Disadvantage is still the limited breaking force and the fact that this is quite stiff. This is pre-stretched copper wire, so it won’t stretch so fast anymore. There are suppliers who sell harddrawn copper. The goal of the radio amateur is to transmit as much energy as possible, isn’t it □ Then what? Doesn’t it work at all? No, it will work, but due to the higher resistance, a small percentage of the emitted energy is converted into heat. Then why don’t we use stainless steel? Simply because the HF conduction of this material is not optimal. Stainless steel has excellent elongation properties and can handle an enormous tractive force. ![]() The chance of a break is very high and the antenna will soon stretch and sag. For permanent set-ups or heavier antenna applications (think of a dipole antenna with hanging 1:1 BalUn) only copper wire is not suitable. I myself regularly use antenna wire that consists only of copper for my holiday EndFed antennas for example, the stretch is hardly noticeable here. ![]() This is not such a problem for very short antennas, experiments and holiday setups. Now we’ve had all aspects of antenna wire, haven’t we? StretchingĬopper tends to stretch quite quickly, causing the antenna to sag and become longer and longer. So make sure you have good weatherproof insulation, such as varying temperatures and UV light from the sun. The outside is exactly the part of the conductor through which the HF current flows. Over time, the cable will corrode, affecting the outside of the conductor. When the cable will be used uninsulated, it will work well in the beginning. With braided copper cable the electrical HF conduction is fine It is strongly recommended to use insulated antenna wire at all times. We’ll take braided copper cable, all right? The Insulation If possible, use braided cable consisting of several thin conductors. Frequentie MHzīy using several small conductors in a cable, the surface area is increased while the total cable diameter remains limited. Just look at the table below where we take three different conductors and show the resistance per meter at different frequencies. The higher the frequency, the greater the skin effect. ![]() For direct current the diameter of the conductor is important but for HF currents the surface of the cable is important. This phenomenon is called the Skin effect. HF currents have the property of running mainly on the outside of a conductor. That is indeed true for direct current, but for HF other laws apply. This makes it obvious to use a thick copper cable which has a low resistance after all. By keeping the resistance in the antenna cable low, the energy is fully radiated instead of converted into heat. Of course it may be clear that the best antenna litz can be used with a low resistance.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |