RF Theory

Gain types, noise figure, P1dB, IIP3, stability — LNA vs PA vs VGA explained.

PA classes A/AB/B/C/D/E/F, Doherty, PAE, load pull. GaN vs GaAs vs LDMOS.

Matching networks, load-line analysis, bias circuits, stability, thermal design and PCB layout for Class AB and GaN PAs.

Upconversion, downconversion, IQ mixers, conversion loss, isolation, image rejection.

Butterworth, Chebyshev, Bessel — prototype tables, denormalisation, SAW vs BAW vs LC.

Read every point on a filter plot — IL, ripple, passband, stopband, rolloff slope, group delay. Annotated interactive charts for LP, HP, BP, BS and all approximation types.

Barkhausen criterion, Colpitts/Clapp/Hartley, phase noise, Leeson's equation, crystal vs MEMS.

Charge pump, loop filter, phase noise, lock time, integer-N vs fractional-N, ΣΔ modulator.

L(f) definition, 1/f³/1/f²/1/f spectrum regions, Leeson model, oscillator FOM, PLL noise budget, impact on EVM and reciprocal mixing. Annotated phase noise spectrum plot.

Ferrite circulators, TX/RX isolation in FDD, diplexer splitting, duplexer filter design.

Directional couplers, branch-line and rat-race hybrids, baluns, circulators, cavity resonators and waveguide components.

Superhet vs direct conversion vs zero-IF, full RX/TX chain, FDD vs TDD, dynamic range.

AM, FM, BPSK, QPSK, 16/64/256-QAM, OFDM — IQ phasor, constellation diagrams, EVM, PAPR.

Subcarrier orthogonality, cyclic prefix, PAPR, 5G numerology μ, resource grid, FR1 vs FR2, massive MIMO beamforming. Interactive subcarrier plot.

Friis free-space, two-ray ground model, log-distance + shadowing, Okumura-Hata, 3GPP 5G NR (UMi/UMa/InH), rain attenuation. Comparison plot for all models.

IF selection, image frequency, half-IF spur, LO placement, mixer spur table, DC offset in zero-IF, coexistence planning. Worked examples for radar and 5G NR.

Thermal noise, noise figure, Friis cascade, receiver sensitivity, SFDR, dynamic range.

EIRP, path loss, sensitivity, fade margin — worked examples for WiFi, LTE, satellite, radar.

GEO/LEO/MEO orbits, link budget, EIRP, G/T, FSPL, rain attenuation, Eb/N0 and ground station design.

Conducted/radiated emissions, immunity, shielding effectiveness, EMI filtering, grounding, FCC/CISPR standards.

Range equation, RCS, pulse vs FMCW vs CW, range resolution, Doppler, pulse compression.

Chirp design, beat frequency, range & velocity resolution, range-Doppler map, CFAR detection. 77 GHz automotive examples.

Amplitude & phase comparison monopulse, sum/difference beams, angle error voltage, boresight accuracy and the tracking loop.

Gain, directivity, EIRP, HPBW, polarisation, near/far field, radiation patterns, feed impedance.

ULA/URA, array factor, beam steering, amplitude tapering, grating lobes, 5G massive MIMO.

Nyquist, aliasing, undersampling, SFDR, ENOB, aperture jitter, ADC architectures, DAC sinc rolloff.

Quantization vs thermal noise, crossover bit depth, Nyquist zones, oversampling SNR gain, noise shaping, undersampling and ENOB vs frequency.

Telegrapher's equations, impedance, VSWR, standing waves, stubs, λ/4 transformer.

Every RF formula, thumb rule, constant and unit conversion on one page — noise, path loss, S-params, tx lines, antennas, filters, amplifiers. Printable.

L-network, pi, T-network, λ/4 transformer, single & double stub. Smith chart walkthroughs.

What each S-parameter means, how a VNA works, calibration, Smith chart geography, Touchstone.

Stackup, return currents, via stubs, crosstalk, EMI, differential pair routing, controlled impedance.

Eye diagrams, jitter, ISI, pre-emphasis FFE, CTLE, DFE, SerDes, NEXT/FEXT, TDR and link budgets for PCIe Gen 4/5, USB 3.2, 100G Ethernet.

130+ RF & microwave terms defined in plain English — NF, VSWR, IIP3, EIRP, EVM, SFDR, phase noise and more. Searchable by category.