Microwave devices – Match each device to its typical application List I (Device) A. Reflex klystron B. Traveling-wave tube (TWT) C. Cavity klystron D. Maser List II (Application) Wideband amplification Very low power amplification (ultra-low-noise front end) Low-power FM (frequency-modulated) generation Frequency multiplication Select the correct matching between List I and List II.
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AA-1, B-2, C-3, D-4
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BA-4, B-3, C-2, D-1
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CA-3, B-4, C-1, D-2
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DA-3, B-1, C-4, D-2
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EA-2, B-1, C-3, D-4
Answer
Correct Answer: A-3, B-1, C-4, D-2
Explanation
Introduction / Context:This matching problem tests core knowledge of classic microwave vacuum devices and masers. Each device has a characteristic role in RF/microwave systems—oscillation, amplification, bandwidth, noise performance, or frequency conversion. Understanding these “textbook roles” helps in system-level block diagram design.
Given Data / Assumptions:
- Reflex klystron is a single-cavity, velocity-modulated tube commonly used as a low-power microwave oscillator.
- TWT is a broadband linear amplifier based on distributed interaction.
- Cavity klystron (multi-cavity) supports amplification and can be configured for harmonic multiplication.
- Maser provides extremely low-noise, very small-signal amplification.
Concept / Approach:
Map each device to the most standard application: reflex klystron → small, tunable microwave source (often FM capable); TWT → wideband amplification; cavity klystron → narrowband high-gain amplification and also used as a frequency multiplier with harmonic extraction; maser → very low power signal amplification with exceptional noise figure.
Step-by-Step Solution:
A (Reflex klystron) → 3 (low-power FM generation).B (TWT) → 1 (wideband amplification).C (Cavity klystron) → 4 (frequency multiplication via harmonic output configurations).D (Maser) → 2 (very low power amplification).Verification / Alternative check:
Historical and modern references consistently place TWTs in broadband amplifier chains (satcom, EW), reflex klystrons as lab signal sources, masers in deep-space or ultra-low-noise front ends, and klystrons both as amplifiers and in some multiplier roles.
Why Other Options Are Wrong:
Pairings that assign wideband amplification to klystrons or FM generation to TWTs contradict the intrinsic device physics and standard usage. Assigning “very low power amplification” to anything other than a maser ignores its defining strength.
Common Pitfalls:
Confusing reflex and cavity klystrons (oscillator vs. amplifier/multiplier) and assuming all tubes are primarily amplifiers.
Final Answer:
A-3, B-1, C-4, D-2.