A simple yet high gain directional antenna can be made from a Sky, Primestar, Galaxy, Foxtel or similar satellite / parabolic dish. A similar commercially made dish antenna can cost upwards of $200!

The parabolic dish works by reflecting a wireless signal from the feeder (placed on the arm in front of the dish) into a long, narrow beam.

Given a good line of sight (LOS) with few trees or buildings in the way, a directional antenna like this can broadcast and receive a wireless signal km's.

A waveguide Can-tenna or biquad antenna can be used to feed the dish.

BiQuad Feeder

• 110x110mm square section of blank PCB (printed circuit board)
• 50mm length of 1/2" copper pipe
• short length of CNT-400 or LMR-400 low loss coax (~300mm long)
• 250mm of 2.5mm² copper wire (approx 1.5mm diameter)
• N connector

Note that you don't have to use blank PCB for the reflector. You can use any material that's electrically conductive, can be electrically connected to the coax braid, and will reflect microwaves (ie, sheet brass or copper, any metal plate will do fine). 
I've also heard of people using CDROM as the reflector, as the silver foil on it will certainly reflect microwaves.