Looks like the strings you are trying to match are utf-16, but burried in a binary file. I'd recommend you use binmode on the file handle you are using to read the data and then you can:

use warnings;
use strict;
use Encode;

my $binstr = "\x{00}\x{01}\x{02}\x{03}\x{04}\x{05}" .
  "\x{00}A\x{00}u\x{00}t\x{00}h\x{00}o\x{00}r\x{00}" .
  "\x{80}\x{90}\x{a0}\x{b0}\x{c0}\x{d0}\x{e0}";
  
my $matchStr = encode ('utf16be', 'Author');

if ($binstr =~ /(\Q$matchStr\E)/) {
    my $match = decode ('utf16be', $1);
    
    print "Found $match\n";
}
[download]

Prints:

Found Author
[download]

Note that this assumes big endien which seems to match your example, but could be little endien which is native for Windows systems and normal for the net.