If you’re using a repeater, however, you should be able to talk much farther. Repeaters typically operate in the 2-meter band and 70-centimeter band and extend the range of VHF and UHF radios. The range of a repeater station is highly dependent on how high the antennas are and the terrain. A repeater station located in the mountains, for example, may have a range of hundreds of miles, while a repeater located where the terrain is relatively flat, such as here in Southeast Michigan, the range will be more like 50 miles or less.
In general, if you want to talk to other amateur radio stations around the world, you’re going to want to operate on the high-frequency (HF) bands. As you can see from the chart, there are 9 amateur radio bands in the HF portion of the spectrum.
The reason for this is that radio waves with a frequency between 3 and 30 MHz will, under the right conditions, refract off the ionosphere, as shown in the figure below. The radio wave is called a sky wave, and the distance between the transmitter and the spot where the sky wave returns to earth is called the skip distance. The skip distance depends on a number of factors including the frequency of the sky wave and how well the ionosphere happens to be reflecting at the time, but skip distances can easily reach 3000 miles or more. And, skywaves can make multiple “hops,” enabling world-wide communications.