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schuberschubs

1,2 Ghz 500-1000mW output +8dbi Antenna what range?

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Hi all,

sooo i just have a question...im going to buy me some FPS-System with 1,2Ghz and 500mW or maybe 1000mW output....and im going to have a 8dbi Patch Antenna ( i dont know where i could get more dbi´s for 1,2Ghz :( ) sooo in the end i would be happey to have a long range system :)

im interested in the range. what range im going to have with 1,2Ghz+500mW+8dbi= ? and with 1000mW?

on the other side i could get some 2,4Ghz but hm i think there would be more interference with WLAN etc... right?

PS: Where i can get Patch Antennas for 1,2Ghz with more then 8dbi?

thanks really much

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what range im going to have with 1,2Ghz+500mW+8dbi= ? and with 1000mW?

hard to say as a lot depends on the exact equipment and installation. I would say 4 miles plus for the 500mW TX and 6 mile plus for the 1000mW system.

I hope you rc link has good range.

Terry

Edited by Terry

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Hi all,

sooo i just have a question...im going to buy me some FPS-System with 1,2Ghz and 500mW or maybe 1000mW output....and im going to have a 8dbi Patch Antenna ( i dont know where i could get more dbi´s for 1,2Ghz :( ) sooo in the end i would be happey to have a long range system :)

im interested in the range. what range im going to have with 1,2Ghz+500mW+8dbi= ? and with 1000mW?

on the other side i could get some 2,4Ghz but hm i think there would be more interference with WLAN etc... right?

PS: Where i can get Patch Antennas for 1,2Ghz with more then 8dbi?

thanks really much

Try these guys: http://www.taiantenna.com

They show 2 x 1.2G - 1.4G patch antennas on their website - on their "Panel" page - claiming Gains of 10 for one, and 14 for the other.

Your other option - use 2 x 8dBi patch anttenas - realise somewhere between 10dBi - 10.5dBi if all setup carefully.

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Stacking? Side by Side would probably be best – on a cross pole (elevation) which is attached to a vertical pole (azimuth) located between the 2 patches. May make it a little heavy for your average RC type servo, but should be no probs for some of the heavy duty multi-turn RC yacht type servos (assuming you’re working towards an antenna tracking setup(?) – are you?)

Connection? – through a combiner/splitter – which you can construct yourself (I can share some diagrams with you for DIY low loss combiner/splitter), or you can purchase one off the shelf. You will need 2 equal lengths of coax of the same spec, to run from each antenna to the combiner/splitter, then whatever length of coax to run from the combiner/splitter to your 1.2Ghz audio/video transmitter.

If you decide to purchase a combiner splitter, other than ensuring it’s for the correct frequency (obviously) and has suifficient band-width, the other spec’s worth checking before parting with your hard earned cash are: Insertion loss, Phase Shift (sometimes also written as Phase Balance or Phase Deviation), Amplitude Balance, VSWR (or SWR - same thing) and Isolation. The lower these figures are the better the combiner/splitter will perform. There can be tremendous difference in these figures from one manufacturers product to another manufacturers product. Generally (but not always!) - the price says a lot about the quality.

The lower the Insertion Loss the better, the closer to 0 [degrees] the Phase Shift the better (coax lengths between each antenna and the combiner/splitter of unequal lengths will increase losses incurred through any Phase differences – so ensure they are of equal length). A figure of 5 (which is the figure attached to the splitter on the above website) is quite acceptable, anything up to around 8 should be acceptable, but you can find combiners/splitters which demonstrate figures as low as 2 or 3 [degrees]. You get what you pay for, is an old saying no less true with electronics than it is in respect of other products.

Amplitude Balance (in simple terms, in a transmitt scenario, the less this figure is the more equally the signal has been divided by the combiner/splitter to feed each antenna). And last but not least, the closer the published VSWR/SWR reading is to one, the less your transmitters output power is been reflected back (by the combiner/splitter) to the transmitter. Any VSWR/SWR figure of around 1.5 or less in this application will be fine.

Note - 3 final points: if you stack 2 (or more) patch antennas you get a reduction in beam-width/angle - so long as your antenna tracking set-up can resolve single figure degree changes, and accumulated error can be controlled (or at least is understood in terms of any single flight flying time) I doubt your model will drift much out of the 3dB beamwidths (which is idealy where you want it to be relative to the antenna), so I wouldn't have thought it anything to be too concerned about.

Good idea to back up the long range patch anttena array with a decent quality omni-directional antenna of some sort (which has a hemispherical/half hemispherical radiation pattern i.e. straight up above the antenna), so that you dont have to worry about any close-in/short range flying scenario in which you may otherwise loose your link with the model because its too close for the antenna to change direction in time, or its flying around in a tight circle above your head (won't take long for any rotating antenna to wind up all the loose coax and/or servo power cable - and then stop following the model!) ..... or some similar scenario. You'll be glad now you have a decent quality omni-directional!!

Give some thought to which method you propose to use to implement "antenna tracking" (if this is what you are going to do). There are several ways that automatic antenna tracking can be implemented - all with varying degrees of accuracy, varying degrees of performance and varying hardware costs. Don't leave it to last.

patrick

Edited by Helix1

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Schubershubs

Seems fine - the surface area (i.e. 24cm x 20cm) and E & H beamwidths are more or less in line with what you'd expect from a patch that size for a 100Meg bandwidth @ 1.2 - 1.3 Ghz.

Quality? Depends what one means by quality? Is the casing watertight, is the Gain actually 14dBi (most - not all though - antennas from the Far East I have measured over the years tend to be a little optimistic with their Gain claims, but overall these tend to be measured differences which turn out to be insiginificant in reality when all the other system gains and/or losses get factored in accurately), are the beamwidths 30degrees, is the F/B ratio what they say it is etc etc ........... all depends what one means by quality.

But overall, theres not much to go wrong with a patch antenna. They're fairly easy to produce so on balance I'd think this antenna is more likley than not to do just what it says.

Price is more or less what you'd expect it cost - overall I wouldn't be concerned about anything. Go for it.

Edited by Helix1

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