You dont have javascript enabled! Please enable it! Frenzel: Reviewer in Microwave Techniques

Frenzel: Reviewer in Microwave Techniques

Frenzel: Reviewer in Microwave Techniques

This is the summary notes of the important terms and concepts in Chapter 10 of the book COMMUNICATIONS ELECTRONICS by Louis E. Frenzel. This book introduces basic communication concepts and circuits, including modulation techniques, radio transmitters and receivers. It also discusses antennas and microwave techniques at a technician level and covers data communication techniques (modems, local area networks, fiber optics, satellite communication) and advanced applications (cellular telephones, facsimile and radar). The work is suitable for courses in Communications Technology. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.

CHAPTER 10 Microwave Techniques

1. Microwaves are radio signals in the frequency range from 1 to 300 GHz.

2. The RF spectrum below UHF is mostly already fully occupied leaving little or no room for the growth of new radio services.

3. At microwave frequencies, tremendous bandwidth is available for new radio services as well as for wide-bandwidth signals such as TV, multiplexed signals, or computer data.

4. The microwave frequencies are used primarily for telephone communications, radar, and satellite communications.

5. Other microwave applications include cable TV, space communications, radio astronomy, and heating.

6. The primary benefit of microwaves is wide bandwidth availability.

7. The main disadvantages of microwaves are that they are limited to line-of-sight transmission distances, conventional components are not usable, and circuits are more difficult to analyze and design.

8. The allocation of the RF spectrum is handled by the Federal Communications Commission (FCC) in the United States.

9. Balanced transmission line is not used for microwaves because of radiation losses. Coaxial cable is not used because of its high attenuation.

10. The preferred transmission line for microwaves is waveguides.

11. Because of the short physical length of transmission lines at microwave frequencies, quarter- and half-wave lines are commonly used for tuned circuits and filters.

12. Two printed circuit board implementations of transmission lines, called stripline and microstrip, are widely used to create resonant circuits and filters.

13. A waveguide is a hollow metal pipe with a circular or rectangular cross section used for carrying microwave signals from one place to another.

14. A waveguide acts like a high-pass filter, passing all frequencies above its cut-of frequency and rejecting those below it.

15. The cutoff frequency fco of a waveguide depends upon its physical size. For a rectangular waveguide, it is 300/2a. where a is the wide dimension of the waveguide in meters.

16. The microwave signal carried by a waveguide is made up of electric (E) and magnetic (H) fields that bounce off the walls of the waveguide as they propagate along its length.

17. The modes of a waveguide describe the various patterns of electric and magnetic fields that are possible.

18. A transverse electric (TE) mode is one where the electric field is transverse or perpendicular to the direction of propagation.

19. A transverse magnetic (TM) mode is one where the magnetic field is perpendicular to the direction of propagation.

20. Waveguides are available in standard lengths and sizes, and special pieces are used for right-angle bends and 90° twists.

21. Half-wavelength sections of waveguides with shorted or closed ends are known as resonant cavities since they “ring” or oscillate at the frequency determined by their dimensions.

22. Cavity resonators are metallic chambers of various shapes and sizes that are used as parallel-tuned circuits and filters. They have a Q of up to 30,000.

23. Point-contact and Schottky or hot-carrier diodes are widely uses as mixers in microwave equipment as they have low capacitance and inductance.

24. Varactor diodes are widely used as microwave frequency multipliers. Multiplication factors of 2 and 3 are common with power levels up to 20 Wand efficiencies up to 80 percent.

25. Step-recovery or snap-off diodes are also widely used as frequency multipliers with multiplication factors up to 10, power ratings up to 50 W. and efficiencies approaching 80 percent.

26. A Gunn diode is a microwave semiconductor device used to generate microwave energy. When combined with a microstrip, stripline or resonant cavity, simple low power oscillators with frequencies up to 50 GHz are easily implemented.

27. Both I MPATT and TRAPATT diodes are GaAs devices operated with high reverse bias to produce avalanche breakdown. Both are used in microwave oscillators.

28. A klystron is a vacuum tube used for microwave amplification and oscillation.

29. Klystrons use a cavity resonant or to velocity modulate an electron beam which imparts energy to another cavity, producing power amplification. Klystrons are available which produce from a few to many thousands of watts.

30. A single-cavity reflex klystron is used as a microwave oscillator.

31. Klystrons are being gradually replaced by Gunn diodes and traveling-wave tubes.

32. A magnetron is a diode vacuum tube used as a microwave oscillator in radar and microwave ovens to produce powers up to the megawatt range.

33. In a magnetron, a strong magnetic field creates circular paths of electron flow to excite cavities into oscillation.

34. A traveling-wave tube (TWT) is a microwave power amplifier with very wide bandwidth.

35. A microwave signal applied to a helix around the TWT produces velocity and density modulation of the electron beam over a long distance which induces a higher-power signal in the helix.

36. The most commonly used microwave antenna is the horn, which is essentially a rectangular waveguide with a flared end.

37. A pyramidal horn flares in both waveguide dimensions. A sectoral horn flares in only one dimension.

38. Horn antennas are directional and produce a beam width in the 10° to 60° range with a gain in the 10- to 20-dB range, depending upon dimensions.

39. A parabolic or dish-shaped reflector is used with most microwave antennas to focus the RF energy into a narrow beam and increase gain.

40. The parabolic reflector usually has a diameter that is no less than 10 wavelengths at the operating frequency.

41. The gain and directivity of a parabolic reflector antenna is directly proportional to its diameter.

42. Parabolic reflector antennas are fed by placing a horn antenna at the focal point or by placing the horn at the center of the reflector and placing a small reflector at the focal point. The latter is known as Cassegrain feed.

43. A helical antenna is made up of six to eight turns of heavy wire or tubing to form a coil or helix. It is fed with coax and is backed up with a reflector.

44. Helical antennas are used at UHF and microwave frequencies and have a gain in the 12- to 20-dB range and a beam width in the 12° to 45° range.

45. Helical antennas produce circular polarization where the electric and magnetic fields rotate. The polarization may be right-hand or left-hand depending upon the direction in which the helix is wound.

46. Helical antennas can receive either vertically or horizontally polarized signals but can only receive a circularly polarized signal of the same direction.

47. A popular omnidirectional microwave antenna is the bicone.

Complete List of Reviewers in Communications Electronics per Chapter

Important List of Communications Engineering Materials

Share your Notes in Introduction to Electronic Communications

If you have some important review notes on this topic kindly write the notes on the comment section below. This will absolutely beneficial to those aspiring to become professional engineers by taking the Board Exam and eventually to become successful in their chosen field. Thank you.

Please do Subscribe on YouTube!

P inoyBIX educates thousands of reviewers and students a day in preparation for their board examinations. Also provides professionals with materials for their lectures and practice exams. Help me go forward with the same spirit.

“Will you subscribe today via YOUTUBE?”




  • Become Premium Member and experienced fewer ads to ads-free browsing.
  • Full Content Access Exclusive to Premium members
  • Access to PINOYBIX FREEBIES folder
  • Download Reviewers and Learning Materials Free
  • Download Content: You can see download/print button at the bottom of each post.


  • Additional upload reviewers and learning materials are also FREE


If you subscribe for PREMIUM today!

You will receive an additional 1 month of Premium Membership FREE.

For Bronze Membership an additional 2 months of Premium Membership FREE.

For Silver Membership an additional 3 months of Premium Membership FREE.

For Gold Membership an additional 5 months of Premium Membership FREE.

Join the PinoyBIX community.

This offer has expired!

Add Comment

THE ULTIMATE ONLINE REVIEW HUB: PINOYBIX . © 2014-2024 All Rights Reserved | | Follow me on Blogarama Protection Status