Figure shows the popular G5RV antenna. Although not without some problems, this antenna is very popular.
It can be used either as a horizontal dipole, a sloper, or an inverted-vee antenna (which is how I used it).
The dipole elements are each 51 ft long. The feedline can be either 300- or 450-Ω twin lead. For 300-Ω cases, use 29 ft of line, and for 450-Ω line, use 34 ft.
One end of the parallel transmission line is connected to the antenna, and the other end is connected to a length of 50-Ω coaxial cable.
Although most articles on the G5RV claim that any length of 50-Ω line will work, J. M. Haerle (HF Antenna Systems: The Easy Way) recommends that the 50-Ω segment should be at least 65 ft long.