RF View

RF library

Concepts, tutorials and component guides, written from handset RF experience.

Concepts

What the numbers mean: short, exact explanations with the formulas.

  • Return Loss vs Insertion Loss: What Each Number Tells You

    Return loss, from S11, tells you how much power bounces back. Insertion loss, from S21, tells you how much fails to arrive. A 10 dB return loss reflects 10 % of the power, yet a matched 10 dB attenuator still has 10 dB of insertion loss.

    Updated 2026-10-13

  • What S21 and S11 of a Low-Pass Filter Look Like

    At the -3 dB cutoff a Butterworth low-pass filter transmits half the power and reflects half, so S21 and S11 are both -3.01 dB. Above the cutoff S21 falls and S11 climbs towards 0 dB, because a lossless filter reflects what it cannot pass.

    Updated 2026-10-13

Tutorials

Step-by-step guides for S-parameters, Smith charts, matching and measurement.

  • How to Open an S2P (Touchstone) File: 6 Ways and a Free Viewer

    An S2P file is a plain-text Touchstone file holding the two-port S-parameters of a device at many frequencies. You can plot it right here in your browser (the file never leaves your computer), read it in a text editor, or open it in RF View, Python, MATLAB or a spreadsheet.

    Updated 2026-10-13