If you need long range wi fi, then take a squiz at this Point to Point Wifi Antenna. It shoots out wi fi EM in an arc, 16° horizontally and 21° vertically and the seller reckons it will work nearly 5km (3 miles) away with a clear line of sight. You’ll need to buy a few adapters and the antenna will replace the standard aerial on your router but if you need wifi in the shed and it’s miles away, this should do the trick. US$89.95 for each antenna, adapters and cables extra.
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This 15 dBi antenna is the best antenna we tested for point to point applications over long distances. In our tests, it provided a much stronger signal than other yagis claiming the same gain, and at half the size. This compact antenna has a narrow beam width (16 degrees horizontal/21 degrees vertical) that directs the WiFi signal and helps to prevent interference with your neighbors.