Gain in an antenna is not the creation of power, but rather a simple refocusing of energy from all directions to a specific direction. Vertical antennas are in fact quite directional, except in the horizontal or azimuth plane. The figure to the left shows the radiation pattern of three different length radiating antenna elements. The vertical antenna works well only when placed over a good ground system. The success or failure of an antenna system depends on whether or not it has a good RF ground.
Poor grounds cause antennas to operate at less than best efficiency.
In fact, it is possible to lose between 50 and 90 percent of the RF power by heating the space under the radiation lobe, instead of transmitting into the air. The advanced ground system internal to all Digital Antenna marine antennas allows 4.5dB through 10dB gain antennas to have a greater range in any sea conditions. The figure below shows the effect that a ground system has on a vertical antenna. Note that by increasing the ground system efficiency, useful RF power is actually directed closer to the water surface where it is needed. Our antennas are superior to the land-based antennas sold by our competitors.