has a dedicated ring-shaped ground plane. Mixture flowing between the central core and the metallic pipe changes the dielectric properties and the resonance frequency of this uniquely designed sensor. WC sensing phenomenon has been validated both in simulations as well as inside a flow loop with measured sensitivity of over 200%.
  • A Machine Learning-Based Microwave Device Model for Fully Printed VO2 RF Switches

    Yang, Shuai; Khusro, Ahmad; Li, Weiwei; Vaseem, Mohammad; Hashmi, Mohammad; Shamim, Atif (Institute of Electrical and Electronics Engineers (IEEE), 2021-01-12) [Conference Paper]
    Fully printed vanadium dioxide (VO2) based Radio Frequency (RF) switches have been recently developed for advanced frequency-reconfigurable RF electronics. A reliable and versatile model for the VO2 switches is required for design and simulations in the modern Computer-Aided Design (CAD) tools. This paper proposes a machine learning (ML) based model for VO2 RF switches, which is much more time and resource efficient as compared to the traditional device models. The computational efficiency, accuracy and robustness of the proposed model over a frequency range of 30 GHz is demonstrated through an excellent agreement between the modelled and measured results. The comparison between the measured and modelled results demonstrate a mean-square error (MSE) of lower than 5 x 10-4 and 5 x10-3 for the magnitude and phase values over the complete frequency range.

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