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E4B03

AMATEUR PRACTICES · Measurement technique and limitations: instrument accuracy and performance limitations; probes; techniques to minimize errors; measurement of Q; instrument calibration; S parameters; vector network analyzers; RF signals

E4B03E4B →

Which S parameter is equivalent to forward gain?

  1. AS11
  2. BS12
  3. CS21
  4. DS22
Why S parameters are written as S(out,in): the first subscript is the port where the signal comes out and the second is the port where it went in. Forward gain means drive port 1 and measure what emerges at port 2, so it is S21. The reflection terms S11 and S22 have matching subscripts because the signal leaves the same port it entered.
Watch out S12 is the same path run backwards, signal in at port 2 and out at port 1, which describes reverse transmission or isolation, not forward gain.
Read S(out,in): forward means in at 1, out at 2, so 2 then 1 = S21. Matching digits = reflection.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
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The rest of E4B

  1. E4B01 Which of the following factors most affects the accuracy of a frequency counter?
  2. E4B02 What is the significance of voltmeter sensitivity expressed in ohms per volt?
  3. E4B03 Which S parameter is equivalent to forward gain?
  4. E4B04 Which S parameter represents input port return loss or reflection coefficient (equivalent to VSWR)?
  5. E4B05 What three test loads are used to calibrate an RF vector network analyzer?
  6. E4B06 How much power is being absorbed by the load when a directional power meter connected between a transmitter a…
  7. E4B07 What do the subscripts of S parameters represent?
  8. E4B08 Which of the following can be used to determine the Q of a series-tuned circuit?
  9. E4B09 Which of the following can be measured by a two-port vector network analyzer?
  10. E4B10 Which of the following methods measures intermodulation distortion in an SSB transmitter?
  11. E4B11 Which of the following can be measured with a vector network analyzer?
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