Can anyone recommend an antenna for this: http://store.3drobotics.com/products/3dr-radio-telemetry-kit-915-mhz
I need at least 2 miles of range. If there is a different way to get more range please explain. Again thank you for helping me (noob).
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Let me put this document in .pdf for people interesting in some of what is being discussed. It touches on a few things and might explain some better. It is from Novatel so some of it wont matter to most of us.
Discussions on RF Signal Propagation and Multipath
Lets face it most of us only need a mile or two but some want much more so this will help those who want to understand the principles better. Anyhow I have spent my 2 cents I hope this helps out.
Check this out.
http://www.rc-cam.com/forum/index.php?/topic/2821-low-cost-diy-900m...
bo W4GHV
There are plenty of options for antennas. I am a amateur radio operator and sometimes a "patch" type antenna is not the best idea for this sort of operation. To really optimize things because of the air to ground a circular polarized antenna system is best. Now if you want to invest in a tracker type setup with beam antennas that have a fantastic front to back ratio you have to spend some more money. I think if you are looking for just a 2 mile range just upgrade both the ground station and copter antennas to higher gain you should do fine without buying amplifiers and such. And of course you can even go the route of circular polarized setup. But honestly you should do some research on antenna ratings because when they say 3dbi over dipole dbi is a rating for a isotropic antenna it does not really exist except on paper. It has 0 gain so 3dbi is not really fantastic in the gain department in fact it should equal pretty much stock antenna that comes with a setup. This is where this hobby is lacking these days people don't understand antennas, the ratings and smith charts on antennas.
Anyhow Just find yourself some high gain 5dbi + antennas ( i have seen 9dbi) and your 2 mile will be no problem. One more thing to keep in mind you have your R/C antennas and a FPV OSD setup too.
Let me state this the rating again to be clear. dBi is referenced to an isotropic radiator.
This is a theoretical antenna that doesn't exist. It is a pinpoint rf source which has the field pattern of a perfect sphere. A dBd is referenced to a half wave dipole. Since the rf radiating from a dipole is focused to a pattern perpendicular to the wire with very little off the ends then this antenna has a gain of 2.14 dBi in the perpendicular direction.
So if you have an antenna that the manufacturer states is 3 dBi then it is only .86 dB better than a dipole. See what I mean? Be careful on the numbers you think you are getting something when you really are not.
Kevin, check jDrones too. We have already 3dbI dipoles same what Seppo is using on his RFD900 modems and we have those too. Range... enough ;)
20km is rather easy to get some people have reported even 40+km ranges on RFD900 modems.
I know that awhile back there was some talk that some company sent 3DR a 900 MHZ amp and it worked out well.....does anyone have links to any antennas?