I believe most satelites operate in the microwave range, which is around 1 to 40 ghz. 1 ghz has a wavelenght of about 30cm. Some operate all the way down in the HF Band. The lowest active sat I know of operates around 28mhz( wavelenght=10 meters). Sputnick operated around 14 mhz or 20 meters.
This website has an excel sheet with all the sats out there. Doesn't give there frequencies though.