Public Safety Licensed 4.9 GHz Max EIRP


#1

I was wondering if anyone out there could provide some clarification on the max EIRP limits for the Public Safety Licensed 4.9 GHz spectrum?

High power maximum conducted output power (dBm) = 33

(2) “High power devices are also limited to a peak power spectral density of 21 dBm per one MHz. High power devices using channel bandwidths other than those listed above are permitted; however, they are limited to peak power spectral density of 21 dBm/MHz. If transmitting antennas of directional gain greater than 9 dBi are used, both the maximum conducted output power and the peak power spectral densityshould be reduced by the amount in decibels that the directional gain of the antenna exceeds 9 dBi. However, high power point-to-point and point-to-multipoint operations (both fixed and temporary-fixed rapid deployment) may employ transmitting antennas with directional gain up to 26 dBi without any corresponding reduction in the maximum conducted output power or spectral density. Corresponding reduction in the maximum conducted output power and peakpower spectral density should be the amount in decibels that the directional gain of the antenna exceeds 26 dBi”.

Using a 20 MHz wide channel (max for this spectrum) it looks like from what I am reading you can go up to an EIRP of 59 dBm.

Any feedback on this would be greatly appreciated.


#2

I found this site in my own research about 4.9: http://urgentcomm.com/rebanding/radio_introduction_ghz

they have this table:
image

Which was corroborated by Colorado’s (My home state!) own study:
http://ntiaotiant2.ntia.doc.gov/top/docs/eval/pdf/086004010e.pdf (page D14)

My guess is that Mimosa’s equipment is certified for the Low power device (FCC Mask L) because that portion of the licensing is most similar to 802.11. The FCC Mask M devices have pretty stringent isolation requirements. Mimosa’s own paperwork says it will only do 20 MHz in the 4.9. I would be willing to bet that you are limited to 20 dBm transmit power with a 9 dBm antenna and corresponding decreases with higher antenna gains.


#3

Thank you for the response. I also read through the same info you cited. I guess what I really need to determine is what FCC Mask the Mimosa equipment falls under, which would make things pretty clear at that point.


#4

Hi @Ethan,

I did some research and found that Mimosa equipment should be under FCC Mask M. The following data is what I used to determine that:

Edit: Corrected PTMP and PTP info for clarification.


#5

Thank you for the information. Much appreciated.


#6

You’re very welcome.