RF Interview & Exam Prep — Q&A Banks for RF Engineers | RFLab

Question Banks

Transmission Lines

35 questions — characteristic impedance, reflections, VSWR, stubs, Smith chart, TDR, loss mechanisms and dispersion.

35 questions — what each Sij means physically, VNA calibration, return loss, insertion loss, stability, Touchstone and cascading.

35 questions — gain definitions, conjugate match, noise figure, P1dB, IP3, stability circles, PA classes and Doherty.

35 questions — gain vs directivity, EIRP, radiation patterns, HPBW, near/far field, polarisation, patch and array design.

35 questions — Butterworth vs Chebyshev vs Bessel, group delay, insertion loss, LP prototype, impedance transformation and SAW/BAW.

35 questions — upconversion, downconversion, image frequency, IQ mixers, conversion loss, IIP3, LO leakage and spurious products.

Phase-Locked Loop (PLL)

35 questions — how a PLL works, VCO, charge pump, loop filter design, phase noise, Leeson's equation, reference spurs, lock time, integer-N vs fractional-N, ΣΔ modulator and 5G mmWave synthesiser design.

How to use this section

► Click any question to expand the full detailed answer
► Use the difficulty filter (Easy / Medium / Hard) to focus your practice
► Easy = concepts & definitions · Medium = analysis & calculations · Hard = design & derivations
► Interview tips are highlighted in yellow boxes inside each answer
► Visual diagrams inside answers — the PLL, radar and system architecture pages explain every concept with inline SVGs