Exercise :: Microwave Communication - Section 2
| 41. | In mode filter of the given figure which of the following modes is unaffected |
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Answer: Option A Explanation: TE01 mode is unaffected because its horizontally oriented electric field is every where perpendicular to the conducting strips. |
| 42. | The directive gain of a transmitting antenna is |
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Answer: Option D Explanation:
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| 43. | A duplexer is used to |
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Answer: Option D Explanation: Same antenna is used for transmission and reception. |
| 44. | A branched duplexer requires |
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Answer: Option C Explanation: A branched duplexer funds use in narrow bandwidth applications. TR tube stands for transmit-receive tube and ATR tube stands for antitransmit receive tube. Both these tubes are used in branched duplexer. |
| 45. | In a backward wave oscillator the wave |
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Answer: Option A Explanation: It is somewhat similar to TWT and can deliver microwave power over a wide frequency band. It has an electron gun and a helix structure. However the interaction between electron beam and RF wave is different than in TWT. The growing RF wave travels in opposite direction to the electron beam. The frequency of wave can be changed by changing the voltage which controls the beam velocity. Moreover the amplitude of oscillations can be decreased continuously to zero by changing the beam current. It features are: 1. Frequency range - 1 GHz to 1000 GHz. 2. Power output - 10 mV to 150 mW (continuous wave) 250kW (pulsed). It is used as signal source in transmitters and instruments. |