EMI, EMC & Filters
Every emi, emc & filters calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
14 calculators in this section
- Bonding Strap Impedance CalculatorA bonding strap is meant to hold two pieces of metal at the same potential, and it stops doing that far lower in frequency than anyone expects, because it is an inductor. Its DC resistance, its inductance from the published flat-conductor formula, its impedance against frequency, and the frequency at which it exceeds the milliohm limit your own standard sets at DC.
- Cable Radiated Emissions CalculatorThe common-mode current an RE102 limit actually permits — usually a couple of microamps — and the field a measured common-mode current on a harness is expected to produce. The bridge between a current-probe reading and a radiated-emissions limit, with both of the model's validity conditions worked out and printed.
- Cable Shield Transfer Impedance CalculatorHow much voltage a shield current puts onto the inner conductor, per metre — and what a pigtail does to it. A few centimetres of wire between the braid and the backshell adds inductance that overtakes the braid's own transfer impedance within tens of kilohertz, after which the shield's quality stops mattering.
- Conducted Emissions Margin CalculatorHow far under a conducted-emissions limit your measured or predicted spectrum sits, at every frequency you care about, with the worst one called out and the extra attenuation a stated design margin would need. MIL-STD-461G's CE102 and all four CE101 limit curves are built in, read from the standard's own figures, with their relaxation rules; any other limit, including the copyrighted ones, you enter as breakpoints.
- Converter Conducted Emissions EstimatorThe differential-mode conducted noise a switching converter will produce before the hardware exists, from the shape of its input current pulse: the trapezoidal Fourier envelope, its two breakpoints, the harmonic amplitudes, and what the LISN turns them into in dB above a microvolt. It is an envelope and it is differential mode only, and the page says so in every place where that matters.
- EMI Filter Designer CalculatorSize the X capacitor, the Y capacitors and the common-mode choke of a single-stage input filter, working back from the attenuation you need in each mode. The two modes are designed separately because the same three components look completely different to them — and the differential inductance is not the choke's inductance, it is its leakage. Every attenuation figure here is computed with the components' parasitics in and in the impedances you state.
- EMI Filter Insertion Loss CalculatorWhat a built filter really does, once the capacitor's ESL and the choke's winding capacitance are in the model and the impedances are yours rather than a 50 ohm jig's. An ideal LC rises at 40 dB per decade for ever; a real one stops somewhere between one and thirty megahertz and comes back down. This page prints the ideal figure, the real one, the 50 ohm / 50 ohm figure a datasheet would quote, and the difference between them.
- Enclosure Aperture Leakage CalculatorWhat a shielded box actually leaks through its slots, seams, display cut-outs and vents — the aperture's own shielding effectiveness, the frequency at which it goes to zero, the penalty for many apertures, and the gain a thick wall buys as a waveguide below cutoff.
- Field Strength and Power Density ConverterElectric field, magnetic field, power density, received power and antenna factor at a point — each from whichever one you have. The far-field boundary is worked out first, and the plane-wave conversions are refused inside it, because E = 377·H is not an approximation in the near field, it is wrong.
- Ground Loop Coupling CalculatorTwo mechanisms that get called the same thing and are not. Common-impedance coupling, where a noisy circuit's return current develops a voltage across a shared conductor that appears as a series source in the quiet one — and magnetic loop pickup, where a changing field through a loop induces a voltage round it. Both against a noise budget you set, and both with the inverse: the impedance, or the loop area, the budget allows.
- Radiated Emissions Margin CalculatorHow far under a radiated-emissions limit your measured or predicted electric field sits, at every frequency you care about, with the worst one called out and the extra attenuation a stated design margin would need. All nine MIL-STD-461G RE102 limit curves are built in, read from the standard's own figures; any other limit, including the copyrighted ones, you enter as breakpoints.
- RS103 Test Field CalculatorWhat amplifier an RS103 radiated-susceptibility test needs: the forward power for a stated field at a stated distance, the power once cable loss and mismatch are paid for, the average against the peak for the standard's own pulse modulation, and the power density the field represents — because a test field of this size is an RF hazard.
- Shielding Effectiveness CalculatorAbsorption, reflection and the multiple-reflection correction for a solid conductive wall, with the wave impedance taken from the exact dipole fields rather than a three-case approximation — so the page shows you what most pages hide: a thin conductive shield is nearly transparent to a close low-frequency magnetic field, which is why mu-metal exists.
- Y Capacitor Limit CalculatorHow large a Y capacitor you are permitted, which is almost never the size you want for filtering. Enter the limit from your own standard or platform specification and this computes the current your capacitance produces, the largest capacitance that limit allows, the common-mode impedance it presents and what the safety limit costs you in decibels of attenuation.