Methods for modeling tunable radio-frequency elements

A method for using a test system to test a device under test, wherein the test system includes a test fixture to which the device under test is attached during testing, the method comprising:

• calibrating the test fixture to remove systematic effects associated with the test fixture;
• when the systematic effects associated with the test fixture have been removed, characterizing the device under test, wherein the device under test comprises an antenna tuning element, wherein characterizing the device under test comprises characterizing the antenna tuning element, wherein the test fixture includes a substrate and a test socket that is attached to the substrate, wherein the test socket is configured to receive the device under test during testing, wherein calibrating the test fixture comprises calibrating the test fixture to remove systematic effects associated with the substrate and the test socket, and wherein the test system further includes a test host and a radio-frequency tester;
• while the device under test is attached to the test fixture, obtaining radio-frequency measurements from the device under test with the radio-frequency tester;
• and
• with the test host, obtaining an equivalent circuit model for the test socket based on the obtained radio-frequency measurements and known frequency response characteristics associated with the device under test.