Mark: Inside or outside? Outdoor antennas make for the best signals, especially at 800 mHz.
I assume from the request, you are speaking about inside. The simplest inside antenna, that would be effective is a good magnetic gain antenna, stuck on a circular quarter wave disk of steel. For example, if I want to listen to primarily high band, you would cut a circular 36 inch, which is 18 inches in every direction, and placing the mag antenna in the middle. Put this as high as cable will allow, like on top of a refrigerater, or a high shelf, and attach it to the scanner. This will be a large improvement over the little antenna they provide. Of course, an outside multiband gain antenna, mounted on a mast as high as possible will outdo the inside one.
73 from WB9OJD for 45 years. DUKE