Usman Ali Khan | University of Wollongong (original) (raw)

Papers by Usman Ali Khan

Higher penalties may apply, and higher damages may be awarded, for offences and infringements inv... more Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong. represent the views of the University of Wollongong.

Electronics

CubeSats are a class of miniaturized satellites that have become increasingly popular in academia... more CubeSats are a class of miniaturized satellites that have become increasingly popular in academia and among hobbyists due to their short development time and low fabrication cost. Their compact size, lightweight characteristics, and ability to form a swarm enables them to communicate directly with one another to inspire new ideas on space exploration, space-based measurements, and implementation of the latest technology. CubeSat missions require specific antenna designs in order to achieve optimal performance and ensure mission success. Over the past two decades, a plethora of antenna designs have been proposed and implemented on CubeSat missions. Several challenges arise when designing CubeSat antennas such as gain, polarization, frequency selection, pointing accuracy, coverage, and deployment mechanisms. While these challenges are strongly related to the restrictions posed by the CubeSat standards, recently, researchers have turned their attention from the reliable and proven whip...

IEEE Open Journal of Antennas and Propagation

IEEE OJAP encourages responsible authorship practices and the provision of information about the ... more IEEE OJAP encourages responsible authorship practices and the provision of information about the specific contribution of each author.

Electronics, 2020

This article presents a compact wideband high gain patch antenna for CubeSat. The proposed metal-... more This article presents a compact wideband high gain patch antenna for CubeSat. The proposed metal-only antenna mainly consists of an upper patch, a folded ramp-shaped patch and shoring pins connecting the antenna with the ground plane. By adjusting the lengths and widths of two arms of the upper F-shaped patch, a second resonant frequency is generated, and hence, the −10 dB bandwidth is increased. Moreover, the effect of arms’ lengths and widths on reflection coefficients, operating frequency and bandwidth is presented. To validate the design and the simulation results, a prototype metal-only patch antenna was fabricated and tested in a Chamber. A good agreement between the simulated and measured results is achieved. The measured results show that the fabricated prototype achieves a −10 dB bandwidth of 44.9% (1.6–2.7 GHz), a small reflection coefficient of −24.4 dB and a high efficiency, i.e., 85% at 2.45 GHz. The radiation performance of the proposed antenna is measured, showing a p...

Applied Sciences, 2021

Flexible wearable wireless devices have found practical uses as their cost has fallen and Interne... more Flexible wearable wireless devices have found practical uses as their cost has fallen and Internet of Things applications have gained further acceptance. These devices are gaining further use and acceptance in the consumer and wearable space for applications such as logistical tracking and maintaining sensor information, including temperature, humidity, and location. In such applications, antennas are exposed to bending and crumbling. Therefore, flexible substrate antennas for use with polymer-based flexible devices are an important area of research that needs to be addressed. In this study, the bending capabilities of flexible polymer substrate antennas for general IoT applications were practically analyzed by fabricating flexible antennas on Polyethylene Terephthalate (PET), Polytetrafluoroethylene (PTFE) Teflon, and Polyvinylchloride (PVC) substrates operating at 2.45, 4.45, and 7.25 GHz frequencies. The basic premise was to investigate the flexibility and bending ability of poly...

2019 19th International Symposium on Communications and Information Technologies (ISCIT), 2019

In this paper, a novel Flexible Chip-less Bow-Tie RFID tag is introduced, and its design, fabrica... more In this paper, a novel Flexible Chip-less Bow-Tie RFID tag is introduced, and its design, fabrication, testing and comparative analyses are presented. The tag uses the Frequency Selective Surface (FSS) approach with a frequency ranging from 4 to 18 GHz. The Bow-Tie design was compared an Octagonal shaped tag already published in the art. They were both designed using CST studio and fabricated through a laser etching technique on low-cost flexible Polyethylene Terephthalate (PET). Through a series of comparative experiments for Radar Cross Section (RCS), results in an anechoic chamber were obtained. The new Bow-Tie RFID tag is shown to be more robust and accurate with the variation of distance up to 1.8m at 0dBm and it can be used to encode a bit sequence.

The Impact of Bending on Radiation Characteristics of Polymer-Based Flexible Antennas for General IoT Applications, 2021

Flexible wearable wireless devices have found practical uses as their cost has fallen and Interne... more Flexible wearable wireless devices have found practical uses as their cost has fallen and Internet of Things applications have gained further acceptance. These devices are gaining further use and acceptance in the consumer and wearable space for applications such as logistical tracking and maintaining sensor information, including temperature, humidity, and location. In such applications, antennas are exposed to bending and crumbling. Therefore, flexible substrate antennas for use with polymer-based flexible devices are an important area of research that needs to be addressed. In this study, the bending capabilities of flexible polymer substrate antennas for general IoT applications were practically analyzed by fabricating flexible antennas on Polyethylene Terephthalate (PET), Polytetrafluoroethylene (PTFE) Teflon, and Polyvinylchloride (PVC) substrates operating at 2.45, 4.45, and 7.25 GHz frequencies. The basic premise was to investigate the flexibility and bending ability of poly...

Advances in Science, Technology and Engineering Systems Journal

This paper is an extension of Novel Flexible Chip-less Bow-Tie RFID tag in which we presented the... more This paper is an extension of Novel Flexible Chip-less Bow-Tie RFID tag in which we presented the design, testing and fabrication of the tag and compared the results with Octagonal Chipless RFID tag. The chipless RFID tag was designed by using simulation software CST microwave studio and fabricated by using laser etching technique on a flexible polymer substrate Polyethylene Terephthalate (PET). The tag operates at frequency ranging from 8 to 18 GHz uses the Frequency Selective Surface (FSS) approach. A series of experiments are performed to measure the Radar Cross Section (RCS) in an anechoic chamber. The tag design is composed of six concentric Bow-Tie shaped loop resonators with one unitary element. In this paper, we demonstrated the Singularity Expansion Method (SEM) based circuit modelling and the transient behaviour of the RFID tag is performed. The coupling coefficients and the induced currents over the surface of Bow tie shaped rings are evaluated. The maximum read range is evaluated and the Bow-Tie RFID tag is proved to be more accurate and efficient with the variation of distance up to 1.8m at 0dBm which is extendable to 2.14m for higher input power. This range is maximum to our knowledge for such a high-frequency range of 8-18GHz. The 4-bits Bow-Tie Chipless RFID tag design is compact and can be deployed commercially for general IoT applications.

Polymers

Flexible substrates have become essential in order to provide increased flexibility in wearable s... more Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance...

Polymers

Flexible substrates have become essential in order to provide increased flexibility in wearable s... more Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance...

Polymers

Flexible substrates have become essential in order to provide increased flexibility in wearable s... more Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance...

Sensor and Actuators A : Physical, 2020

This paper presents the design, fabrication and testing of two embroidered chipless octagonal-sha... more This paper presents the design, fabrication and testing of two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable applications. The first tag is designed by using silver-coated polyamide conductive fibre (HC12) and the second tag is embroidered by using highly conductive Vec-tran (LIBERATOR 40) which is highly conductive multifilament yarn spun from Liquid Crystal Polymers(LCP), on cotton fabrics. In contrast to the traditional RFID tag, the chipless RFID tagging, the ID code isnot saved in the memory, instead, it uses the physical features of the tag to send data. The proposed tag’sdesign uses a Frequency Selective Surface (FSS) technique for the frequency range of 8–18 GHz. These tags are designed using CST studio and precisely fabricated by using commercial ZSK Technical EmbroiderySystem JCZA (0109–550). The tag design is composed of six concentric octagonal loop resonators with one unitary element. The electromagnetic scattering waves behaviour and Singularity Expansion Method(SEM) based circuit modelling for the octagonal-shaped tag is performed, and the coupling coefficients are evaluated. The desired data bits are obtained by a series of comparative experiments for Radar CrossSection (RCS) in an anechoic chamber. The experimental results obtained show that the 4-bit data is accurately retrieved with the variation of distance by up to 1.8 m at 0 dB m. Moreover, the average transition from minimum ‘0’ to maximum 1’ is -27 dB for both designs. Furthermore, the experimental results for on-body RCS measurements and the bending effects on both tags down to 7 mm is observed. This octagonal embroidered Chipless RFID tag is a fully textile design which is compact and can be deployed commercially in various IoT applications.

IEEE GLOBECOM 2020, 2020

In this work, two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable a... more In this work, two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable applications are presented. The first tag is designed by using silver-coated polyamide conductive fibre (HC12) and the second tag is embroidered by using highly conductive Vectran (LIBERATOR 40) which is a highly conductive multifilament yarn spun from Liquid Crystal Polymers (LCP), on cotton fabrics. The proposed tag's design uses a Frequency Selective Surface (FSS) technique for the frequency range of 8 to 18GHz and fabricated by using commercial ZSK Technical Embroidery System JCZA. The tag design is composed of six concentric octagonal loop resonators with one unitary element. The desired data bits are obtained by a series of comparative experiments for Radar Cross Section (RCS) in an anechoic chamber. The experimental results obtained show that the 4-bit data codeword is accurately retrieved with the variation of distance by up to 1.8m at 0dBm. Moreover, the experimental results include on-body RCS measurements and the bending effects on both of the tags. The tags are compared to the state of the art tags in a comparative table.

Higher penalties may apply, and higher damages may be awarded, for offences and infringements inv... more Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong. represent the views of the University of Wollongong.

Electronics

CubeSats are a class of miniaturized satellites that have become increasingly popular in academia... more CubeSats are a class of miniaturized satellites that have become increasingly popular in academia and among hobbyists due to their short development time and low fabrication cost. Their compact size, lightweight characteristics, and ability to form a swarm enables them to communicate directly with one another to inspire new ideas on space exploration, space-based measurements, and implementation of the latest technology. CubeSat missions require specific antenna designs in order to achieve optimal performance and ensure mission success. Over the past two decades, a plethora of antenna designs have been proposed and implemented on CubeSat missions. Several challenges arise when designing CubeSat antennas such as gain, polarization, frequency selection, pointing accuracy, coverage, and deployment mechanisms. While these challenges are strongly related to the restrictions posed by the CubeSat standards, recently, researchers have turned their attention from the reliable and proven whip...

IEEE Open Journal of Antennas and Propagation

IEEE OJAP encourages responsible authorship practices and the provision of information about the ... more IEEE OJAP encourages responsible authorship practices and the provision of information about the specific contribution of each author.

Electronics, 2020

This article presents a compact wideband high gain patch antenna for CubeSat. The proposed metal-... more This article presents a compact wideband high gain patch antenna for CubeSat. The proposed metal-only antenna mainly consists of an upper patch, a folded ramp-shaped patch and shoring pins connecting the antenna with the ground plane. By adjusting the lengths and widths of two arms of the upper F-shaped patch, a second resonant frequency is generated, and hence, the −10 dB bandwidth is increased. Moreover, the effect of arms’ lengths and widths on reflection coefficients, operating frequency and bandwidth is presented. To validate the design and the simulation results, a prototype metal-only patch antenna was fabricated and tested in a Chamber. A good agreement between the simulated and measured results is achieved. The measured results show that the fabricated prototype achieves a −10 dB bandwidth of 44.9% (1.6–2.7 GHz), a small reflection coefficient of −24.4 dB and a high efficiency, i.e., 85% at 2.45 GHz. The radiation performance of the proposed antenna is measured, showing a p...

Applied Sciences, 2021

Flexible wearable wireless devices have found practical uses as their cost has fallen and Interne... more Flexible wearable wireless devices have found practical uses as their cost has fallen and Internet of Things applications have gained further acceptance. These devices are gaining further use and acceptance in the consumer and wearable space for applications such as logistical tracking and maintaining sensor information, including temperature, humidity, and location. In such applications, antennas are exposed to bending and crumbling. Therefore, flexible substrate antennas for use with polymer-based flexible devices are an important area of research that needs to be addressed. In this study, the bending capabilities of flexible polymer substrate antennas for general IoT applications were practically analyzed by fabricating flexible antennas on Polyethylene Terephthalate (PET), Polytetrafluoroethylene (PTFE) Teflon, and Polyvinylchloride (PVC) substrates operating at 2.45, 4.45, and 7.25 GHz frequencies. The basic premise was to investigate the flexibility and bending ability of poly...

2019 19th International Symposium on Communications and Information Technologies (ISCIT), 2019

In this paper, a novel Flexible Chip-less Bow-Tie RFID tag is introduced, and its design, fabrica... more In this paper, a novel Flexible Chip-less Bow-Tie RFID tag is introduced, and its design, fabrication, testing and comparative analyses are presented. The tag uses the Frequency Selective Surface (FSS) approach with a frequency ranging from 4 to 18 GHz. The Bow-Tie design was compared an Octagonal shaped tag already published in the art. They were both designed using CST studio and fabricated through a laser etching technique on low-cost flexible Polyethylene Terephthalate (PET). Through a series of comparative experiments for Radar Cross Section (RCS), results in an anechoic chamber were obtained. The new Bow-Tie RFID tag is shown to be more robust and accurate with the variation of distance up to 1.8m at 0dBm and it can be used to encode a bit sequence.

The Impact of Bending on Radiation Characteristics of Polymer-Based Flexible Antennas for General IoT Applications, 2021

Flexible wearable wireless devices have found practical uses as their cost has fallen and Interne... more Flexible wearable wireless devices have found practical uses as their cost has fallen and Internet of Things applications have gained further acceptance. These devices are gaining further use and acceptance in the consumer and wearable space for applications such as logistical tracking and maintaining sensor information, including temperature, humidity, and location. In such applications, antennas are exposed to bending and crumbling. Therefore, flexible substrate antennas for use with polymer-based flexible devices are an important area of research that needs to be addressed. In this study, the bending capabilities of flexible polymer substrate antennas for general IoT applications were practically analyzed by fabricating flexible antennas on Polyethylene Terephthalate (PET), Polytetrafluoroethylene (PTFE) Teflon, and Polyvinylchloride (PVC) substrates operating at 2.45, 4.45, and 7.25 GHz frequencies. The basic premise was to investigate the flexibility and bending ability of poly...

Advances in Science, Technology and Engineering Systems Journal

This paper is an extension of Novel Flexible Chip-less Bow-Tie RFID tag in which we presented the... more This paper is an extension of Novel Flexible Chip-less Bow-Tie RFID tag in which we presented the design, testing and fabrication of the tag and compared the results with Octagonal Chipless RFID tag. The chipless RFID tag was designed by using simulation software CST microwave studio and fabricated by using laser etching technique on a flexible polymer substrate Polyethylene Terephthalate (PET). The tag operates at frequency ranging from 8 to 18 GHz uses the Frequency Selective Surface (FSS) approach. A series of experiments are performed to measure the Radar Cross Section (RCS) in an anechoic chamber. The tag design is composed of six concentric Bow-Tie shaped loop resonators with one unitary element. In this paper, we demonstrated the Singularity Expansion Method (SEM) based circuit modelling and the transient behaviour of the RFID tag is performed. The coupling coefficients and the induced currents over the surface of Bow tie shaped rings are evaluated. The maximum read range is evaluated and the Bow-Tie RFID tag is proved to be more accurate and efficient with the variation of distance up to 1.8m at 0dBm which is extendable to 2.14m for higher input power. This range is maximum to our knowledge for such a high-frequency range of 8-18GHz. The 4-bits Bow-Tie Chipless RFID tag design is compact and can be deployed commercially for general IoT applications.

Polymers

Flexible substrates have become essential in order to provide increased flexibility in wearable s... more Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance...

Polymers

Flexible substrates have become essential in order to provide increased flexibility in wearable s... more Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance...

Polymers

Flexible substrates have become essential in order to provide increased flexibility in wearable s... more Flexible substrates have become essential in order to provide increased flexibility in wearable sensors, including polymers, plastic, paper, textiles and fabrics. This study is to comprehensively summarize the bending capabilities of flexible polymer substrate for general Internet of Things (IoTs) applications. The basic premise is to investigate the flexibility and bending ability of polymer materials as well as their tendency to withstand deformation. We start by providing a chronological order of flexible materials which have been used during the last few decades. In the future, the IoT is expected to support a diverse set of technologies to enable new applications through wireless connectivity. For wearable IoTs, flexibility and bending capabilities of materials are required. This paper provides an overview of some abundantly used polymer substrates and compares their physical, electrical and mechanical properties. It also studies the bending effects on the radiation performance...

Sensor and Actuators A : Physical, 2020

This paper presents the design, fabrication and testing of two embroidered chipless octagonal-sha... more This paper presents the design, fabrication and testing of two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable applications. The first tag is designed by using silver-coated polyamide conductive fibre (HC12) and the second tag is embroidered by using highly conductive Vec-tran (LIBERATOR 40) which is highly conductive multifilament yarn spun from Liquid Crystal Polymers(LCP), on cotton fabrics. In contrast to the traditional RFID tag, the chipless RFID tagging, the ID code isnot saved in the memory, instead, it uses the physical features of the tag to send data. The proposed tag’sdesign uses a Frequency Selective Surface (FSS) technique for the frequency range of 8–18 GHz. These tags are designed using CST studio and precisely fabricated by using commercial ZSK Technical EmbroiderySystem JCZA (0109–550). The tag design is composed of six concentric octagonal loop resonators with one unitary element. The electromagnetic scattering waves behaviour and Singularity Expansion Method(SEM) based circuit modelling for the octagonal-shaped tag is performed, and the coupling coefficients are evaluated. The desired data bits are obtained by a series of comparative experiments for Radar CrossSection (RCS) in an anechoic chamber. The experimental results obtained show that the 4-bit data is accurately retrieved with the variation of distance by up to 1.8 m at 0 dB m. Moreover, the average transition from minimum ‘0’ to maximum 1’ is -27 dB for both designs. Furthermore, the experimental results for on-body RCS measurements and the bending effects on both tags down to 7 mm is observed. This octagonal embroidered Chipless RFID tag is a fully textile design which is compact and can be deployed commercially in various IoT applications.

IEEE GLOBECOM 2020, 2020

In this work, two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable a... more In this work, two embroidered chipless octagonal-shaped RFID tags on cotton fabric for wearable applications are presented. The first tag is designed by using silver-coated polyamide conductive fibre (HC12) and the second tag is embroidered by using highly conductive Vectran (LIBERATOR 40) which is a highly conductive multifilament yarn spun from Liquid Crystal Polymers (LCP), on cotton fabrics. The proposed tag's design uses a Frequency Selective Surface (FSS) technique for the frequency range of 8 to 18GHz and fabricated by using commercial ZSK Technical Embroidery System JCZA. The tag design is composed of six concentric octagonal loop resonators with one unitary element. The desired data bits are obtained by a series of comparative experiments for Radar Cross Section (RCS) in an anechoic chamber. The experimental results obtained show that the 4-bit data codeword is accurately retrieved with the variation of distance by up to 1.8m at 0dBm. Moreover, the experimental results include on-body RCS measurements and the bending effects on both of the tags. The tags are compared to the state of the art tags in a comparative table.