TRANSMISSION LINES AND OPTICAL FIBRES
Learning outcomes of the course unit
The course will provide in-depth technical knowledge regarding the functioning and applications of transmission lines as well as the basic concepts of microwave waveguides and optical fibres. Design issues related to use will also be explored.
Electrical engineering AB, General physics C
Course contents summary
Revision of Farady’s and Ampere’s laws and Maxwell’s integral and differential equations. Charge continuity. Revision of differential operators. Wave equations, forward and backward propagating waves and phase velocity. Ideal and lossy waves. Continuity conditions. Maxwell’s equations transformed; phase concepts. Helmholtz’s equations. Active, reactive, instantaneous and average power. Power carried by a wave. Poynting’s theorem and its application.
Introduction to guided propagation. Classification of cylindrical structures. Telegraph and telephone equations; their relationship to Maxwell’s equations.
Circuit line description; lossy lines, propagation constant calculation, phase velocity, characteristic impedance, and line parameters. Scattering parameters. S-matrix and T-matrix: their use and the Smith Chart. Short-circuited and open-circuited transmission lines. Standing waves. Exercises on the Smith Chart. Impedance inverter and input impedance for l=λ/4 and l=λ/2.
The problem of matching a line in terms of power and impedance or uniformity. Power supplied to the load, discharges on the lines, transfer function and non-distortion condition. Single-stub, double-stub and triple-stub adapters at λ/4 and their use. Exercises in line matching with single-stub adapters in series and parallel, double-stub and at l=λ/4. The problem of matching broadband signals.
Stripline and microstrips. Characteristic parameters, calculation methodologies and numerical approaches. Applications. T and S parameters; definition, use and exercises.
Time domain transmission lines; propagation of transients. Bounce diagrams. Load conditions. Exercises. Outline of microwave guides.
Propagation in dielectric guides. Outline of x-ray optics and fibre optics. Performance and applications. Outline of dielectric guides, integrated optics and optoelectronic devices.
S. Selleri, “Propagazione Elettromagnetica Guidata”, MUP, Parma, 2006.
F.T. Ulaby, "Fondamenti di Campi Elettromagnetici - Teoria e Applicazioni", - Edizione italiana a cura di S. Selleri, McGraw-Hill, Milano, 2005.
U.S. Inan, A.S. Inan “Engineering Electromagnetics”, Addison Wesley, 1999