Practical Foil Metal Antennas - John Portune - W6NBC
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- čas přidán 16. 11. 2021
- Hams are used to building antennas out of copper tubing, aluminum tubing and wire.
However, there are other very versatile materials available;
which allow for the construction of some unique antennas.
John, W6NBC, will discuss this subject with a presentation titled “Practical Foil Metal Antennas”.
His presentation contains, among other things, a good technical tutorial covering:
• Tape width and thickness to handle power.
• Skin effect issues.
• Antenna efficiency.
• Examples of how to design various small sized tape HF & VHF antennas.
John has written many articles for QST.
He also has a very interesting web site at www.w6nbc.com - Věda a technologie
One very interesting thing about using foil tape
is that it has a much lower inductance per unit length than a round narrower wire.
The wider the tape the lower the indictance per unit length.
This can also be very useful
depending on your antenna design.
You can also use foil tape with a foam double sided tape as the dielectric (in between)
as a balanced feeder with a low Charecteristic Impedence.
This Paralel line has increased capacitiance and decreased inductance.
I have created 50 OHm balanced feedlines with this concept.
Great Video Mate
& 73 from DownUnder 🇦🇺
Wow! Looking through the questions leads me to think people either never actually watched this or never took in what was being said. It's very informative for the newbie.
I've watched some really great videos on your channel regarding small space antennas and this one really inspires some experimentation. very interesting lectures 👍
I asked the President of my radio club to review your website. He did and he liked it.
This Type of Antennas can be Use in a Home Owner Association on the Vinal Siding of a House,
Hi. Great antenna. Do you have a formula to calculate the copper tape length for other bands please.
Looking to build one for 4M (70mhz)
73
Steve M0UEH
Quick question, when you say off center fed, does that mean part below the feed is doubled over and cancels itself out? Does this only radiate from the top? Also curious what difference the pipe diameter makes.
Where do you connect the coax cable at?🤷♂️🎙👍
Thank you for an informative video. Is the amount of RF loss, in the adhesive on the tape, and in the plastic pipe, significant?
Very good video Sir. I learned a lot. How did you find this information Sir ???
What kind of unun or balun is used at the feedpoint? Not enough details to build this.
I've heard W6NBC reject the idea of a flat conductor magnetic loop due to skin effect on the edges of the conductor, but here, he is promoting a fist conductor on the same bands for vertical dipoles.
What am I missing?
Can anyone answer a question for me. I am in S Fla so the first question on my mind about the use of this tape and weather exposure. How does the tape hold up to water and sunshine?
The tape holds up just fine, at least in my trial. 🙂 I built a Yagi antenna for the six-meter band, using aluminum foil tape applied to PVC conduit to form the parasitic elements. The tape is 3M type 3340, 2.5 inches wide. The PVC conduit is the grey "1/2 inch" size, which is nearly 7/8 inch in outside diameter. The tape is not wide enough to wrap all the way around the conduit, leaving a gap of exposed PVC at the bottom. I consider the gap to be of no consequence. I laid the tape down in one continuous strip on the upper side of each element from end to end and wrapped the width of the tape around the element so the gap would be on the underside. Using a wood dowel as a burnishing tool, I rubbed the tape firmly all over to assure a good bond everywhere between the tape and PVC.
The antenna has been up outside above my house continuously for five years, with no delamination or deterioration of performance. It is exposed to direct sunlight and has experienced summer air temperatures frequently in the upper 90's (as high as 98 degrees F). It has also experienced humidities to 100%, as well as rain, snow, and ice storms, and windstorms that have felled trees and felled large branches in this area. The antenna elements flex in the wind but the tape remains tightly affixed and uncracked. The antenna has the following advantages: quite low cost compared to aluminum tubing and no aluminum-to-aluminum joints that can lose electrical continuity over time.
I can't say the PVC would survive a Florida hurricane, but I would expect the tape to remain attached except where the PVC folded or broke!
How i may predict the magnitude of the radiation resistance of any antenna
Assuming a HF skin depth on the order of .001 inches, does the RF use both sides of a tape? Does the RF use both inner and outter surfaces of Tube?
Can multiple tape layers be stacked flat? Is there a layer seperation requirement to minimize skin effects?
New antenna build material: There is this new Fiberglass ReBar.. I believe 5/8 down to 1/4, although locally haven't seen bigger that 1/2. Very Stiff, but flexes some. I believe I saw 20' lengths although I don't believe you could cantilever that far. For a higher Radiation resistance antenna like a yagi.. Wrapping even a 1/2" with copper tape should be ample. Worthy of consideration!
@@markhall3434 Interesting idea. 1/2" x 10' fiberglass rebar only $5.75 (Lowe's). If I fed the cantilever calculator right it would droop about 17" over the 10', and you are correct that 20' would be too far.
I thougt this video was to discuss foil antennas for receiving.
It does, the antenna receives also.
Do us a favor and please rerecord this video, all the messing around is distracting.
You didn't need 20 min to tell how lol
I find it comical you watched the entire video without searching for the answers you want by skipping forward in the video and then making fun of the video production. 😂
ham radio is a dying hobby, not directed at you, but ham's need to stop yelling get off my lawn when asked whats up.