Agilent Technologies 4294A Specifications download pdf (Page 62)

Figure 4-11. Measurement error due to extended cable length

The cable length compensation works for test cables whose length and propagation constants are

known, such as the Agilent-supplied test cables of 1 m (2 m or 4 m). If different types of cable in dif-

ferent lengths are used, it may cause bridge unbalance in addition to measurement error.

In practice, the measurement error is different for the cable termination types of the instrument;

that is, wide-frequency 4TP instruments that internally terminate cables with its characteristic

impedance differ from general 4TP instruments without cable termination. A measurement error in

case of no termination is discussed first, and the case of terminated cables follows.

(1) Cable extension without termination

Extending test cable from the 4TP instrument without cable termination will produce an impedance

measurement error, which is typically given by the following equation:

Error = k ×∆L × f

(%)

Where, k: A coefficient specific to the instrument,

∆L: Cable length difference (m) from 0 m or 1 m,

f: Measurement frequency (MHz)

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Agilent Technologies 4294A Specifications Page 62