1420MHz, what would I need?

Recently I managed to use an old 1 metre dish with an old LNB to work with my rtl-sdr, I had to buy a bias tee for it to work, I am enjoying using my current setup and managed to detect presumably geostationary satellites. I am thinking of what antenna or feed I would need to tune in on 1420MHz-1662MHz. As everyone knows, LNBs detect signals from 10GHZ-12GHZ approximately so I want to know what I need for the hydrogen line.