If you are a scanner hobbyist then you must be enjoying being entertained by all that you get to hear or overhear on your radio. As many vehicles like police cars, fire engines, ambulances, taxis and even airplanes are all equipped with radios you can listen in to them also. You can learn of things as they might be happening before news reporters hear about them.
Hostage dramas, bank robberies, car crashes, chemical spills, neighbor and domestic disputes, tornado sightings are all for you to hear about. These scanners come with a built in antenna, permitting reception up to about 20 miles or so. Portable scanners are supplied with a helical (spring shaped) antenna, covered by rubber.
The rubberized antennas furnished with current models are too stiff and place stress on the antenna jack. Older scanners to be supplied with more flexible antennas can do well by using portable scanners like Icom FA-1433B dual band flex antenna, Premier (Prime) RD-9 and RD-9SMA, or Austin Condor. The "Thin-Stick" is an 18 inch telescoping antenna for extended range.
Outdoor antennas, like the Channel Master 5094A extend reliable reception to 50 miles or more, depending on terrain. If you do use an outdoor antenna, be sure to disconnect and ground it during storms and when not in use to avoid a lightning hazard. Discone and ground plane type antennas can be more prone to cause scanner damage due to static charge buildup.