High Frequency System Techniques

Overview

Lectures:

• Noise Theory: Noise mechanisms, noise definitions; noise figure, noise temperature, Friis formulae, minimum detectable signal.
• Antenna and Front-End Techniques: Basic array theory, front-end architectures.
• Non Linear Circuits and Systems Qualification: intermodulation products, mixer fundamentals, power compression, dynamic range.
• Direct Broadcast Satellite (DBS) System: Geostationary orbit, EIRP, free space loss, received power density, Earth station design, G/T; design example, roof top Earth station for DBS TV reception.
• Transmission Line (TL) Theory: High frequency circuit building blocks and component design, wave propagation modes, incremental TL Line model and analysis, terminated TL, performance metrics and figure of merit definitions.
• Microwave & RF Circuit Design Techniques: Transmission line topologies, fabrication and selection of materials, concept of effective permittivity, performance optimisation of microstrip TL, stubs and couplers, graphical design methods using the Smith Chart and the Hammerstad equivalent circuit technique, design example, a low pass microwave filter.
• Impedance Matching Techniques: Design consideration based on Q factor, conjugate matching, L and T circuit design, distributed elements, the microstrip stub, single and double stub matching design using the Smith chart.
• Two Port Parameters and Amplifier Design: Scattering parameters, cascaded networks and T parameters, introduction to microwave measurements, amplifier gain definitions, signal flow analysis, Mason’s non-touching rule, unilateral amplifier design.

Coursework:
1. Design of a basic communications system: Top level system design for satellite TV reception.
2. Two Stage Microwave Amplifier Design: The design of three different distributed impedance matching circuits using Smith charts, and the creation of the physical layout of the microstrip components using a graphical technique.

Learning Objectives

1. Have a strong grasp of the fundamental concepts and electronics principles needed for high frequency electronics system and circuit design.
2. Understand the basic concepts used in the generic design of modern wireless communications systems.
3. Physical understanding of the techniques that are used to design, fabricate and measure circuit components operating in the GHz frequency band.
4. Interpretation and application of design figures of merit as specified on component and sub-assembly manufacturer data sheets.
5. Experience of making an overall top level communications systems design to a constrained specification with particular reference to a microwave system.
6. Interpretation of manufacturers microwave amplifier data sheets and extraction of relevant electrical performance metrics.
7. Experience of impedance matching circuit design using Smith charts, and concepts used for performance optimisation of distributed circuit matching elements.
8. Practical experience in obtaining the geometrical dimensions and creating the physical layout of microstrip components and circuits.

Skills

1. To engender the philosophy of structured top-level communication system
design.
2. To be able to apply theoretical concepts in an iterative fashion in order to create a paper design to a given specification.
3. Understand transmission line theory and the use of a design tool based on the Smith chart for solving impedance matching circuit problems.
4. Use of a graphical technique to create the physical layout of printed microwave circuits.
5. Knowledge of key electrical and physical properties of microwave substrate materials, and design considerations for the construction of circuits based on different topologies.
6. Measuring components operating in the GHz frequency band

Assessment

None