Wire antenna, Why insulated and multistrand?

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eHam.net Forum : Elmers : Wire antenna, Why insulated and multistrand?

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Wire antenna, Why insulated and multistrand?	Reply
by BZ001GB on July 21, 2002	Mail this to a friend!
Hi , Please explain to me why, If a wire antenna is isolated at the ends and suspended in free space must it be insolated copper wire, surely it has nothing to short with and the very ends is "open" in any case?? Please further explain why multistrand is better than the same gauge solid wire. Thank you and pardon me if the answers is obvious to the informed. 73 Etienne

RE: Wire antenna, Why insulated and multistrand?	Reply
by W8CAR on July 21, 2002	Mail this to a friend!
Etienne, The stranded wire is usually stronger than solid wire unless it is copperclad steel. Antennas swing in the wind and whip around during storms-all my antennas are stranded wire -I have never had a failure. I have had failures with copperclad steel wire -if it gets a kink it signicantly reduces the strength. Solid wire also tends to stretch over time compared to stranded. As far as insulation-I have seldom used insulated wire for antennas unless it will come in contact with trees, etc. Some antennas develop very high voltages -especially near the ends and insulated wire would help to prevent arcing. The insulation on the wire also changes the length needed to reach resonance. Go with a good stranded, uninsulated wire and you'll be fine. 73 and good luck Dan W8CAR

RE: Wire antenna, Why insulated and multistrand?	Reply
by AC5E on July 21, 2002	Mail this to a friend!
Hi Etienne: There is no "law" that antenna wire must be either stranded, copper, or insulated. Stranded is usually easier to work with, has less stretch, and is more durable. Most of my wire antennas are stranded but I have two that are "hard drawn solid copper" up now. Copper is easily available, other potential antenna materials are more difficult to obtain. Copper has very low resistance so the resistance losses in the antenna element are also small. However, I have a friend who lives both near the sea and chemical plant who says copper corrodes away in a few months. He uses Monel metal wire for his antennas; trading off increased loss and a slightly reduced signal for durability and convenience. Insulated wire is easily available, costs very little more than bare wire, it can be a bit easier to work with, and it prevents arcing and other problems that occur with bare wire. There is one minor negative to insulated wire. Since insulation is a dialectric your finished and tuned antenna will be slightly shorter than one made of bare wire. 73 Pete Allen AC5E

RE: Wire antenna, Why insulated and multistrand?	Reply
Anonymous post on July 21, 2002	Mail this to a friend!
Most of my antennas aren't even made with wire and they radiate as well or better that wire antennas. Use the cheapest larger gauge wire you can get. Stranding, insulation, gauge may make some difference at 432mc but at hf to 2meters, it doesn't care.

RE: Wire antenna, Why insulated and multistrand?	Reply
by WB2WIK on July 22, 2002	Mail this to a friend!
I prefer stranded wire for its flexibility: For any given wire gauge (diameter), the more strands used in its construction, the more flexible it is, and that makes it much nicer to work with. I prefer insulated wire for a variety of reasons: -It usually lasts longer; -It's protected from the elements, including acid rain, salts, etc; -If it comes in contact with tree limbs or branches, well-insulated wire "wipes" those surfaces without damaging the wire itself, and therefore lasts longer; -If used for transmitting, the highest voltage points of any center-fed doublet are the very tips, or ends, of the antenna; when substantial transmitter power is used, the peak RF voltages at these points can be several thousand volts, which can arc quite a long distance. Using insulated wire, and forming each end in a "loop" rather than leaving it as a sharp point, help prevents such arc'ing, and this is a good idea for improved safety in operation. WB2WIK/6

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