35112 - Autonomous RF Sistems (2nd Cycle)

Learning outcomes

At the end of the course, the student knows the tools necessary for the analysis and design of the circuits and subsystems that make up the RF and microwave front-ends. He also knows the non-linearities that underlie their operation and the CAD tools that allow them to be accurately characterized. Finally, the student has knowledge of the methods for realizing the energy autonomy of the front-ends by exploiting the received radio waves and the relative environmental advantages due to the absence of batteries. The student also knows the applications in the field of RF and microwave identification (RFID) and in the field of sensor networks for environmental control.

Course contents

Functional blocks of radiofrequency (RF) wireless systems and main nonlinearities of their operating functions, and tools for their analysis and design.

Analytical methods for the characterization of nonlinearities in sinusoidal and multi-tone regime: frequencies generation, saturation, AM-PM conversion, frequency conversion, and nonlinear distortion.

Circuit model of nonlinear devices for power generation (transmitter side) and for RF-dc conversion (receiver side): MESFET and DIODES.

Harmonic Balance method and introduction to commercial simulation tools for RF circuit analysis/design. Hints on electromagnetic software tools. Main network functions definition for circuital performance evaluation of RF systems. In particular, the efficiency of an entire link for Wireless Power Transfer (WPT) is considered, and its different contributions are described from both a circuital and a systemistic point of view. Analyis and design of WPT subsystems both radiative (far-field) and non-radiative (near-field).

Analysis of passive RF/microwave components such as couplers and power dividers.

Near-field techniques

Inductive and capacitive couplings: design of the wireless link and efficiency definition

Scheme and design of the transmitter and the receiver

Far-field techniques

Energy harvesting from environmental sources and intentional wireless power transmission

Main characteristics of the antennas to be adopted

Possible schemes for the receiving power systems. Different rectenna (rectifying antenna) topologies

The final part of the course is devoted to the study of:

- some systems for near-field power transfer for wearable or implantable devices

- Rectennas for wide-band energy hravesting from the environment (far-field)

Readings/Bibliography

• D. Pozar, Microwave engineering, 4th Edition, Wiley

Teaching methods

Lab activities are also planned in order to have the students practising with electromagnetic simulations and circuital design for rectenna characterization.

Given the type of activity and the teaching methods adopted, attendance of this training activity requires prior participation by all students in Modules 1 and 2 of the safety training course for study environments, available in e-learning mode at [https://elearning-sicurezza.unibo.it/ ].

Assessment methods

The exam consists of an oral test.
In addition to the evaluation, students have the opportunity to carry out a group project focused on the design of a rectenna. Lab hours will be dedicated to the development of the project, during which students can interact with the instructor and clarify any doubts. These sessions are to be carried out in parallel with the students' independent work, if necessary.

Project work is recommended to consolidate the knowledge of the topics covered in the course, but it is not mandatory. Projects will be presented at the end of the course through PowerPoint presentations given by the students, during which the instructor may ask technical questions about the development process.

Submission of the project by each group grants the possibility of obtaining the highest grade (30 cum laude), while failure to submit the project limits the maximum achievable grade to 27.

Duration and structure of the exam.
The exam consists of an oral test comprising two questions, which may require the use of the board or a sheet of paper. The questions cover topics addressed throughout the course, as outlined in the syllabus. The use of notes, books, handouts, or calculators is not allowed. A third question may be asked at the instructor's discretion to better define the final evaluation.

Evaluation criteria for the exam:

• Insufficient knowledge of the course topics, inadequate critical analysis skills, and use of incorrect or imprecise language will result in a failing grade. In case of a failed oral exam, the student will have to retake it, while a previously submitted project will remain valid.

• Preparation showing a limited understanding of the course topics. Very limited autonomy in solving the proposed problems and reasoning questions. Weak analytical skills that manifest mainly with the instructor’s support. Expression is generally correct, though simple. → Indicative grade: 18–19.

• Preparation demonstrating a good understanding of the course topics. Limited autonomy in solving the proposed problems and reasoning questions. Good analytical skills, also shown without the instructor’s support. Use of generally correct language. → Indicative grade: 20–24.

• Preparation demonstrating an excellent understanding of the course topics. Good autonomy in solving the proposed problems and reasoning questions. Appropriate command of technical terminology.

  → Indicative grade: 25–27 (if the project is not completed),
  → Indicative grade: 25–29 (if the project is completed and submitted).

• Preparation demonstrating an outstanding understanding of the course topics. Excellent autonomy in solving complex problems and reasoning questions, along with successful completion and submission of the group project.
  → Indicative grade: 30–30 cum laude.

Registration for the exam must be completed through ALMAEsami.

Office hours

See the website of Francesca Benassi