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United States, FL, Maitland
Joined Apr 2011
2,109 Posts
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It's really simple to draw in AutoCAD. This is what it looks like on a regular printer(I assume you don't have a designjet): Make sure the scale is right so you have accurate printout. ![]() If you don't have AutoCAD or any Autodesk software get Trueview because it's free... http://usa.autodesk.com/adsk/servlet...&siteID=123112 |
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I get way too much wind here. Crashed my plane into a power line today because of it. (and because of my bad piloting)
I am gonna be in Denver weekend after next, after Thanksgiving, a couple of us are getting together for some FPV if you are interested. http://www.rcgroups.com/forums/showt...431921&page=32 |
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Markus |
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United States, FL, Maitland
Joined Apr 2011
2,109 Posts
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What's the difference with a 4th lobe?(pros/cons)? I made a stand for my Rx cloverleaf today and it should be a bit better at 15 inches off my car instead of resting on the roof.
I have a feeling I'll be moving to UHF on a Turnigy 9X for Christmas. If you look at 6:00 in my video on the other page there is a cessna at my altitude about 500 meters west(flies from left of screen to right)... flew right by. I'm not sure why they keep looping around the lake. The executive airport is like 3 miles south and I'm in class D airspace. |
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Most likely because you are broadcasting in an aerial navigation band (1040mhz) next to an airport!
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The fourth lobe (but pay attention, the lobes are of DIFFERENT size for the SPW) adds sensitivity to the antenna. In genreal, and especially for reciveing antennas you can't have enough wire in the air. The wires catch the signal, so the more wire you have, the more of a signal you can catch. Of course, the "wire" has to be shaped propperly and resonant etc but in general the equation is right. It would be a good idea to have even more lobes, but doing so would require to match/tune their lenght and positions to get the antenna propperly resonant. Others did that in the past, and one of Alex newer designs (Pentalobe) goes this way. But without measuring equipement and software to simulate such a new design, go for an SPW as there is a tutorial with propper formulas etc. The SPW is a wonderfull omni directional antenna that works very well. Quote:
Quote:
Markus |
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More on what Markus said: You can't simply add lobes. I wish it were that easy. The Skew wheel is generally better than the cloverleaf as an RX antenna. However, the omni distance record is set at 7.5 miles with a cloverleaf on the RX, so the change in performance isn't that much bigger.
I do have another 5 lobe design, but the geometry is very different to get it to work correctly. It is slightly better than the skew-wheel but I find the antennas is very fickle and therefore hard to get correct unlike the cloverleaf where you can really mess up and get a good antenna. I have released the Pentalobe sphere antenne into the TV productioin world, but not FPV just yet. Still working on a few things before it's FPV ready ![]() -Alex |
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Latest blog entry: Project Covert Ops: Long range ground...
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Joined Sep 2008
7 Posts
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Could I be a pain and get your thoughts on this?
I've built a SPW for the receiver end and I've built a Cloverleaf for the TX end. Both made from 0.8mm MIG wire. The cloverleaf is currently on a long piece of RG316, I've yet to add the connector. So, I'm thinking of mounting the cloverleaf in one of two positions as seen in the picture below. A. On top of the horizontal stabiliser, red line shows cable route B. On the DPCAV Vee antenna mast, blue line shows cable route I would love some advice on where you think the best position would be. I'm not very radio-wave intelligent and some, if not most, of the technical speak on the issue baffles me. Does cable length have a significant impact on performance? And does anyone know of a tutorial of how to add the rp-sma connector, with particular attention to the measurements of wire stripping? Thanks |
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United States, FL, Maitland
Joined Apr 2011
2,109 Posts
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At high frequencies cable length matters but if you're on 900MHz you can get away with even a few feet of cable before worrying about attenuation.
I got some multipathing today. That interference caused my capture card to freak out and go all gray and lose sync(vsync?). Video is uploading and I'll post it later. I thought having my RX antenna mounted properly in the air would fix the problems but it doesn't seem like it did. It's 20-30mph winds now so I'll have to wait for saturday to fly again. |
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Markus |
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United States, FL, Maitland
Joined Apr 2011
2,109 Posts
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http://www.youtube.com/watch?v=wOpjOE7qYOo
Also if anyone can tell me why the video has apparent horizontal lines and jagged edges please tell me if I can fix that with OSD settings. |
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Last edited by chatch15117; Nov 18, 2011 at 12:04 PM.
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United States, FL, Maitland
Joined Apr 2011
2,109 Posts
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Here's the setup. I use the patch antenna base(not in use anymore) for structural support as a base for the cloverleaf. The silver rod is an old 72MHz antenna.
Maybe I'll move the antenna to the left wing. I like to fly in counter clockwise circles so that should work out nicely. ![]() ![]()
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Last edited by chatch15117; Nov 18, 2011 at 12:54 PM.
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-Alex |
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Latest blog entry: Project Covert Ops: Long range ground...
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Joined Oct 2006
360 Posts
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TX <-------------> RX a) Pentalobe <-----> SPW b) Pentalobe <-----> Helical c) Pentalobe <-----> CP Patch d) CL <------------> Pentalobe Cheers, Hartwig |
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