ANTENNAS AND RADIOPROPAGATION

The course aim is to provide basic concepts and techniques of Applied Electromagnetics, together with its most relevant applications in electronics engineering. Moving from the unavoidable theoretical background (basically Maxwell's Equations and their solutions) required for deeply understanding the generation and propagation of electromagnetic waves in different environments, the course of Antennas and Radiopropagation gives the students basic tools for designing transmission lines, radio-links, antennas, as well as concepts to evaluate quantitatively the interaction of electromagnetic fields with single/multi-layer metallo-dielectric structures, anisotropic media, cold plasma etc.

The course includes both theoretical lectures and laboratories.

- Intermediate knowledge of Integral and Differential Calculus for multivariable vector and scalar functions.

- Intermediate knowledge of General Physics II (Electrostatics, Magnetostatics and Optics).

- Basic knowledge of Circuit Theory and Signal Processing.

Although lecture attendance is not mandatory, it is strongly recommended.

0) Brief Overview of differential operators and reference systems

• First order and second order operators: gradient, divergence, curl, Laplacian.
• Overview of orthogonal coordinate systems.

1) Maxwell's equations

• Maxwell's equations in time-domain (axiomatic viewpoint).
• Charges in electromagnetic fields: Lorentz force.
• Constitutive relations and boundary conditions.
• Conservation Laws, energy density and energy flow.
• Time-harmonic electromagnetic fields.
• Classical models for dielectrics, conductors and plasma.
• Causality.

2) Simple solutions of Maxwell's equations: plane waves

• Uniform plane waves in lossless media (time-domain).
• Monochromatic plane waves (frequency-domain).
• Uniform plane waves in lossy media (frequency-domain).
  • Propagation in weakly-lossy dielectric.
  • Propagation in good conductors: skin effect.
• Wave polarization.
• Uniform plane waves in lossy media.
• Propagation in oblique directions.
• Classification of complex (or inhomogeneous) waves.
• Group velocity and energy velocity.

3) Transmission Lines, Matching Techniques and Waveguides

• TEM propagation in transmission lines.
• Distributed circuit model of a transmission line.
• Characteristic impedance, reflection coefficient, VSWR, SWR.
• Overview of commonly-used transmission lines.
• Matching techniques.
• Helmholtz decomposition in waveguides.
• Classification of modes: TE, TM and TEM.
• Waveguides: TE/TM modes, power transfer, group velocity.

4) Reflection and Transmission of plane waves

• Planar interface between two media: TE/TM modes.
• Reflectionless slab and planar multi-layer structures.
• Equivalent transmission line model for TE/TM propagation in multi-layer slabs.
• Overview of Geometrical Optics, Fermat’s principle and ray tracing.

5) Pulse Propagation in Dispersive Media

• Wavefront velocity and causality.
• Pulse propagation and spreading.
• Dispersion compensation techniques.
• Anomalous dispersion: slow, fast and negative group velocities.
• RADAR applications: chirp and pulse compression.

6) Radiation Theory and Antennas

• Charges and currents as sources of EM fields.
• Retarded potentials and signal propagation.
• Time-harmonic radiation theory: potentials.
• Far-field approximation and plane-wave spectrum (PWS).
• Antenna relevant parameters: pattern, gain, directivity, effective area, polarization.
• EM Field radiated by an elementary dipole.
• Wire and loop antennas: description and relevant antenna parameters.
• Overview of commonly-used kinds of antennas.

7) Transmitting and Receiving Antennas

• Coupled antennas: Friis’ Formula. Polarization matching.
• Antenna Noise Temperature and data rate limit.
• Satellite links.
• RADAR Equation.

8) Laboratory

• Plane waves: Fresnel coefficients measurement.
• Study and design of waveguides and linear antennas using numerical CAD.
• Antenna pattern measurements.
• RADAR systems.

[1] S. J. Orfanidis, "Electromagnetic Waves and Antennas".

[2] C. G. Someda, "Electromagnetic Waves", CRC Press.

[3] C. A. Balanis, "Advanced Engineering Electromagnetics", Wiley.

[4] G. Franceschetti, "Campi Elettromagnetici", Bollati Boringhieri.

[5] F. S. Marzano, N. Pierdicca, "Fondamenti di Antenne", Carocci.

[6] C. A. Balanis, "Antenna Theory: Analysis and Design", Wiley.

Written and Oral Exams.

Frequently asked questions are closely related to the detailed course program.