From circuit impedance to traveling waves

RF & Microwave Engineering Laboratory

Follow reflections around a Smith chart, build a matching network, inspect measured two-port data, or explore the geometry that controls a microwave circuit. Every experiment connects the result to its equations, assumptions, and numerical checks.

No account, no installation, and no uploads to a server. Projects and imported network data remain in your browser unless you export them.

Choose an experiment

Use the examples first, then vary one input at a time. Guided mode adds procedures and automatically graded concept questions.

Six experiments
  1. introductoryReviewed 2026-09-17

    Transmission Lines & Smith Chart

    See how mismatch, line length, and attenuation change input impedance, standing waves, and delivered power.

  2. intermediateReviewed 2026-09-17

    Impedance Matching & Bandwidth

    Design low-pass or high-pass L networks and quarter-wave transformers, then test their frequency dependence.

  3. advancedReviewed 2026-09-17

    S-Parameters & Virtual Network Analyzer

    Sweep ideal two-port networks or import a Touchstone .s2p file. Inspect reflection, transmission, group delay, reciprocity, and passivity.

  4. intermediateReviewed 2026-09-17

    Receiver Gain & Noise Budget

    Build and reorder a receiver chain, identify dominant noise contributions, and compare sensitivity with small-signal headroom.

  5. intermediateReviewed 2026-09-17

    Microstrip Geometry & Impedance

    Analyze a thin PCB trace or synthesize its width for a target impedance, with effective permittivity and guided wavelength exposed.

  6. intermediateReviewed 2026-09-17

    Rectangular Waveguide & Cutoff

    Explore TE10 cutoff, guided wavelength, phase and group velocity, evanescence, and the onset of higher modes.

Learn what a good RF result looks like

Low reflection, low insertion loss, low noise, and wide bandwidth are different design goals. A lossy line can hide a bad load match. An exact match at one frequency can be narrowband. A high-gain receiver can still have poor sensitivity if loss appears ahead of the first amplifier.

The lab keeps those distinctions visible through power fractions, complex impedance, sampled network diagnostics, stage-by-stage noise contributions, and geometry limits. Plots include numerical tables and downloadable data, so you can independently inspect the evidence.

Use measured data and keep your work

The network analyzer imports the two-port S-parameter subset of Touchstone 1.x. Real/imaginary, magnitude/angle, and dB/angle formats are supported with a common real reference impedance. It preserves the original complex samples, shows the actual probe frequency, and exports standard .s2p data.

Save project JSON to move between browsers. Use data CSV for further work in the Measurement, Data Analysis & Uncertainty Lab. Shared experiment exports include plots, current measurements, validation, and guided answers. Changing an input requires a fresh run before results can be exported.

Numerical validation6/6 published reference checks passReviewed 2026-09-17
View benchmark details

100 Ω load on a 50 Ω line

Expected: |Γ| = 1/3; VSWR = 2; delivered fraction = 8/9

Observed: |Γ| = 0.3333333333333333; VSWR = 1.9999999999999998; delivered = 0.8888888888888888

pass

Quarter-wave impedance inversion

Expected: 50 Ω source to 200 Ω load: transformer 100 Ω; input 50 Ω

Observed: Transformer 100 Ω; input 50 + j-4.592425496802574e-15 Ω

pass

Series 100 Ω element between 50 Ω ports

Expected: S11 = S21 = 0.5; maximum singular-value squared = 1

Observed: S11 0.5; S21 0.5; power bound 1

pass

Two-stage Friis reference

Expected: F1 = 2, G1 = 10, F2 = 4: total F = 2.3

Observed: Total F = 2.3

pass

Air dielectric and impedance synthesis

Expected: εeff = 1 in air; synthesized 50 Ω line resolves within 10⁻⁸ Ω

Observed: Air εeff 1; synthesized 50.00000000000001 Ω

pass

WR-90 TE10 reference

Expected: Cutoff 6.557140376 GHz; vp·vg = c² at 10 GHz

Observed: Cutoff 6.557140376202975 GHz; vp·vg/c² = 1

pass
Model scope and limits

These are bounded steady-state educational models. They do not include full-wave field solving, antenna radiation, nonlinear transistor models, fabrication tolerances, or a calibrated measurement instrument. The microstrip model is quasi-static and assumes zero conductor thickness; the waveguide model uses perfect conductors. Receiver budgets assume matched linear stages and exclude mixer sideband noise.

The two-port analyzer checks sampled passivity and reciprocity; it does not certify causality, stability, or accuracy of an imported measurement. Group delay needs adequate frequency resolution. Each experiment includes its governing equations, source references, and specific assumptions.