82072 - Antennas for Wireless Systems M

Course Unit Page

Academic Year 2018/2019

Learning outcomes

The role of antenna as strategic interface between transmitter/receiver and channel. Design rules for the principal families of antennas (wire, aperture, and microstrip antennas), and for their combination in array architectures. Exploitation of antennas in modern energy-aware applications, such as radio-frequency energy harvesting or wireless power transfer systems.

Course contents

Lecture items

1. Analysis approach

Recall of Maxwell’s equations: solution in a normal homogeneous medium

The non-homogeneous medium problem: scattering problem and interpretation of the antenna as a scatterer

2. Properties of the antenna operated in the transmitting and in the receiving mode

Antenna current distribution; radiated field; antenna reflection coefficient, antenna operating band

In far-field conditions: antenna polarization; radiated power; radiation intensity; radiation patterns; directivity; radiation efficiency and antenna (power) gain; antenna effective area

Impedance and polarization mismatch, received power

Friis transmission equation: basic analysis and design of a radio link

3. Electromagnetic dipoles and loop antennas

Closed-form and numerical analysis of dipoles

Loop antennas as magnetic dipoles

Basic analysis of NFC systems

Comparison between NFC and far-field systems

4. Array theory

Array factor and the principle of pattern multiplication

One- and two-dimensional arrays

Shielded arrays

Electronic scanning and phased arrays

Smart antennas

Parasitic elements

Arrays for terrestrial TV reception: Yagi-Uda, log-periodic, and bow-tie

5. Basic treatment of plane aperture antennas

Far field radiated by a plane aperture with arbitrary aperture field

TEM apertures

Radiation properties of uniform TEM apertures of circular shape

Parabolic reflectors

Applications: direct broadcast satellite receivers, radio telescopes

6. Microstrip patch antennas

Patch description as an array of magnetic apertures

Patch feeding techniques

Reduced-size PIFA antennas for 2G/3G mobile terminals

Multiresonant PIFA’s

Antenna broadbanding by the resonance envelope technique

Multiband antennas for 4G/LTE terminals

Self-scaling antennas for ultra-wideband applications

7. Rectifying antennas

Definition of rectifying antennas (or RECTENNAS) for both RF energy harvesting and Wireless Power Transfer applications

Choices in terms of i) rectenna architecture, ii) antenna.

8. Laboratory

Electromagnetic design of cell-phone multi band antenna

Realization of few samples of single band patches and their characterization from both near-and far-field point of view

Readings/Bibliography

- Lectures slides

- "Antenna Theory: Analysis and Design", Constantine A. Balanis

- "Lezioni di Sistemi d'Antenna", Vol. 1 and Vol. 2, V. Rizzoli, D. Masotti


Teaching methods

- Lectures with slide

- Application examples with realistic antennas both commercial and designed by the lecturer

- Laboratory experiences with a commercial electromagnetic tool for antenna design

Assessment methods

Oral exam on both theoretical and laboratory parts

Teaching tools

During the theoretical study of the different classes of antenna, the lecturer will bring in class examples of antennas developed during his recent research activity

Links to further information

http://emlab.dei.unibo.it/

Office hours

See the website of Diego Masotti