Which S parameter is equivalent to forward gain?
The correct answer is C: S21. Which S parameter is equivalent to forward gain is S21. S21 represents forward transmission (gain) from port 1 to port 2. For amateur radio operators, this is important for RF measurements. Understanding this helps when using network analyzers.
Exam Tip
S parameter for forward gain = S21. Think 'S'21 = 'S'ignal from port '2' to port '1' (forward). S21 represents forward transmission (gain) from port 1 to port 2. Not S11 (input reflection), not S12 (reverse), not S22 (output reflection) - just S21.
Memory Aid
"S parameter for forward gain = S21. Think 'S'21 = 'F'orward gain. S21 represents forward transmission (gain) from port 1 to port 2. Important for RF measurements."
Real-World Application
S parameters: S21 is equivalent to forward gain. S21 represents forward transmission (gain) from port 1 to port 2. For example, in an amplifier, S21 would be the gain. This is the parameter - S21 is forward gain.
Key Concepts
Why Other Options Are Wrong
Option A (S11): Incorrect. S11 is input reflection, not forward gain - S21 is forward gain. S11 is reflection.
Option B (S12): Incorrect. S12 is reverse transmission, not forward gain - S21 is forward gain. S12 is reverse.
Option D (S22): Incorrect. S22 is output reflection, not forward gain - S21 is forward gain. S22 is reflection.
题目解析
The correct answer is C: S21. Which S parameter is equivalent to forward gain is S21. S21 represents forward transmission (gain) from port 1 to port 2. For amateur radio operators, this is important for RF measurements. Understanding this helps when using network analyzers.
考试技巧
S parameter for forward gain = S21. Think 'S'21 = 'S'ignal from port '2' to port '1' (forward). S21 represents forward transmission (gain) from port 1 to port 2. Not S11 (input reflection), not S12 (reverse), not S22 (output reflection) - just S21.
记忆口诀
S parameter for forward gain = S21. Think 'S'21 = 'F'orward gain. S21 represents forward transmission (gain) from port 1 to port 2. Important for RF measurements.
实际应用示例
S parameters: S21 is equivalent to forward gain. S21 represents forward transmission (gain) from port 1 to port 2. For example, in an amplifier, S21 would be the gain. This is the parameter - S21 is forward gain.
错误选项分析
Option A (S11): Incorrect. S11 is input reflection, not forward gain - S21 is forward gain. S11 is reflection. Option B (S12): Incorrect. S12 is reverse transmission, not forward gain - S21 is forward gain. S12 is reverse. Option D (S22): Incorrect. S22 is output reflection, not forward gain - S21 is forward gain. S22 is reflection.
知识点
S parameter, Forward gain, S21, Forward transmission
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.