I have read almost all the articles on antenna range and configurations. Now, I never truly understood good versus bad antenna designs. I am looking for recommendations for off the shelf antenna designs and where to buy that people have used, as well as picture/designs that anyone has used with great success. Right now I use a single coiled wire from the moteino, not sure if this is bad a good they work, but now I am trying to get distance from my base station to other moteino's over my 5 acres.
Thanks.
Thumb rule for monopole wire (as stated in other topics in the forum ) is to keep it straight (not coiled) and orthogonal (perpendicular) to the GND plane (the PCB basically). Ideally you could add a 1/4 wavelength (same length as wire antenna) GND wire to extend the theoretical GND plane (ie solder to the GND pin hole next to antenna and keep it perpendicular with the antenna. So theoretically this should give you the best range you can get. Also keeping the antennas parallel to each other seems to yield a few extra dB or sensitivity on the 2 ends.
That's the theory and some observations from my practice. Play around with a pair of Moteinos in different positions and add obstacles (wood, drywall, walls, metal, concrete, house, trees, a metal box, snow, fog, rain, etc etc etc). That's the easiest way to see what you can expect. There's a million possible scenarios and the only way to see what works well is to test in your own environment.
5 acres is a sizable parcel, depending what the distance is between the farthest 2 points is you can get up to 500m open air range without too much effort.
You might get a few extra dBm with dipoles or higher gain antennas but those will quickly add up to the cost. From my own experience and based on some user feedback, the monopole 1/4 or 1/2 wavelength wire antennas yield excellent price/performance ratio.
Perhaps my searching is weak, but I thought there would be a lot of 915 MHz directional antennas for sale, not so much. These patch antennas look good:
http://www.ebay.com/itm/PAIR-of-Alien-Technology-ARL-9610-AL-902-928-915-MHz-RFID-Antenna-/321316595605?pt=LH_DefaultDomain_0&hash=item4acff62795
6 dB gain, vertically polarized.
They are enclosed but I think they were designed for indoor use so you might have to weatherproof them if used outdoors.
Just cut the connector off the end, strip back the coax and solder the center wire to the Moteino antenna hole and the outer braid wire to a ground on the Moteino.
I'd try using directional antennas on the remote Moteino(s) and a 1/4 or 1/2 wave dipole on the base (gateway) Moteino so you can point the remote(s) to the base and the base will radiate 360 degrees to all remotes.
If that doesn't work and you only have one remote Moteino, or the remotes are all somewhat close together, you could use a directional antenna at the base too to get more gain.
OK, like the 1/4 length idea, I have read that would be about 3.2" long, have you tried any other lengths?