Anyone have a 100% reliable 5.8Ghz video downlink ?

[ZAxis]

Hi Andy

The idea of the diversity box is to select the strongest signal from one of two antennas so there isnt much point in using two cloverleaf antennas at the receiver as they're both going to receive the same signal levels.

Use the circular patch antenna and a 4 element cloverleaf (skew-planar) antenna at the receiver. The patch will give you long range reception in the direction you point it and the cloverleaf will give you good 360 degree coverage closer in. The diversity box will choose whichever signal is the strongest. Mount the cloverleaf antenna a little above the patch antenna so one doesnt create a shadow for the other. The patch usually has a horizontal beam width of around 60 -70 degrees depending on the gain so try to aim it into the centre of the area youre flying into and raise the elevation by tilting it backwards about 15 - 20 degrees to account for the altitude you intend to fly.

Thanks for that.
My thinking for having 2 cloverleaves was to allow the diversity Rx to cope with multipath reception. We like to fly down in the woods as much as open country and trees will disrupt signal pathways potentially compromising reception at one aerial. It would then be up to the diversity Rx to switch antenna to ensure we get the strongest signal. Am I correct here ?

 

[kloner]

this turned into a great read and excellent info

I see they offer the clover leafs with and without the whip part and it looks like the pairs they offer only have straight out instead of 90 degree out. Do the whips bend so you can point it how you want? Why are the ones without whips available? i noticed rcnut has a huge long lead going to his, is that the desireable way to do it? Assuming thats so the ant doesn't get shadowed?

 

[Jake Bullit]

If you fancy making your own some useful info here:

http://rcexplorer.se/page14/CPantennas/CPantennas.html

 

[Tomstoy2]

Kloner, no, you either have to add a sme 90 female to female adapter and a straight male to female adapter, or an extention cable to remote locate the antennal.
Adding the adapters, or the extentions for that matter, will eat up db, but it doesn't appear to be much of an issue, really.

My own short tests have produced excellent results. A quick example being;

My hex on a coffee table, vtx powered up, my 7" monitor outside on the back porch, with the cloverleaf it was more than capable of establishing a signal with no noise.
If I used the standard dipole antenna I got noise like crazy just trying to get a signal with the monitor in the dining room with only a couch in the way.

I haven't done any range testing, and probably won't. With my knee I have resigned myself to flying no farther than I am willing to walk. Right now we have snow on the ground and lots of mud underneith so it's going to be at least a month before I'm willing to take it out even a few 100 meters.

But still, with my test of it's ability to see the signal noise free thru a closed sliding glass door was amazing to me.

 

[kloner]

I've had my wife wear my goggles inside the house, taken the heli out and flown away 200 yards or more with trees, and flying down in a canyon and asked if shes ever had static and she said nothing. it is a chick though, but she usually tells me the truth. I'm gonna stick a camera on the goggles and go fly around and see what it does.

Thanks for the intel

 

[RCNut]

Thanks for that.
My thinking for having 2 cloverleaves was to allow the diversity Rx to cope with multipath reception. We like to fly down in the woods as much as open country and trees will disrupt signal pathways potentially compromising reception at one aerial. It would then be up to the diversity Rx to switch antenna to ensure we get the strongest signal. Am I correct here ?

Ah yes -if you were using the original dipoles then you are correct. However you dont get as many issues with multipath reception using a cloverleaf, especially if you use the 4 element skew-planar version at the receiver which is particularly good at rejecting multipath interference. IBCrazy's bluebeam antennas usually come in pairs with one 3 element and one 4 element version. Whether you buy his or build your own, use the 3 element cloverleaf at the transmitter and the 4 element skew-planar at the receiver to minimise mutlpath issues.

 

[RCNut]

this turned into a great read and excellent info

I see they offer the clover leafs with and without the whip part and it looks like the pairs they offer only have straight out instead of 90 degree out. Do the whips bend so you can point it how you want? Why are the ones without whips available? i noticed rcnut has a huge long lead going to his, is that the desireable way to do it? Assuming thats so the ant doesn't get shadowed?

The short ones can be mounted directly to the transmitter or receiver. Just mount the transmitter to the Quad with the connector facing directly up (or down) so the antenna is in the clear.

The longer ones can be bend at right angles if your transmitter cant be mounted vertically. The main reason for the length I chose was to raise it up high enough to get good visibility to the ground even at high angles of bank. The down side is if I flip the F450 over on landing (which Ive done a few times) the cloverleaf gets damaged and I have to reshape it (and sometimes resolder it again). The length of the cable on mine was just a visual "that should be long enough" approach. I used a 30cm cable that came with preinstalled connectors which I then cut to produce two cables - one at 20cm and the other at 10 cm - each with a connector on one end. I then soldered a cloverleaf onto the other end of the 20cm cable for the transmitter and a skew-planar onto the other end of the 10cm cable for the receiver. The 20cm cable is probably longer than it needs to be but it gets the antenna above everything and into its own airspace.

Now that I have Yuri's leg extensions I'm going to try mounting the antenna underneath on a shorter cable to help protect it from damage.

 

[Vortex]

I'm looking at IBCrazy 5.8G antennas and see there are a few different types and it has me a bit stumped.....

Skew Planar Wheel Whip
Cloverleaf Whip
Bluebeam Whip

Can someone please let me know what the differences are??

Thanks,

Lance

 

[RCNut]

Hi Lance.

The skew-planar wheel is the 4 element receiving antenna Ive mentioned that is best for reception. The cloverleaf is the 3 element version that is used for the transmitter. You'll need one of each. I think readymaderc sell them as a set but if youre building them or buying them somewhere else you'll need one of each.

The bluebeam models come in two variations. One is the short stubby one that is just the antennas mounted directly onto the connector. The other is the 'whip' version which isnt really a whip but is the same set of antennas with a short length of cable feeding to the connector. I prefer the 'whip' version because it gives you a bit of flexibiity in mounting in that you can chose to mount the transmitter horizontally and bend the cable at right angles to get the antenna vertical (the cable is fairly stiff and self supporting). It also raises the antenna above the metal frame of the transmitter which improves the radiation pattern.

[EDITED]
I forgot to mention - if you have foxtech transmitters and receivers you probably have different sex (polarity) RF connectors on them to the normal standard - in which case you'll also need two of the "RP SMA female to SMA female" adapters. It seems the foxtech transmitters and receivers (also sold through Hobby King) use a mixed-sex connector on their antennas and you cant just connect a standard SMA connector or another brand of antenna without an adapter. I had that problem myself and had to buy two adapters. If you need them the correct one is here;

http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_58&products_id=432

Ian

 

[Vortex]

Thanks Ian......I appreciate your assistance.

Regards,

Lance

 

[Lifter]

Thanks

Thxs for your useful info and suggestions RCNut, I am sure this thread will come in handy for future reference..
Cheers
Alan

 

[Jack]

I have the exact same problem. MK Okta XL, 500mW Tx, clover leaf antenna on the Tx and Patch on the Rx, Lilliput 7" Screen. Have you found a solution?

 

[ZAxis]

I have the exact same problem. MK Okta XL, 500mW Tx, clover leaf antenna on the Tx and Patch on the Rx, Lilliput 7" Screen. Have you found a solution?

We now use a 3 lobe skew planar on the Tx and a 4 lobe plus a patch antenna on the diversity Rx. Performance improved by an order of magnitude over the rubber duck/ patch setup. As with all things radio, it is not perfect. We still get some breakup on the picture which causes the Lilliput grief, it blacks out for a second or so until the signal strength is high enough again. This just a 'feature' of the Lilliput ! If you look at the video below where we were feeding the downlinked signal to a big arena screen you can see the breakup. The Rx was about 50m away from the copter. On the Lilliput this would cause the screen to blank out. Its an annoyance but we live with it. We have also noticed that the picture improves tremendously as we move further away from the Rx so maybe the Tx output is just too high for short range stuff. We are going to check things out with a 100mW Tx to prove it one way or the other.
Its impossible to mount the Tx antenna anywhere without some blanking of the signal by the airframe. We ended up with it on the lower landing gear rail about half way along. Thats for a Droidworx ADX3H but you could try strapping the Tx to leg low down.

andy

 

[Jack]

Thanks Andy.. Keep me posted.. this is turning out to be a huge problem.. can's have video blanking out.. In case i come up with something, will tell you

 

[AerialVue]

Antenna Tracking... A big patch antenna (flycamone). We use Lilliput and immersion Diversity RX with antenna tracking and have a very good down link experience. The only time we have drop out is when the copter is directly overhead. If you plan your flight path and Video down link set up and position this should never happen. The problem with the Lilliput is that the screen just goes blank rather than snowy which is just one of the problems with it. There are better monitors out there but the LP is a good value solution.

 

[Malcr001]

Anyone have a 100% reliable 5.8Ghz video downlink ?

Theres no such thing, its the nature of the frequency and no matter wt you do or buy wont change that fact. 5.8ghz is prone to multipathing and is LOS frequency meaning its penetration is poor.