Need clearity on a paragraph on Antennas (dipole)??

Question

Need this to be in English if you know what i mean? the text I need translated is "you already know that the main disadvantage to a twin wire transmission line is its radiation loss. however, provided that the separation between the leads is short compared with the wavelenght, the radiation loss is small because the fields associated with the two conductors will tend to cancel out. (what separation , between what leads?) I'm assuming its the separation ========} d ( of the transmission line or the refernce point =====:== (or where the half wave lenght begins for a dipole ???????

Answer 1

It helps if you have had some actual contact with transmission lines. This picture may give you some idea.

<>http://users.telenet.be/on4vlm/images/g5...

What you are looking at is a coiled up dipole called a G5RV among Hams. The black line at the top is the transmission line. It consists of two wires held at a constant distance apart by molded plastic insulation. Periodically the insulation is removed to cut down losses (the square cutouts). The size of the wire, the distance apart and the insulation give the transmission line it's characteristic impedance. The wire is balanced (unlike co-axial cable which is un-balanced).

The material separating the two bare copper wires is provided to allow connections between the feeder and the actual Dipole. The bare wires form the dipole proper. This particular antenna is fed in the center. However, any antenna can be fed anywhere along the dipole at all. A dipole is simply a half wave length of wire. How you couple into it is up to you.