My recommendation is that you stop worrying about the full range the scanner is designed for and look for an antenna that covers the range(s) you actually listen to. Antennas are designed for specific frequency range(s) and if you extend that range too far (like the 20 MHz - 1200 MHz a typical scanner will cover) will get you an antenna that works everywhere, but never really works well anywhere. If you concentrate on just a few specific ranges (like VHF-Hi and UHF) or just a single range (like the 800 MHz band) you can get a really great antenna that works extremely well over that range and may also work on other areas. Since most of the scanning in an area only use one or two main bands, this is pretty easy to do and you won't give up much at all by ignoring bands where there is nothing much in your area that use them.
If you don't know what band or bands to concentrate on, check out the RR database (that second tab labeled "Database") and drill down by country and then county (also called parish, province, etc.) to find your area. You may discover that nearly everything of interest is on the same system and all you need is a good antenna for the band that system uses.