Comunicações Rádio

Communication Systems
Electromagnetism

There are no classes for this course unit of any topology.
However, students who wish to do so may attend Radio Communications (61002199) classes from the Electrical and Computer Engineering degree programme.
Any questions arising from independent study can be clarified during office hours.

Objectives: To acquire scientific knowledge about radio communications systems. Assumes particular relevance the understanding and analysis of guided transmission media and antennas; digital modulation techniques; most common systems using Wireless Personal Area Networks (WPAN) and Low Power Wide Area Networks (LPWAN) technologies.

Generic skills: Ability to analyze and synthesize; ability to develop autonomous and team work; ability to apply technical knowledge to the design and implementation of different aspects related to radio communications systems; ability to speak and write in Portuguese.

Specific skills: Know and understand the characteristics of transmission lines; to know and understand the radiation diagrams and the fundamental parameters of the antennas; know and understand the different types of antennas and modulation techniques used in today’s radio communications systems. Among them, special attention is given to WPAN and LPWAN systems, namely those used in energy and automation monitoring and control applications: smart metering and smart grids; Internet of Things (IoT) and Industry 4.0; between others.

Introduction

• Motivation; historical perspective and social impact of radio communications;
• Radio spectrum: Frequency assignment table;
• Current radio communications systems;

Transmission lines

• Two-wire transmission line; coaxial cable; microstrip line, etc.
• Telegrapher equation; characteristic impedance and propagation constant;
• Terminated transmission line: reflection coefficient; VSWR; RL and input impedance.

Fundamental concepts and parameters of antennas

• Antennas in radio communications systems;
• Radiation mechanism topics;
• Antennas fundamentals
• Poynting vector, power density and radiation intensity;
• Electromagnetic waves propagation impedance of free space.
• Fundamental parameters:
• Radiation pattern in polar and Cartesian coordinates (main lobe, side lobe; HPBW; FNBW; etc.);
• Directivity; gain; effective area; efficiency; bandwidth; polarization; input Impedance; etc.

Wire, aperture and printed antennas

• Linear antenas: dipoles and monopoles;
• Microstrip antennas: analysis and synthesis;
• Aperture antennas and reflectors.

Digital communications (Band-pass digital modulations)

• Elementar digital modulations techniques: ASK, PSK, FSK and QAM.
• Linear digital modulations with coherent detection:
• binary modulation (ASK e PSK); and non binary (MPSK) .
• Nonlinear digital modulations with coherent detection:
• binary modulation (FSK e MSK); and non binary (MFSK).
• QAM modulation;
• error probabilities and spectral efficiency evaluation.

Wireless Personal Area Networks (WPAN) and Low Power Wide Area Networks (LPWAN) systems

• IEEE 802.15.x standards;
• Bluetooth / IEEE 802.15.1;
• ZigBee versus IEEE 802.15.4;
• LoRa and LoRaWAN;
• Topics about Sigfox and other LPWAN systems.

Radio technologies applications for energy and automation systems

• Smart metering and smart grids applications;
• Applications for Internet of Things (IoT) and Industry 4.0;
• Topics on wireless interface for smart sensors (IEEE 1451.5);
• Topics on Industrial 5G applications;
• Other applications: fleet management and warehouse management; RFID technologies; security and access control, etc.

Assessment method: Evaluation by a written exam (official designation "Avaliação por exame")

The assessment of the course unit is carried out through a formal written examination and laboratory practical work.

The Final Grade (FG) of the course unit is obtained from the following components:

• Written examimation (Exam), to be held during the official examination period at the end of the semester
• Practical Work (PW), to be completed during the practical classes and submitted within the established deadlines.

Option 1 – Assessment Based Solely on the Final Exam

By default, the final grade (FG) is determined exclusively by the mark obtained in the final written examination, according to:

 FG = Exam

To successfully complete the course unit, a minimum mark of 9.5 (out of 20) in the final examination is required.

or

Option 2 – Assessment Including Practical Work

Students who choose to complete and submit the Practical Work (PW) may obtain a weighted final grade, calculated as follows:

FG  = 0.7 x Exam + 0.3 x PW

To successfully complete the course unit under this assessment option, the following conditions must be simultaneously met:

• a minimum mark of 8.5 (out of 20) in the final written examination;
• a minimum mark of 10.0 (out of 20) in the Practical Work (PW) component;
• a minimum weighted final grade (FG) of 9.5 (out of 20).

The PW component includes the individual resolution of theoretical-practical worksheets and the preparation of laboratory reports, which may be carried out in groups of up to three students.

Whenever laboratory measurements are required for the completion of the practical work, these will be provided by the instructor.
All submitted materials will be subject to an individual oral defense during the final week of classes.

NAO