Concept Notes
Short, self-contained explanations: the idea in plain English, the math that matters, the misconceptions to avoid, and where on the site to try it for real.
Anechoic Chambers
intermediateWhy antennas are measured in echo-free rooms — RF absorbers, the quiet zone, and near-field to far-field measurement.
Antennas
beginnerHow a piece of metal converts electric current into radio waves, why antenna size follows wavelength, and the common antenna types.
Decibels
beginnerWhy RF uses logarithmic units, how dB math turns multiplication into addition, and the 3-6-10 landmarks worth memorizing.
Link Budget
beginnerAdd the gains, subtract the losses, compare against receiver sensitivity — one line of arithmetic that predicts whether a radio link works.
Modulation
intermediateHow a carrier wave learns to carry information — AM and FM, digital keying from BPSK to QAM, and reading constellation diagrams.
Noise and SNR
beginnerThe noise floor, signal-to-noise ratio, and noise figure in plain English — why every receiver hears a hiss and why it matters.
Path Loss
beginnerWhy radio signals fade with distance — the inverse square law, the FSPL formula, the +6 dB doubling rule, and what obstacles cost.
Radiation Patterns
beginnerOmnidirectional vs directional antennas, gain in dBi, the gain-beamwidth tradeoff, and how to read a polar plot.
The FFT
intermediateTime domain vs frequency domain, what an FFT shows, how bin width sets frequency resolution, and why windowing matters.
The Radio Spectrum
beginnerA tour of the radio spectrum from AM radio to millimeter waves — who uses which frequencies, and the universal low-vs-high tradeoff.
The Smith Chart
intermediateWhat the Smith Chart is, the intuition behind impedance matching, and why RF engineers still reach for this circular map.
Waves and Frequency
beginnerWhat radio waves actually are, and the one formula — c = fλ — that connects speed, frequency, and wavelength.