Why is copper tubing used to make high q antennas?

In summary, copper tubing is used instead of normal wire or enameled wire to make antennas and coils at high frequencies because it offers less resistance due to its greater surface area. Although aluminum is cheaper and lighter, it is not as reliable for electrical contact and can be difficult to solder, making copper a better option for certain applications. However, aluminum is still commonly used for TV antennas where periodic replacement is acceptable due to its lower cost.
  • #1
baconman71
25
0
My question is just what the title says. Why is copper tubing used instead of normal wire or enameled wire to make antennas and coils at high frequencies? Does it offer less resistance than normal wire?
 
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  • #2
copper has higher conductivity than nearly any other metal than silver (and silver is only marginally better). at high frequencies, there is a lot of "skin effect" where the great majority of the current flows in the outside layer of the conductor and the internal part of the conductor has nearly no current.

but i always thought that these high-frequency antennas were made out of tubular aluminum, because Al is light and, in a tubular shape, it is strong, to stand up to wind, etc.

i don't think copper is used too much, simply because it tarnishes when exposed to air over long periods.
 
  • #3
baconman71 said:
My question is just what the title says. Why is copper tubing used instead of normal wire or enameled wire to make antennas and coils at high frequencies? Does it offer less resistance than normal wire?

Tubing is mostly used for strength. Like rbj, I haven't seen much in the way of copper tubing used for antennas, except for J-Pole antennas where you need to weld two pieces of tubing together...
 
  • #4
I don't think conductivity play much roll in this. Conductivity goes up, skin depth goes down. It all null out particularly the conductivity is not that big a difference between good conductors. Most common rod antenna like rabbit ear are not copper! Skin depth is:

[tex]δ_s=\frac 1 { \sqrt{\pi f \mu σ}}[/tex]
 
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  • #5
rbj said:
...
i don't think copper is used too much, simply because it tarnishes when exposed to air over long periods.

and is substantially more expensive than aluminium!

Berkeman, I do have one copper tube antenna, a 40m band magnetic loop :)


Dave
 
  • #6
baconman71 said:
My question is just what the title says. Why is copper tubing used instead of normal wire or enameled wire to make antennas and coils at high frequencies? Does it offer less resistance than normal wire?

Copper tubing is used instead of copper wire because it has a much lower resistance.

Because of skin effect, the resistance of the tubing or wire depends on the surface area of the conductor and tubing has a much greater surface area than wire, for the same length.

Copper is used instead of aluminum where a reliable electrical contact is needed. It can be easily soldered and connected to a feedline where copper conductors are also used.

Aluminum can be soldered with great difficulty and it corrodes rapidly, especially near the sea.
It is lighter and cheaper than copper, though, and is used for TV antennas where periodic replacement due to corrosion is acceptable.
 
  • #7
vk6kro said:
Copper tubing is used instead of copper wire because it has a much lower resistance.

Because of skin effect, the resistance of the tubing or wire depends on the surface area of the conductor and tubing has a much greater surface area than wire, for the same length.

Copper is used instead of aluminum where a reliable electrical contact is needed. It can be easily soldered and connected to a feedline where copper conductors are also used.

Aluminum can be soldered with great difficulty and it corrodes rapidly, especially near the sea.
It is lighter and cheaper than copper, though, and is used for TV antennas where periodic replacement due to corrosion is acceptable.

Agree, particular aluminum is next to impossible to solder. I was told that you have to scrape the surface under oil and solder under oil after scrapping the surface to prevent oxidation of the surface. Tube for the same weight has a lot more surface area than solid wire.
 

1. Why is copper tubing used for high q antennas?

Copper tubing is used to make high q antennas because it has a high conductivity and low resistance, making it an ideal material for transmitting and receiving radio signals. Additionally, copper tubing is durable and can withstand harsh weather conditions, making it suitable for outdoor use.

2. Is copper tubing the only material that can be used for high q antennas?

No, copper tubing is not the only material that can be used for high q antennas. Other materials such as silver, gold, and aluminum can also be used. However, copper is the most commonly used material due to its availability, cost-effectiveness, and properties that make it suitable for antenna construction.

3. How does copper tubing help improve the performance of high q antennas?

Copper tubing has a high surface area to volume ratio, which allows for better heat dissipation and decreases the chances of signal loss due to heating. This helps improve the overall performance and efficiency of high q antennas.

4. Are there any disadvantages to using copper tubing for high q antennas?

One disadvantage of using copper tubing for high q antennas is its susceptibility to corrosion. If not properly protected, exposure to moisture and other environmental factors can cause the copper tubing to corrode, reducing its effectiveness as an antenna material.

5. Can copper tubing be used for both transmitting and receiving antennas?

Yes, copper tubing can be used for both transmitting and receiving antennas. Its high conductivity and low resistance make it suitable for both purposes, allowing for efficient transmission and reception of radio signals.

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