2.4.2 Return Loss vs Distance
The RTF system measures the distance to return loss faults using the well-known technique of Frequency Domain
Reflectometry (FDR). This involves measuring the vector reflection coefficient of the device under test over a range of
discrete frequencies, and then computing the inverse Fourier transform of the results.
At each point in the sweep, the RTF module generates a single low-power carrier in the transmit band of the iQA/iPA.
This tone is emitted from the test port and propagates into the device under test, where reflections are generated by
impedance mismatches in the components and interconnects therein. The RTF module then measures the amplitudes
of the forward and reflected waves and their relative phase. This process is repeated at every point in the frequency
sweep. Upon completion of the sweep, the measured results are post-processed by the iQA/iPA, and the return loss fault
locations and amplitudes are displayed on the screen.
3. Features of The RTF System
• Accurately and rapidly measures distance to PIM faults in RF infrastructure
• Also measures distance to Return Loss faults in RF infrastructure
• Multiple display options, including overlay plot of PIM and Return Loss
•
Proprietary resolution enhancement algorithm significantly improves effective resolution of system
• Simple sweep setup:
• Tx start/stop frequencies automatically chosen (within user-defined limits) so that PIM frequencies land in
receive band of system
• Receiver automatically tuned to PIM frequency
• Rapid one-step calibration procedure
• RTF module enclosed in durable, compact housing which attaches directly to output RF connector of iQA/iPA
•
All existing iQA/iPA functionality still available, including fixed-tone testing, time trace, frequency sweep and spectrum
monitor
4.
Specification
PIM Mode
Measurement Method
Reflected PIM, frequency swept
RF Power
2 x +43 dBm supplied by iQA/iPA
Available PIM Products for RTF Analysis
3rd order (IM3), 5th order (IM5)
Residual PIM
< −115 dBm max (< −125 dBm typ)
PIM vs Distance Measurement Accuracy
Distance: ± 1 m (typ)¹
Magnitude: ± 3 dB (typ)
Return Loss Mode
Measurement Method
Frequency Domain Reflectometry (FDR)
RF Power
−33 dBm supplied by RTF module
Effective Directivity of Calibrated System
40 dB (approx)
¹ Assumes input return loss of 10 dB or better for all components & interconnects in device under test. Accuracy
specification is applicable to PIM faults with levels of −110 dBm or greater. When multiple PIM faults are present, the
stated accuracy is applicable only when adjacent faults are separated by a distance greater than the system resolution.
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