A few years back there was a group of kids on a field trip to Abrams Falls in the Great Smoky Mountain NP. The terrain down at the falls is steep except for following the trail along the creek. While the kids were there a boy fell in the water below the falls and drowned. One of the kids had brought his handheld HAM Radio and he was able to hit a repeater and summon the Park Rangers. Otherwise someone would have had to walked two miles back to the parking area.
That band spectrum is VHF at about 164 MHZ IIRC. VHF at that frequency and below can work considerable distance even with a hand held. My last employer had a business radio in the 150's MGH range and a base unit at the building. I could talk across town back to base on the handheld. With my antenna farm and scanners I could sometimes hear the base unit 20 miles away when I was home.
I've also heard 154-159 MHZ Police Comms as far away as Indiana and I'm in East Tennessee. If a person simply wants to monitor Police, Fire, Ambulance, Rescue, HAM, Air, USCG, the power company, wreckers, drive through windows, GMRS, Mall Security, Hospitals, and business radio with one radio then a Police Police Scanner is the right choice. But you need to see it you need to determine what type radio system is used in your area. It is 800MHZ with analog voice a Trunk Tracker will work. In more rural areas the Law Enforcement usually uses either the 150's or 460 MHZ Spectrum in the clear. You will not pick up Feds on one generally though. Most agencies except maybe BLM have gone digital.
You can turn a discarded old Outdoor TV antenna into a scanner antenna fairly easy. But the Rubber Duck antenna they come with will get most local agencies.
Most repeaters used to cover wide areas are sited as high as possible above the surrounding terrain, They have high gain antennas and the receive sensitivity is usually adjusted to be as sensitive as possible which aids in picking up the weaker signal of a hand held transceiver (HT or walkie-talkie or talkie). Our local Ham repeaters in this Texas county a co-sited on the Sheriff's VHF tower and the EMS/Fire local tower. Each site has 2 voice repeaters and a digipeater. They are about one mile apart. The voice repeaters at both sites are on the 2 Meter band (144.00 to 148.00mHz) and the 70 Centimeter band (420.00 to 450.00 mHz). The digipeaters are for packet radio and are on the digital allocation part of the 2 Meter band. We get these choice locations by agreeing to provide emergency communications during times of emergency and hold regular practice nets weekly. We have routine coverage to about 50 miles when using a mobile rig and 15 to 20 on a talkie. YMMV.
73,
Cal