Typical Characteristic Impedance of an RF Coaxial Cable The characteristic impedance of a widely used RF coaxial cable is approximately:
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A300 Ω
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B50 Ω
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C5 Ω
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D2 Ω
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E150 Ω
Answer
Correct Answer: 50 Ω
Explanation
Introduction / Context:Common RF systems standardize on specific characteristic impedances to ensure component interoperability and minimal reflections.
Given Data / Assumptions:
- “RF coaxial cable” refers to general-purpose coax for transmit/receive paths (laboratory, radio, cellular).
- Matched systems target a uniform impedance.
Concept / Approach:
Two common impedances are 50 Ω (general RF, power handling) and 75 Ω (video, CATV, low-loss receive). The most widely used standard in RF test, radios, and antennas is 50 Ω.
Step-by-Step Solution:
1) Identify typical standards: 50 Ω and 75 Ω are prevalent; 50 Ω dominates active RF paths.2) The question asks for “the characteristic impedance of a cable” in the RF context—50 Ω is the mainstream default.3) Therefore, select 50 Ω.Verification / Alternative check:
Examples: RG-58, RG-213, and modern low-loss coaxial cables use 50 Ω.
Why Other Options Are Wrong:
300 Ω is twin-lead, not coax; 5 Ω and 2 Ω are unrealistic for practical coax; 150 Ω is uncommon.
Common Pitfalls:
Confusing 75 Ω video distribution cables with general RF coax defaults.
Final Answer:
50 Ω