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Old Feb 10, 2012, 11:12 AM
CEL abuser
USA, CO, Denver
Joined Dec 2010
392 Posts
Mini-HowTo
Build a cheap shroud for your CP omni antenna

I don't know how many of you are extremely organized and careful with your gear, but I am not.

Having said that, I've got to say that no matter how beefy they are made, the bigger CP antennas are no match for the back of my SUV. I happen to have a 1.3 GHz turbine from Hugo that I've had to repair three times now due to transportation and other mishaps and I got a little sick of it. Enter: cardboard.

So I started out measuring the diameter of the antenna and it came out to about 3", so I created a trusty compass composed of two pens, one that is the center of the circle, a string attaching them together at 3" and the other that was to mark my circumference.

I did this twice, cut the circles out, punched the center of one for the coax to go through and began to tape the antenna to the top of the other.

Once the antenna was taped down (I didn't want to make it permanent in case it sucked) I cut out some 1" wide strips of cardboard and folded them into "V" shapes and glued them down to the top in between the ribs of the antenna. This is going to give your structure some strength. After getting one between each rib, I put the bottom circle of cardboard on and glues the bottoms of the ribs to it.

Then I finished with a turgid roll of cardboard that I found in my garage from something that once was my wife's and cut it to length so that I could reach the SMA connector to screw it on. Ta-da you're done!

I went so far as to add an OMM low pass filter on my RX side, not sure how much good it will do to reduce noise but I thought I'd give it a try. I then cobbled together a toothpick structure around it for stability and ta-da now I'm done.

Please check the pictures out, I think they will be a better aid than my narrative.
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Old Feb 10, 2012, 01:33 PM
Project Tormentor is flying!
United States, WA, White Salmon
Joined Nov 2005
2,066 Posts
Cool! I have been dreaming of a system to make a light weight shroud for a cloverleaf. My only worry is the possible drag it could create.
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Old Feb 10, 2012, 02:04 PM
CEL abuser
USA, CO, Denver
Joined Dec 2010
392 Posts
This is strictly for the ground station. The wind resistance of this on an airplane would be ridiculous. Maybe what you could do for your plane is make something that could cover it up for transport (anchored with some light magnets or something) and remove it for flight. As is the drag of these antennas isn't too bad at the speeds most of us are going.

Yeah the goal of this was to protect the antenna while it is not in use, so it doesn't get snagged by clothing, wires and such while transporting and setting up/tearing down the ground station.
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Old Feb 10, 2012, 02:25 PM
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rob38's Avatar
Noord Holland
Joined Oct 2007
979 Posts
hi

look great


idea




rob
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Old Feb 10, 2012, 03:33 PM
Registered User
Joined Feb 2011
472 Posts
low pass filter on my RX side

?? thats not needed. you need the filter at the TX side!
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Old Feb 10, 2012, 03:50 PM
CEL abuser
USA, CO, Denver
Joined Dec 2010
392 Posts
Quote:
I went so far as to add an OMM low pass filter on my RX side, not sure how much good it will do to reduce noise but I thought I'd give it a try.
I know the iterated purpose is for the transmitter side, however when trying to reduce interference, why would you not want to filter your RX side? If 2.4GHz is a harmonic and is everywhere, why not filter it out? I mean *gasp* you could put an amp on your RX side as well if you felt you were getting excessive losses from your antenna to your RX. I'm just giving it a shot because I had one extra laying around.
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Old Feb 10, 2012, 03:52 PM
CEL abuser
USA, CO, Denver
Joined Dec 2010
392 Posts
Quote:
Originally Posted by rob38 View Post
hi

look great


idea




rob
Rob, this would have been the smart, fast and good looking way to do what I did. Heck I might just try that next. We'll see how the cardboard holds up.
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Old Feb 10, 2012, 03:56 PM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
29,080 Posts
Quote:
Originally Posted by V_Okto View Post
low pass filter on my RX side

?? thats not needed. you need the filter at the TX side!
Ya, it seems many people are confused about LPF and HPF these days.
You put a LPF on 1.2-1.3Ghz video Tx to keep 2nd order harmonics out of 2.4Ghz Rx
You put an OMM dual notch filter on 1.2-1.3Ghz video Tx to keep primary harmonic noise out of the GPS Rx, and secondary noise out of the 2.4Ghz band.
You put a LPF (typical cutoff around 600Mhz) on 433Mhz UHF control system Tx, to keep 3rd order harmonics out of 1.2-1.3Ghz video Rx.
You can put a HPF filter on 1.2-1.3Ghz Rx to block harmonics coming from 433Mhz control system,
but it's usually easier to use the LPF on the 433Mhz system (some have it integrated already).

ian
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Old Feb 11, 2012, 12:11 AM
BEOWULF
North vancouver, B.C. Canada
Joined Apr 2008
18,828 Posts
it would be cool to see your video and how well you do with video

there are way easier ways to make it simple



Quote:
Originally Posted by pr0ject42 View Post
I don't know how many of you are extremely organized and careful with your gear, but I am not.

Having said that, I've got to say that no matter how beefy they are made, the bigger CP antennas are no match for the back of my SUV. I happen to have a 1.3 GHz turbine from Hugo that I've had to repair three times now due to transportation and other mishaps and I got a little sick of it. Enter: cardboard.

So I started out measuring the diameter of the antenna and it came out to about 3", so I created a trusty compass composed of two pens, one that is the center of the circle, a string attaching them together at 3" and the other that was to mark my circumference.

I did this twice, cut the circles out, punched the center of one for the coax to go through and began to tape the antenna to the top of the other.

Once the antenna was taped down (I didn't want to make it permanent in case it sucked) I cut out some 1" wide strips of cardboard and folded them into "V" shapes and glued them down to the top in between the ribs of the antenna. This is going to give your structure some strength. After getting one between each rib, I put the bottom circle of cardboard on and glues the bottoms of the ribs to it.

Then I finished with a turgid roll of cardboard that I found in my garage from something that once was my wife's and cut it to length so that I could reach the SMA connector to screw it on. Ta-da you're done!

I went so far as to add an OMM low pass filter on my RX side, not sure how much good it will do to reduce noise but I thought I'd give it a try. I then cobbled together a toothpick structure around it for stability and ta-da now I'm done.

Please check the pictures out, I think they will be a better aid than my narrative.
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Old Feb 11, 2012, 01:37 AM
Registered User
Romania, Dolj, Craiova
Joined Sep 2007
15,432 Posts
For all of the above I am on 5.8GHz...
No Filters, no special need to protect the five times smaller antennas.
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Old Feb 13, 2012, 08:28 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,571 Posts
For protecting a 2.4GHz antenna, I use a 75mm play pen ball. Fits perfectly and is nice and aerodynamic.

-Alex
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