S.R. Wylie

Experimental Investigations of Electromagnetic Wave Propagation in Seawater

It is often preferable to avoid using divers to undertake sub-sea activities, the alternatives being autonomous or remotely operated robotic vehicles and manipulators. This will only be achievable if robust communications can be established through seawater. Presently for such sub-sea activities it is necessary to use acoustic modems, which are only capable of operating with data rates of up to 50kbs-1. Optical sensors can also be used but these rely on clear water and in many sea conditions propagation beyond 10m is not possible. This paper presents new experimental results for electromagnetic wave propagation through seawater at MHz frequencies. These frequencies would enable the use of high speed data rates, suitable for a wide range of sub-sea activities

RF sensor for multiphase flow measurement through an oil pipeline

We have developed, in conjunction with Solartron ISA, an electromagnetic cavity resonator based sensor for multiphase flow measurement through an oil pipeline. This sensor is non-intrusive and transmits low power (10 mW) radio frequencies (RF) in the range of 100–350 MHz and detects the pipeline contents using resonant peaks captured instantaneously. The multiple resonances from each captured RF spectrum are analysed to determine the phase fractions in the pipeline. An industrial version of the sensor for a 102 mm (4 inch) diameter pipe has been constructed and results from this sensor are compared to those given by simulations performed using the electromagnetic high frequency structure simulator software package HFSS.

Design and construction of a 2.45 GHz waveguide-based microwave plasma jet at atmospheric pressure for material processing

We have designed a low-cost and reliable 2.45 GHz waveguide-based applicator to generate a microwave plasma jet (MPJ) at atmospheric pressure. The MPJ system consists of a 1-6 kW magnetron power supply, a circulator, a water-cooled matched load and the applicator. The applicator includes a tuning section, which is required to reduce the reflected power, and the nozzle section. The plasma is formed by the interaction of the high electrical field, generated by the microwave power, between the waveguide aperture and the gas nozzle. A variety of gases have been used to produce the plasma including argon, helium and nitrogen. A 2 kW, 2.45 GHz MPJ, constructed using a rectangular waveguide WG9A (WR340), has been investigated. An MPJ has been used for material processing applications including cutting, welding, glass vitrification and quartz/ceramic processing. This paper discusses the design parameters and the potential of the MPJ for industrial applications and how the jet can be tailored to suit different tasks, by adjusting the various parameters such as the type of gas, the flow rate, the input power and the nozzle design.

Atmospheric microwave plasma jet for material processing

We have designed a low-cost and reliable 2.45-GHz waveguide-based applicator to generate a microwave plasma jet (MPJ) at atmospheric pressure. The MPJ system consists of a 1-6 kW magnetron power supply, a circulator, a water-cooled matched load and the applicator. The applicator includes a tuning section, which is required to reduce the reflected power and the nozzle section. The plasma is formed by the interaction of the high electrical field, generated by the microwave power, between the waveguide aperture and the gas nozzle. A variety of gasses have been used to produce the plasma including argon, helium, and nitrogen. A 2-kW 2.45-GHz MPJ constructed using a rectangular waveguide WG9A (WR340) has been investigated. An MPJ has been used for material processing applications including cutting, welding, glass vitrification, and quartz/ceramic processing. This paper discusses the design parameters and the potential of the MPJ for industrial applications and how the jet can be tailored to suit different tasks, by adjusting the various parameters such as the type of gas, the flow rate, the input power, and the nozzle design.

Electromagnetic (EM) wave propagation for the development of an underwater Wireless Sensor Network (WSN)

Environmental concerns in aquatic environments have increased and require new and cost-effective real-time monitoring systems. Furthermore the Water Framework Directive (WFD) across the European Union (EU) and the growing international emphasis on the management of water quality and its sustainability are giving rise to a market for intelligent underwater monitoring systems. The aim of this paper is to study the feasibility of using electromagnetic (EM) waves in an underwater communication system and to develop a Wireless Sensor Network (WSN) using cheap commodity motes in the unlicensed (ISM) frequency bands for applications including environmental monitoring.

Real time EM waves monitoring system for oil industry three phase flow measurement

Monitoring fluid flow in a dynamic pipeline is a significant problem in the oil industry. In order to manage oil field wells efficiently, the oil industry requires accurate on line sensors to monitor the oil, gas, and water flow in the production pipelines. This paper describes a non-intrusive sensor that is based on an EM Waves cavity resonator. It determines and monitors the percentage volumes of each phase of three phase (oil, gas, and water) in the pipeline, using the resonant frequencies shifts that occur within an electromagnetic cavity resonator. A laboratory prototype version of the sensor system was constructed, and the experimental results were compared to the simulation results which were obtained by the use of High Frequency Structure Simulation (HFSS) software package.

Non invasive rail track detection system using microwave sensor

As fuel costs continue to rise, efficient public transport, especially rail will play an increasingly important role in the UK and worldwide. For the safe operation of the rail system, it is necessary that the condition of the rails can be monitored on a continual basis. An important part of this monitoring process is crack detection. Much research effort has been spent in the development of reliable, repeatable crack detection methods for the use on the service rail. In this research a new crack detection method has been investigated which utilizes microwave sensors to inspect the rail surface. Initial data from experiment are presented.

Microwave plasma system for material processing

The microwave plasma system operates at various ranges of frequencies including 0.896, 2.45, and 10 GHz, and uses a waveguide-based applicator to generate a microwave plasma jet (MPJ) at atmospheric pressure. The plasma is formed outside the cavity due to the strong electric field, generated by the microwave power, which occurs between the gas nozzle and an aperture in the applicator. The MPJ system has produced plasmas using a variety of gases and gas mixtures, including argon, helium, oxygen, and nitrogen. The MPJ has been used successfully for various materials processing including welding, cutting, and production of fibers from high-melting temperature materials, such as ceramic.

A matched Bow-tie antenna at 433MHz for use in underwater wireless sensor networks

Electromagnetic (EM) wave propagation underwater is been disregarded because of attenuation at high frequencies, however the theory predicts that propagation is possible at some useful distance in the lower Industrial, Scientific and Medical (ISM) band. Common transceivers rely on narrowband antennas and matching circuit. The aim of this paper is to design a broadband 433MHz bow-tie antenna and experiment it in air and water without a matching circuit. This antenna could be attached to wireless transceivers and form a Wireless Sensor Network for deployment in various underwater applications. The bow-tie antennas were designed, simulated and constructed in laboratory. Experiments were setup carefully by using a completely isolated transmitter from electronics to avoid airborne transmission. The 433MHz. bow-tie proved its suitability for use in Underwater.

Experimental characterization of an atmospheric argon plasma jet generated by an 896 MHz microwave system

This paper presents experimental results on an atmospheric plasma jet generated by a rectangular wave-guide based microwave system operating at 896 MHz. Argon gas emerging from a copper nozzle, which is placed inside the wave-guide short circuited at one end (hereafter referred to as the cavity for convenience), jets into the atmosphere through an aperture in the cavity wall. The plasma jet can be visually divided into two parts: a very bright patch (active zone) where microwave discharge takes place and a large, weakly illuminating tail attached to the active zone. The plasma jet is characterized in this work by measuring the electron number density, temperature and an excitation temperature of the argon atoms in the active zone over a range of microwave source power from 2 to 5 kW and argon flow rate from 2 to 7 litre min−1. Results show that the plasma is not in a local thermodynamic equilibrium state and the temperature of electrons is considerably higher than the excitation temperature of the heavy particles which indicates the upper limit of the translation temperature of the heavy particles.