With broadband antennas, one can track a large number of frequencies thus enabling us to track several devices with a single design.

A tiny GPS chip embedded onto a cell phone can help you to trace it. This is how mobile tracker works.

All cab services in most of the cities like radio cab, city cab,etc.. use a GPS receiver on top of each vehicle that gives its location to the master controller who manages cab assignment.

Cable TV wire is called co-axial cable. It has one inner conductor(wire) and one outer conductor(meshed sleeve) separated by a dielectric. Fields propogate through dielectric.