In this format the rows and columns represent the number of ports present. These complex numbers arise from a mathematical representation known as a scattering matrix. On its own, Moku:Lab is capable of measuring S 12 or S 21 of a 2-port system, but not the S 11 and S 22. Moku:Lab’s FRA is capable of driving a DUT with a swept sine wave into a system’s input port and extracting the amplitude and phase response at a system’s output port. The first number is the output port (emerging) and the second number is the input port (applied) as depicted in this figure below.įor example, S 22 represents the reflected power (magnitude and phase) of the system from port 2 at a certain frequency. Notice that the four S-parameters for this 2-port network have subscripts relating the ports that are under consideration. Below is a figure representing a 2-port DUT network along with all the signal paths captured by S-parameters.įigure 1: S-parameter representation in a 2-port network The beauty of S-parameters is that we can fully understand a DUT by just analyzing the transmitted and reflected signals as described by its S-parameters. This box can contain a multitude of system variables: resistors, filters, integrated circuits, or transmission lines, the details of which are hidden. S-parameter characterization of a Device Under Test (DUT) treats that DUT as a black box with one or more ports, where signals can both enter and exit any port. Since we care mainly about power gain or loss we will focus on the magnitude as a function of frequency. S-parameters are complex numbers, meaning they have both imaginary and real parts, thus can represent both magnitude and phase. We will visualize transmission line problems and impedance matching with Smith charts. We will be exploring this parameter in depth and showcasing its implementations when analyzing systems and filters at high frequencies using Moku:Lab’s Frequency Response Analyzer. In other words, it helps describe how RF energy propagates through a multi-port network. It is used to describe the reflection/transmission characteristics of a port network system. One useful parameter when designing at high frequencies is the S-parameter, or “Scattering parameter”. This reflection is suboptimal in RF design as it reduces transmission quality and efficiency. Any mismatch in impedance along the transmission lines of an RF system will result in signal reflection. This phenomenon of reflection is analogous to dealing with high frequency signals (hundreds of MHz or GHz) in the RF world. This time, when you shout your voice is reflected by the wall and echoes back at you. Next, imagine doing the same thing, but the hallway is truncated with a wall. The sound travels into the abyss with no discontinuity and eventually just fades into nothingness. Imagine shouting into a long, endless hallway. In this application note, Moku:Lab’s Frequency Response Analyzer is used in conjunction with an RF directional coupler for a complete S-parameter characterization of a two port network. We may also share this information with third parties for this purpose.Transmission and reflection signal information is vital when designing and validating RF components and systems. We will use this information to make the website and the advertising displayed on it more relevant to your interests. Targeting/Profiling Cookies: These cookies record your visit to our website and/or your use of the services, the pages you have visited and the links you have followed. Loss of the information in these cookies may make our services less functional, but would not prevent the website from working. This enables us to personalize our content for you, greet you by name and remember your preferences (for example, your choice of language or region). Functionality Cookies: These cookies are used to recognize you when you return to our website. This helps us to improve the way the website works, for example, by ensuring that users are easily finding what they are looking for. Analytics/Performance Cookies: These cookies allow us to carry out web analytics or other forms of audience measuring such as recognizing and counting the number of visitors and seeing how visitors move around our website. They either serve the sole purpose of carrying out network transmissions or are strictly necessary to provide an online service explicitly requested by you. The cookies we use can be categorized as follows: Strictly Necessary Cookies: These are cookies that are required for the operation of or specific functionality offered.
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