Bepto
EN
ENEnglish繁中繁體中文ESEspañolARالعربيةFRFrançaisITItalianoPTPortuguêsRUРусскийDEDeutschJA日本語VITiếng ViệtKO한국어THไทยTRTürkçe
Request a Quote
EN
ENEnglish繁中繁體中文ESEspañolARالعربيةFRFrançaisITItalianoPTPortuguêsRUРусскийDEDeutschJA日本語VITiếng ViệtKO한국어THไทยTRTürkçe

AI Search

Tell us in one sentence about your application or question to search related products, technical articles and calculators.

Engineering Calculator · 115

Shielding Ratio & dB Converter

Convert a stated shielding reduction ratio to decibels, or decibels to a linear ratio, with an explicit amplitude or power basis.

Electrical continuity
Start calculationReview the method

Live calculation

Enter the known values.

Units remain visible beside every field and result. Change any input to recalculate immediately in your browser.

01

Inputs

02

Results

Attenuation40dB
Reference / residual ratio100:1
Residual on the selected quantity basis1%

Formula
a=clog⁡10Ra=c\log_{10}RR=10a/cR=10^{a/c}c={20amplitude10powerc=\begin{cases}20&\text{amplitude}\\10&\text{power}\end{cases}

The calculation runs locally in this browser. Values are not submitted or stored by this tool.

Direct answer

What this result means

For a reference-to-residual amplitude ratio R, attenuation is 20 log₁₀(R); for a power ratio it is 10 log₁₀(R). A 100:1 amplitude ratio is 40 dB, while a 100:1 power ratio is 20 dB. Choose the measured quantity and ratio direction before interpreting the result.

Shielding Ratio & dB Converter engineering relationship diagramR is the reference quantity divided by the residual quantity, so attenuation is positive for R > 1. The same quantity basis applies to the residual percentage 100/R. The diagram shows a larger reference signal and a smaller residual signal; it does not predict shielding from braid coverage or gland geometry. This dedicated schematic represents shielding reference residual ratio and is not to scale.ReferenceResidualR = reference / residual20 log amplitude · 10 log powerAMPLITUDE OR POWER RATIO · TOOL 115Known attenuation quantityAttenuation
Calculator-specific engineering relationship diagram — schematic, not a product drawing, and not to scale.

Formula & theory

Make the assumptions visible.

R is the reference quantity divided by the residual quantity, so attenuation is positive for R > 1. The same quantity basis applies to the residual percentage 100/R. The diagram shows a larger reference signal and a smaller residual signal; it does not predict shielding from braid coverage or gland geometry.

Calculation relationship
a=clog⁡10Ra=c\log_{10}RR=10a/cR=10^{a/c}c={20amplitude10powerc=\begin{cases}20&\text{amplitude}\\10&\text{power}\end{cases}

R is the reference quantity divided by the residual quantity, so attenuation is positive for R > 1. The same quantity basis applies to the residual percentage 100/R. The diagram shows a larger reference signal and a smaller residual signal; it does not predict shielding from braid coverage or gland geometry.

Variables

aAttenuation on the selected quantity basisdB
c20 for field/amplitude ratios; 10 for power ratios—

Use sequence

From measurement to review

  1. Identify field/amplitude or power as the measured quantity and confirm reference divided by residual.
  2. Choose the known ratio or dB value, then enter it on the matching basis.
  3. Retain frequency, test method, fixture and quantity basis with the converted result when comparing shielding measurements.

Limits

What this calculation does not confirm

  • Compared quantities share a compatible measurement definition, frequency and fixture. For voltage-to-power equivalence, impedances must be equal.
  • Screening attenuation uses the appropriate feeding-to-coupled power ratio defined by its test method; generic field shielding uses the corresponding field ratio.
  • This converter does not calculate measured shielding, coupling loss, transfer impedance or standards compliance from an EMC gland or braid construction.

Related articles

Continue the check

View all 130 calculators
116

Transfer impedance

Calculate a measured transfer-impedance magnitude and, where the cable test method permits, its value per effective coupling length.

Open calculator →070

Cable Braid Coverage Estimator

Estimate a simplified single-layer fill and optical coverage from braid carriers, wires, pick density and cable diameter.

Open calculator →072

Aperture to Wavelength Ratio Calculator

Calculate free-space wavelength and its ratio to a cable-entry aperture for preliminary EMC geometry discussion.

Open calculator →

Calculator FAQ

Use the number without losing the engineering context.

These answers clarify what the tool calculates and where a product-specific review still begins.

01Calculator guidanceWhy can the same 100:1 ratio give either 20 dB or 40 dB?

A power ratio uses 10 log₁₀, while a field or amplitude ratio uses 20 log₁₀. A 100:1 amplitude ratio corresponds to a 10,000:1 power ratio when impedances are equal. Always identify which physical quantity the original ratio describes.

02Calculator guidanceIs 1% residual amplitude the same as 1% residual power?

No. With equal impedances, 1% residual amplitude corresponds to 0.01% residual power. The percentage shown by this tool follows the selected amplitude or power basis and is not a universal shielding percentage.

03Calculator guidanceCan this dB conversion predict an EMC gland’s screening attenuation?

Only an already defined ratio can be converted. Product performance requires suitable measurements at specified frequencies and fixtures; geometric braid coverage and nominal 360° contact are insufficient to supply that measured ratio.

Product selection support

Connect the calculation with cable-entry product options.

Bepto Cable Glands can help relate a preliminary result to the product family and current model information for your application. You can start with the details you have; a complete drawing package is not needed to ask a question.

Request product support