Swap Adapters Calibration Method

Although Swap Adapters calibration (also known as Swap Equal Adapters and Equal Length Adapters) method is NOT included in the PNA firmware, you can still perform this calibration.  

Before we introduced the Unknown Thru method, the Swap Adapters method was often used as a quick alternative to the more tedious adapter removal method. In that case, you would be trading measurement accuracy for convenience. You might still want to perform Swap Adapters if you do NOT have calibration standards with the same connector type as your DUT. A procedure for this is shown below.

For any other reason, the Swap Adapters method is NOT recommended because the Unknown Thru method is more convenient AND more accurate.

There are many variations on the Swap Adapters calibration depending on the number of ports to be calibrated and whether the DUT is insertable or non-insertable. However, the concepts are the same: you perform connect and measure the reflection standards (OPEN, SHORT, and LOAD) with one adapter in place, then swap for a different adapter for the Thru measurement. The adapters must have the same delay, loss, and impedance. The better the adapters match, the better measurement results. Measure the adapters with a calibrated PNA to be sure.

Procedure

The following is an example procedure showing how to perform a Swap Adapters 2-port calibration for a non-insertable DUT. The DUT has 2.92 mm connectors. You do NOT have 2.92 mm calibration standards, but you DO have 2.4 mm standards and adapters that have the same electrical properties as the 2.92 mm adapters.

Adapters A1 and A2 = test port to 2.4 mm adapters

Adapters B1 and B2 = test port to 2.92 mm adapters

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