power equivalent bandwidth

Complete explanation here:
https://www.eutelsatamericas.com/files/contributed/PDF/support/Eutelsat-Americas...

I suggest you download it and keep a copy.

It says that your share of the power you are allowed from the transponder must be proportional to your paid-for bandwidth versus the bandwidth of the transponder.

The transponder will be backed off for multi-carrier operation, to keep the intermodulation noise level acceptable.

So, for example
If transponder single carrier EIRP=50 dBW  (on some contour)
Output back off = 1.5 dB
Total of all carriers in transponder, output EIRP = 48.5 dBW

Transponder bandwidth = 72 MHz.
Your leased bandwidth = 18 MHz

You get 50 - 1.5 + 10 log(18/72) dBW.
= 50 -1.5 -6 dBW

Your downlink carrier EIRP = 42.5 dBW

Best regards, Eric.