PMP 450 5Ghz Transmit Power 5.7 vs 5.4

Does anyone know why the 5Ghz PMP450 allows 22dBi TX in the 5.4Ghz band, but only 19dBi TX in the 5.7Ghz band?

The SMs don't seem to care.  They transmit at 22dBi regardless of the band.


Additionally, the PTP450 allows 22dBi in the 5.7 band, but only 21dBi in the 5.4 band... confusingly enough.

Perhaps because of antenna gain that they were certified with?  Assuming FCC domain 5.4 is limited to 30dBm EIRP regardless of PTP/PtMP use.

Jacob has this right...

This product is restricted to limits as required by regulatory law.  In the case of the FCC, the maximum EIRP allowed for the 5.7 GHz band is 36 dBm, and in 5.4 it is 30 dBm.

Because the radios can be connectorized, the equipment may not know which antenna is attached, and the professional installer must set the correct parameters in the "External Gain" field.  Then, the maximum Transmit power can only go up to the legal limit of the band you're operating in.

If you see any errors with this calculation, please highlight this, and we will make sure we get it fixed. 

The max TX for 5.7 is 3dbi less than that for 5.4ghz.  This is what I'm questioning

For example:  If I'm using a 8dBi antenna, the radio allows me to select 22dBm under 5.4Ghz, but only 19dBm under 5.7Ghz.  The question is why?  I assume I should be able to transmit 22dBi using 5.7Ghz using up to a 14dBi antenna, but I cannot, because the radio can only go up to 19dBi max.

Yes, the radio calculates the EIRP based on the numbers entered for antenna and cable loss and limits the transmit accordingly... this is all well and fine.  The radio even recognizes that 30dbm is the max for 5.4 and 36dbm is the max for 5.7.  None of that is in question.

I recieved a call from Cambium support.  After an uneccessary conversation where their support simply repeats information I've already provided myself (grumble grumble), I'm told that 5.4Ghz being a lower frequency requires more power than 5.7Ghz and that is why there is a 3dBm different in transmit power.

Maybe? I think that is just a story though.  My PTP450 is capable of transmitting 22dBm in the 5.7Ghz band.  So if a PTP450 can do it, why not a PMP450?

Want to know what is even more confusing?  When I switch to 5.4Ghz on the PTP450, it will only transmit up to 21dBm!  Can't explain it.

in 365MGz

450 pmp sm.

what would be external gain?

8 because of internal patch?

with dish? add 12DBi for toatal of 20?

looking for guidance.


Yes, more or less. Are you in the US wanting to run CBRS? If so, you will need to request a grant through our CBRS management tool in cnMaestro and the tool will give you the internal and external gains. For a PMP450 integrated SM with reflector dish it is 8dBi internal gain and 13dBi external gain for 21dBi total. 

If it is the integrated 3.65 GHz Integrated SM (naked)... then the "External Gain" is zero.

If you add the reflector dish, then the "External Gain" should be 12 dBi.

The radio already accounts for the 8 dBi patch.

All the things Brian says about CBRS are correct, but I suspect you're in Canada... so go with the above.