The majority of late model vans I have seen use car radio setups. You just use a standard car aerial with these.

If you are trying to install home type equipment (some people do,) what type of antenna is used in your home situation?

We fitted a car aerial to our last van fairly cheap one from accessories shop and it was still going strong six years later so dont need a special or expensive one to achieve good results.

That's all I use. Will work on both FM and AM. Suggest mount in such a way that it can be raised (at least partly) clear of the rig if reception is "iffy"