This article focuses on the design and investigation of a pair of unequally sized wireless electricity (Witricity) devices that are equipped with integrated planar coil strips. The proposed pair of devices consists of two different square-shaped resonator sizes of 120 mm × 120 mm and 80 mm × 80 mm, acting as a transmitter and receiver, respectively. The devices are designed, simulated and optimized using the CST Microwave Studio software prior to being fabricated and verified using a vector network analyzer (VNA). The surface current results of the coupled devices indicate a good current density at 10 mm to 30 mm distance range. This good current density demonstrates that the coupled devices' surface has more electric current per unit area, which leads to a good performance up to 30 mm range. Hence, the results also reveal good coupling efficiency between the coupled devices, which is approximately 54.5 % at up to a 30 mm distance, with both devices axially aligned. In addition, a coupling efficiency of 50 % is achieved when a maximum lateral misalignment (LM) of 10 mm, and a varied angular misalignment (AM) from 0° to 40° are implemented to the proposed device.
Detection of atrial fibrillation is done by checking the variations in the period of the heart rate, if a patient has atrial fibrillation then the period between each heart beat will vary. A light-based sensor can be used to detect these variations in heart rate; this is done by using Photoplethysmography (PPG) sensor which is non-invasive. The sensor consists of a LED with a photodetector and is able to detect the variations in blood volume or blood flow in the body and directly correlates to heart rate. The detected signal needs to be amplified and filtered as the signal contains a lot of high frequency noise as well as low frequency motion artifacts. The benefits of compact low-cost Wi-Fi module can be harnessed to develop a wireless continuous heart rate monitoring system enhancing possibility of atrial fibrillation detection.
This paper focus on new modulation technique to improve the performance of the conventional modulation that uses intensity modulation/direct detection (IM/DD) for On-Off Keying (OOK) modulation. This new modulation technique that is Dual Diffuser Modulation (DDM) can create superior modulation with able to reduce scintillation index, enhance power received and threshold signal level. The analysis result shows that the free space optical (FSO) can have good performance of power received under strong turbulence. The DDM are better performance as compare with conventional IM/DD-OOK and IM/DD-OOK with diffuser. This can help FSO system to combat with severe turbulence effect for optimum operation.
This paper demonstrates a new design of 3 dB coupler operating in UWB frequency band between 3.1 GHz and 10.6 GHz. Together with UWB phase shifter, this coupler is claimed to be one of the key factors in designing a Butler Matrix that can operate in very wide frequency range. Butler Matrix has been seen to be the most preferable technique to realize the beam-forming network besides provide compact in size and more cost-effective. The arrangement between beam-forming and multiple-input and multiple-output (MIMO) can broaden the coverage and capacity of users for wireless communication system. The proposed coupler design was accomplished in multilayer microstrip-slot technology by employing broadside coupling technique. The initial dimension of the coupler was obtained using a simple mathematical formula and finalized using CST Microwave Studio simulator. The simulation results show the coupler is having a very tight coupling of 3 dB ± 2 dB, the return loss and isolation are better than 21 dB and the phase difference performance is in the range of 90 0 ± 2 0 over the designated band. The designed device occupies an area of 25 mm x 15 mm.
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