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Mar 24, 2010, 03:52 AM
Marcin
hondahirny's Avatar
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Discussion

X-Ray of 2.4GHz Antennas


Just wanted to share some x-ray images i captured of the transmitter antennas inside the DX7, JR 9303, and a Linksys router antenna. They're all on 2.4 and i was wondering what's inside the plastic stub.

Looks like 1/2-wave dipoles, made out of the coax center conductor and a piece of metal tubing. Simple, but effective.

The image below was combined in Photoshop from 3 seperate images i made. I wish i could have gotten the whole plastic part of the antenna in view, but my x-ray at work is really not meant for large objects like this.

Anyways, I hope this is a bit of useful extra info, just in case you too were wondering about what is inside that plastic tube.

BTW, judging by the shape of the BODA (antenna) on the new 2.4ghz Hitec receivers, i'm willing to bet they use this same design for the TX and the RX. I guess since Hitec has telemetry, they're both transmitting antennas.

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Mar 24, 2010, 06:54 AM
Rust: The poor man's Loctite.
TomM's Avatar
Cool pics. A much more elegant solution than me wacking the antenna open with a hammer.
The metal tube is a sleeve balun.
Mar 24, 2010, 11:46 AM
Guz
Guz
Gutless wonder
Guz's Avatar
Yep, the Hitec BODA is just a "transmitter antenna" but without the plastic.
Jun 16, 2010, 11:54 AM
Registered User
aerofer's Avatar

Great!


Quote:
Originally Posted by hondahirny
Just wanted to share some x-ray images i captured of the transmitter antennas inside the DX7, JR 9303, and a Linksys router antenna. They're all on 2.4 and i was wondering what's inside the plastic stub.

Looks like 1/2-wave dipoles, made out of the coax center conductor and a piece of metal tubing. Simple, but effective.

The image below was combined in Photoshop from 3 seperate images i made. I wish i could have gotten the whole plastic part of the antenna in view, but my x-ray at work is really not meant for large objects like this.

Anyways, I hope this is a bit of useful extra info, just in case you too were wondering about what is inside that plastic tube.

BTW, judging by the shape of the BODA (antenna) on the new 2.4ghz Hitec receivers, i'm willing to bet they use this same design for the TX and the RX. I guess since Hitec has telemetry, they're both transmitting antennas.

Great Job!!
Can you measure the tubing?? maybe can be useful to improve the cheaper systems!!, I wondering if this is really useful in standard receivers to (without telemetry) since this is not "transmitting" any signal
Jun 16, 2010, 04:17 PM
65 years of RC flying
Daedalus66's Avatar
Quote:
Originally Posted by aerofer
Great Job!!
Can you measure the tubing?? maybe can be useful to improve the cheaper systems!!, I wondering if this is really useful in standard receivers to (without telemetry) since this is not "transmitting" any signal
Do you understand that "improve" generally means increase gain? About the only way to do this is to increase directionality, which is precisely what you don't want in a receiver antenna for a moving object like a plane?

The best way to improve a cheap system is to find another cheap system that works better! There are a number of inexpensive systems that give ample range and reliable signal without "improvement."


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