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Old Feb 03, 2012, 07:19 AM
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Originally Posted by melsailsnorth View Post
So I would guess maybe a CP Helical but we will see what the experienced guys say....
Or a Crosshair: http://fpvlab.com/forums/showthread....utorial!/page2

Tutorial just released on FPVLAB two days ago

-Alex
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Old Feb 03, 2012, 05:03 PM
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Alex- I don't know if you're willing to do this or not, but it would be super helpful if you also sold just plain welding/ memory wire on your website. Not necessarily for a 'kit' but as an option if someone (me) needs to build an antenna and/or needs to repair one. Just makes things easier if I can get everything from one location instead of having to track down individual parts. Plus you get compensated for all the time and effort you put in for designing these things.
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Old Feb 04, 2012, 03:37 PM
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Thanks for the great guide. I'm getting ready to try and build a couple of these. I think I'm going to just butcher the stock whip antennas for the base (never had much luck with them anyways, and don't want to wait 3 weeks for parts to come in the mail).

I've read both this guide, and the RCexplorer guide, and both have slight differences. The RCexplorer guide shows cutting 3 identical lobes. This guide shows building 2 of the lobes out of a single piece of wire, and the 3rd lobe out of a seperate one. Is there any real difference, or advantage/disadvantage to either method?

Thanks.
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Old Feb 04, 2012, 09:18 PM
Dixie Normious
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Posted this over on the SPW thread, figured i post it here!!
Skew Planer Wheel and Cloverleaf Build (1 min 42 sec)


Hopefully they work good.
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Old Feb 05, 2012, 07:07 AM
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Quote:
Originally Posted by Eastcoast78 View Post
Posted this over on the SPW thread, figured i post it here!!
http://www.youtube.com/watch?v=bHwZ9fuGTng

Hopefully they work good.
It seems to me like the angles of attack of the lobes is a bit on the "flat" side. Make them more like 45 degrees by bending them up. Otherwise circularity will suffer.

Markus
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Old Feb 06, 2012, 05:06 PM
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Guessing SWR from the TX supply current?

HI all,
I built a cloverleaf for my 5.8G 200mW TX and (of course!) I tried to do it the best possible. I don't have equippment to measure SWR directly so I at least tried to measure supply current for the TX with different antennas. Stock whip was at 12V taking 145mA , SPW 135mA, a (very bad) helical 100mA and my cloverleaf (in the picture) 110mA. Is there any simple relation between quality of the matching the antena and TX supply current?
Seems this CL with cuprextite support to be a good matched?
It's made from 1mm (0.04'') Cu - isn't is too thick for 5.8GHz?
Originaly I had at the bottom solid cuprextite triangle - TX current with this was 135mA, then I decided to cut off the "bridges" between the arms (and make this nice cuprextite leaves:-) ), after that TX current even lovered to 110mA.
Going to test tomorrow (if I won't get frozen, we have -20 deg. Celsius)
Any oppinions wellcome.
Thanks!
Roman
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Old Feb 07, 2012, 12:57 PM
Dixie Normious
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Originally Posted by markus123456 View Post
It seems to me like the angles of attack of the lobes is a bit on the "flat" side. Make them more like 45 degrees by bending them up. Otherwise circularity will suffer.

Markus
Ok , after looking at it last night agaist a jig made with a 45 drawn on it, you are right , there only around 30 degrees.

So while trying to bend the lobes up on the CL, i broke one of the arms! I resoldered it and all and it works.

But i said to hell with it, it was on the old Striped ducky and i have 3 wires now with a RP-SMA on each end.

So i remade one this time i used that jig with the 45 on it!
I could get the lobes in tighter! Next time!! hehe


Ohh have a question regarding the hot glue usage for the center. Is it soley for protection of the solder?

Would a little blob of GOOP! i.e Contact cement work? Or should i say well it ruin the signal!

I want to test these antennas outside, i did inside and there a lot better then the stock.
I can walk into another room and it well drop out if theres a sudden movement, But its not drastic. I don't get any snowy signal loss, its just a black screen drop out!
I also loose it momentary if i shake it really fast!

Someone said that a Big LCD TV may be a lot more sensitive then a small 7'' monitor. But im not too sure!?

All in all i think once outside, this is going to work great. Im not looking to break records, just fpv on my Quad or Radain or my
Home depot Scratchbuilt KFm4 wing..the Pink Pig
FPV Wing Maiden (6 min 19 sec)



Heres the new one built last night!
Cloverleaf build (2 min 46 sec)
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Old Feb 07, 2012, 02:36 PM
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Originally Posted by Eastcoast78 View Post
Ohh have a question regarding the hot glue usage for the center. Is it soley for protection of the solder?
Alex uses the hot glue to tune his antennas, well, he posted that a bit back in either this thread or the SPW one.

You would not want to "tune" your antenna if you have no means of measuring it anyways right? So, since you are shooting in the dark, leave it as is. The soldering will be way strong enough for 5.8ghz. Remember, all that floats between those wires is air. Not much drag really with those small antennas.

Markus
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Old Feb 07, 2012, 03:49 PM
Dixie Normious
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OK, i never seen that it was used for Tuning,and yes you are correct, i do not plan on tuning them.

I have not the knowledge, nor the equipment! i just love that the quality of video is so great!

Me and friend are taking them outside tonight and testing, when we do some Night QuadCopter flying. ;0)


Thanks for your Help!
Cheers
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Old Feb 07, 2012, 04:48 PM
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Originally Posted by markus123456 View Post
The numbers relate to the speed of electromagnetic waves that propagate through space and thus the lenght of a wavelenght (a full sinus curve).

Its the speed of light divided through the frequency. What number thus depends on how you measure the speed of light (meters versus imperial). For meters a good aproximation that also takes the fact into account that electromagnetic waves travers a wee bit slower throug air than the vacuum is 300 / frequency in megaherz = wavelenght in meters. In imperial units you would have to convert the 300 meters into i.e. feet. I don't have that number ready out of the top of my head but if you ask google or look at the first posts in this thread I'm sure you'l find it instantly.

A lobe of an SPW antenna equals one full wavelenght. Alex found throug experiments that for the cloverleave, such a lobe has to be about 2 - 3% bigger than a full wavelength. I'm I'm not mistaken he has no explanation for this fact (as usually antenans have to be made a little bit shorter to compensate the medium "air"), but that's how it is.

As for the lobe per se, the bow should be about half a wavelenght and the legs one quarter wavelenght each. However, the factor by which the leg lenghts is compared to the bow is subject to discussions. Generally somewhat longer legs is what's proposed, but OMM seems to prefer a higher factor (in favour of an even longer leg) than i.e. Alex. That factor does not seem to be totally critical though.

Now obviousely if the "original" wavelenght we calculated matches the total lenght of a lobe, but that lobe is subdivided into sections, multiplying the divisor takes this into account and here you have the other numbers that are shown.

HTH

Markus
thanks
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Old Feb 09, 2012, 04:07 AM
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Originally Posted by ashdec87 View Post
Alex- I don't know if you're willing to do this or not, but it would be super helpful if you also sold just plain welding/ memory wire on your website. Not necessarily for a 'kit' but as an option if someone (me) needs to build an antenna and/or needs to repair one. Just makes things easier if I can get everything from one location instead of having to track down individual parts. Plus you get compensated for all the time and effort you put in for designing these things.
I have used the centre core wire from 50ohm coax cable to make the cloverleaf s...its good quality and solders easily
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Old Feb 09, 2012, 08:14 PM
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I ordered some 0.5mm brass rods to make 5.8G CL/SPW antennas with, but I just discovered that brass has a much higher resistance than copper. Will using brass affect my range, or cause extra heat or battery drain? If so, how much?
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Old Feb 09, 2012, 09:10 PM
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A couple of questions.

1. Does the length of the solder joint, or other parts, have any effect on the frequency? For example, you have to leave about 1-2mm of the center conductor to have something to solder to, does that make any change to the frequency? If so, should you ever cut your lobes 1-2 mm shorter to compensate?

Same way with how you solder to the shield, I'm guessing you try to overlap the shield as much as possible to not change length, but if you did have an extra couple millimeters of shielding exposed, would that effect the frequency?

2. A couple people above mentioned something about using hot glue for tuning? Is this true? I made my first CL antenna, and put a huge glob of hot glue in the middle to help durability and keeping the angles right. Could this potentially throw my whole antenna out of tune?
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Old Feb 10, 2012, 04:34 AM
Quads, 4 times the fun.
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The lobe length is measured from the point that the shield is split (no longer shielding) to the point that the lobes meet at the emitter. So if you have twisted your shield in to three or four parts to give yourself something I solder the base of the lobe to, make sure you push the base of the lobe up against the emitter insulation, but also ensure it's a clean solder without an unsoldered stub of lobe at the start. If you have some shield wire extending the length then you should make the lobe correspondingly shorter.

I'm not sure about the hot glue except I've heard it does alter the frequency, so I use it sparingly.
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Old Feb 10, 2012, 07:23 AM
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Originally Posted by rogueqd View Post
I ordered some 0.5mm brass rods to make 5.8G CL/SPW antennas with, but I just discovered that brass has a much higher resistance than copper. Will using brass affect my range, or cause extra heat or battery drain? If so, how much?
Brass is ok. It's the thickness that determines resistance. Thicker wire makes the antenna more wide band, but also keeps the antenna from converging to proper SWR at any frequency. For 5.8GHz, I use .023" MIG welding wire. .5mm is the proper thickness, so your antennas will work just fine.

_Alex
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