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headhunter23

spektrum 2.4ghz antenna replacements

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Have searched google... stopped looking after three pages of just descriptions of spectrum receivers..

Ok, I've got a few receivers that I've embedded into a many foamies. Bad things occur when pulling em out no matter how careful such as antenna's being striped on a couple. On top o that my really really small ar6300's have a single wire that is incredibly breakable as I've done one already and a second one is on it's way. The question is what material should I be looking for as a replacement? Single blade of copper? Or some other metal?

Secondly should I look at extending the antenna's to get more range? If so what should I be doing? Double original? The receivers I have are generally ar7000, 6100, 6300 and some other 6 channel with the satellite receiver.

Thanks in advance.

Ivan.

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I only have a AR6100. It uses simple stranded wire for the aerial elements.

Changing the factory length by making it twice as long would be expected to reduce performance in a normal installation. So, don't change it.

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I would be surprised to find that they don't already use the correct length for optimum performance. But in case they don't, without the proper test gear that would mean some serious experimentation would be needed.

At microwave frequencies, tiny antenna length alterations will cause dramatic changes (usually for the worse). Also, keep in mind that a "better" antenna on your Spektrum Rx could just as easily be shorter (instead of longer) than the stock length. Even though it is a simple hunk of wire, we're still dealing with a tuned antenna system. So, best length is up to the receiver's input circuitry and the attached aerial working as one.

Personally, I think the main cause for poor performance with these 2.4GHz R/C receivers is the issue with the small wavelengths being blocked by the model's components as well as multipathing interference from the environment it is used in. The solution to that is adding more satellite receivers, which is usually the only effective cure. Spektrum sells rx's that can be daisy chained together to accomplish this.

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whoah... hadn't seen the daisy chain part. Had seen a 9000 or a 9 channel one with 3 separate satillites but ... will check out. Got a link just in case?

ummmm... had installed a 5 channel receiver in my dads plane a week or so ago(got him the spektrum 5 channel stuff for bday). The receiver had one antenna the same length as your 6100 but the other one was 4 times the length or so. Didn't measure it, should have... anyways sealed in fuse now untill he blows up the model bad enough can't measure.

That's why I was curious whether the length could be more.

Ivan.

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Had seen a 9000 or a 9 channel one with 3 separate satillites

That is what I mean. The satellites are daisy chained to the main rx. Not all of their systems can do this.

The receiver had one antenna the same length as your 6100 but the other one was 4 times the length or so.

That would only make sense if the longer aerial was partially coax feedline. If the entire active element is 4X longer than my AR6100's 3.75 inch element then I don't know what to say. A 15" long 2.4Ghz antenna would be insane. The 3.75" length is actually longer than I would normally expect, but as I said before, the Rx and antenna form an RF system and there is more to it than just the element's physical length.

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mmmm just a couple links... what ya think?

http://www.spektrumrc.com/Products/Default...?ProdID=SPM9546

in photoshop this appears to be 4x... but because of angle it could be off by a few mm.

this is the one i stuck in my dads plane recently... actually seems longer in terms of photo... should really have measured... darn

http://www.spektrumrc.com/Products/Default...ProdID=SPMAR500

Any ideas? Oh one other question if I just substitute regular wire, does gauge matter?

Ivan.

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The entire length of the long version is not the antenna element. The actual antenna would be a small element section at the tip.

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SPMAR500-250.jpg

On the long one, the element is the bit that is stripped at the end of the wire.

Usually it's a bit of coax, and the shielding is removed at the end over a length matching the frequency.

Edited by Kilrah

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Ohhh... i see so essentially the second antenna is still the same length, just repositioned a good 5-6in from receiver. Neat trick. Although I don't remember seeing any shielding on it.

Edited by headhunter23

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There is shielding in the coax, but the neat thing about it is it lets you route the antenna farther away from the other electronics and wires, and in the case of carbon fiber fuselages the antenna can easily be routed to a point outside that is usually more convenient.

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Ahhh very clever indeed. So in order to duplicate this I would just need some sheilded wire and expose the right mm by removing shielding. Nice.

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That's correct. In addition, it's easy to make a dipole antenna as discussed elsewhere in these forums by using the shield or another relatively piece of stiff wire of the same length as the other element of the dipole. Also it's easy to fold the shield back over the outer insulation of the coax to make a bazooka (I think that's what it's called) antenna however I'm not sure how well that type would work with our applications at these frequencies. Perhaps Mr RC and others will comment on it.

Edited by W3FJW-Ron

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