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Safe measurement of the output of transmitters

Calculating with dB is not too difficult.
Every factor of 10 increase of the power of a signal raises the dB level with +10dB
Every factor of 10 decrease of the power of a signal reduces the dB level with -10dB

Typical output power of a transmitter

  • 100W equals +50dBm
  • 10W equals +40dBm
  • 1W equals +30dBm

For best measurement of harmonics in the output of transmitters the input level of the tinySA should aim between -20dBm and -10dBm

Required attenuation between transmitter and tinySA

  • For 100W : between 60 and 70dB
  • For 10W : between 50 and 60dB
  • For 1W : between 40 and 50dB

The best approach is to use ALWAYS a 30dB attenuator directly connected to the tinySA and to use power attenuators to reduce the output of the transmitter to the target input level of this 30dB attenuator, that is +10dBm

So you will need these power attenuators

  • For 100W output: 30-40dB
  • For 10W output: 20-30dB
  • For 1W output: 10-20dB

Another option is to use a dummy load and an inline 50dB attenuating sampler. A nice example of how to build one yourself can be found here

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Page last modified on February 24, 2021, at 01:58 PM