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Electromagnetics Knowledge Map

Electromagnetic spectrum with frequency, wavelength and representative scales. — The same field theory spans enormous ranges of wavelength and frequency, linking the many branches in this knowledge map. Image source: Wikimedia Commons, adapted from NASA material.

Physical intuition in 30 secondsMost electromagnetic technologies can be described by the same recurring questions: What fields exist? How do they propagate? How do they interact with matter? What device converts that interaction into a useful signal or force? How does the complete system use it?

The organizing chain for this site is

\[\boxed{\text{fields}\rightarrow\text{waves}\rightarrow\text{interaction with matter}\rightarrow\text{devices}\rightarrow\text{systems}\rightarrow\text{applications}.}\]

1. Foundations: the field description

2. Classical engineering branches

3. Classical-to-quantum bridge

For a semiclassical atom–field description,

\[\mathbf E(t)\rightarrow H_E=-\mathbf d\cdot\mathbf E(t),\qquad \mathbf B(t)\rightarrow H_B=-\boldsymbol\mu\cdot\mathbf B(t).\]

Atom–field Hamiltonian→Rabi / EIT / AT→Floquet dressing→Optical/RF readout

Zeeman interaction→Larmor precession→Optical pumping→SERF / OPM

4. From Maxwell to complete systems

Architecture → high-speed IO silicon

system BER / power / channel→TX / RX / PLL / CDR→AMS circuit blocks + calibration→RTL / STA / physical design / GDS→silicon characterization

Architecture → SoC → tapeout

RISC-V / Arm + PCIe / DDR / Ethernet / UCIe→controller + PHY + NoC→synthesis + floorplan + P&R→STA / DRC / LVS / IR / EM→GDSII / tapeout

PCB/package → reliable high-speed link

stackup + geometry→channel / PDN impedance→loss + reflection + crosstalk + droop→eye / BER / rail margin→PCIe / USB / GPU system

Maxwell → wireless link

Maxwell→wave equation→current distribution→antenna→propagation→receiver

Maxwell → AESA radar

Maxwell→element pattern→array factor→beam steering→radar equation→detection

Maxwell → MRI

static $B_0$→spin precession→RF $B_1$→RF coil→gradient encoding→image

X-ray field → CT image

accelerated electrons→X-ray spectrum→attenuation line integrals→detector projections→reconstructed image

EM geometry → superconducting quantum Hamiltonian

chip + package→Maxwell solver→modes / S-parameters / participation→effective circuit→quantum Hamiltonian

Laser system → coherent atomic excitation

laser oscillator→cavity lock→SHG / wavelength conversion→$-\mathbf d\cdot\mathbf E$→EIT / Rabi coupling

Maxwell → Rydberg RF sensor

RF $\mathbf E$→$-\mathbf d\cdot\mathbf E$→Rabi coupling→EIT / AT / Floquet→photodetector→field estimate

Sky signal → cryogenic receiver → correlator

astronomical EM field→feed / cryogenic LNA or mixer→IF / ADC / PFB→correlator / beamformer→spectrum / image

Frequency → operating band → application

RF frequency→GSM / LTE / NR / L-S-C-X-Ku-Ka→wireless / radar / GNSS / space

Digital waveform → calibrated RF stimulus

bits / waveform→DSP / DDS / DAC / RF synthesis→calibrated RF stimulus→DUT

RF channel → transceiver architecture → baseband

antenna / RF front end→superhet / zero-IF / low-IF / RF sampling→ADC/DAC + DDC/DUC→modem / DSP

RF signal → analyzer → digital spectrum

RF signal→superhet + ADC + FFT→RBW / detector / averaging→spectrum / persistence / IQ

Wireless standard → RF requirement → conformance

3GPP requirement→RF / RRM / protocol test→measurement setup→UE / gNB pass-fail

Interface → PCB channel → bring-up

PCIe / USB / Thunderbolt / HDMI / I²C / SPI→schematic + PCB/flex constraints→SI/PI + DFM→scope / TDR / VNA / protocol debug

Analog ↔ digital conversion

sensor / RF / analog waveform→ADC→DSP / FPGA / MCU→DAC→analog / RF output

Sensor / control → embedded hardware

sensor / switch→MCU / Arduino→GPIO / ADC / timer / serial bus→driver / actuator / instrument

Component → RF chain → spacecraft link

LNA / mixer / PLL / PA / filter→receiver / transmitter→antenna / array→spacecraft RF system→mission link

Earth ↔ Moon communications

Orion / lunar asset→RF / optical terminal→NSN / DSN / lunar relay→ground network→Mission Control

rotation→MEMS / FOG / RLG / HRG gyro→angular rate→attitude + strapdown mechanization→PNT

RF field → trapped ion

RF drive→quadrupole electric field→Mathieu stability / pseudopotential→trapped-ion motion→quantum control

Charged particle → measured current

$q(\mathbf E+\mathbf v\times\mathbf B)$→trajectory→$q\mathbf v\cdot\mathbf E_w$→TIA→oscilloscope / spectrum

5. Electrical-size regimes

A useful dimensionless parameter is

\[ka=\frac{2\pi a}{\lambda}.\]

Regime	Common model class	Typical applications
$ka\ll1$	electro/magneto-quasistatics	capacitors, inductors, small sensors
$ka\sim1$	full-wave Maxwell solution	antennas, resonators, scattering
$ka\gg1$	full-wave or high-frequency asymptotics	electrically large spacecraft, reflectors, radar scenes

See Scaling Laws & Dimensionless Numbers for a larger regime map.

The map is intentionally recursive: a sophisticated system usually contains several simpler electromagnetic problems nested inside one another.

Spacecraft and RF system extension

The Advanced Engineering Learning Map connects seven subject areas to detailed chapters on detector electronics, radiometry, spacecraft systems, inverse electromagnetics, coherent RF arrays and precision measurements. It includes instrument case studies and numerical experiments.