Tan Hoa Vuong

Antenna Ultra Wideband Enhancement by Non-Uniform Matching

In this paper, antenna ultra wideband enhancement by non-uniform matching is proposed. The antenna consisted of a rectangular shaped radiator with two convex circled corners. Simulated results using CST Microwave Studio and measured results of a fabricated antenna concord well to prove that it can operate from about 3.5 GHz to 4.6 GHz and from 7.4 GHz to 12.7 GHz for S11(dB) <-10 dB. In addition, a good impedance matching is noted in the IEEE radar engineering X band range since the return loss coefficient remains below -50 dB value at 9.5 GHz and can reach -45 dB at 11 GHz. A current density comparison at 11 GHz, supporting our argument, between a stepper corner and convex corner demonstrates that the current density can reach 52A/m with a convex corner whereas it does not exceed 33A/m for the antenna with a stepper corners. Radiation patterns at various frequencies and peak gains show clearly interesting features of such antennas.

A Wireless On-line Temperature Monitoring System for Rotating Electrical Machine

Wireless communication can be a useful method to monitor the electrical machine as it provides the main characteristics of online signal processing. Our contribution in this current paper consists in studying a new system to monitor the rotating electrical machines based on wireless communication. The main objective of this system is to detect the temperature value of the squirrel cage induction machine’s rotor, using the IEEE 802.11 protocol. However, the application of wireless communication inside the rotating electrical machines is not self-evident due to the fact that the electromagnetic compatibility problems between devices isn’t obviously guaranteed. So, in order to obtain a good reliability for wireless communication, the study of the electromagnetic field inside rotating electrical machine is essential. As a first step in this paper, we are going to focus mainly on the flux effect of the rotating electrical machine through the finite element method which offers so much information on the phenomena characterizing the electrical machine operation. This method proves that the high frequency domain transmitter won’t be disturbed by the low frequency existing flux inside the machine. As a second step in this study, the proposed network system design is presented. Then, the communication protocol, the hardware design based on the transmitting chip Roving Networks (RN-171) as well as the software design are illustrated. Finally, the experimental results of the proposed system are investigated to validate its feasibility.

Design and implementation of wireless sensor network node for rotating electrical machine

The wireless sensor network for rotating electrical machine is beneficial for both real time monitoring and diagnosis purposes. In this paper, our contribution is to realize a wireless sensor network node based on IEEE 802.11 for detecting the temperature value of electrical machines rotating component (shaft). The IEEE 802.11 has been chosen for its low power, low cost and high flexibility. As for the choice of the temperature value, it is mainly due to the fact that it defines the rotating electrical machines lifetime. The experimental result, illustrated in this paper, shows a temperature variation. This variation represents one of the signal fading effects of the transmitter rotation. First, the proposed network system design is presented. Then, the communication protocol, the software and hardware design based on the transmitting chip RN-171 (Roving Networks) used for the system are illustrated and finally, the experimental results of the proposed wireless sensor network node are investigated.

Modelling and characterization of rotor temperature monitoring system

A rotor temperature monitoring system corresponds to a wireless communication between a transmitter module, fixed inside the electrical machine, and a fixed receiver located outside the electrical machine. Nowadays wireless communication for rotating electrical machines is interesting for both real time monitoring and diagnosis objectives. However, applying this technology can lead to some problems. One of them is that the material components of the electrical machine have a deep impact on the electromagnetic wave propagation between the transmitter and the receiver. This paper deals with the electrical machine effect on the rotor sensor transmission and propagation through the characterization of the radiation pattern. The simulation results obtained via HFSS have shown that the presence of the electrical machine components has a significant effect on the propagation characteristics.

A two dimensional magneto-inductive lens for near field imaging

In this paper, a planar near field magnetoinductive lens operating in the microwave range is presented. The proposed structure consists of two parallel planar arrays of metallic resonators, which are, once scaled in term of size as well as the array periodicity, the frequency of operation can be tuned over a wide frequency range. Thus the proposed design is potentially useful for many applications.

Subdiffraction resolution super lens based on negative refractive index transmission line metamaterial for free space imaging

In this paper, we propose a transmission line metamaterial super lens operating at 15.4 Ghz. The unit cell is built with a printed transmission line loaded with shunt inductor and series capacitor and it is designed to exhibit a negative refraction index equal -1. Such a microwave super lens can go beyond the diffraction limit and can be used for free space imaging.