ELEC 401 MICROWAVE ELECTRONICS Instructor: M. İrşadi Aksun E-mail: iaksun@ku.edu.tr Phone: 0212 338 1539 Textbooks: “Microwave Engineering” by D. M. Pozar, 2nd Edition, John Wiley & sons, Inc. 1998. “Modern Microwave Circuits” by N. Kinayman and M. I. Aksun, Artech House 2004.

to make students familiar with high-frequency concepts: The aim of the course is to make students familiar with high-frequency concepts: wave nature of the voltages and currents; analysis and design of high-frequency circuits; understanding of the effects of high-frequency signals in circuits and in materials.

What do we mean by high-frequency? We mean frequencies at which the wavelength is comparable to or less than the physical sizes of the interested components

What is Wavelength? WAVELENGTH is a distance a single frequency wave propagates during its complete cycle (=period T)

Outline Chapter 1: Motivation & Introduction Chapter 2: Review of EM Wave Theory Chapter 3: Plane Electromagnetic Waves Chapter 4: Transmission Lines (TL) Chapter 5: Microwave Network Characterization Chapter 6: Smith Chart & Impedance Matching Chapter 7: Passive Microwave Components

Chapter 1 Motivation & Introduction What do we mean by “Microwave” signals and circuits? Electrical signals within 300 MHz and 300 GHz range are referred to as microwave signals, and circuits operating in this frequency range are called microwave circuits. 1 MHz 1 GHz 1 Mega Hertz = 1 x 106 Hz 1 Giga Hertz = 1 x 109 Hz

Motivation & Introduction Why do we need to work in “Microwave” frequencies? Because systems designed in Microwave frequencies have some unique features: More bandwidth Line-of-sight communications More antenna gain

Motivation & Introduction Why do we need new tools for the analysis of high-frequency circuits? What is wrong with the traditional AC circuit theory? To partially understand the answers to these questions, let us study a simple one-component circuit operating at a high frequency !!!

Motivation & Introduction Example: Find the current I2 at the output terminal of a series resistor when the current at its input port is known. I2=I1, is this correct ?

Motivation & Introduction I2=I1 is an approximation valid for low-frequency operations; Current is the propagation of electron disturbances; Physical disturbances take finite amount of time to travel from input to output. Time delay for a disturbance to travel to output

Motivation & Introduction Assume l=1 cm, and v=c=3.0x108 m/sec (speed of light) for f= 300 KHz, for f=300 MHz for f=3 GHz

Motivation & Introduction A high-frequency capacitor and its frequency characteristics

Motivation & Introduction High-frequency resistors and their typical frequency characteristics

Motivation & Introduction A typical amplifier circuit: circuit diagram

Motivation & Introduction and realization

Motivation & Introduction Reflection and Transmission (Refraction)

Motivation & Introduction Although we have plenty of experience on reflection and transmission of light, like reflections on mirrors, mirages and rainbow, we have very little information how these phenomena occur.

Motivation & Introduction Microwaves, Antennas and Optics Problems are governed by the following Maxwell’s Equations: Microwaves engineering can be defined as applied electromagnetic fields engineering.