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Module 11 - Microwave Principles
Navy Electricity and Electronics Training
Series (NEETS)
Chapter 2: Pages 2-61 through 2-66
Pages i, 1-1, 1-11, 1-21, 1-31, 1-41, 1-51, 1-61, 2-1, 2-11, 2-21, 2-31, 2-41, 2-51, 2-61, 3-1, 3-11, AI-1, Index-1, Assignment 1, Assignment 2
The TWT is a wide-bandwidth, velocity-modulated tube used primarily as an amplifier. The electron beam is bunched by a signal applied to the Helix. The bunching causes an energy transfer from the electron beam to the traveling wave on the helix.
The MAGNETRON is a DIODE Oscillator capable of delivering microwave energy at very high power levels. Three fields exist within a magnetron that influence operation: (1) the DC ELECTRIC FIELD between the anode and cathode; (2) the AC ELECTRIC FIELD produced by the oscillating resonant cavities and on the same plane as the dc field; and (3) the Magnetic FIELD produced by the permanent magnet which is perpendicular to the dc electric field.
Magnetrons are of two basic types, the Negative-Resistance MAGNETRON and the
ELECTRON-RESONANCE MAGNETRON. a diagram of a magnetron is shown at the right.
2-61
SOLID-STATE Microwave DEVICES are becoming increasingly widespread in microwave equipment with new developments almost daily. Most of the currently available solid-state devices are two-terminal diodes with the capability to generate or amplify microwave energy. Many of the solid-state devices, such as the TUNNEL DIODE and the BULK-EFFECT DIODE, apply the property of Negative Resistance to amplify microwave signals or generate microwave energy. a characteristic curve illustrating the negative-resistance property of the tunnel diode is shown at the right.
The VARACTOR is a two-terminal diode that acts as a variable capacitance and is the active element of PARAMETRIC AmplifierS. The parametric amplifier is a low-noise microwave amplifier that uses variable reactance to amplify microwave signals. The illustration shows an example of a NONDegenerative PARAMETRIC Amplifier.
2-62
Answers to Questions Q1. Through Q74.
A-1. Impedance decreases.
A-2. Degenerative feedback.
A-3. Transit time causes the grid voltage and plate current to be out of phase.
A-4. Transit time.
A-5. Velocity.
A-6. The electron will be accelerated.
A-7. By alternately speeding up or slowing down the electrons.
A-8. The buncher grids.
A-9. There is no effect.
A-10. The frequency period of the buncher grid signal. A-11. Velocity modulation.
2-63
A-12. The accelerator grid and the buncher grids.
A-13. The catcher cavity.
A-14. Amplifier.
A-15. Intermediate cavities between the input and output cavities.
A-16. a large negative pulse is applied to the cathode.
A-17. The middle cavity.
A-18. The bandwidth decreases.
A-19. Stagger tuning.
A-20. The reflector or repeller.
A-21. Velocity.
A-22. Three-quarter cycle.
A-23. Mode 2.
A-24. Power is reduced.
A-25. The half-power points of the mode.
A-26. Voltage amplification.
A-27. used to focus the electrons into a tight beam.
A-28. The directional couplers are not physically connected to the helix.
A-29. The traveling wave must have a forward velocity equal to or less than the speed of the electrons in the beam.
A-30. The helix.
A-31. Helix.
A-32. a magnetic field.
A-33. Anode or plate.
A-34. The resonant cavities.
A-35. The permanent magnet.
A-36. The critical value of field strength.
A-37. Circular.
A-38. The negative-resistance magnetron has a split plate.
A-39. The application of the proper magnetic field.
2-64
A-40. To reduce the effects of filament bombardment.
A-41. Rising-sun block.
A-42. Series.
A-43. Working electrons.
A-44. Greater power output.
A-45. Loops and slots.
A-46. Inductive.
A-47. a cookie-cutter tuner.
A-48. Baking in.
A-49. The tunneling action.
A-50. The tuned circuit or cavity frequency.
A-51. To increase the stability.
A-52. Prevent feedback to the tuned input circuit.
A-53. Stability problems.
A-54. Variable capacitor.
A-55. Reactance.
A-56. The low-noise characteristic.
A-57. By varying the amount of capacitance in the circuit.
A-58. Supplies the electrical energy required to vary the capacitance.
A-59. Exactly double the input frequency.
A-60. The pump signal of a nondegenerative parametric amplifier is higher than twice the input signal.
A-61. Idler- or lower-sideband frequency.
A-62. The sum of the input frequency and the pump frequency.
A-63. Larger microwave power outputs.
A-64. The electrons become immobile.
A-65. Threshold.
A-66. a field of much greater intensity.
A-67. The frequency.
2-65
A-68. PNIN.
A-69. The negative-resistance property.
A-70. To form a small region of p-type material.
A-71. Lower.
A-72. Lower forward resistance and low noise.
A-73. Variable resistance.
A-74. a switching device.
2-66
| NEETS Modules | |
| - | Matter, Energy, and Direct Current |
| - | Alternating Current and Transformers |
| - | Circuit Protection, Control, and Measurement |
| - | Electrical Conductors, Wiring Techniques, and Schematic Reading |
| - | Generators and Motors |
| - | Electronic Emission, Tubes, and Power Supplies |
| - | Solid-State Devices and Power Supplies |
| - | Amplifiers |
| - | Wave-Generation and Wave-Shaping Circuits |
| - | Wave Propagation, Transmission Lines, and Antennas |
| - | Microwave Principles |
| - | Modulation Principles |
| - | Introduction to Number Systems and Logic Circuits |
| - | - Introduction to Microelectronics |
| - | Principles of Synchros, Servos, and Gyros |
| - | Introduction to Test Equipment |
| - | Radio-Frequency Communications Principles |
| - | Radar Principles |
| - | The Technician's Handbook, Master Glossary |
| - | Test Methods and Practices |
| - | Introduction to Digital Computers |
| - | Magnetic Recording |
| - | Introduction to Fiber Optics |
| Note: Navy Electricity and Electronics Training Series (NEETS) content is U.S. Navy property in the public domain. | |
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