TRANSMISSION LINES and ANTENNAS

Knowledge and understanding: Acquisition of basic methodologies concerning radiation and propagation of electromagnetic fields for the study and analysis of trasmission media and antennas.

Applying knowledge and understanding: Analyze guiding structures and antennas for transmission of signals.

Making judgements: Ability to identify and compare the most appropriate methods for studying real problems.

Communication skills: Ability to present orally and through written tests using technical language and proper methodology.

Learning assessment may also be carried out on-line depending on specific circumstances required.

PART I - INTRODUCTION AND GENERAL PRINCIPLES

Introduction to electromagnetics, relevance and applications. Maxwell equations in time domain. Lorentz force. Fields conditions on discontinuity. Maxwell equations in sinusoidal regime.Polarization of the electromagnetic fields. Constitutive relations. Electromagnetic properties of media. Cold and collisionless plasma. Poynting vector and uniqueness conditions. Sommerfeld's radiation conditions.

PART II - TRANSMISSION LINES AND WAVEGUIDES

Guiding structures with cylindrical symmetry and metallic contour. TEM modes. Voltage and current on a transmission line. Telegraphers' equations in time and frequency domain. Phase velocity. Solution of Telegraphers' equations in progressive and stationary form. Reflection coefficient. Impedance transformer formula. Matched load, reactive load, generic load. Voltage standing wave ratio (VSWR). Matching techniques, quarter-wave transformer, matching with stubs. Resonant conditions on transmission lines. Transmission lines with losses. Narrowband signal propagation and group velocity. Modes in waveguide. Equivalent transmission lines. Dispersive propagation in waveguides and cutoff frequencies. Fundamental and high order modes. TE and TM modes in rectangular waveguide.

PART III - REFLECTION AND TRANSMISSION OF PLANE WAVES

Homogeneous and inhomogeneous plane waves. Normal incidence. Penetration depth. Snell's laws. Fresnel coefficients for parallel (TM) and orthogonal (TE) polarization. Transmission in lossless media. Total transmission and total reflection. Transmission in lossy media. Leontovic condition.

PART IV - RADIATION AND ANTENNAS

Electromagnetic potentials. Field radiated by an elementary electric dipole. Field radiated by an elementary current loop. Duality. Field radiated by linear antennas. Far field conditions. Input resistance and radiation resistance. Effective length. Transmitting antenna, directivity and gain. Short dipole, half-wave dipole, monopole. Receiving antennas. Polarization and power matching. Effective area. Friis's formula for link budget. Image sources.

LABORATORY ACTIVITIES

Experimental verification of Snell's laws at optical frequencies. Study, design and experimental characterization of trasmission media. Measurement of radiation patterns of linear antennas.

G. Franceschetti, Electromagnetics, Theory, Techniques, and Engineering Paradigms, Springer

S. J. Orfanidis, Electromagnetic Waves and Antennas

R. Sorrentino e G. Bianchi, Microwave and RF Engineering, John Wiley & Sons

G. Manara, A. Monorchio, P. Nepa, Appunti di Campi Elettromagnetici, SEU, Pisa.