Yagi antenna made of 4 elements
Let's add one more directior to a three-element Yagi antenna. This way we will recieve a four-element antenna. Its" power gain will increase by 1-2 Db and it will be 8-9 Db, so it will enlarge the zone of confident reception by a few kilometers.
The next increasing of the number of elements will not lead to the strong growth of power gain since each subsequent director will be giving less growth of antenna"s gain.
For making such an antenna copper wire or a tube with the diameter 2-5 mm are usually used. The director, the driven element which is a folded dipole and the reflector are soldered to the antenna guide. It is common to fasten the construction to the dielectric pole located close to the cable (look at the picture)