H-Shaped Eight-Element Dual-Band MIMO Antenna for Sub-6 GHz 5G Smatphone Applications

The design of an eight-element H-shaped dual-band multiple-input multiple-output (MIMO) antenna system for sub-6 GHz fifth-generation (5G) smartphone applications is presented in this work. The radiating elements are designed on the side edge frame of the smartphone, placed on both sides of the main printed circuit board (PCB). Each side edge consists of four radiating elements, which ensures low mutual coupling between antenna elements. The total size of the main PCB is 150×75 mm 2 , while the size of the side edge frame is 150×7 mm 2 . A single antenna consists of an H-shaped radiating element fed using a 50Ω microstrip feeding line designed on the main board of the smartphone. The results show that, according to −6 dB impedance bandwidth criteria, the designed MIMO antenna radiates at two different frequency ranges within the allocated 5G spectrums, i.e., 3.1–3.78 GHz and 5.43–6.21 GHz with 680 MHz and 780 MHz bandwidths, respectively. It is also observed that the antenna elements are able to provide pattern diversity for both the frequency bands. Furthermore, an isolation of >12 dB is observed between any two given radiating elements. Numerous MIMO critical performance characteristics are assessed, including diversity gain (DG), envelope correlation coefficient (ECC), and channel capacity (CC). A prototype is built, measured, and it is observed that the measured and simulated data correspond well. On the basis of performance characteristics, it can be claimed that the suggested MIMO system may be used in 5G communication networks.Dr. Mohammad Alibakhshikenari acknowledges support from the CONEX-Plus programme funded by Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 801538

Stretchable and highly conductive carbon nanotube-graphene hybrid yarns for wearable systems

Carbon Nanotubes (CNTs) have emerged as potential candidates for replacement of conventional metals due to their significant mechanical, electrical, thermal properties and non-oxidizing abilities [1, 2]. The density of CNT composites is about five times lower than copper and around half that of aluminium. Moreover, their thermal conductivity is about ten times that of copper. With the above mentioned distinguishing features, CNTs have been of interest in medical, electronics and antenna applications [3]. CNTs are drawn into yarns by pulling and twisting them from CNT forests. Previously we have presented microwave characterization of CNT yarns [4]. Our results have shown that the CNT yarns exhibits frequency independent resistive behavior and is beneficial for wideband applications such as ultra-wideband (UWB) and wireless body area networks [4]. Electrical conductivity of a CNT yarn depends on the properties, loading and aspect ratio of the CNTs. It also depends upon the twist angle and the characteristics of the conductive network. By doping or adding materials, such as gold, silver or NiCr, electrical conductivity of CNTs can by varied. In [5], highly conductive carbon nanotube-graphene hybrid yarns are reported. They are obtained by drawing vertically aligned multi-walled carbon nanotubes (MWCNT) into long MWCNT sheets. Then graphene flakes are deposited onto the MWCNT sheet to form a composite hybrid structure that is transformed into yarns by twisting. The electrical conductivity of these composite MWCNT-graphene hybrid yarns is over 900 S/cm. In this work, we have modeled this hybrid material as a potential data transmission line and compared it with a transmission line made out of copper on the same substrate. The results are tabulated in Table-I. They show a good agreement between copper based and composite MWCNT-graphene hybrid material based transmission lines. The hybrid material is high conductive, flexible and stretchable. This makes it suitable to use as transmission lines and connecting wires in systems that require stretching and flexibility, such as wearable systems

Novel MIMO Antenna System for Ultra Wideband Applications

The design of a 4 x 4 MIMO antenna for UWB communication systems is presented in this study. The single antenna element is comprised of a fractal circular ring structure backed by a modified partial ground plane having dimensions of 30 x 30 mm2. The single antenna element has a wide impedance bandwidth of 9.33 GHz and operates from 2.67 GHz to 12 GHz. Furthermore, the gain of a single antenna element increases as the frequency increases, with a peak realized gain and antenna efficiency of 5 dBi and >75%, respectively. For MIMO applications, a 4 x 4 array is designed and analyzed. The antenna elements are positioned in a plus-shaped configuration to provide pattern as well as polarization diversity. It is worth mentioning that good isolation characteristics are achieved without the utilization of any isolation enhancement network. The proposed MIMO antenna was fabricated and tested, and the results show that it provides UWB response from 2.77 GHz to over 12 GHz. The isolation between the antenna elements is more than 15 dB. Based on performance attributes, it can be said that the proposed design is suitable for UWB MIMO applications.The authors would like to appreciate Universidad Carlos III de Madrid and the European Union’s Horizon 2020 research and innovation programme for the funding of this research work under the Marie Sklodowska-Curie Grant 801538

Uni-Planar MIMO Antenna for Sub-6 GHz 5G Mobile Phone Applications

This article presents the design of a uni-planar MIMO antenna system for sub-6 GHz 5G-enabled smartphones. The MIMO antenna designed comprises four loop-shaped radiators placed at each corner of the mobile phone board, which follows the principle of pattern diversity. The single-antenna element resonates at 3.5 GHz, its impedance bandwidth is noted to be 1.28 GHz (3-4.28 GHz) for S11 90%. The isolation of >10 dB between antenna elements is achieved for the MIMO configuration. Furthermore, the MIMO antenna designed provides enough radiation coverage to support different sides of the mobile phone board, which is an important feature for future 5G-enabled handsets. In addition, the impacts of human hands and heads on MIMO antenna performance are investigated, and acceptable performance in the data and conversation modes is observed.The authors sincerely appreciate the support from Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant 80153

Antennas and components for modern telecommunication systems including wireless body area networks

Empirical thesis.Bibliography: pages 179-196.1. Introduction -- 2. Background and related work -- 3. Narrow band antennas -- 4. Wide band antennas -- 5. Ultra wideband antenna with band notching -- 6. Antennas with reflectors -- 7. Reconfigurable antennas -- 8. Carbon nanotubes yarns -- 9. Conclusions and future work.With the advancements in wireless communications, there is a constant need to develop novel antennas and components to support modern communication systems. These systems are targeted for applications in medical, defence, healthcare, public security, communications. The antenna is a vital front end component in any wireless system. Although many narrow- and wide-band antennas have been designed over the past decades, still there are several challenges when designing such antennas for modern systems. These challenges include compactness, space constraints, desired radiation characteristics, low cost, light weight, multi-band operation, interference mitigation, reconfigurability, and stable performance under varying conditions. Motivated by the increasing demand for modern telecommunication systems inclusing wireless body area networks (WBAN), this thesis addresses such challenges and presents several solutions.In this thesis, in addition to characterization of carbon nanotube yarns, several antennas are deigned and investigated. The designed antennas are broadly classified into narrow-band antennas, wide-band antennas, embroidered antennas on polymer composites, wide-band antennas with notching, antennas with Frequency Selective Surface (FSS) and High Impedance Surface (HIS) reflectors, and reconfigurable antennas.The narrow-band antennas provide single- and dual-band operation for the2.45GHz industrial, scientific and medical (ISM) band and for 4.9GHz public safety wireless local area network (WLAN)/5GHz IEEE 802.11 WLAN. These antennas have significant advantages of compactness (only 14mm wide), full groundplane to minimize radiation towards the body, a wide radiation pattern over thebody surface to provide maximum coverage, and less sensitivity to the variation of the gap between the antenna and the human body. These advantages make them suitable for on-body communications and wearable applications.The wide-band antennas target ultra-wideband (UWB) systems. One such antenna is fabricated using conductive fibres on polymer composite substrate (PDMS) that is exible and semi-transparent. A UWB antenna with a notch band provides design exibility to reject a desired frequency band. A mathematical expression is presented to predict initial design parameters of these antennas and to avoid excessive numerical computations required otherwise. These antennas are compact, have stable wide radiation patterns and provide band rejection with a high VSWR.FSSs are employed with UWB antennas to achieve a uni-directional pattern by reecting the radiation from the lower hemisphere to the upper hemisphere.The presented design has a stable radiation pattern over a wide bandwidth and is suitable for applications using uni-directional beam. It also helps to save and use the power that otherwise could propagate into the human body, thus are suitable for off-body communications. Periodic and quasi-periodic sequences of modulated line based HIS are also investigated and is used to achieve controlled radiation patterns.Reconfigurable antennas are designed for the 2.45GHz ISM band and 5GHz WLAN to operate in close proximity of the human body. They have same advantages as narrow-band antennas mentioned above. A reconfigurable antenna to provide UWB operation in one mode and a narrow-band operation in another mode is presented. It is designed using a low cost substrate, has planer configuration, avoids the need of vias and has a fully printed bias circuit.Theoretical and experimental characterization of Carbon Nanotubes (CNT) yarns is a valuable contribution that opens new paths of research related to CNT. Electrical properties of CNT yarns were known for Direct Current (DC), however they were not available at RF and microwave frequencies. In this thesis, CNT yarns are modelled as transmission lines and are characterized for a frequency range from 500MHz to 20GHz. Results show that the yarns exhibit a frequency independent resistive behaviour and are suitable for wide-band applications including wireless body area networks.Mode of access: World wide web1 online resource (xxxvi, 196 pages) colour illustration

Editorial for the Special Issue on the New Trends in Microwave/Millimeter Antennas/Filters: From Fundamental Research to Applications

The rapid growth of wireless communication systems has led to high demand for the design of microwave/millimeter components with multiband characteristics, high performance, and ease of integration with other devices [...

Sensitivity of a wearable printed antenna with a full ground plane in close proximity to human arm

This paper presents sensitivity analysis of a printed antenna with a full ground plane, suitable for wearable armbands and other such body area network devices operating in the industrial, scientific, and medical (ISM) band (2.45 GHz). Antenna input impedance and radiation characteristics are presented along with the parametric analyses. Antenna performance is investigated in free space and in close proximity to various human arm models (i.e. flat, rectangular and elliptical). The full ground plane makes the antenna highly insensitive to the gap between the antenna and the arm in addition to reducing electromagnetic radiation absorption in the arm. Small width (14mm) of the antenna makes it feasible to position along the length of a human arm without bending, which causes shift in resonant frequency.4 page(s

A Switchable printed antenna with a ground plane for 2.45/5 GHz wireless body area networks

This paper presents a switchable printed antenna with a full ground plane for wireless body area network devices operating in the industrial, scientific, and medical (ISM) band at 2.45 GHz and 5 GHz IEEE 802.11 Wireless Local Area Networks (WLAN) (5.15-5.35 GHz, 5.25-5.35 GHz). The operating bands can be switched between 2.45 GHz and 5 GHz by turning the switches ON/OFF. Investigations have been carried out in near body scenario to assess its performance for body centric wireless communication. The proposed antenna exhibits a wide radiation pattern along the body surface to provide wide coverage and its narrow width (14mm) makes it suitable for on-body applications.3 page(s

Reconfigurable antenna options for 2.45/5 GHz wireless body area networks in healthcare applications

This paper presents electronically reconfigurable antenna options in healthcare applications. They are suitable for wireless body area network devices operating in the industrial, scientific, and medical (ISM) band at 2.45 GHz and IEEE 802.11 Wireless Local Area Network (WLAN) band at 5 GHz (5.15-5.35 GHz, 5.25-5.35 GHz). Two types of antennas are investigated: Antenna-I has a full ground plane and Antenna-II has a partial ground plane. The proposed antennas provide ISM operation in one mode while in another mode they support 5 GHz WLAN band. Their performance is assessed for body centric wireless communication using a simplified human body model. Antenna sensitivity to the gap between the antenna and the human body is investigated for both modes of each antenna. The proposed antennas exhibit a wide radiation pattern along the body surface to provide wide coverage and their small width (14mm) makes them suitable for on-body communication in healthcare applications.4 page(s

An Armband-wearable printed antenna with a full ground plane for body area networks

This paper presents a printed antenna with a full ground plane, suitable for wearable armbands and other such body area network devices operating in the industrial, scientific, and medical (ISM) band (2.45 GHz). Performance and characteristics are presented along with parametric analyses. Antenna performance is investigated under conformal bending over human arm to assess its suitability for armband-type body centric wireless communication devices. The full ground plane makes the antenna performance highly insensitive to the gap between the antenna and the arm. It also reduces electromagnetic radiation absorption in the arm. The proposed antenna exhibits a wide radiation pattern along the body surface to provide better coverage and its narrow width (14mm) makes it suitable for wearable on-body applications.2 page(s