Thank you, all of you.
According to your valuable responses, I found the following bandwidths for each Deep Space allocated frequency channel:
S-band --> 370 kHz/channel
X-band --> around 1.4 MHz/channel
Ka-band --> around 5 MHz/channel
The full range of the bands are 2 to 4 GHz (S), 8 to 12 GHz (X), and 27 to 40 GHz (Ka); see Wikipedia IEEE radar bands for the whole list.
DSN uses only a small fraction of those ranges. For example, in S band, DSN stays inside 2025 to 2120 MHz and 2200 to 2300 MHz, but doesn't fill it everywhere (part of that is unused by the Madrid station due to ...