In what conditions can a two-way radio deliver its maximum range rating?

A. From a high vantage point looking down into a flat valley or lowland area with minimal tree cover. Flat, obstruction-free settings are also good for transmitting radio signals, but the addition of height greatly boosts your range potential.

2 way radios range

One example: a large lake with nearby hills — a setting where two-way radios are often tested. During such tests, three or more radio users may be deployed around a lake:

1. On a boat
2. On the lakeshore
3. On a hilltop several hundred feet high

Depending on what type of radio is being used, the boat and lakeshore users can typically communicate at distances of 4 to 6 miles. The hilltop user and the boat use can potentially hit the top of a radio's range (if the lake is large enough and distant topography does not interfere).

From high vantage points — say, a 1000' hill in the vicinity of a population center located below in an open valley — you may find a radio has too much range. It's possible you'll hear people talking on every channel. In such an ideal situation, even a half-watt radio could send its signal 25 miles or more.

Ultimately, a key rule for optimizing coverage is achieving good line of sight. You will increase your ability to increase your range as you increase the elevation of your position. Attaining a high point above an otherwise flat area can be a huge benefit toward optimizing your radio's maximum range.

Radio waves travel longer distances when emitted from higher elevations, which is why high points near major metropolitan areas (such as Mt. Wilson near Los Angeles) are popular places to erect radio and television transmission towers. High-elevation transmission locations help radio signals overcome impediments and even the curvature of the earth.

2 way radios range