EMC — Tool

Field strength calculator

Two jobs, kept separate. Convert one field value into every unit you'll meet on a limit line — or work between transmitter power, antenna gain, distance and the field it produces. Antenna placement rules have their own page.

1 — Convert a field value

One box. Type a value, pick its unit, and every equivalent updates. Plane-wave (far-field) relationships assumed throughout: H = E / 377 Ω.

Input

Field value

Magnetic and power-density figures assume the plane-wave relationship, valid in the far field.

Equivalents

2 — Field ↔ power at a distance

The far-field link between what the amplifier delivers and what the EUT sees. Choose which way you're working.

E = √30 · P · Gd

Inputs

I want to…

Power into the antenna (W)

Antenna gain (dBi) Typical horn 8–15 dBi; log-periodic 6–7 dBi; biconical ≈ 2 dBi mid-band.

Distance to EUT (m)

Results

Far-field, free-space maths — no chamber reflections, no near-field gain reduction, no cable loss. For a test level like RS103's 20 V/m, add real margin for modulation (a 1 kHz 80% AM CW signal needs the amplifier to deliver the peak, not the RMS) and check the antenna's spec at your actual distance. Placement and spacing rules live on the standards placement page.