The brand is ANTENEX...Its a vhf base loaded antenna..I had it for my ham 2meter rig..its an extra one wanted to use it on the business band..151.805..but lost the cutting chart..thanks Mike
the ''fg1520'' www.wpsantennas.com if thats the antenna, range is 152-156 mhz. so prob doesnt need cut.
otherwise if its unknown model u need a swr meter.
N3GKu