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Video Equipment => FPV Antennas => Topic started by: BigT on April 01, 2014, 09:37:19 AM

Title: Skew antenna covers
Post by: BigT on April 01, 2014, 09:37:19 AM
I want to mount my tx antenna with the lobes underneath the fuselage of my Skywalker. I have tried this and found an improvement in range etc. However the lobes can get all bent up on landing so I am looking for a suitable cover. Is there such a product available or other way of protecting the lobes? I have heard of dipping in latex rubber?



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Title: Re: Skew antenna covers
Post by: rob.thomson on April 01, 2014, 09:56:05 AM
Probably simplest to make a vacform blister cover?

Not sure why nobody makes and sells them!

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Title: Re: Skew antenna covers
Post by: Loopdreams on April 01, 2014, 10:09:37 AM
Or just make one out of some scrap foam.  Or carve some foam out of the fus and have the antenna just inside instead of sticking out.
Title: Re: Skew antenna covers
Post by: Ratty on April 01, 2014, 10:12:39 AM
Cut up the right sized yogurt pot and just glue it over and paint to match.  ;D
Title: Re: Skew antenna covers
Post by: skyscraper on April 01, 2014, 10:25:46 AM
How about a 3D printed one? I have printed stuff down to a 1mm wall thickness. Dunno whether that will affect range or not but only one way to find out :)

Let me know some dimensions and I would be happy to give it a go for you ! I'm seeing a nice streamlined airfoild shape in my mind!

Alternatively if you are any good with cad. sens me an .stl of your whims!

regards
Andy
Title: Re: Skew antenna covers
Post by: Jake Bullit on April 01, 2014, 10:47:36 AM
or treat yourself to a Kinder egg ,then use the toy container on your aerial.
Title: Re: Skew antenna covers
Post by: Jake Bullit on April 01, 2014, 10:48:42 AM
(http://img.tapatalk.com/d/14/04/01/y3ypunap.jpg)
Title: Re: Skew antenna covers
Post by: CurryKitten on April 01, 2014, 01:31:22 PM
Quote from: Jake Bullit on April 01, 2014, 10:48:42 AM
(http://img.tapatalk.com/d/14/04/01/y3ypunap.jpg)

I'm sure it flies lovely, and it doesn't matter how it looks - but the phrase "Discovery: special 'found it on a skip' edition" runs into my head :)
Title: Re: Skew antenna covers
Post by: Jake Bullit on April 01, 2014, 02:02:26 PM
Cheeky sod ;) ;D Thats one of my tidy builds too :)

Its been in the wars a bit.
Title: Re: Skew antenna covers
Post by: gtv on April 01, 2014, 07:03:12 PM
Quote from: CurryKitten on April 01, 2014, 01:31:22 PM
Quote from: Jake Bullit on April 01, 2014, 10:48:42 AM
(http://img.tapatalk.com/d/14/04/01/y3ypunap.jpg)

I'm sure it flies lovely, and it doesn't matter how it looks - but the phrase "Discovery: special 'found it on a skip' edition" runs into my head :)

Lol I didn't want to be the first to say that.........
Title: Re: Skew antenna covers
Post by: rob.thomson on April 01, 2014, 08:13:57 PM
Ping pong ball?

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Title: Re: Skew antenna covers
Post by: rob.thomson on April 01, 2014, 08:14:50 PM
Just mange sure you don't get it hot.

Pinf pong balls are often made of celluloid.  Don't want it to go Puff :)

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Title: Skew antenna covers
Post by: BigT on April 01, 2014, 10:14:07 PM
I thought table tennis ball. I will have a go with solid works  when I get time. Cannot get tt balls locally


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Title: Skew antenna covers
Post by: BigT on April 01, 2014, 10:14:51 PM

Quote from: Loopdreams on April 01, 2014, 10:09:37 AM
Or just make one out of some scrap foam.  Or carve some foam out of the fus and have the antenna just inside instead of sticking out.
. Not strong enough


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Title: Skew antenna covers
Post by: BigT on April 01, 2014, 10:15:32 PM

Quote from: rob.thomson on April 01, 2014, 09:56:05 AM
Probably simplest to make a vacform blister cover?

Not sure why nobody makes and sells them!

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. Could make a balsa mould?


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Title: Skew antenna covers
Post by: BigT on April 01, 2014, 10:16:28 PM

Quote from: Ratty on April 01, 2014, 10:12:39 AM
Cut up the right sized yogurt pot and just glue it over and paint to match.  ;D
good thought.


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Title: Re: Skew antenna covers
Post by: gtv on April 03, 2014, 08:21:25 AM
I kept this thread in mind and noticed this on the wife's dresser,
(http://img.photobucket.com/albums/v460/gtv/DSC02885_zpsec887847.jpg) (http://smg.photobucket.com/user/gtv/media/DSC02885_zpsec887847.jpg.html)

Thought, humm looks about the right size. And on further inspection, yes indeed its almost spot on for my aerials I have from Flyn

(http://img.photobucket.com/albums/v460/gtv/DSC02886_zpsdb4903ba.jpg) (http://smg.photobucket.com/user/gtv/media/DSC02886_zpsdb4903ba.jpg.html)

(http://img.photobucket.com/albums/v460/gtv/DSC02889_zpsbc28dd9c.jpg) (http://smg.photobucket.com/user/gtv/media/DSC02889_zpsbc28dd9c.jpg.html)

Quite thick plastic so it should give good protection. 
Title: Skew antenna covers
Post by: BigT on April 03, 2014, 09:11:12 AM
Love it.


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Title: Re: Skew antenna covers
Post by: Coyote on April 03, 2014, 01:23:25 PM
Some good ideas, I've used the kinder egg one myself but always instead reverted back to plan B

Plan B : Don't land on your antenna ;)

Works better than any cover, more streamlined, less drag, all good ! :)
Title: Re: Skew antenna covers
Post by: BigT on April 05, 2014, 10:20:58 AM
Quote from: Coyote on April 03, 2014, 01:23:25 PM
Some good ideas, I've used the kinder egg one myself but always instead reverted back to plan B

Plan B : Don't land on your antenna ;)

Works better than any cover, more streamlined, less drag, all good ! :)

Difficult if its under the fuz at the rear of a Skywalker
Title: Re: Skew antenna covers
Post by: rob.thomson on April 05, 2014, 11:02:07 AM
Why not just put the antenna way out on the wing tip?

I have found when I do this, I don't get any masking issues.

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Title: Re: Skew antenna covers
Post by: Coyote on April 05, 2014, 12:09:59 PM
Then relocate it, I had mine on the rear but stuck out to the side to stop blocking while I flew the Walker, worked great, no blocking, no air catching cover needed ;)

Difficult if its under the fuz at the rear of a Skywalker
Title: Skew antenna covers
Post by: BigT on April 05, 2014, 11:56:43 PM
Given that the antenna radiates upwards I thought it would be more efficient pointing down. Also on the wing means another multi plug connector. So I will try sideways.


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Title: Re: Skew antenna covers
Post by: Coyote on April 06, 2014, 12:01:14 AM
The antenna radiates equally above as below its horizontal axis so pointing up or down makes no difference in performance
Title: Re: Skew antenna covers
Post by: pk-surfing on April 06, 2014, 08:23:15 AM
I bought a set of the cheap HobbyKing electric retracts last year with the idea to fit one of them in the belly of the X8.

http://www.hobbyking.com/hobbyking/store/__17539__Twist_and_Turn_Electric_Retract_with_3mm_Landing_Gear_Leg_2pc_29_0g.html (http://www.hobbyking.com/hobbyking/store/__17539__Twist_and_Turn_Electric_Retract_with_3mm_Landing_Gear_Leg_2pc_29_0g.html)

Launch it, drop the retract which would have the antenna coax fastened to the short leg so the SP was then pointing straight down underneath, then remeber to retract it just before landing !

Haven't tried it as the X8 is still on the top shelf.......

PK
Title: Re: Skew antenna covers
Post by: rob.thomson on April 06, 2014, 09:01:17 AM
That would work.  Seen similar things done with a single servo in the past.

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Title: Skew antenna covers
Post by: BigT on April 06, 2014, 09:52:29 AM

Quote from: Coyote on April 06, 2014, 12:01:14 AM
The antenna radiates equally above as below its horizontal axis so pointing up or down makes no difference in performance

So pointing  the antenna horizontally makes no difference to the signal but gets it out of the line of the motor? Good tip.


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Title: Re: Skew antenna covers
Post by: Coyote on April 06, 2014, 10:02:50 AM
As long as the antenna at the end still is sat vertically yes, if the antenna is sat horizontally the nulls are then on the horizontal axis. The way I did it was to have the antennas tail out horizontally, then the end bent so the actual antenna itself still pointed upwards. Worked great.

The motor on the Skywalkers not normally the problem, its the lipo that does the vast majority of the blocking
Title: Skew antenna covers
Post by: BigT on April 06, 2014, 10:09:46 AM
So I could have the coax horizontal to the wing at 90 deg to the fuz then bend the coax 90 deg to have the skew under the fuz. I'll take a snap later and post.


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Title: Re: Skew antenna covers
Post by: rob.thomson on April 06, 2014, 10:43:05 AM
Just install the vtx on then wing tip :)

I was stunned on my phantom to find that when I did that, u had no drop outs.  When in the middle, it happens all the time.

Easiest way - use a balance lead as an interconnect, and send all the av lines up a channel in the wing.

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Title: Skew antenna covers
Post by: BigT on April 06, 2014, 11:26:09 AM
Maybe on the next build. For now I have a set up that gives more video range than radio range so that's ok. I get 1400m from radio before rssi drops and kicks in failsafe but still have video. That's good enough for now. But on the odd occasion the video signal degrades and I think it is to do with the lipo masking the signal. I hung the antenna down under the fuz and it was perfect until I had a  off piste landing and bent the skews out of shape. That's why I wanted a cover.


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