Additionally, a ferrite choke bead is used to contain RF power in the antenna system. By using a choke bead, all RF power is directed into the radiating element and prevented from leaking back to the transmission cable. This technique increases usable RF power and minimizes cable interference with other electronic equipment. Also, Digital Antenna uses its exclusive marine grade low loss UV stable RG-8X cable to reduce transmission line loss in all Digital Antenna marine antennas. 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.