SeeFields

SeeFields invisible electromagnetic world

Drag transmitters, phone or wallDrag floor to orbitScroll to zoom

–dBm

–

d = – mλ = –

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Frequency

Transmit power 20 dBm

Wall

Phone tilt 0°

Engineering model Wavefronts: conceptual

What is and isn't modelled

Free-space path loss between two antennas with fixed gains (2 dBi router, 0 dBi phone).
Wall penetration: one slab at normal incidence, ITU-R P.2040-3 material constants, interface plus bulk loss. No multiple internal reflections.
Polarisation: router vertical, phone linear; mismatch loss cos²Δθ, saturating at 25 dB cross-polar discrimination.
Second transmitter: same frequency, phase-locked to the first, so the two waves add coherently. That is how a reflection or an antenna array behaves, not two independent routers. Floor shows the fringe pattern; when it would be finer than the screen can draw it shows average power instead.
Room reflections: the four room walls are 20 cm concrete. One bounce per wall by the image method, with the Fresnel coefficient Γ⊥ at the actual incidence angle, summed coherently with the direct path. The mottled floor is multipath fading.
Not modelled: floor and ceiling bounces, double bounces, diffraction around the wall edge, antenna patterns.
Inside one wavelength of the transmitter the far-field formula is invalid; the readout says so. The two rings on the floor mark λ/2π (reactive near field of a small antenna) and 1 λ (where this model starts applying the 1/r law). Zoom in to see them at true scale.
E / B vectors: a vertically polarised wave sampled along the direct path. E (amber) and B (teal) are in phase, perpendicular to each other and to the direction of travel k. Arrow length shows the instantaneous phase, not field strength; the 1/r decay is what the floor colour shows. Same slowed time as the wavefronts. Conceptual.
Floor colour is the same engineering model evaluated at every point. Rings are true-to-scale wavefront spacing (λ) but a conceptual animation.

Move the transmitter

Drag the router. Watch the phone.