Try search under ANDREW, or Decibel Products.
sounds like you have the 222 series (4 folded
dipoles stacked either in the same plane, or in
4 different directions. Tho doubtful that you
can change resonant freq, most likely with what
you have will be entirely adiquate for a band, even
10-20 MHz from its design frequency (these are
fairly broadband devices. As info, Jim NN7K

Ed Bailen wrote:
Among the stuff my neighbor left behind when moved out were two
antennas. Each looks like a dBProducts 4-bay VHF array. Can anyone
tell me how I can tell from the measurements what frequency these
might be designed for? Also, is is possible to change the resonant
frequency on this type of folded-dipole antenna?

Thanks,
Ed - N5KZW