Look in amateur radio publications - lots of field strength meters used by that group. American Radio Relay League (ARRL) or Radio Society of Great Britain (RSGB) are two organizations with lots of publications.
Just a note - I use the word publication to encompass all sorts of material that included printed/electronic publications that are not viewable via the internet. In fact I'd argue that most of the good stuff won't be found on the internet - just a reference to the publication.