RF View

RF tutorials

Practical RF guides on S-parameters, Smith charts, impedance matching and measurement, written from handset RF experience.

  • VNA IF Bandwidth and Averaging: Noise vs Sweep Time2026-10-26Each 10 dB of noise reduction costs about 10 times the sweep time, whether you cut the IF bandwidth by 10 or average 10 sweeps. Averaging cannot remove drift, systematic errors or crosstalk, so check those first.
  • SOLT Calibration Step by Step: Short, Open, Load and Thru2026-10-25A SOLT calibration measures an ideal short (reflection coefficient -1), an open (+1) and a load (0), then a thru between the ports. The result holds only for the frequency range, IF bandwidth, power level and cable setup used.
  • L-Network Matching: Low-Pass or High-Pass Version?2026-10-20Matching 50 ohm to 200 ohm needs Q = sqrt(3) = 1.732. The low-pass version uses 13.78 nH and 1.378 pF, the high-pass version 1.838 pF and 18.38 nH, and the choice depends on the DC path and the filtering you want.
  • Microstrip Width for 50 Ohm on a 1.6 mm FR-4 Board2026-10-19On FR-4 (er 4.4) a microstrip line reaches 50 ohm at a width-to-height ratio of about 1.9, which is about 3 mm on a 1.6 mm board. Wider strips lower the impedance and narrower strips raise it.
  • When to Put an Attenuator Pad in an RF Chain2026-10-19A fixed pad of A dB passes 10^(A/10) of the power, so a 10 dB pad passes 0.1 and turns the other 0.9 into heat. It can improve return loss by up to twice its attenuation, but it costs signal level and, in front of a receiver, noise figure.
  • How to Read One Line of an S2P File (MA, DB and RI Formats)2026-10-14A two-port S2P data line holds nine numbers: the frequency, then the pairs for S11, S21, S12 and S22 in that order. The option line tells you whether each pair is MA, DB or RI, and a magnitude of 0.9975 is about -0.022 dB.
  • How to Open an S2P (Touchstone) File: 6 Ways and a Free Viewer2026-10-13An 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.