Transmission Measurements Using Bandpass Mode; Transmission Measurement In Time Domain Bandpass Mode - Agilent Technologies 8719D User Manual

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Transmission Measurements Using Bandpass Mode

The bandpass mode can also transform transmission measurements to the time domain. For
example, this mode can provide information about a surface acoustic wave (SAW) lllter that
is not apparent in the frequency domain. Figure 6-64 illustrates a time domain bandpass
measurement of a 321 MHz SAW lllter.
Figure 6-64. Transmission Measurement in Time Domain Bandpass Mode
Interpreting the bandpass transmission response horizontal axis. In time domain
transmission measurements, the horizontal axis is displayed in units of time. The time axis
indicates the propagation delay through the device. Note that in time domain transmission
measurements, the value displayed is the actual delay (not x2). The marker provides the
propagation delay in both time and distance.
Marker 2 in Figure 6-64(a) indicates the main path response through the test device, which
has a propagation delay of 655.6 ns, or about 196.5 meters in electrical length. Marker 4 in
Figure 6-64(b) indicates the triple-travel path response at 1.91 ps, or about 573.5 meters The
response at marker 1 (at 0 seconds) is an RF feedthru leakage path. In addition to the triple
travel path response, there are several other multi-path responses through the test device,
which are inherent in the design of a SAW illter.
Interpreting the bandpass transmission response vertical axis. In the log magnitude
format, the vertical axis displays the transmission loss or gain in dB; in the linear magnitude
format it displays the transmission coefficient (7). Think of this as an average of the
Reflection CoeBkient (unitless) (0
Reflection Coefficient (unitless) (-1
Return Lo&3 (CEI)
Standing Wave Ratio (unitless)
1)
1)
Application and Operation Concepts