The subject Microwave Circuits introduces the student to the fundamental principles that govern the propagation of voltage and current waves in transmission lines, establishing the conceptual basis necessary to understand the behavior of high-frequency circuits. Based on this foundation, the use of Smith's letter as an essential tool for the analysis and design of adaptation networks is presented, allowing the student to address the first examples of microwave circuits. The subject then delves into the characterization of devices using S parameters, providing criteria for their calculation and interpretation. Finally, several elementary passive circuits and their functionality are studied, showing how these can be combined to develop more complex systems, which offers the student a progressive and structured vision of circuit design in the field of microwaves.
Elementary circuit theory, and basic notions of propagation of electromagnetic waves.
The purpose of the course is for the student to understand the fundamental principles of the propagation of voltage and current waves in transmission lines and to develop the ability to analyze and apply these concepts to the basic design of microwave circuits. It also aims for students to use Smith's chart appropriately as a representation and design tool, especially in the development of high-frequency adaptation networks. In the same way, it seeks that the student assimilate the theory of S parameters, interpret its physical meaning and use these parameters to characterize and evaluate microwave circuits. Finally, the subject guides the student to understand and relate the structure and functionality of fundamental passive circuits, so that they can integrate these elements in more complex configurations consistent with real applications in the field of microwaves.
1. Transmission lines
1.1. Steady State
1.2. TL, definition and simbology
1.3. Modelling of transmission lines
1.4. Impedance, reflection coefficient and standing wave ratio
1.5. Excitation of transmission lines
1.6. Lossy transmission lines
1.7. Parameters of physical transmission lines
1.8. The Smith chart
1.9. Impedance matching networks
2. Analysis of microwave circuits
2.1. Microwave networks
2.2. Networks of one port. Normalized waves and generalized reflection coefficients
2.3. Normalized waves between generator and load
2.4. Networks of more than one port. S parameters of a circuit
2.5. Computation of the S parameters
2.6. Connections between ports
3. Passive microwave circuits
3.1. Power dividers and combiners
3.2. Hybrid rings
3.3. Directional couplers
3.4. Filters
3.5. Circulators and insulators
3.6. Attenuators
3.7. Switchable circuits.
The subject is taught in the format of master classes. The theoretical classes are complemented with problem classes that aim to settle the theoretical concepts and present a wide range of applications. It is expected that the student works on his / her own the theoretical concepts learned and applies them to different situations through problems suggested in the problem collections. For the analysis of complex circuits or situations, microwave simulators are used.
The subject is evaluated through continuous-evaluation assignments and a final exam (in May/June or, if needed, a supplemental final exam in July). The continuous-evaluation assessments may heavily rely on computer-aided analysis or design and presentations in class, and are evaluated by means of an individual interview. At the lecturer's discretion, some of the assessments may be evaluated by means of problems done in class. A late submission of a continuous-evaluation assessment (after the deadline given by your lecturer) will be penalized by -20% points of the maximum mark which can be achieved with the submission. If the mark of each of the continuous-evaluation assessments is greater than or equal to 7, the student passes the subject without having to take the exam with an unrounded grade equal to the average of the marks of the continuous-evaluation assessments. Otherwise, the final grade for the course is computed as follows: 1. A continuous-evaluation grade is computed as the mean of the marks of the three continuous-evaluation assignments. 2. If the May/June exam grade (or, if the student does not pass the subject then, the July exam grade) is greater than or equal to 4.0, then the unrounded grade for the course is the maximum of: -The exam grade -0.6 times the exam grade plus 0.4 times the continuous-evaluation grade. If the exam grade is less than 4.0, the unrounded grade for the course is the exam grade. The final grade for the course is obtained by rounding the unrounded grade to the nearest whole number with one decimal. Cheating of any valuable activity (even some parts of) will be penalized as established in the academic regulations of university. Both the source and the cheating students will be penalized.
The results will be evaluated according to the following criteria:
1. Mastery of the basic analysis tools of microwave circuits, both theoretical and software
2. Ability to apply the knowledge learned to complex situations or in other fields than microwave circuits
3. Critical capacity.
[1] D.M. Pozar, Microwave Engineering, 3rd edition, John Wiley &Sons [2] J. Bará, Circuitos de microondas con lineas de transmission, Edicions UPC.
[1] R.E. Collin, `Foundations for microwave Engineering´, 2nd editon, IEEE Press - John Wiley &Sons [2] R. Sorrentino et al., `Microwave and RF Engineering´, John Wiley & Sons, 2010.