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How to Calculate Power Splitter Losses

Power splitters are very useful circuits that allow signals to be split into multiple, identical copies. Unfortunately, each copy has less power than the original signal. This is known as power loss. This happens because the power splitter is a passive electric device and doesn't add any power to the input signal. A power splitter is made up of two types of resistors: input resistors and output resistors. The more copies are made, the more loss each copied signal experiences due to the resistors. You can calculate power splitter loss with a convenient formula.

Instructions

- 1
  Determine how many splits your n-way power splitter has. If it has one input port and four output ports, it's a 4-way power splitter. Write down the "n" value of your splitter for easy reference.
- 2
  Determine the power level of the signal being transmitted into the splitter; this will usually come with the documentation for your power transmitter.
- 3
  Study the formula below, which shows you how to calculate the amount of dissipated power across the input resistor A (PdissA) and the output resistors B(PdissB), given the number of splits (n) and the input power (Pin).
  
  PdissA = Pin * (n-1)/(n+1)
  
  PdissB = Pin *(n-1)/[(n+1)*n^2]
  
  In the above equation, the "^2" symbol means "raise to the power of two," or square the value.
- 4
  Solve the equation above for a 4-way splitter, assuming a 1 watt power source, like this:
  
  PdissA = 1 watt * (4-1)(4+1) = 0.6 watts
  
  PdissB = 1 watt **\ (4-1)/[(4+1)*4^2] = 0.0375 watts
- 5
  Determine the Power Factor, which is equal 1 -- ([PdissA + (PdissB * n)]. Following the above example, you will get a power factor of:
  
  Power Factor = 1 -- [0.6 + (0.0375 * 4)] = 0.25
- 6
  Divide the Power Factor by the number of output ports, or n. Concluding the example above, the total loss on one single output line of a four-way splitter is equal to:
  
  0.25 / 4 = 0.0625 = 6.25%
  
  For every watt that enters the splitter, only 6.25% of a watt exits on each of the four ports.

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