Beyond Evanescent Electromagnetic Fields: Via Metal Wireless Surface Wave Power - Data transmission System and Wireless Power Transfer Based Sensor

Abstract

The presented thesis explores the evanescent electromagnetic waves concept to design wireless transmission to address two difficult practical engineering problems (a.)Wireless power/data transmission across metal complexes such as ships, submarines, oil-rigs is a challenging engineering problem. Primarily, due to the fact that the wireless electromagnetic waves undergo electromagnetic interference shielding due to the metal structures. Henceforth marine vessels utilize wired systems. An average ships requires several kilometers of cables just to establish communications. Apart from this, critical systems such as safety alarms require continuous power supply. Unfortunately, the backup fault detection systems of the fire alarms rely on cables. In an event of cable snapping fault detection systems fail. These factors become even more serious in case of oil-rigs and submarines. The solution presented in this thesis establishes noise free wireless radio communication across several metal floors (300 meters)and continuous wireless power supply of 16watts and 40 watts upto 4 meters and 1.2 meters, respectively. This is done by utilizing the concept of establish surface electromagnetic waves over metal air interfaces, which travel in a backward and forward fashion on the metal surfaces. (b.) An all in one touch, proximity and hover sensor system, whose performance does not degrade as the size of the touch screen panels increase or are contoured. The degraded performance stems from the large RC-time constant delays. This thesis addresses this problem by using a wireless power transfer based sensor system. Wireless power transfer systems transmit power at optimal efficiency under resonance matched conditions, the human body offers bioelectrical impedance. Hence, an approaching human finger shall disturb the resonance, which causes a drop in efficiency. This drop in efficiency can be registered as touch, proximity or hover sensing. Being wireless it has longer range and linearity as compared to capacitive sensors, resistive sensors or inductive sensors. The sensor presented in this thesis is based on evanescent wireless power transmission, implying that the electromagnetic waves decay exponentially normal to the surface of the transmitter. This property of the system has advantages as it does not effect the nearby electronic circuitry. The sensor performs normal even when placed under LCD screen under ON condition. Also, there is no performance degradation observed in the electronic system such as the LCD screen.