Hello, Im trying to model an RF attenuator for use in a control system. The control voltage is from 0-2.1V and I applied a step function signal from 0-2.1V and measured the output. I was able to model it as a first order system in the form Kdc / Xs + 1. The issue I'm having is understanding how to represent the DC gain component in the numerator. I understand that the DC gain is the value that the output settles at, but I feel like I need to normalize it to a unit step function rather than a 2.1V step. I input 0dBm of RF power and step the control voltage from 0-2.1V and the output swings from -27.6dBm to -1.4dBm. How would the DC gain be normalized to a unit step function input for analysis and design of the control loop. Thanks.