|Oct 25, 2011, 03:26 PM|
It's most likely someone has this kind of building but if not here is a short version of my CL/SPW productions.
Photoshoot "The Making Of" 5.8GHz Vtx Cloverleaf.
Idea came from someone else but I did change a few little things and combined it with an other way to build these antennas.
At this manner they are really strong.
The pictures magnify it a bit but it's really small for 5.8
Bending 0.8mm Mig/mag weldingwire
Bending the arc with a small pliers.
Bending it 45 degrees (Left handed this way)
Coax stripped and tinned.
Leafs pre-tinned and placed in the mold
And a piece of wood with 45 degrees angle.
Soldering the outer shield.
Hooking up the innercore. (bend it a bit so it will hook around the core.
Soldering inner core. If you need some extra tin to get it fully flown you can tap it hard to the table so the most exiss will fall af. After that heat it up again and put a little new tin to it to get a smooth joint..
Without mold. Afterwards grind down some exiss solderingtin.
Small drop op 5min epoxy
Used a permanent marker to get it black and spayed a little blank paint over it.
Dimensions: Vertical leg 11.5mm (2mm feed)
Horizontal leg 12.5mm
Arc lenght 25.2mm.
Arc 110 degrees.
Cut a 8cm piece of wire
Bend a short leg on the end and cut it down as short as possible.
Put it in the caliper to meassure the vertical leg.
Hook it on the outside. And bend it the right way. So on the right side of the pliers or it will be a few mm longer than you want.
adjust the caliper at 25.2 (26mm) and do the same
Also do this for the horizontal leg at 12.5 (13mm)
Solderingjoint it about 5mm.
I'm playing a bit with the lenghts so don't hang on it. Bit more or less is possible.
|Oct 25, 2011, 03:55 PM|
Very cool jig!!! Thanks for sharing this!
I have a question regarding the use of a marker and paint. Is the marker enough to protect from rust, and how badly will it affect the waves?
I also need to drop some epoxy at the base of mine to make it more sturdy, as long as I don't get any on the actual lobes I should be fine right?
|Oct 25, 2011, 07:01 PM|
just another idea:
Do you know exactly if there is no DC voltage on the VRX antenna input?
Try to check with a digital voltmeter between center and sleeve.
Some RX have a DC voltage present in the antenna signal path that supplies the first stage of the amplifier. If a Cloverleaf or similar antenna is connected, this will short this voltage, disabling the first stage and perhaps frying the VRX.
Does it still work like before when using stock whip antennas? Otherwise the offset coupling resistor might alreday be roasted...
See attached schematic: most times, the C93 is simply omitted and bridged in the VRX, to reduce cost and to increase sensitivity with open-loop antennas. If a voltage is present, you may need a foreward coupler (the part with the two propagation lines and the capacitor), or a sheath current filter or at least a capacitor to break the DC-path.
About painting the antenna wire: A dielectric coating will shift the Poynting Vector, resulting in slower wave propagation (shifting resonant frequency) and transmission loss. Normal wires do not need to be painted, as they are not exposed to really strong corrosion and a thin oxide coat will do lesser harm.
|Oct 25, 2011, 08:24 PM|
Ai thanks for the advice, good to know a little oxidation won't do much harm.
I am pretty sure my Fatshark built in ariwaves module is the newer ones because it still works on the stock antenna.
I also did some real field tests today.
First test was about 600m with good LOS. I had crystal clear video This was with just the VRx and CL, not mounted on the tricopter. I want to mount it using a CF rod so I tried mounting the VRx on the CF rod and no noticeable difference at 600m range.
Then the only other LOS distance I could get was about 2,1Km. This time I barely had a signal, lots of static but here and there when I moved the VTx around as if it were flying really really low to the ground I sometimes had a clear picture for a couple seconds. All this was done at sea level, I guess with the VTx up in the sky I would get a better signal at this distance.
I also tried switching channels at 2,1Km and since I made my antenna at 5740MHz, lowest possible choice, by going up in channels it only made things worse. So if anything my antennas are not tuned to a higher frequency, maybe even the right one if I am lucky.
Next set will be made for the middle of my channels, 5.8GHz for sure!
All in all I am very impressed by the antennas and will try some 1km range flying and see how it goes. Oh yeah only problem is how low my SPW is on the fatsharks, I kinda need to be facing the direction of the model if it is not high up in the sky. My head is a massive fresnel zone it seems like
|Oct 25, 2011, 08:50 PM|
I'm about to bit the bullet and build a CL antenna. I was thinking CL on both VTx and VRx, but it looks like the skew/plannar is better on the VRx side? I'll be picking up some RG-58 cable and SMA connectors this weekend. I'll have to pick up some mig wire too I guess.
Question on the mig wire. I read it's hard to straighten out after being wrapped on the roll. Any hints on the best/easiest way to straighten the wire? Now to get off my arse and give this a try.
|Oct 25, 2011, 09:32 PM|
Oh, don't sweat the build, Van! building cloverleafs can be fun! Or impossibly frustrating, but the rewards are great. You'll come out with some great performing antennas for a pretty minimal cost.
I fly with 2 cloverleafs. I didn't feel like trying to learn how to build both at the same time, so I just made two cloverleafs. They work great, but I have nothing else to compare to, other than the P.O.S. stock duckies. Generally, the SPW is geared towards the VRx but I have no problems with two CLs
|Oct 25, 2011, 09:46 PM|
I would advise with getting the right coax cable right away, RG316. I also would not be bothered with bare SMA connectors and would just buy short runs of RG316 cable with the connectors you want on either side.
|Oct 25, 2011, 10:39 PM|
|Oct 25, 2011, 10:45 PM|
I think diversity is good be cause of the combo of an helical and a skew planar.
I also want to keep the onboard setup as light and cheap and going for a full fledge OSD with GPS would not fit the bill. I'd rather invest on the ground station than the onboard stuff.
Anyways there is this topic also by IBCrazy about no-osd tracking using another set of helicals to know which way to point. http://www.rcgroups.com/forums/showthread.php?t=1337608
I'd much rather spend time and money getting this work than something I can loose on my multirotor. I guess flying a plane FPV is way different as it can do one really really cool thing, glide...
|Oct 26, 2011, 02:35 AM|
Don't know how much the inkt/paint will have influence.
But the building tollerances are so big I never know where it will be in frequency.
Don't come further than 1250m with CL/SPW on a good day with 600mW
Using a Fatshark aviator Edition with build in receiver.
And it's really different each day. One day it's perfect. The other that totally crap and I will try an other CL/SPW.
i think the noise levels in my country are quite high and the Build in receiver isn't sensitive enough.
Even it so worse. My buddy has a good image when flying my plane and when I fly it still has drop outs :S
Methanol and gas engines have influence and when more TX systems are on it also has some image losses.
|Oct 26, 2011, 06:06 AM|
Quick video of my latest fly ( with crash ) using Cloverleaf/Skew combo on 1.2ghz with my quadricopter.
As you can see almost not a glitch during the flight. Perfect video without interferences. When using inverted vee I have lot of glitches and dropout, the difference is insane.
Next test will be long rage with 8 turn helical+skew&cloverleaf using diversity.
|Oct 26, 2011, 07:23 AM|
|Oct 26, 2011, 07:39 AM|
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