best antenna

[abcd567]

I want to put it on top of the roof. I got an Amplifier, DC 15v and I made a DC power inserter same like the one you abcd567 made and you use it, but I am confused I don't know what to do what works or what's the best to use Amplifier.
Here take and look at the picture see what I got and what I know so far, but I can't do anything I want to be sure.
[ATTACH=CONFIG]4605[/ATTACH]

What do you guys think? Any idea ?

Thanks

I'd not do (1) the down lead will pick up noise in competition to the signal before both are amplified - in fact I'd only use (1) with no amplifier.

I'd probably not do (3) since it has an extra thing that will reduce signal (don't know if every connector = 2db loss rule applies).

(2) wins - maybe slip a sleeve over the copper and smother the bottom and end of sleeve in silicon chalk (bathtub stuff) - that will come off again with determination - there' s 1001 ways to do this.

If the Cantenna is not in an enclosure or not waterproofed, another option is to install the Amplifier inside the building, very close to the point where cable enters the building.

Please see option 1A in revised drawing below.

[abcd567]

I have received an email on my email address "abcd567@hotmail.com", which has valuable information about CoCos. I am copying it below:

Captain ABCD567,

I tried adding a comment to the fr24 forum "best antenna" thread, but it seems my message was lost in moderation. I thought you might find some of this interesting:

LENGTH AND PHASING.—Although the 1/2 wavelength is the basis for the collinear element, you will find that greater lengths are often used. Effective arrays of this type have been constructed in which the elements are 0.7 and even 0.8 wavelength long. This type of array provides efficient operation at more than one frequency or over a wider frequency range. Whatever length is decided upon, all of the elements in a particular array should closely adhere to that length. If elements of different lengths are combined, current phasing and distribution are changed, throwing the system out of balance and seriously affecting the radiation pattern.

SPACING.—The lower relative efficiency of collinear arrays of many elements, compared with other multi-element arrays, relates directly to spacing and mutual impedance effects. Mutual impedance is an important factor to be considered when any two elements are parallel and are spaced so that considerable coupling is between them. There is very little mutual impedance between collinear sections.
Where impedance does exist, it is caused by the coupling between the ends of adjacent elements. Placing the ends of elements close together is frequently necessary because of construction problems, especially where long lengths of wire are involved.

The effects of spacing and the advantages of proper spacing can be demonstrated by some practical examples. A collinear array consisting of two half-wave elements with 1/4-wavelength spacing between centers has a gain of 1.8 dB. If the ends of these same dipoles are separated so that the distance from center to center is 3/4 wavelengths and they are driven from the same source, the gain increases to approximately 2.9 dB.

A three-dipole array with negligible spacing between elements gives a gain of 3.3 dB. In other words, when two elements are used with wider spacing, the gain obtained is approximately equal to the gain obtainable from three elements with close spacing. The spacing of this array permits simpler construction, since only two dipoles are used. It also allows the antenna to occupy less space. Construction problems usually dictate small-array spacing.

The above from:
http://www.navymars.org/national/tra.../14182_ch4.pdf
More on element spacing at:
http://www.w8ji.com/stacking_broadside_collinear.htm

It seems most people agree that a "free-space" tuned CoCo will be detuned by placing it inside a plastic tube. However, if this detuning makes the antenna "appear" too long, the detuning might not be disastrous, because longer-than-λ/2 elements are not necessarily that bad? And with a "too long" antenna, the apparent element spacing would also be longer, which might actually be beneficial. All in all, to PVC or not to PVC might be a moot point?

Also, simulating insulated wires is supposed to be possible in 4NEC2, see this post:
http://kk7s.net/2012/07/12/modeling-...ks-in-4nec2-4/

It's a bit disheartening to see how much trouble people have getting these coco designs to work, but I'm going to give it a shot anyway. Or actually three shots; I would like to try 1) classic cable coco, 2) rod/pipe air dielectric vf 1.0 coco, 3) 0.75λ; element spacing coco. It might be a month until I have time to actually do this.


Cheers from Norway,

XXXXX

.
EDIT: Email sender's name removed as per sender's request

[abcd567]

.
One of the 1001 ways of water proofing the Cantenna

[abcd567]

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How about using this sealant for Cantenna?


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[abcd567]

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I chose the name "Cantenna" because:
Cantenna = Can Antenna
Cantenna = Canadian Antenna

[abcd567]

.........I'd probably not do (3) since it has an extra thing that will reduce signal (don't know if every connector = 2db loss rule applies)...........

"Cheers from Norway" sent this link:
http://forums.qrz.com/showthread.php...r-adapter-loss

[trigger]

Hi abcd,
In post #1416 above I think I've found a mistake. Alongside the 2 phasing stubs you have a measurement of 28mm. I think it should be 18mm. As it is raining here today I thought I'd have a go at building a couple more antennas and went back to the copper tube drawing you made.

[abcd567]

Hi abcd,
In post #1416 above I think I've found a mistake. Alongside the 2 phasing stubs you have a measurement of 28mm. I think it should be 18mm. As it is raining here today I thought I'd have a go at building a couple more antennas and went back to the copper tube drawing you made.

Thanks for correction. Yes it is a mistake. It should be 18 mm (16/2 mm + 5 mm + 10/2 mm). I will correct the drawing shortly.

[Rooster]

The "cantenna" is a DC open circuit, so adding an amplifier needs NO blocking unit at the feedpoint !!!!

As for waterproofing, Id slice a pop bottle in half and invert it over the lot... leaving the bottom open (as any attempts to seal it would result in condensation corroding things)

[abcd567]

The "cantenna" is a DC open circuit, so adding an amplifier needs NO blocking unit at the feedpoint !!!!

That is absolutely correct, but since member 747-8F who originally made his setup drawing already has the blocking capacitor and want to use it, I have left this as it is. However I have mentioned in Setup-3 of his drawing revised by me, that DC Blocking is optional as Cantenna does not have a short.

As for waterproofing, Id slice a pop bottle in half and invert it over the lot... leaving the bottom open (as any attempts to seal it would result in condensation corroding things)

This is a good proposal. I have earlier mentioned that my proposal of using a plastic Jar is just a guide line and it is up to ingenuity of forum members to find variants. Peter (peterhr) has already said: "...there are 1001 ways to do this...."

[abcd567]

Hi abcd,
In post #1416 above I think I've found a mistake. Alongside the 2 phasing stubs you have a measurement of 28mm. I think it should be 18mm. As it is raining here today I thought I'd have a go at building a couple more antennas and went back to the copper tube drawing you made.

Thanks for correction. Yes it is a mistake. It should be 18 mm (16/2 mm + 5 mm + 10/2 mm). I will correct the drawing shortly.

I have just now replaced the old drawing by the corrected drawing.

[abcd567]

The "cantenna" is a DC open circuit, so adding an amplifier needs NO blocking unit at the feedpoint !!!!

As for waterproofing, Id slice a pop bottle in half and invert it over the lot... leaving the bottom open (as any attempts to seal it would result in condensation corroding things)

Your concept put into practice..... The Genie is in the bottle now...Enjoy: )

Step 1 of 4



Step 2 of 4



Step 3 of 4



Step 4 of 4 .. THE GENIE IN THE BOTTLE
(apply strong adhesive at the joint of two parts of the bottle)






.

[Forum Error]

This latest design is a beauty. A compact, rugged, Canada Dry I.V. antenna. Attach a fishing line at the top, throw the line over a branch and hoist the antenna up in a tree when you're out and about.

Cheers

[peterhr]

Neat!

Now if a shot length of stiff plastic pipe was tightly (gled) unto the bottle neck - it would provide something that could be used to fit the assembly to a pole.

I'm not really thinking of a tower or a mast here - someone who has invested th oney for one of those won't seriously be making a cantenna, this will be for the guy to fix to the top of the TV antenna pole.

[abcd567]

Another of 1001 ways....
Just a concept...very easy to make, provides rain water protection, but bottle will blow away with wind unless glued to the Coke can.

Picture 1 of 2: Without water protection



Picture 2 of 2: With inverted bottle-without-neck slipped over Cantenna.