RF · Microwave Series

Impedance, Reflection, and S-parameters

Reference planes connect load impedance, reflection, VSWR, the S-matrix, VNA practice, and cascade calculations.

2 · 50 ohm · port · reflection coefficient · matching

Reading 50 Ohms, Ports, and Matching as One Flow

Memorizing 50 ohms, ports, and matching separately made S-parameter setups confusing. I drew the source-line-load reference planes first and connected all three terms on one path.

4 · Gamma · return loss · VSWR · S11

Converting Reflection Coefficient, Return Loss, and VSWR

I rewrote the conversion order so that sign conventions and ratios are not mixed when one mismatch is expressed three ways.

5 · S11 · S21 · S31 · isolation · VNA

Reading the S-Parameter Matrix and VNA Screens

I relabeled S11, S21, S31, and S23 by excitation and observation ports rather than treating them as curve names.

8 · VNA · SOLT · TRL · reference plane · de-embedding

Recording VNA Calibration and Reference Planes

Before placing simulation and instrument results in one table, I drew the calibration plane and fixture boundary.

9 · noise factor · noise figure · Friis · LNA · available gain

Cascade Noise Figure and First-Stage Gain

I revisited Friis' equation to see why receiver noise figures cannot simply be added in dB.

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