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Friis Transmission Calculator

The Friis transmission equation, as shown below, gives the ratio of received to transmitted power for given antenna gains, ranges, and wavelengths under ideal conditions. The calculator below uses this equation to find any one of the variables, provided all the other variables are known.

friis

Leave the unknown value blank and fill in the remaining values. When one available unit for a value is filled in, the other available units are automatically converted from the entered unit value. Once all but one value is entered in, press Calculate next to the unknown value.

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Transmit Power, Pt  W
dBm
Transmit Antenna Gain, Gt  dBi
dBd
Receiver Antenna Gain, Gr  dBi
dBd
Received Power, Pr  W
dBm
Range, meters
miles
Frequency kHz
MHz
GHz
Wavelength, λ  meters
cm
mm

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Attenuator Calculators

Pi Attenuator Calculator

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Enter values and press Enter or click on the Calculate button

Schematic of Pi Attenuator Attenuation: dB
Input Impedance: Ohm
output Impedance: Ohm
Ideal Values
R1 Ohm
R2 Ohm
R3 Ohm
E12 Values E12 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E24 Values E24 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E48 Values E48 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E96 Values E96 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E192 Values E192 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm

 

T Attenuator Calculator

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Enter values and press Enter or click on the Calculate button

Schematic of T Attenuator Attenuation: dB
Input Impedance: Ohm
Output Impedance: Ohm

Ideal Values
R1 Ohm
R2 Ohm
R3 Ohm
E12 Values E12 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E24 Values E24 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E48 Values E48 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E96 Values E96 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm
E192 Values E192 Performance
R1 Ohm Attenuation dB
R2 Ohm Zin Ohm
R3 Ohm Zout Ohm

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VSWR <=> Return Loss <=> Reflection Coefficient Converter

Enter any one of the parameters below and the rest will be calculated automatically.

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Return Loss:  dB
Reflection Coefficient ( S11 ):
VSWR: :1


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LC Resonance Calculator

When an inductor or capacitor are placed in series or parallel
they will have a resonant frequency which is determined by the
design equation below. LC resonant circuits are useful as notch
filters or band pass filters. They are also found in oscillator circuits.

 

Design
Equation:

Lc_resonance

Enter in any two parameters for a resonant circuit,
and this calculator will calculate the third missing parameter.

 

Frequency:
(MHz)
Capacitance:
(pF)
Inductance:
(nH)

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Watts <> dBm <> Volts Converter

This calculator converts between watts, dBm, volts and dBmV.

Select the Impedance then enter any one of the other parameters below and the rest will be calculated automatically

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Impedance (Ω):  50Ω Common in RF and Microwave Systems
75Ω Common in TV and Video Systems
600Ω Common in Audio Systems
Custom Value
 
milli Watts (mW):
Watts (W):
 
dBm:
dBW:
 
VRMS:
VPeak: Assuming a sine wave
VP-P: Assuming a sine wave
 
dBmV: dB relative to 1mV RMS. Often used in the cable TV industry and only valid in 75Ω systems

Most RF engineers will have memorised the following values:

dBm mW Notes
  0   1 Exact by definition of dBm
  3   2 3 dBm is actually 1.995 mW but that’s near enough for most practical purposes
 10  10 Exact
 +3  X 2 Adding 3 to the power in dBm is the same as multiplying the power in Watts by two (actually 1.995 but that’s near enough for most practical purposes)
+10 X 10 Adding 10 the the power in dBm is exactly the same as multiplying the power in Watts by 10