So far as I know the maxium consistent power you can have on the 2.4gig band is 100mW eirp. It’s more like 1W in a lot of places, including here, but there ya go, try get all the countries in the world to agree on anything 
The other bands are even less consistent
Ah, hmmm… you’re not moving much data, and this IS the Zigbee protocol. If they have a power averaging testing method, you might be able to boost signal output significantly for that 1-2% duty cycle that Zigbee’s designed for.
I’ve used some FGR-900Mhz radios from Freewave technologies before with good success. Worked just fine at just over a mile with a small whip on one end, and a car mounted reciever on the other. (we didn’t try to go any farther, and I believe that was transmitting at 115Kbaud)
http://www.freewave.com/fgr900series.html
Line of site: 60 Miles, 1W output. Pretty cool really.
A pair of radios will set you back about $2500-3000 though… maybe worth a look though?
edit: here’s a price list from one of their distributors http://www.scadata.net/web_objects/docu … ceList.pdf
what is total amout of data to be sent back please!
you can use argos satellite systems for minute amounts of data (upto 200 bytes a day)
http://www.radiometrix.co.uk/products/tx1rx1.htm
10km legal range
without yagi you may get around 5-6 km
Russel,
Have you had a chance to try the XBeePro yet? I’m considering it myself for a similar range to yours. Any idea how long the range will be on 10mW (legal maximum in Europe)? Also, my aerial has to be omnidirectional, so I’m stuck with 10mW ERP as well.
I’ve used the XBee Pro and SiLabs modules for some time now.
With and without ZigBee.
Maxstream’s 900MHz radios with a good Yagi will go a mile or more, depending on path obstructions. Trees are surprisingly problemmatic at 900MHz.
Have you considered the high power Jennic zigbee module?
http://www.jennic.com/products/products … 0000000023
It has an 18dBm power amp, and sma connector for external antenna (sector, maybe, if you have to target
distant moving objects). They claim 4+km of range on the site.
Also, it is already certified to FCC and various other ISM
regulations, which takes a load off you.
Since it is zigbee, have you considered a few router devices in the intervening distance? If you’re only sending
a small amount of data, you might be able to organise some
very aggressive power duty cycling, which combined with big chunky batteries and a solar trickle charge, might make it
practically maintenance free.
(Note: I don’t have any connection with Jennic, other than
wanting to get their modules and try them myself for a
few ideas I have.)
For 802.15.4/ZigBee modules, Jennic and Maxstream and a couple of others make 60mW modules. Connected to a 14dBi gain antenna, for both ends of the link, you might get 1-2 miles LINE OF SIGHT. You can do a link budget using one of the on-line calculators. '15.4 will have a longer path length than WiFi because it’s a 2MHz bandwidth (250Kbps) system whereas WiFi 802.11 is 20MHz.
The US FCC limits for EIRP (effective isotropic [antenna radiator] radiated power] is 4 watts, but only with a certain narrow beamwidth. The rules permit increasing power as the antenna directionality increases (reduced potential for interference).
There are (expensive) bi-directional amplifiers for 2.4GHz but they tend to (a) distort the 802.11g OFDM waveform (would not do so for the OQPSK waveform in 802.15.4), and (b) add a lot of noise on the receiver side.