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Microwave engineering basics
The document summarizes key components and concepts in basic microwave engineering. It discusses waveguides and their operating frequencies based on dimensions. It also describes electric and magnetic fields in rectangular waveguides. Additional components summarized include coaxial to waveguide transitions, choke joints, coupling loops, phase shifters, junctions, tuners, mixers, isolators, circulators, directional couplers, and cavity resonators. Isolators, circulators, and directional couplers are multi-port devices that control the direction of signal propagation with differing levels of attenuation.
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Microwave engineering basics
- 1. © 2010 METS MALA Basic Microwave Engineering AJAL.A.J - Dept of ECE
- 2. The dimensions ofa waveguide determine its operating frequency range
- 3. Electric (E )and magnetic (H) fields in a rectangular waveguide.
- 6. Coaxial to waveguidetransition
- 7. A choke jointpermits sections of waveguide to be interconnected with minimum loss and radiation.
- 8. Injecting a sinewave into a waveguide and extracting a signal.
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- 20. Isolators • An isolatoris a two-port non-reciprocal device which produces a minimum attenuation to wave propagation in one direction and very high attenuation in the opposite direction.
- 21. Working • Thus wheninserted between a signal source and load almost all the signal power can be transmitted to the load and any reflected power from the load is not fed back to the generator output port.
- 22. Advantages • This eliminatesvariations of source power output and frequency pulling due to changing loads.
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- 25. Circulators – A circulatoris a three-port microwave device used for coupling energy in only one direction around a closed loop. – Microwave energy is applied to one port and passed to another with minor attenuation, however the signal will be greatly attenuated on its way to a third port. – The primary application of a circulator is a diplexer, which allows a single antenna to be shared by a transmitter and receiver.
- 26. Waveguides and CavityResonators Figure Cavity resonator made with waveguide. (a) A section of rectangular waveguide used as a cavity resonator. (b) Side view of cavity resonator showing coupling of energy by a probe.
- 27. Circulators • A circulatoris a multi port junction in which the wave can travel from one port to next immediate port in one direction only. • Commonly used circulators are three-port or four-port devices although more number of ports is possible.
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- 33. 3 Port Circulator– wave guide type
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- 36. Directional Coupler -DEFINITION • A directional coupler is a four-port passive device commonly used for coupling a known fraction of the microwave power to a port (coupled port) in the auxiliary line while flowing from input port to output port in the main line. The remaining port is ideally isolated port and matched terminated.
- 37. There are threebasic types of directional couplers. • One is a multiple aperture waveguide type, • second one is a coupled coaxial, or strip or micro strip line, and the • third one is branch line couplers
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- 40. Bethe-hole directional coupler. •The theory of the waveguide coupler was first established by ‘ Bethe’ , using a single hole in the common broad wall of two rectangular waveguides. • Commonly known as Bethe-hole directional coupler.
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- 42. Practical SCENARIO • Practicalwaveguide directional couplers are multi hole couplers in which the desired coupling response vs frequency can be achieved by proper selection of the number of holes and size of the holes.
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- 44. The performance ofa directional coupler is measured in terms of four basic parameters, i.e., 1. coupling (C) 2. transmission loss 3. directivity (D) and the 4. re turn loss (R) when all the ports are matched.
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