EMC Related Formulae
Log ↔Linear Voltage
dB µV to Volts ()()
20/12010−=V dB V µVolts to dB µV ()120
log 20+=V V dB µdBV to Volts ()
20/10dBV V =Volts to dBV ()V dBV log 20=dBV to dB µV 120
+=dBV V dB µdB µV to dBV
120
−=V dB dBV µLog ↔Linear Power
dBm to Watts ()()
百香果的功效与作用及食用方法
10/3010−=dBm W Watts to dBm 30
)
log(10+=W dBm dBW to Watts ()
10/10dBW W =Watts to dBW )log(10W dBw =dBW to dBm 30+=dBW dBm dBm to dBW
30
−=dBm dBW Log ↔Linear Current
独面筋的家常做法dBuA to uA ()
20/10A dB A µµ=uA to dBuA )
log(20A A dB µµ=dBA to A ()
20/10dBA A =A to dBA )log(20A dBA =dBuA to dBA 120−=A dB dBA µdBA to dBuA
120
+=dBA A dB µLog ↔Linear Impedance
dB(ohms) to ohms ()20/)(10ohms dB Z =ohms to dB(ohms)
()
Z ohms dB log 20)(=Term Conversion
dBm to dBuV dBm Z v dB ++=)log(1090µdBuV to dBm )
log(1090Z V dB dBm −−=µdBuA to dBm 90)log(10−+=Z A dB dBm µdBm to dBuA 90)log(10+−=Z dBm A dB µdBuA to dBuV
)log(20Z A dB V dB +=µµdBuV to dBuA
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log(20Z V dB A dB −=µµVolts to Amps & Watts
Z
V A =Z
V W 2=
Amps to Volts & Watts Z
A V *=Z A W *2=Watts to Volts & Amps
痛风消肿止痛最快方法
Z
W V *=Z
W A =
RF related, Field Strength & Power Density
dBuV/m to V/m )
20/)120)/(((10/−=m V dB m V µV/m to dBuV/m ()120
/log 20/+=m V m V dB µdBuv/m to dBmW/m2
8.115/2/−=m V dB m dBm µdBmW/m2 to dBuV/m 8
.1152//+=m dBm m V dB µdBuV/m to dBuA/m 5.51//−=m V dB m A dB µµdBuA/m to dBuV/m 5.51//+=m A dB m V dB µµdBuA/m to dBpT 2/+=m A dB dBpT µdBpT to dBuA/m 2/−=dBpT m A dB µW/m2 to V/m
377*)2/(/m W m V =V/m to W/m2
377
2)/(2/m V m W =
wound coil Flux Density ),(20))((4m radius amps turns T πµ=
uT to A/m 25
.1/T m A µ=
A/m to uT
)
/(*25.1m A T =µ
Antenna (Far Field)
Gain, dBi to numeric
)
10/(10dBi numeric Gain =Gain, numeric to dBi
)
log(10numeric Gain dBi =Gain, dBi to Antenna Factor
79
.29)log(20−−=dBi MHz AF Antenna Factor to gain in dBi
79
.29)log(20−−=AF MHz dBi Field Strength given Watts, Numeric Gain, Distance in meters
Meters
Gain watts m V numeric
**30/=
Field Strength given Watts, dBi gain, Distance in meters
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发明家
Meters
watts m V dBi )
10/(10**30/=
Transmit Power needed, given desired V/m, Antenna numeric gain, Distance in meters.
numeric
Gain meters m V watts *30)*/(2=
Transmit Power needed, given V/m, Antenna dBi gain,Distance in meters
)
10/(210*30)*/(dBi meters m V watts =
Amplitude Modulation
Peak power, given CW power and modulation %.(sine wave AM)
2
))01.0*%(1(Mod W W CW peak +=Average power, given CW power level and modulation %(sine wave AM)
2
)
)01.0*%(2(*2Mod W W cw avg +=
Average power, given peak power and modulation %
2
2))01.0*%(1(*2))01.0*%(2(*Mod Mod W W peak avg ++=
Current Probe
dB(ohm) to Zt (transfer impedance)
)
20/)((10ohm dB t Z =Zt to dB(ohm)
)
log(20)(t Z ohm dB =Conductance (Gt) in dB(s) to transfer impedance, (Zt) in dB(ohms)
t
G t Z −=Transfer Impedance in Zt (dB(ohms)), to Conductance in Gt (dB(s))
t
Z t G −=Power needed for BCI Probe (50Ω), given voltage level into 50Ω load (V) and Probe Inrtion Loss L I .
)
10/))50/2log(10((10
V L I watts +=Watts needed for 150 Ohm EM Clamp
)
10/))150/2log(10((10
V L I watts +=Conducted current level using current measuring probe given probe factor in dB(ohm) and probe terminal voltage in dBuv
)
(ohm dB V dB A dB −=µµConducted current level, given probe factor in Zt (ohms) and terminal voltage in dBuv
)
log(20t Z V dB A dB −=µµdB calculations
Compute db delta (volts)
=21log 20V V dB Compute dB delta (amps)
=21log 20A A dB Compute dB delta (watts)
=21log 10W W dB compute new voltage w/ db delta
+∆=20)log(20(10
given V dB new
V compute new wattage w/ db delta
+∆=10)log(10(10given W dB new
W
VSWR/reflection coefficient/return loss VSWR given Fwd/Rev Power
fwd
rev fwd rev P P P P VSWR −
+
=
11VSWR given reflection coefficient
ρ
ρ−+=
11VSWR Reflection coefficient, ρ, given Z1/Z2 ohms
2
121Z Z Z Z +−=
ρReflection coefficient, ρ, given fwd/rev power
fwd
rev P P =
ρReturn Loss, given fwd/rev power
=rev
fwd
P P dB RL log 10)(Return Loss, given VSWR
+−−=11log 20)(VSWR VSWR dB RL Return Loss, given reflection coefficient
设计空间)
log(20)(ρ−=dB RL Mismatch loss, given fwd/rev power
=−rev fwd fwd
P P P dB ML log 10)(Mismatch loss, given reflection coefficient
)
1log(10)(2ρ−−=dB ML Misc
Linear interpolation with log of freq
L
L U L U L X X X X F F Log F F Log Value +−=)(*)
/()
/(where
F L = lower frequency F U = Upper frequency
X L = Value at lower frequency X U = Value at upper frequency F X = Frequency of desired value
飚风TEM Cell Power Needed
Z
Height V Watts 2
)5.0**(=where
V = field strength in V/m
Z = TEM cell impedance in ohms
