20cm band would be around +/- 2GHz (2000 MHz). So, no, the VHF Kenwood TM-281 cannot be used on 2 GHz.
As kayn1n mentioned, the radio is only capable of 138-174 MHz. It's physically impossible for the radio to be a dual band, short of replacing all of the circuits inside the radio.
If you're looking for a good dual band radio from Kenwood, I would suggest the TM-V71A. It covers 2m and 70cm.
Not sure what you would find for 20cm, as it's not an amateur band.
23 cm (1240-1300 MHz) is an amateur band, there are a few radios on the market that cover that band. Here's a few off the top of my head:
- Kenwood TS-2000 with 23cm module installed
- Alinco DJ-G7T handheld
- Icom ID-1 D-Star mobile radio