Vertical Sleeved Dipole How-To

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HomerBB
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Vertical Sleeved Dipole How-To

Post by HomerBB » Friday 20th Jan 2012, 8:48

There has been some repeated interest in homebrewing a suitable dipole for vertical use on several forums and numerous threads. I decided to put this info up so a forum seach could take them directly to this method of getting on the air with an easy to make, pole mountable, rigid version of the vertical dipole.
I hope it helps.

If you want a vertical dipole then:

1. get two 1' pieces of PVC with sufficient diameter to insert an aluminum tube into.

2. cut the end off of a coax feedline and separate the braid from the center for about two inches.

3. put this prepared end of the coax all the way through one of the 1' PVC nipples

4. cut both of the tubes of aluminum to 8' 7" length.

5. push the prepared end of the coax all the way through one of the aluminum tubes.

6. this results in the PVC nipple and one of the tubes sharing the coax through them, so now insert the aluminum tube into the PVC nipple for at least six inches and secure them to each other with a short self-drilling screw.

7. take the second PVC nipple and drill into the side of it exactly in the middle a 1/4" hole, or one large enough to feed the coax through.

8. push the coax into one end of the PVC nipple and pull it out of the nipple through the hole you drilled into the side.
9. Push the nipple onto the Aluminum tube 5.5" deep.

10. You should now see your prepared end of the coax sticking out the hole in the side of the PVC nipple. Press the other aluminum tube into the PVC nipple for a distance of 5.5". Secure both tubes with short self-drilling screws.

11. Now take the prepared end of the coax that is sticking out through the center PVC nipple and fasten them into the ends of the two aluminum tubes with short self-drilling screws through the center PVC separator/insulator.

12. Take either silicone, tape, or heat shrink and place it on/over the coax to dipole connection for weather-proofing. Optionally you may cap the end of the dipole which has no PVC insulator on it. This is the top.

13. Where the coax comes out of the bottom tube/PVC insulator make a coax choke of 4" - 5" diameter x 5/6 wraps.

The bottom PVC insulator provide a means of mounting the dipole to a mast. If more sturdy mounting than the PVC provides is needed you can wrap the PVC with fiberglass, or use an old fiberglass shovel handle instead. I've done both. If the dipole needs tuning as it may be too long by a little due to its diameter trim from both ends of the aluminum tubes as you would any wire dipole.


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HomerBB
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Re: Vertical Sleeved Dipole How-To

Post by HomerBB » Sunday 22nd Jan 2012, 3:44

Due to questions on various forums I am posting this re the dipole.

The one in the above photos over the Yagi was mine, the other I made for a fellow across town who lacked funds for a decent antenna and was using a mobile mag-mount on a window air conditioner.

Both of them performed as well as a dipole usually does, except better for local because this design is vertical as opposed to horizontal.
As we know, dipoles have no gain making them the antenna against which gain is compared for other antennas. So the beauty of this antenna is that once the materials are laying on the floor/bench in front of you it can be on the air talking within 1/2 hour. Being a tubing dipole it has the rigidity to be mounted from the bottom as other verticals are, and have greater bandwidth due to the greater diameter of the tubes over wire dipoles on the same band.

Other than comparing gain to antennas such as .625/.64, or beam antennas, I'd rate this antenna as a homebrew a 10 on a scale of 1 to 10.

materials availability ------- 10 (any hardware store has these materials)
ease of construction ------- 10 (tools - hacksaw, drill, wire strippers, tape)
ability to mount ------------ 10 (u-clamps to mast pole on the bottom insulator)
meets standards of design -- 10 ( performance exceeds wire dipole bandwidth, and permits local vertical communication)
cost ----------------------- 10 (< $15 US dollars)

It can be seen that the slimness of this vertical design does not offend the skyline when picky spouses and neighbors are to be considered.

Additionally the antenna is a great portable design, too. Simply removing the top tube from the center insulator for transporting reduces it's length by half. It is very lightweight, but strong, and will endure years of use.

It a winner on virtually every level.

HomerBB
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Re: Vertical Sleeved Dipole How-To

Post by HomerBB » Thursday 9th Feb 2012, 3:39

I was asked by some to break the steps down and add photos for them. This is it.
If you want a vertical dipole then:

1. get two 1' pieces of PVC with sufficient diameter to insert an aluminum tube into. Because my materials for this dipole
Require I have a taper on each end I am making the lower insulator more than 1' long. The center one is actually 13" but I used it anyway.
Image Image

2. cut the end off of a coax feedline and separate the braid from the center for about two inches.
Image

3. put this prepared end of the coax all the way through one of the 1' PVC nipples
Image

4. cut both of the tubes of aluminum to 8' 7" length.
Image

5. push the prepared end of the coax all the way through one of the aluminum tubes.
Image Image

6. this results in the PVC nipple and one of the tubes sharing the coax through them, so now insert the aluminum tube into the PVC nipple for at least six inches and secure them to each other with a short self-drilling screw.
Image

7. take the second PVC nipple and drill into the side of it exactly in the middle a 1/4" hole, or one large enough to feed the coax through.
Image Image

8. push the coax into one end of the PVC nipple and pull it out of the nipple through the hole you drilled into the side.
Image

9. Push the nipple onto the Aluminum tube 5.5" deep. Because I cut the center PVC nipple 23", I put the Aluminum tubes in 6" leaving a 1" space in the center.
Image

10. You should now see your prepared end of the coax sticking out the hole in the side of the PVC nipple. Press the other aluminum tube into the PVC nipple for a distance of 5.5". Secure both tubes with short self-drilling screws.
Image

11. Now take the prepared end of the coax that is sticking out through the center PVC nipple and fasten them into the ends of the two aluminum tubes with short self-drilling screws through the center PVC separator/insulator.

12. Take either silicone, tape, or heat shrink and place it on/over the coax to dipole connection for weather-proofing. Optionally you may cap the end of the dipole which has no PVC insulator on it. This is the top.
Image


13. Where the coax comes out of the bottom tube/PVC insulator make a coax choke of 4" - 5" diameter x 5/6 wraps.( i haven't mounted this in the air yet, so step 13 will have to wait.

The bottom PVC insulator provide a means of mounting the dipole to a mast. If more sturdy mounting than the PVC provides is needed you can wrap the PVC with fiberglass, or use an old fiberglass shovel handle instead. I've done both. If the dipole needs tuning as it may be too long by a little due to its diameter trim from both ends of the aluminum tubes as you would any wire dipole.

Image Image


Adding an expansion of the info in step 11.

Notice in the photos below how the coax is pulled through the hole in the side-center of the center dipole insulator.
The dipole tubes (black in this demo photo) are pushed into the center insulator only as far as the marks on the nipple. There are four screws holding the dipole together. Two of these are strictly to hold the 3 tubes together as a unit, but the two dipole elements remain separated. The second set of screws are in each of the dipole tubes with the center wire of the coax going to the upper dipole tube, and the braid going to the lower dipole tube.*


*Note: All materials used in this post are for demo purposes only. No animals were harmed in the process, but would have been had they been in the shack and behaving viciously.
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