Mode Error Analysis of Impedance Measurement using Twin Wires

TL;DR

This paper analyzes the mode error in impedance measurements using the twin wires method with a two-port network analyzer, providing theoretical insights and practical error estimates for accelerator component testing.

Contribution

It offers a theoretical analysis of mode errors in twin wires impedance measurements and quantifies errors based on specific equipment isolation and splitter accuracy.

Findings

Mode error is a few percent with proper hybrid and splitter specifications.

Theoretical analysis of mode error in twin wires impedance measurement.

Practical guidelines for equipment selection to minimize measurement errors.

Abstract

Both longitudinal and transverse coupling impedance for some critical components need to be measured for accelerator design. The twin wires method is widely used to measure longitudinal and transverse impedance on the bench. A mode error is induced when the twin wires method is used with a two-port network analyzer. Here, the mode error is analyzed theoretically and an example analysis is given. Moreover, the mode error in the measurement is a few percent when a hybrid with no less than 25 dB isolation and a splitter with no less than 20 dB magnitude error are used.