Dual-Band Resonator Designs for Near-Field Wireless Energy Transfer Applications

Dual-band near-field wireless energy transfer (WET) designs outweigh single-band system with regard to either concurrent energy and data transfer or multiple wireless charging standard functionalities. There are two major approaches in resonator designs, namely, multi-coil and single-coil. This chapter presents a review on design constraints for each design approach and rectification techniques available in counteracting impediments of dual-band near-field WET systems. Challenges pertinent to link design are discussed primarily followed by methods implemented to mitigate detrimental impact on performance metrics. Front-end dual-band resonator design methods are accentuated in this chapter in lieu of end-to-end WET system. This is envisioned to offer insights for designers contemplating on design modes or developing ways to facilitate a boost in rectification options currently available

Measurement of excess loss for fixed terrestrial links in vegetated campus environment

In the design of fixed wireless links, having Fresnel zone clearance or in other words Line-of-Sight (LOS) link is highly recommended. Without the presence of obstacles in the first Fresnel ellipsoids, the signal attenuation of the transmission path is equivalent to free space attenuation. Nonetheless, this ideal unobstructed link cannot be attained at all times especially when the transmitting and receiving antennas are positioned near to the ground particularly below rooftop level as well as when wireless propagation channel depends on the conditions of the environment. Besides the terrain and buildings, the presence of vegetation dong the path will have an adverse effect on the receiving signal. Furthermore, trees growth over time of operation will affect the condition of the link even if the link is initially unobstructed. Hence, this research aims to determine the average value of excess path loss which is inclusive of foliage attenuation by measuring and characterizing the signal distortion attributed to vegetation that exists in the vicinity of point-to-point links based on Institute of Electrical and Electronics Engineers (IEEE) 802.11a Wireless Local Area Network (WLAN) standard at 5.8 GHz. The study on the effect of vegetation blockage is performed within the campus of Universiti Teknologi Malaysia (UTM) for both Line-of-Sight (LOS) and Near Line-Of-Sight (NLOS) links. Data acquisition is performed based on the concept of remote data logging in which data can be gathered via a remote server constantly for 24 hours and seven days a week together with the integration of daily scheduled data logged e-mailing. The behaviour of the link performance is studied and the average excess path losses are found to be 12.2 dB and 4.6 dB for NLOS links obstructed by a single tree and a row of trees respectively

Investigation of foliage effects via remote data logging at 5.8 GHz

This paper presents an unconventional methodology in examining the extent of vegetation blockage effects imposed on near line-of-sight (NLOS) fixed wireless links based on Institute of Electrical and Electronics Engineers (IEEE) 802.11a Wireless Local Area Network (WLAN) standard operating at frequency 5.8 GHz of Unlicensed National Information Infrastructure (UNII) band. By employing the concept of remote data logging, power received measurements were acquired constantly via a remote server for 24 hours and seven days a week from three dissimilar NLOS links within the campus of Universiti Teknologi Malaysia (UTM) in which it can best be described as suburban environment. These point-to-point links deployed in conjunction with wireless campus are impeded directly or indirectly by vegetation. The behaviour of these site-specific links performance is studied. The average excess path loss inclusive of foliage loss which is relevant to the climate of a tropical country is derived. Comparison of tabulated results between these divergent fixed wireless links besides exploratory data analysis is presented

Displacement-tolerant printed spiral resonator with capacitive compensated-plates for non-radiative wireless energy transfer

A printed spiral resonator without external lumped elements is proposed. Instead of employing surface-mount device capacitors, the series-parallel capacitive plates are designed and etched on the same substrate to achieve simultaneous conjugate matching between a pair of symmetrical near-field coupled resonators. Simulations are conducted with the aid of CST Microwave Studio. The proposed design displayed satisfactory tolerance toward planar displacement at z-axis plane, lateral displacement at x- and y-axis planes, as well as concurrent planar and lateral displacement. Positioned at perfect alignment with a transfer distance of 15 mm, the simulated and measured maximum power transfer efficiency achieved are 79.54% and 74.96%, respectively. The variation ratio for planar displacement acquired is 0.29% when receiving resonator is rotated from - 180° till 180° with a step size of 15°. Under rotational angle from 0° till 180°, the measured average variation ratio for lateral displacement at x- and y-axis up to 15 mm is 20.14%. The feasibility of sustaining power transfer efficiency under various offsets depicts the possibility of integrating the proposed simple design for low power wireless energy transfer applications, such as wireless charging for handheld devices in consumer electronics and implanted biomedical devices

Antenna design using left-handed materials

Smart antenna technologies are emerging as an innovative way to meet the growing demand for more powerful, cost-effective and highly efficient wireless communication systems. In this project, from broad category of smart antenna techniques, the switch beam digital-beamforming technique in the downlink is deployed to improve the fidelity and performance of WiMax application. In this regards, the designed system forms and steer the beam according to the user location which is known to the system. In addition, the system performs sidelobe cancellation base on the chebyshev algorithm to optimize the antenna radiation pattern. The design and implementation steps are as follow: the system is firstly modeled by MATLAB software. After modeling, the algorithm is implemented in DSP by using C and Code Composer Studio. After DSP hardware implementation, the signal management is performed in DSP before transmission to the FPGA board. This management is necessary, in order to make processed signal in DSP suitable for channel separation process in FPGA. FPGA is deployed to split the data stream into sixteen channels corresponding to number of antenna elements. Next, the FPGA and DSP are integrated together to form the baseband switch beam smart antenna system. After integration process, the hardware is tested; the results prove that the system functions properly as we expected from simulation model. In this project, lastly, the initial design of IF, RF-front-end and their necessary circuits are also portrayed to be used in the next smart antenna research project

Polymer conductive fabric grid array antenna with pliable feature for wearable application

A flexible microstrip grid array antenna designed on polydimethylsiloxane (PDMS) substrate and copper conductive fabric as the patch and ground plane is presented. The proposed rectangular geometry designed at 15 GHz is made of 19 cells with 22 radiating elements. The proposed antenna achieves almost 40% wideband characteristics at −10 dB reflection coefficient from 11.10 GHz until 16.2 GHz with measured maximum gain of 14.0 dBi in normal state. Analysis on performance of antenna at bend state with various value of bend radius has been done. The measured reflection coefficient shows low sensitivity to bending effect where the antenna operates well at designed frequency which is at 15 GHz. Due to these criteria, it is a suitable candidate for wearable applications