30  N9912A FieldFox User’s Guide  
2-Port Insertion Loss Measurements 
A 2-port Insertion Loss measurement, available with option 110, is used to 
measure the loss through a DUT (device under test) – or cable – over a specified 
frequency range. The FieldFox signal source is transmitted out the RF OUT 
connector, through the DUT, and into the RF IN connector. Both ends of the DUT 
must be connected to the FieldFox, either directly or indirectly using the cable 
used in the normalization cal.  
‘Insertion’ loss simply means loss through a device, usually expressed in dB. It is 
exactly the same measurement as “S21 Transmission” in NA Mode.   
2-port Insertion Loss measurements are generally more accurate than 1-port 
Cable Loss measurements.  
NOTE  A Normalization Cal is REQUIRED for making accurate 2-port CAT or NA 
measurements. Learn how on page 64. 
For highest accuracy, when measuring the DUT also attach any cable or adapter 
that was used in the normalization cal. 
How to make a 2-port Insertion Loss Measurement 
1.  Press Mode then CAT. 
2.  Then More  then Insertion Loss (2-Port) . 
3.  Press Freq/Dist  and enter Start and Stop frequency values of the 
measurement.  
4.  Press Sweep 3, then select a Resolution setting. 
5.  Press Cal 5, then press Normalization. Perform normalization as explained 
on page 64. 
6.   Connect the DUT and view the insertion loss measurement results. 
When measuring very long lengths of cable, it may be necessary to increase the 
sweep time.  Learn how on page 26. Learn why in the Supplemental Online 
Help: www.agilent.com/find/fieldsfoxsupport