By extending it down to the shed, the plan is to have a wireless or wired camera for a little bit of security at the shed.
chevrolux: Yep the Loco M5 is still a great option. On a link that short though you will want to pull the transmit power right down.
There is also the little AirGateway available now which would be perfect of you want wifi down their too -only $30-$40!
Have done a search but a few things come up at Ascent.
Dynamic: We wet up a collection of these in a warehouse recently with stellar results. Just in case you are not aware, the Lomo M5 is the 5GHz model and the Loco M2 is the 2.4GHz variant. If you are rural it probably doesn't matter which you use. In a built-up area the 2.4GHz band can be crowded or have significant interference.
If you have a wireless camera with a removable antenna and are feeling lucky you could try putting a directional antenna on it (example: http://img.dxcdn.com/productimages/sku_37185_1.jpg) and just use one of the Loco's set up as a standard wireless access point. I'm 80% sure you would have a reliable connection.
A safer bet would be two of the Loco's talking to each other in a wireless bridge. Over that relatively short distance you could probably wind the transmission power back to it's minimum setting on both devices and still have a stable connection. The annoyance of having more stuff to plug in and more cables (from the far-end M5 to the camera) isn't a big deal, or your desired camera may not be wireless. In the Wireless Bridge mode you can't connect a laptop to them for example (as best I recall).
The AirGateway that chevrolux mentioned would let you use a laptop or smartphone down at the shed with Option 2. The one you mentioned is correct and there is also a non-LR one (i.e. short range with no antenna sticking out).
Checked on option 1 - I would give it a try but currently listed as - out of stock.
jonb: Is trenching some Cat5 cable an option?
If the stable is on the same circuit as the house a Powerline adapter could be also be an option.
Azzura: I have been doing some reading but without ever having any hands on experience in setting this up, or having this hardware in hand ...I am still not sure how this Ubiquiti equipment is suppose to work.
jonb: If the stable is on the same circuit as the house a Powerline adapter could be also be an option.
Taylor Broadband (rural hawkes bay)
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For my general guide to extending your wireless network Click Here