摘要：
OK, this topic isn't for everyone, but this year, I have encountered so many people struggling with frequency-domain descriptions of transmission-line behavior that I thought I'd pass along some interesting tricks.
My last column extracted a complete curve of pc-board-trace impedance versus frequency from TDR (time-domain-reflectometry) or S11-type measurements (Reference 1). This column concentrates on trace gain using a similar trick. For the purpose of this column, the trace gain is the gain measured between two points along an infinitely long structure, where distance x separates the points and the signal travels in only one direction.
To measure trace gain, hook a network analyzer to any short, unterminated pc-board trace and capture its S11 data. Now, convert that data to the time domain and integrate it to produce a picture such as the one in Figure 1. (If you have a TDR-type instrument, it may already produce such a picture;
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