All of my J-Pole and Slim Jim antennas are constructed out of Type-M hard copper tubing. Type-M, also known as Red Copper is primarily used in the plumbing industry for supplying drinking water in homes and businesses. Although with the cost of copper continually increasing, the construction industry is shifting towards other materials for plumbing. But like copper tubing carries water in homes, it also can carry electrons in our antennas.
One thing that makes copper an outstanding choice for antennas is that it is a very efficient conductor of electrical energy. In fact about the only common element that is more conductive than copper is silver. You can imagine what an antenna built out of silver would cost.
Weight for weight, outside of precious metals, copper is the best conductor of electricity and heat, it is hardly surprising that about 60% of total copper use is for these purposes.
Copper is used in high, medium and low voltage power networks, and copper conductivity is considered to be the standard to which other conductors are compared.
Aluminum cables are being replaced with copper ones, because copper conductivity is twice that of aluminum, making copper cables extremely energy efficient, thus helping reduce energy consumption on a global level.
Copper wire has long been the preferred conductor material in the majority of cables used for power and telecommunications. Having high conductivity combined with a ductility that makes it easy to draw down to close-tolerance diameters, it can also be readily soldered to make economic, durable connections.
|Copper (hard Drawn)||89.5|
Table from the Electrical Conductivity of Metals.
With copper being twice as conductive as aluminum and 6 times more conductive than steel, it makes an excellent choice as an antenna material. The increased electrical efficiency means more of your RF energy will go up and out the antenna and not be trapped, creating heat energy. More efficient radiation also means that you can run higher powers with a copper antenna than with other building materials. My J-Poles have been tested to 500 watts without issue and there is no reason why they couldn’t go the full legal limit of power if need be.
Now copper isn’t a perfect building material for antenna, there are a couple of downsides. One is the cost. Copper has almost become a semi-precious metal and its cost continues to rise. As the the housing market improves, copper could again take big price increases.
Copper is a best suited material for base antennas. The metal, while soft and malleable, is quite rigid. Stainless steel has a higher tensile strength, so thinner wire can be used. This makes steel an excellent choice for mobile whip antennas where flexibility is a must. But I wouldn’t use stainless on a base antenna as flexibility isn’t an issue and its low electrical conductivity greatly decreases its efficiency.
On a pure energy efficiency standpoint, copper is the best material to choose for a base station or permanently mounted antenna. More of your signal will get into the air and less RF energy will be turned into heat by the internal resistance of the metal.