I know this is a broad question but here is my situation. I have a Radio Shack Pro-2051 mobile scanner hooked to a Radio Shack mag-mount mobile scanner antenna (cat. #20-032) all on a 2007 Chevy Impala. It is starting to rust out where the element screws into the base so I will be replacing it. On the antenna I have now I am only using the top element because it is the correct length for monitoring the railroad band (160-161 mhz). That is what I primarily listen to but find it picks up well on all bands. I want some input on what people think is better as I know the one I have from radio shack is not the best even though it works well for me. Also I mount it in the center of my roof so to get the best ground plane effect. I'm not going to spend hundreds of dollars but may be willing to go as high as $200 (if the wife allows)!!!!!
The "Best" antenna for you may be a combination of several that you swap out as needed. Just make sure that they all use the same type mount and swapping will take only a few seconds (recommend the standard NMO since that's what many use). Since you're mainly interested in the railroad band what I'd recommend is this:
* a standard 1/4 wave whip cut for your main frequency (see the manufactur's instructions for the correct length). This will be rather short (about 16" or so) and work well, but provide no gain.
* a 5/8 wave whip with loading coil such as the NMO-150 already recommended. It's rather long, but will provide you additional range since it has some gain.
* a multi-band antenna such as the Larsen tri-band 150/450/800. It's also fairly short (about 19") and covers the most popular scanner bands well.
Getting all three, including the single mount should be well within your $200 price limit and provide you with flexibility as well as some form of backup if one gets damaged.
