how to stream vhf video

hi friends,

i have an application, where i want to stream video wirelessly using VHF frequency. i want to make use of the wireless video modem in VHF range.

i also want to stream the video from a mobile vehicle for the purpose of surveillance. im unable to find the modem with these specifications.

i want the range for this application as 20kms n if possible with out line of sight.

can anybody plz help me how to find out the VHF modem with these specifications? if not atleast tell me good websites where i can found at this type of information.

thanxs in advance

with regards
kiran