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Published byAidan Gilbert Modified over 4 years ago

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EMLAB 1 Introduction to EM theory 1

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EMLAB 2 Electromagnetic phenomena The globe lights up due to the work done by electric current (moving charges). Steady state current (simple DC circuit)

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EMLAB 3 Electromagnetic wave : signal propagation The electrical signal propagate along the line trace at the speed of light.

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EMLAB 4 Electromagnetic wave – Crosstalk

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EMLAB 5 Electromagnetic wave : radio communication Moving charges on the antenna generate electromagnetic waves.

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EMLAB 6 Electromagnetic wave : automotive radar Moving charges on the antenna generate electromagnetic waves.

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EMLAB 7 Electromagnetic wave : ground penetrating radar The EM wave from the transmitter refracts into the ground and is reflected back by the underground facilities.

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EMLAB 8 Electromagnetic wave generation : antennas Many kinds of antennas are built and utilized.

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EMLAB 9 EM theory helps understand how electrical signals propagate along conductors as well as free space. Predicts voltages and currents using the concept of electric and magnetic field. Importance of electromagnetic theory

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EMLAB 10 Basic laws – Maxwell equations 1.Electromagnetic phenomena are explained by the four Maxwell equations. 2.Through the equations, electric field and magnetic field are coupled to each other. 3.Quantities on the right hand side are the source terms. 4.Quantities on the left side are the resulting phenomena. J 5.The independent variables are current density vector J and charge density. Maxwell equations Solution (free space)

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EMLAB 11 Electromagnetic theory Electric field (E) Magnetic field (H) Electro-magnetic field (E,H ) Sources (q, J) Material (ε, μ) Mathematics Coordinate systems Vector calculus (divergence, curl, gradient) EM-theory Material

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EMLAB 12Contents 1.Electric field Coulombs law Gausss law (divergence) Electric potential (gradient) Capacitance Ohms law 2.Magnetic field Biot-Savart law Amperes law (curl) Inductance 1.Sources Charge Current 2.Material Conductor (semi-conductor, lossy material) Dielectric (insulator) Magnetic material

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EMLAB 13 3.Electro-magnetic field Faradays law Displacement current Maxwells equations Plane wave Reflection/transmission 4.Transmission lines Impedance matching Smith chart Waveguides 5.Radiation

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EMLAB 14 Electric field A charged particle undergoes acceleration which is proportional to the electric field nearby.

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EMLAB 15 Coulombs law 1. The electric field is generated by the charge Q and spread into the space. 2.The speed of electric field transmission is the same as the speed of light.

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EMLAB 16 Electrons(-) are absorbed. (+) charges are generated Electrons(-) are generated. (+) charges are absorbed. Generation of charges : battery Electrons are generated via electro-chemical reaction. An amount of positive charges are generated such that the terminal voltages are sustained.

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EMLAB 17 Potential distribution near charged plates Charges emanate from a battery.

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EMLAB 18 Induction charging Droplets of an inkjet printer emission. A conducting sphere can be charged by induction.

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EMLAB 19Micro-machine MEMS devices can be controlled by electrostatic forces.

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EMLAB 20 Magnetic field A charged particle in motion generates magnetic field nearby. In the same way, current s generate magnetic field nearby.

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EMLAB 21 Motion of a charge in a magnetic field Charged particles in motion are influenced by magnetic fields

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EMLAB 22 Biot-Savart law Direction of H-field Current segment The generated magnetic field can be predicted by Biot-Savarts law

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EMLAB 23 Amperes law

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