2017 International Symposium on Antennas and Propagation (ISAP), 2017
The features of compact-range communication system is introduced briefly. The system in presence ... more The features of compact-range communication system is introduced briefly. The system in presence of a shadowing object is simply modelled. Modified Edge Representation is applied to evaluate field strength of the system. In the end, bit error rate (BER) is roughly estimated under the multipath-free condition.
2021 IEEE Indian Conference on Antennas and Propagation (InCAP), 2021
This paper presents a high gain rectangular open-ended waveguide (OEWG) antenna terminated by a g... more This paper presents a high gain rectangular open-ended waveguide (OEWG) antenna terminated by a grooved metallic flange in mmWave frequencies. The conventional OEWG antenna has low gain. A metallic circular flange is utilized to enhance its gain. However, this does not improve gain to the required values. Next, some grooves are cut on the circular flange to enhance the gain further. This work shows the systematic study of the role of cutting grooves in the flange that enhances the gain of OEWG antenna from 5.74 dBi to 18.86 dBi. The full-wave simulator, Ansys HFSS, is used to optimize the OEWG antenna to validate the proposed approach.
The 60 GHz band compact-range communication is very promising for short-time, short distance comm... more The 60 GHz band compact-range communication is very promising for short-time, short distance communication. Unfortunately, due to the short wavelengths in this frequency band the shadowing effects caused by human bodies, furniture, etc are severe and need to be modeled properly. The numerical methods like the finite-difference time-domain method (FDTD), the finite-element method (FEM), the method of moments (MoM) are unable to compute the field scattered by large objects due to their excessive time and memory requirements. Ray-based approaches like the geometrical theory of diffraction (GTD), uniform geometrical theory of diffraction (UTD), uniform asymptotic theory of diffraction (UAT) are effective and popular solutions but suffer from computation of corner-diffracted field, field at the caustics. Fresnel zone number (FZN) adopted modified edge representation (MER) equivalent edge current (EEC) is an accurate and fast high frequency diffraction technique which expresses the fields in terms of line integration. It adopts distances, rather than the angles used in GTD, UTD or UAT but still provides uniform and highly accurate fields everywhere including geometrical boundaries. Previous work verified this method for planar scatterers. In this work, FZN MER EEC is used to compute field distribution in the millimeter-wave compact range communication in the presence of three dimensional scatterers, where shadowing effects rather than multi-path dominate the radio environments. First, circular cylinder is disintegrated into rectangular plate and circular disks and then FZN MER is applied along with geodesic path loss. The dipole wave scattering from perfectly conducting circular cylinder is discussed as numerical examples.
The future mobile network called "5G" is becoming a hot topic. The heterogeneous networ... more The future mobile network called "5G" is becoming a hot topic. The heterogeneous networks using multi-band "HetNet" is one of the promising candidates which provide more than 1000 times system capacity. Millimeter-wave is expected to be utilized for the pico cell coverage as well as the fronthaul to connect these enhanced RRHs. This paper reviews the antennas and propagation research works developed in "Tokyo Tech wireless fiber project", where many of the project outputs are directly applicable for realization of multi-band HetNet utilizing millimeter wave. The 60GHz compact range communication is focused upon.
2021 IEEE International Conference on RFID Technology and Applications (RFID-TA), 2021
This paper presents a MIMO antenna using two elements in the shape of a ring with a rectangular s... more This paper presents a MIMO antenna using two elements in the shape of a ring with a rectangular stub for RFID applications. The proposed MIMO antenna is multiband with center frequencies at 2.45GHz, 3.5GHz, and 5.4GHz. Mutual coupling between the two antenna elements is improved by placing a U-type resonator. The isolation between the antenna elements is more than -15 dB on these three frequency bands. The diversity gain is 10dB, while the ECC is less than 0.05. The antenna is fabricated on a low-cost substrate, FR4, and its dimensions are $31 \times 31 \times 0.8$ mm3.
2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2021
This work presents the systematic approach for improving the radiation patterns of monopole holog... more This work presents the systematic approach for improving the radiation patterns of monopole holographic antenna. Most of the present works show unwanted high sidelobe level (SLL) for monopole holographic antenna. The radiation patterns from such designs have another beam of high gain near the main beam. By changing the location of the monopole feed over the holographic surface, this extra unwanted beam can be altered and eventually removed. This helps to improve SLL significantly. This study compares results of different designs and presents guidelines to achieve proposed design with very low SLL.
This paper considers the problem of designing MIMO fixed-structure controllers based on a polynom... more This paper considers the problem of designing MIMO fixed-structure controllers based on a polynomial framework for both Linear Time-Invariant (LTI) and Linear Parameter-Varying (LPV) systems having input-output models. For SISO systems, a polynomial method has been proposed recently to solve such problems, where the a priori selection of a central polynomial is carried out heuristically, and for LPV systems the synthesis problem is solved using a sum-of-squares relaxation approach. To reduce the complexity of the design procedure, we propose a combined gradient and LMI-based algorithm for optimizing the choice of the central polynomial matrix in terms of the closed-loop performance. Moreover, for LPV systems, the computational complexity of the sum-of-squares approach is reduced by introducing polytopic input-output LPV representations. Quadratic stability and performance is guaranteed in the admissible scheduling range. The proposed methods are illustrated with simulation examples.
2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio Science, 2020
Vibrating carbon nanotube (CNT) generates electromagnetic (EM) field. This is experimentally veri... more Vibrating carbon nanotube (CNT) generates electromagnetic (EM) field. This is experimentally verified through our present works. CNTs are synthesized by alternating current (AC) arc discharge between the two high pure graphite rods of the same diameter in an open air environment. To confirm the synthesis of CNTs, scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs of the deposited carbon on the electrode ends are taken. During the arc discharge EM field is detected in an anechoic chamber.
In millimeter-wave (mmWave) communications, the antenna gain is a crucial parameter to overcome p... more In millimeter-wave (mmWave) communications, the antenna gain is a crucial parameter to overcome path loss and atmospheric attenuation. This work presents the design of two cylindrical conformal antenna arrays, made of modified rectangular microstrip patch antenna as a radiating element, working at 28 GHz for mmWave applications providing high gain and beam steering capability. The microstrip patch antenna element uses Rogers RO4232 substrate with a thickness of 0.5 mm and surface area of 5.8 mm × 5.8 mm. The individual antenna element provides a gain of 6.9 dBi with return loss bandwidth of 5.12 GHz. The first antenna array, made by using five conformal antenna elements, achieves a uniform gain of approximately 12 dBi with minimal scan loss for extensive scan angles. In the second antenna array, a dielectric superstrate using Rogers TMM (10i) was used to modify the first antenna array. It enhanced the gain to approximately 16 dBi while still maintaining low scan loss for wide angles...
2019 IEEE Indian Conference on Antennas and Propogation (InCAP), 2019
This paper presents a design approach to achieve the operational frequency ranging from 40MHz to ... more This paper presents a design approach to achieve the operational frequency ranging from 40MHz to 160 MHz with VSWR ≤ 3 and 5 dBi realized gain in prefixed antenna size of 30 cm width and 100 cm height. A body of revaluation (BoR) monopole antenna was optimized with respect to lowest frequency (flow) for the specified parameters resulting in lowest achievable frequency of flow = 50.21 MHz. To improve flow, capacitive hat and parasitic ring are used without changing surface profile of the BoR monopole, resulting in flow = 40 MHz.
2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2018
The paper presents a robust and systematic strategy for handling the problem of platform modifica... more The paper presents a robust and systematic strategy for handling the problem of platform modification, which requires a retuning of the antenna designed to cover multiple frequency bands. We show that the key is to design the antenna with multiple arms such that varying the parameters of the arms can systematically retune the antenna in different bands, when such retuning is needed as the geometry of the platform itself is modified by the designer.
2019 IEEE International Symposium on Smart Electronic Systems (iSES) (Formerly iNiS), 2019
The several radiations hardened based design (RHBD) had been developed to address the soft error ... more The several radiations hardened based design (RHBD) had been developed to address the soft error problem. But they all consume relatively high total, static power with more area and delay. The 10T cell is designed to overcome the area and power dissipation problem. However, the 10T cell suffers from a large number of write failures under process variations of 45 nm CMOS technology, due to its high delay. Therefore, both boosted word-line and bit-line on 10T have been proposed the first time for improvement the writability of the cell. The 10T-boosted cell has no write failure problem. The result shows that the boosted 10T cell consumes 20.53%, 29.21%, 8.23%, and 14.7%, 42.7%, 85.9% less static, and total power compared to Dice (12T), WeQuatro (12T), and boosted Quatro (10T) respectively. The hold noise margin has been improved by 79.4%, 38.4%, and 38.9% compared to Dice, We-Quatro, and boosted Quatro, respectively. Also, the area overhead and soft error resilience of the 10Tboosted ...
2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2021
This paper presents a modification of a rectangular microstrip patch antenna (MPA) which improves... more This paper presents a modification of a rectangular microstrip patch antenna (MPA) which improves the S11 bandwidth from 6.6% to 17.5% at center frequency of 28 GHz. The gain of this antenna at center frequency has been improved by using dielectric superstate from 6.81 dB to 10.73 dB. Further, gain improvement and cross-polarization suppression are also achieved by using multi-strip frequency selective surface (FSS) as a superstrate.
Abstract The SRAM cells suffer from soft errors under high radiation environment like aerospace a... more Abstract The SRAM cells suffer from soft errors under high radiation environment like aerospace and satellite applications. Few radiations hardened based popular cells are 12T Dice and 12T We-Quatro. But these cells required more area and power consumption. To address these problems a 10T SRAM cell is designed, which gives perfect balance among all the parameters with higher delay. Hence, it is the most suggestible cell under high radiation environment. However, the 10T SRAM cell for high frequency under process variations gives a large number of write failure, which impeding the application of 10T SRAM cell. In this paper, a new SRAM cell has been proposed, which provides less power, more stability, less area, and very high soft error resilience. The proposed cell provides 17.48%, 5.26% less static power loss compared to We-Quatro and Dice, respectively. The total power loss of the proposed cell is reduced by 39.26%, 9.56% compared to We-Quatro and Dice cell respectively. The hold stability is increased by 45%, 81.59% compared to We-Quatro and Dice cell respectively. Also, the proposed cell gives moderate area overhead, comparable write speed, and perfect balance among all the parameters. The proposed cell is also verified using Monte Carlo (M.C) simulation in 45 nm CMOS technology.
The reduction of the surface integration to line integration provides numerical computation time ... more The reduction of the surface integration to line integration provides numerical computation time and resource savings. Modified edge representation (MER) is a unique concept for a complete definition of equivalent edge currents (EECs) for arbitrary points on the edge, including ones that do not satisfy the diffraction law. By using classical Keller-type diffraction coefficients in EECs, MER recovers the fringe wave (FW) contribution and has the enhanced accuracy of the order of the geometrical theory of diffraction (GTD). The line integration of MER EEC results in uniform and accurate fields everywhere, including geometrical boundaries at the caustics as inherent advantages and geometrical boundaries, such as the reflection shadow boundary (RSB) and incident shadow boundary (ISB). The authors have developed the applicability of MER and arrived at the advanced form of MER (new MER) in which FW components in EEC are weighted by the Fresnel zone number (FZN). This article demonstrates the higher accuracy and wider applicability of this method over GTD and the uniform geometrical theory of diffraction (UTD) for the canonical problem of a large circular disk where the rigorous solution is available. In grazing incidence as an extreme case, the FZN weighting effectively enhances the accuracy of GTD MER. It is also demonstrated that the inherent advantage of GTD MER over GTD and UTD in slope wave diffraction remain unchanged in new MER with this weighting.
2017 International Symposium on Antennas and Propagation (ISAP), 2017
The features of compact-range communication system is introduced briefly. The system in presence ... more The features of compact-range communication system is introduced briefly. The system in presence of a shadowing object is simply modelled. Modified Edge Representation is applied to evaluate field strength of the system. In the end, bit error rate (BER) is roughly estimated under the multipath-free condition.
2021 IEEE Indian Conference on Antennas and Propagation (InCAP), 2021
This paper presents a high gain rectangular open-ended waveguide (OEWG) antenna terminated by a g... more This paper presents a high gain rectangular open-ended waveguide (OEWG) antenna terminated by a grooved metallic flange in mmWave frequencies. The conventional OEWG antenna has low gain. A metallic circular flange is utilized to enhance its gain. However, this does not improve gain to the required values. Next, some grooves are cut on the circular flange to enhance the gain further. This work shows the systematic study of the role of cutting grooves in the flange that enhances the gain of OEWG antenna from 5.74 dBi to 18.86 dBi. The full-wave simulator, Ansys HFSS, is used to optimize the OEWG antenna to validate the proposed approach.
The 60 GHz band compact-range communication is very promising for short-time, short distance comm... more The 60 GHz band compact-range communication is very promising for short-time, short distance communication. Unfortunately, due to the short wavelengths in this frequency band the shadowing effects caused by human bodies, furniture, etc are severe and need to be modeled properly. The numerical methods like the finite-difference time-domain method (FDTD), the finite-element method (FEM), the method of moments (MoM) are unable to compute the field scattered by large objects due to their excessive time and memory requirements. Ray-based approaches like the geometrical theory of diffraction (GTD), uniform geometrical theory of diffraction (UTD), uniform asymptotic theory of diffraction (UAT) are effective and popular solutions but suffer from computation of corner-diffracted field, field at the caustics. Fresnel zone number (FZN) adopted modified edge representation (MER) equivalent edge current (EEC) is an accurate and fast high frequency diffraction technique which expresses the fields in terms of line integration. It adopts distances, rather than the angles used in GTD, UTD or UAT but still provides uniform and highly accurate fields everywhere including geometrical boundaries. Previous work verified this method for planar scatterers. In this work, FZN MER EEC is used to compute field distribution in the millimeter-wave compact range communication in the presence of three dimensional scatterers, where shadowing effects rather than multi-path dominate the radio environments. First, circular cylinder is disintegrated into rectangular plate and circular disks and then FZN MER is applied along with geodesic path loss. The dipole wave scattering from perfectly conducting circular cylinder is discussed as numerical examples.
The future mobile network called "5G" is becoming a hot topic. The heterogeneous networ... more The future mobile network called "5G" is becoming a hot topic. The heterogeneous networks using multi-band "HetNet" is one of the promising candidates which provide more than 1000 times system capacity. Millimeter-wave is expected to be utilized for the pico cell coverage as well as the fronthaul to connect these enhanced RRHs. This paper reviews the antennas and propagation research works developed in "Tokyo Tech wireless fiber project", where many of the project outputs are directly applicable for realization of multi-band HetNet utilizing millimeter wave. The 60GHz compact range communication is focused upon.
2021 IEEE International Conference on RFID Technology and Applications (RFID-TA), 2021
This paper presents a MIMO antenna using two elements in the shape of a ring with a rectangular s... more This paper presents a MIMO antenna using two elements in the shape of a ring with a rectangular stub for RFID applications. The proposed MIMO antenna is multiband with center frequencies at 2.45GHz, 3.5GHz, and 5.4GHz. Mutual coupling between the two antenna elements is improved by placing a U-type resonator. The isolation between the antenna elements is more than -15 dB on these three frequency bands. The diversity gain is 10dB, while the ECC is less than 0.05. The antenna is fabricated on a low-cost substrate, FR4, and its dimensions are $31 \times 31 \times 0.8$ mm3.
2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2021
This work presents the systematic approach for improving the radiation patterns of monopole holog... more This work presents the systematic approach for improving the radiation patterns of monopole holographic antenna. Most of the present works show unwanted high sidelobe level (SLL) for monopole holographic antenna. The radiation patterns from such designs have another beam of high gain near the main beam. By changing the location of the monopole feed over the holographic surface, this extra unwanted beam can be altered and eventually removed. This helps to improve SLL significantly. This study compares results of different designs and presents guidelines to achieve proposed design with very low SLL.
This paper considers the problem of designing MIMO fixed-structure controllers based on a polynom... more This paper considers the problem of designing MIMO fixed-structure controllers based on a polynomial framework for both Linear Time-Invariant (LTI) and Linear Parameter-Varying (LPV) systems having input-output models. For SISO systems, a polynomial method has been proposed recently to solve such problems, where the a priori selection of a central polynomial is carried out heuristically, and for LPV systems the synthesis problem is solved using a sum-of-squares relaxation approach. To reduce the complexity of the design procedure, we propose a combined gradient and LMI-based algorithm for optimizing the choice of the central polynomial matrix in terms of the closed-loop performance. Moreover, for LPV systems, the computational complexity of the sum-of-squares approach is reduced by introducing polytopic input-output LPV representations. Quadratic stability and performance is guaranteed in the admissible scheduling range. The proposed methods are illustrated with simulation examples.
2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio Science, 2020
Vibrating carbon nanotube (CNT) generates electromagnetic (EM) field. This is experimentally veri... more Vibrating carbon nanotube (CNT) generates electromagnetic (EM) field. This is experimentally verified through our present works. CNTs are synthesized by alternating current (AC) arc discharge between the two high pure graphite rods of the same diameter in an open air environment. To confirm the synthesis of CNTs, scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs of the deposited carbon on the electrode ends are taken. During the arc discharge EM field is detected in an anechoic chamber.
In millimeter-wave (mmWave) communications, the antenna gain is a crucial parameter to overcome p... more In millimeter-wave (mmWave) communications, the antenna gain is a crucial parameter to overcome path loss and atmospheric attenuation. This work presents the design of two cylindrical conformal antenna arrays, made of modified rectangular microstrip patch antenna as a radiating element, working at 28 GHz for mmWave applications providing high gain and beam steering capability. The microstrip patch antenna element uses Rogers RO4232 substrate with a thickness of 0.5 mm and surface area of 5.8 mm × 5.8 mm. The individual antenna element provides a gain of 6.9 dBi with return loss bandwidth of 5.12 GHz. The first antenna array, made by using five conformal antenna elements, achieves a uniform gain of approximately 12 dBi with minimal scan loss for extensive scan angles. In the second antenna array, a dielectric superstrate using Rogers TMM (10i) was used to modify the first antenna array. It enhanced the gain to approximately 16 dBi while still maintaining low scan loss for wide angles...
2019 IEEE Indian Conference on Antennas and Propogation (InCAP), 2019
This paper presents a design approach to achieve the operational frequency ranging from 40MHz to ... more This paper presents a design approach to achieve the operational frequency ranging from 40MHz to 160 MHz with VSWR ≤ 3 and 5 dBi realized gain in prefixed antenna size of 30 cm width and 100 cm height. A body of revaluation (BoR) monopole antenna was optimized with respect to lowest frequency (flow) for the specified parameters resulting in lowest achievable frequency of flow = 50.21 MHz. To improve flow, capacitive hat and parasitic ring are used without changing surface profile of the BoR monopole, resulting in flow = 40 MHz.
2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2018
The paper presents a robust and systematic strategy for handling the problem of platform modifica... more The paper presents a robust and systematic strategy for handling the problem of platform modification, which requires a retuning of the antenna designed to cover multiple frequency bands. We show that the key is to design the antenna with multiple arms such that varying the parameters of the arms can systematically retune the antenna in different bands, when such retuning is needed as the geometry of the platform itself is modified by the designer.
2019 IEEE International Symposium on Smart Electronic Systems (iSES) (Formerly iNiS), 2019
The several radiations hardened based design (RHBD) had been developed to address the soft error ... more The several radiations hardened based design (RHBD) had been developed to address the soft error problem. But they all consume relatively high total, static power with more area and delay. The 10T cell is designed to overcome the area and power dissipation problem. However, the 10T cell suffers from a large number of write failures under process variations of 45 nm CMOS technology, due to its high delay. Therefore, both boosted word-line and bit-line on 10T have been proposed the first time for improvement the writability of the cell. The 10T-boosted cell has no write failure problem. The result shows that the boosted 10T cell consumes 20.53%, 29.21%, 8.23%, and 14.7%, 42.7%, 85.9% less static, and total power compared to Dice (12T), WeQuatro (12T), and boosted Quatro (10T) respectively. The hold noise margin has been improved by 79.4%, 38.4%, and 38.9% compared to Dice, We-Quatro, and boosted Quatro, respectively. Also, the area overhead and soft error resilience of the 10Tboosted ...
2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2021
This paper presents a modification of a rectangular microstrip patch antenna (MPA) which improves... more This paper presents a modification of a rectangular microstrip patch antenna (MPA) which improves the S11 bandwidth from 6.6% to 17.5% at center frequency of 28 GHz. The gain of this antenna at center frequency has been improved by using dielectric superstate from 6.81 dB to 10.73 dB. Further, gain improvement and cross-polarization suppression are also achieved by using multi-strip frequency selective surface (FSS) as a superstrate.
Abstract The SRAM cells suffer from soft errors under high radiation environment like aerospace a... more Abstract The SRAM cells suffer from soft errors under high radiation environment like aerospace and satellite applications. Few radiations hardened based popular cells are 12T Dice and 12T We-Quatro. But these cells required more area and power consumption. To address these problems a 10T SRAM cell is designed, which gives perfect balance among all the parameters with higher delay. Hence, it is the most suggestible cell under high radiation environment. However, the 10T SRAM cell for high frequency under process variations gives a large number of write failure, which impeding the application of 10T SRAM cell. In this paper, a new SRAM cell has been proposed, which provides less power, more stability, less area, and very high soft error resilience. The proposed cell provides 17.48%, 5.26% less static power loss compared to We-Quatro and Dice, respectively. The total power loss of the proposed cell is reduced by 39.26%, 9.56% compared to We-Quatro and Dice cell respectively. The hold stability is increased by 45%, 81.59% compared to We-Quatro and Dice cell respectively. Also, the proposed cell gives moderate area overhead, comparable write speed, and perfect balance among all the parameters. The proposed cell is also verified using Monte Carlo (M.C) simulation in 45 nm CMOS technology.
The reduction of the surface integration to line integration provides numerical computation time ... more The reduction of the surface integration to line integration provides numerical computation time and resource savings. Modified edge representation (MER) is a unique concept for a complete definition of equivalent edge currents (EECs) for arbitrary points on the edge, including ones that do not satisfy the diffraction law. By using classical Keller-type diffraction coefficients in EECs, MER recovers the fringe wave (FW) contribution and has the enhanced accuracy of the order of the geometrical theory of diffraction (GTD). The line integration of MER EEC results in uniform and accurate fields everywhere, including geometrical boundaries at the caustics as inherent advantages and geometrical boundaries, such as the reflection shadow boundary (RSB) and incident shadow boundary (ISB). The authors have developed the applicability of MER and arrived at the advanced form of MER (new MER) in which FW components in EEC are weighted by the Fresnel zone number (FZN). This article demonstrates the higher accuracy and wider applicability of this method over GTD and the uniform geometrical theory of diffraction (UTD) for the canonical problem of a large circular disk where the rigorous solution is available. In grazing incidence as an extreme case, the FZN weighting effectively enhances the accuracy of GTD MER. It is also demonstrated that the inherent advantage of GTD MER over GTD and UTD in slope wave diffraction remain unchanged in new MER with this weighting.
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Papers by Maifuz Ali