On the previous page has been told about the most simple wire antenna. There was noted that the antenna can radiate harmonics, but apart from the higher harmonics in the absence of ground antenna can emit harmful or dangerous high-frequency voltage. What to do if you can not make a good ground, or how to reduce this harmful radiation? It turns out there is a way. To supply wire antenna can be used open-wire line. In other words, for the power antenna, a second same wire that passes close by and driven out of phase. Such a wire antenna is called "antenna Zeppelin." This antenna is shown in the figures below. Antenna length of 41.15 meters to 41.85 meters. At the points of "AA" Zeppelin wire antenna has an input resistance of 600 ohms. To connect this to the output of the transmitter antenna coaxial cable to use a power line that has a length L / 4 (quarter-wave) or 3L / 4, this line will perform the role of a transformer. Since the line is formed around a strong electromagnetic radiation, which is the mirror image of the real antenna, the space next to the line supply must be free from all subjects. Otherwise, there is distortion of radiation. This antenna as well as wire type antenna L emits harmonics. If the point of "BB" to include a balun, the level of these harmonics can be a little lower. If the feed line length is a multiple of the wavelength, this dish is similar to the L-type wire antenna and power line starts to radiate. In order to prevent this from happening you need to select the length 12.8 meters - 13.75 meters. If used with a line impedance 300 ohms, the line length must be 11.9 m (Figure b). C The figure shows double wire antenna Zeppelin for five HF bands.