Module and antenna question with new Turnigy 9XR

[Var]

So the new 9XR specs say it has an internal antenna. What does that mean for people using a plug-in module where the antenna screws directly into the back like this one ?

http://www.hobbyking.com/hobbyking/stor ... ible_.html

Is it bad having 2 powered antennas?

[ShowMaster]

It appears that HK will make modules that use the internal antenna connection.
Any module with the antenna connection on the back now would not use the internal one if you just plug it in.

As for 2 antennas or two transmitters on at the same time,
If the antennas are kept at 90 deg to each other( one vert and one horiz) they will be isolated by as much 20 db.
Think of every 3 db as half level energy coupling.
A generalization, but close enough to understand the theory going on.
SM


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[aesmith]

So the new 9XR specs say it has an internal antenna. What does that mean for people using a plug-in module where the antenna screws directly into the back like this one ?

http://www.hobbyking.com/hobbyking/stor ... ible_.html

Is it bad having 2 powered antennas?

The internal one won't be connected to anything if you fit a normal JR type module.

[G550Ted]

With the design of the anticipated RF modules for the 9XR having a U.FL antenna connection to the internal antenna, I found this while doing some research:

"Female U.FL connectors are not designed with reconnection in mind, and they are only rated for a few reconnects before replacement is needed. The female U.FL connectors are generally not sold separately, but rather as part of a pigtail with a high-quality 1.32 mm doubly shielded cable, which allows for a low-loss connection."

For those with experience with these type connectors, what are you opinions as to the long term durability and performance of the antenna connector?

Ted

[ShowMaster]

I found this

The U.FL connector for all of those mini-pci cards and PC cards that have gone to this new connector. The U.FL (Hirose / IPAX) connector on RG178 cable
Special note with the U.FL connector - these are NOT a duty rated connector. Once it is connected it is strongly suggested to leave it connected. Due to its size and design its use in a plug and unplug situation will be very limited

Let's see what HK has to say as this drama unfolds!
SM

[Kilrah]

The connector they chose between module and radio is NOT u.fl, it's much much larger and completely different. To me it looks like SSMB, but as there are no specs nor detailed photos around I guess we'll have to wait until someone gets a radio to check it.

[Scott Page]

Might be my imagination and obviously won't know until it arrives -- but it looks to me like an RP SMA connector. If that's the case -- one could buy a u.fl to RS SMA cable from sparkfun and connect FrSky (or probably others as well) receivers to the connection.

[Kilrah]

RP-SMA requires screwing, that wouldn't work as intended (insert module , antenna's connected).

[cre8tiveleo]

http://www.hobbyking.com/hobbyking/stor ... 548X52.jpg

[ShowMaster]

The note about not changing the antenna wire (coax)length or type is interesting.
It tells me that the the connector is not a good 50 ohm impedance match and probably creates a SWR issue in the antenna transmission line path. If the RF output circuit has SWR protection this impedance change and resulting SWR could ramp back the output power.
One way around that is to creatively alter the transmission line length to trick the output stage by putting it at a null in the return wave energy due the SWR issue.
Those that treat this as a piece of wire and alter its length in the module or case without some device like a field strength meter run the risk of reduced power out or final shutdown.
RF is magic, and a science.
Any connector in the path can be trouble. Is any case the less times the connector is mated and unmated the better at these power levels of 50-60 Mw.
SM


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[kaos]

This internal antenna design seems to negate the advantage of being modular and you can't use the original Turnigy module. Does not seems to be a good idea for me. Actually, an antenna stick out on top/back looks sexier to me.

[Crucial]

Why can't you use the original turnigy module?

[Kilrah]

Well you can, but you have to install an antenna on it. It isn't related to the radio's internal antenna really.

[kaos]

yes, I should rephrase it. YOu can't use it as is. You have to remod every module you have already. Even using the original T9x module, still need to mod it to use that int. antenna.
To me, any change needs to consider the existing equipment. Unless there is dramatic function/capability improvement, existing equipment needs to be compatible. Otherwise, people loose interest in it fast.
Another nice thing about ext. SMA attached antenna is I can change to a higher gain / directional antenna easy.

[Kilrah]

You have to remod every module you have already.

Huh why?
All my modules that have their own antennas will work perfectly fine. Existing modules simply won't benefit from the internal antenna, but they won't magically cease to function...

The internal antenna is there, you can use it or not, that's it...

[kaos]

yes, that is what i meant 'to use that int. antenna' . so for us who already has the modded module, it is a useless thing to be there.
gee, has to write in Nerdish to get the idea across. I am learning but still not very good at Nerdish you know.

[JakeStew]

All the hype with the 9XR about how they listened to the RC community and developers.... and nobody told them it was a stupid idea to include a c**p internal antenna?

Pretty obvious you should have a connector or just let the actual TX have the antenna. I think the new design is even further in the stupid direction. Now you have a connector, but it's a non-standard connector and it doesn't even let you change the antenna! Worthless, pointless, AND it's costing us money!

[JakeStew]

Why is C-R-A-P censored? Is this a board for preschoolers or something?

[kaos]

Pretty obvious you should have a connector or just let the actual TX have the antenna. I think the new design is even further in the stupid direction. Now you have a connector, but it's a non-standard connector and it doesn't even let you change the antenna! Worthless, pointless, AND it's costing us money!

that is plain English.

[Crucial]

You have to remod every module you have already.

Huh why?
All my modules that have their own antennas will work perfectly fine. Existing modules simply won't benefit from the internal antenna, but they won't magically cease to function...

The internal antenna is there, you can use it or not, that's it...

You would have to mod any "late model" turnigy module to use it in a different radio. I thought he was saying that it was necessary for the 9xr specifically.

All the hype with the 9XR about how they listened to the RC community and developers.... and nobody told them it was a stupid idea to include a c**p internal antenna?

Pretty obvious you should have a connector or just let the actual TX have the antenna. I think the new design is even further in the stupid direction. Now you have a connector, but it's a non-standard connector and it doesn't even let you change the antenna! Worthless, pointless, AND it's costing us money!

The internal antenna is just as good as any other rubber ducky antenna and you don't have to use it if you have a module that has it's own antenna. It just sits there and doesn't do anything if not used.

[jhsa]

In other words, that antenna will only be good for the 9XR module then..
I would never use it anyway as I don't trust this kind of connector for 2.4Ghz

[JakeStew]

> The internal antenna is just as good as any other rubber ducky antenna

I guess it's as good as any bare minimum stripped piece of coax inside plastic antenna. But IMHO that is pretty crappy. I would think most people who care about range would want at least a small step up from the absolute lowest end antenna you can produce.

> you don't have to use it if you have a module

Yes, but I still had to pay for it, it's still in the way, and it's still just plain useless. Try to come up with even one reason to have it there. There just isn't one. It's a stupid non-feature that should have been corrected rather than making it worse.

> It just sits there and doesn't do anything if not used.

That's my point. But it does do something, it gets in the way, looks cheap, and it pisses me off to have to constantly look at stupidity.

I know, just cut it off or remove it. But then the stock module I paid for needs work to be functional again (for my regular 9X). It just gets tiresome to have to fix other people's design flaws, then see them do the same thing again in the next version.

The 9XR doesn't seem quite as bad, but they continue to spend my money for shite I don't need and has no use! Just put the antenna on the transmitter stupid! It makes no sense to include parts for something else in the design of the control box, then also make it with poor components with no connectors (or now useless connectors).

[Crucial]

What other radio system uses a different antenna than this?

You don't have to cut it off if you don't use it. It's internal to the radio and doesn't get in the way of anything if you use a turnigy, frsky or any other module. The planned use for this antenna is to be used with the coming hobby king dsm/dsmx module. THAT module will plug into the back of the radio and THAT module will have a protrusion that will plug into the internal antenna.

[JakeStew]

> What other radio system uses a different antenna than this?

Most radios have a weak, cheap antenna that comes with them so people can use them out of the box. If you're serious the first thing you'll do is throw that one in your junk box and screw on a real antenna.

That's all those antennas are meant for. It's there so people don't power up the radio without an antenna and fry their PA. Most users will want to install an antenna to their liking. The 9X people don't seem to understand that.

[jhsa]

So, which antenna should I buy to replace the cheap antenna that came with my frsky module??

[Rob Thomson]

Have to say... I have never had a range issue with the frsky stock antenna?

[Kilrah]

The simple dipole antenna is perfectly fine for anyone who flies "normally", i.e. within visual range, i.e. 90% or more of potential users.

Most users will want to install an antenna to their liking. The 9X people don't seem to understand that.

No, most users just want a cheap radio that works and allows them to fly their models, they aren't looking for best possible performance and multiple mile ranges. Those who want that have options, all the others have the convenience of no antenna sticking out and likely to be broken during transport.
HK probably figured the majority of users would just get the radio with the DSM module that uses the internal antenna and would never change it. They try to push manufacturers to make modules that use it too - we'll see how that turns out.

All the hype with the 9XR about how they listened to the RC community and developers....

No, the hype is about how they did NOT listen, did (apparently) not use an atmega128 instead of a 64, did not think about making the telemetry connection easy, etc.

[dvogonen]

Most users will want to install an antenna to their liking. The 9X people don't seem to understand that.

I can not understand the excitement. If anyone wants a radio system with maximum performance and stability, they will have to use a radio module with an external antenna. That gives them ample possibility to use whatever antenna they happen to believe in.

The built in antenna can only be used with HobbyKings not yet released DSM TX module. Anyone worried about transmission link stability and maximum antenna efficency will naturally not use a completely unproven implementation of DSM of all protocols. I guess I will end up buying the HK module since it will be convenient for flying BNF toys. But I will not trust it for anything else.

And to all those who are worried about interference from the unconnected internal piece of wire that is the antenna: open any transmitter and try to count all the wires and circuit board copper strip that are roughly the length of a multiple of a 2.4 GHz antenna. All of those will be just as bad.

[JakeStew]

> So, which antenna should I buy to replace the cheap antenna that came with my frsky module??

I ordered one like this...
http://www.hobbyking.com/hobbyking/stor ... ules_.html

You can search HK for antennas, they have tons of them. Most are in the $4-10 range. You can't trust the rated dBi of the antenna, quality and performance is pretty much a random crapshoot IMHO. You can also go on ebay and find tons for cheap. It's always a crapshoot, so order a few and find one that works.

I just don't understand why anyone would be satisfied with a cheap 1 dBi antenna when they can double, tripple, or quadruple their range for $5-10.

As I mentioned, stock antennas are throwaway garbage unless you don't care at all about performance. That's why it seems especially stupid for companies to be building garbage antennas that the user will certainly want to change right into the unit with no way to change them.

[ShowMaster]

More gain from these types of antennas comes from modifying the 360 donut radiation patten into something much more directional like pear shape.
Of course more gain but no free ride, The pattern becomes more directional. This defeats the purpose of a non directional antenna system.
To put it technically, more peaks of signal strength and more lower signal strength valleys.
Not perfect for omnidirectional flying.
Of course most reading up on antenna theory knows that so this is old news.
It's hard to argue antenna theory in the hobby world so I'm just happy I get paid for it in the professional word.
Try it, if you're happy with the results then your good to go.
SM





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