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Old May 01, 2013, 08:37 AM
Registered User
Blacksburg, VA 24060 USA
Joined Feb 2000
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Bad 2.4 gHz Transmitter Antenna Design

Gents,

In the Tactic TTX650 thread I complained about the delicate hinge on the antenna, and how I broke one and had to "repair" another because the hinge was loose. I think the notion of poor antenna design deserves a thread of its own. Do you think I'm the only crank? Try this: http://www.rcgroups.com/forums/showthread.php?t=1877219 You'll see a pic that shows a well-known brand transmitter which has plenty of tape wrapped around its delicate antenna hinge. There is a comment in that thread, Post #8.

In the days of the telescoping antenna, it could be collapsed so the transmitter could be stowed conveniently in a case or in a field box, with little risk to the antenna. If it was damaged the antenna could be replaced by unscrewing the old antenna and screwing in a new one. To eliminate that risk, some folks offered a "rubber ducky" replacement. Electrically, it wasn't perfect, but mechanically it solved a problem.

To replace a damaged 2.4 antenna, because of a broken or loose hinge, requires removing the back of the TX case. I've done that, and I nearly lost one of the case screws. Attaching the tiny, delicate connector securely to the RF board is also no treat.

Why can't TX makers build a transmitter with a rubber ducky antenna? Or offer a rubber ducky 2.4 gHz antenna as a final replacement for existing Txes? It could be flexible enough to be positioned where the user wants it, with little or no risk of damage through poor handling or dropping.

Who's with me?

Jim R.
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Last edited by JRuggiero; May 01, 2013 at 08:47 AM.
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Old May 01, 2013, 08:57 AM
Air, Ground & Water
freechip's Avatar
Canada, ON, Rockland
Joined Aug 2008
23,096 Posts
Lost count how many telescoping antenna ps I broke in many surface rc career prior to 2.4 and since getting back into the hobby as well as getting into flying with 2.4 I have never broken one.

I fully understand your point, I did once drop my surface radio while it was in its case but it landed on its top/antenna and it came apart at the hinge point but quickly and easily snapped back into place. Lucky maybe.

Now my current air radio has two fixed antennas, if you break one if them I'm sure there will be enough damage that it will warrant a trip to the service depot for repair.

I have seen many post where people have placed the antenna inside the case. Depending on what you fly it might be something that interests you.

Good luck and have fun
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Old May 01, 2013, 09:42 AM
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richard hanson's Avatar
United States, UT, Salt Lake City
Joined Oct 2007
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Have yet to see anyone stick a 2.4 antenna in a prop-------
excitement!
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Old May 01, 2013, 10:00 AM
AndyKunz's Avatar
Illinois
Joined Sep 2001
22,103 Posts
Quote:
Originally Posted by JRuggiero View Post
Who's with me?
Conceptually, yes. There are limits to practicality, though. I think the DX18 has the best compromise between styling, functionality, and damage protection.

Andy
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Old May 01, 2013, 01:09 PM
12th Pursuit Squadron
TheAeronut's Avatar
Garland, Tx.
Joined Mar 2002
1,101 Posts
Lousy and cheapa$$ designs in my book. Why don't they just use the dead common screw on antenna so it can be replaced if broken? Some transmitters and many 2.4G modules do, as well as almost every WiFi device... Replacement antennas are available, but you do have to check the connector polarity as some use SMA and some use reverse SMA.

J.P.
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Old May 01, 2013, 01:22 PM
AndyKunz's Avatar
Illinois
Joined Sep 2001
22,103 Posts
The insertion loss is too high and with mfg tolerances that would reduce the permissible power to ALWAYS be legal.

People would also be tempted to replace the correct antenna with something that looks the same, not realizing that a 2dB antenna will behave very differently than a 5dB antenna. Then they'd blame their crashes on the radio instead of the replacement antenna they substituted into it.

Andy
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Old May 01, 2013, 02:08 PM
ElIntocable's Avatar
United States, LA, Shreveport
Joined Jul 2010
679 Posts
Here's a better idea, start paying attention and take care of your equipment. I get a kick how people will knock a brand because the antenna broke when they dropped their radio. Well no crap it broke! Yes, accidents happen, you can't prevent that. You can reduce them though by taking your time and just being careful. I have yet to drop my DX8 or XG11. I don't plan too either. If I do though, I expect something to break. As for P.S. (post 8), stop carrying it in a backpack; use a transmitter case.
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Old May 01, 2013, 03:21 PM
KC
Registered Loiterer.
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United States, FL, Orlando
Joined Sep 2006
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Quote:
Originally Posted by JRuggiero

Who's with me?

Jim R.
Already been there. Here is my solution. Does Size Matter?

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Old May 01, 2013, 03:38 PM
Radio? Screwdriver!
United Kingdom, England, Bristol
Joined Aug 2011
937 Posts
The A9 antenna is a pretty neat design and I've yet to break it!
Hitec Aurora 9 - Why the wire antenna is good thing! (0 min 9 sec)


The Futaba T8J has its antenna internally, which pretty much solves the problem...


This is the future to be honest. It's a bit like how mobile (cell) phones in America for a long time had external antennas - the extendable bit was never operational. However users felt they got better coverage with them, hence why they lasted so long on US handsets (Europe for a long time has had antenna-less designs).
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Old May 03, 2013, 11:53 AM
Registered User
Blacksburg, VA 24060 USA
Joined Feb 2000
3,118 Posts
Speaking of antennas in the handle, the first RC radio set I had was a well-used item. I forget the brand, but it was not Kraft or Ace or Futaba. It was on 72 mHz, and the antenna WAS the handle. It was a square U shape about 8 inches by 7 by 8. It worked, though I never flew an airplane very far, because I was a rank beginner. (Though I'm no longer a beginner, I may be a little more rank )

So a decent antenna that won't break or suffer a loose hinge can be made. It shouldn't be a big state-of-the-art trick to engineer, even for a basic 4-channel transmitter.

Jim R....
... all out of tricks
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Last edited by JRuggiero; May 03, 2013 at 11:58 AM.
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Old May 11, 2013, 09:29 AM
Registered User
Blacksburg, VA 24060 USA
Joined Feb 2000
3,118 Posts
Gents,

Here's another victim of poor antenna design for 2.4 gHz transmitters:
http://www.rcgroups.com/forums/showthread.php?t=1634237

This time it's a Dynam TX. Next time, it could be a Walkera, or you name it.

I note that the non-computer Tactic TXes, TTX600 and TTX400, do not have bendy antennas. So, when it comes time to build a more ambitious, computer TX, what's the appeal to makers of the inferior design?

Likewise breakable trim tabs and menu rollers, but that's a discussion for another thread.

Jim R.
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Old May 11, 2013, 01:24 PM
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Ken Myers's Avatar
Commerce Township, MI
Joined Aug 2001
4,341 Posts
I wish I could figure out why 'Tactic' didn't put the antenna in the handle on the TTX650. The handle is part of the transmitter case design, which easily separates into two halves, the guts and the empty back, so the routing should have been easy. It would certainly be a good idea.

Just thinking aloud.

Ken
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Old May 12, 2013, 12:19 PM
Registered User
Blacksburg, VA 24060 USA
Joined Feb 2000
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Thank you, Ken. Coming from a new owner of a Tactic TTX650, who will get a chance to wring it out, your antenna experience should be enlightening.

Jim R.
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Old May 13, 2013, 11:42 AM
AndyKunz's Avatar
Illinois
Joined Sep 2001
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Just because you assume it's inferior doesn't mean it is. There are legal requirements regarding positioning as well as technical and manufacturing considerations.

Andy
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Old May 14, 2013, 10:26 AM
Registered User
Blacksburg, VA 24060 USA
Joined Feb 2000
3,118 Posts
Andy,

With respect, the problem with the bendable-breakable antenna lies in the fact that it does loosen or break. The other, shorter, rigid style does not. Which is inferior?

Could a "rubber ducky" style of antenna have been employed, that can bend to withstand bumping? As it is, on my DX8 I had to resort to putting a piece of heatshrink tubing around the loose joint, which is a sort of rubber ducky fix.

I would like to know what those technical and manufacturing considerations and legal requirements for positioning are.

Jim R.
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Last edited by JRuggiero; May 14, 2013 at 10:41 AM. Reason: Added comment
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