I have designed an RF front end in the 915 MHz ISM band. This front end is for two radios that interface with an SDR.

The TX portion of the front end will transmit 3 W. My problem is that after doing a link budget, if my radios are 1 meter away from each other, then the RX portion on the other radio will have roughly 4 dBm incident. The SDR has a recommended input power of <-15 dBm, so I need my front end to limit the power, not attenuate it.

I have searched for anti-parallel diode solutions, but it seems that I cannot find anything that operates at that low a level.

Here is the link to the SDR SDR ettus

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How can I limit the output level of the front end to -15 dBm to protect the SDR?

  • \$\begingroup\$ Your question lacks detail. Are you trying to prevent the front end from overloading your SDR, or are you trying to find an SDR with that level of sensitivity? \$\endgroup\$
    – gbarry
    Commented Aug 15, 2022 at 19:53
  • 2
    \$\begingroup\$ So basically the problem is that you have a signal of (how many dBm?) and you want to reduce it down to -15 dBm and you have no clue how to do that? \$\endgroup\$ Commented Aug 15, 2022 at 19:55
  • \$\begingroup\$ I think OP means his SDR requires an input power level 0 dBm > Pwr > - 15 dBm. \$\endgroup\$
    – SteveSh
    Commented Aug 15, 2022 at 20:04
  • 1
    \$\begingroup\$ I think it means -15dBm recommended, 0.1dBm has a risk of causing permanent damage \$\endgroup\$ Commented Aug 15, 2022 at 20:29
  • \$\begingroup\$ Just use an attenuator 20db/50 Ohm before SDR to be sure if the ouput front end level is too high. \$\endgroup\$
    – Antonio51
    Commented Aug 15, 2022 at 20:36


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