The following link will give you a variety of antennaes that are compatible with the 1260.
Have a read of the "Cisco Aironet Antennas and Accessories Reference Guide" first. Remember that the 1260 has three antennaes for both the 2.4Ghz and 5Ghz so in some cases you may need to buy three per radio.
The latest offer from Cisco is the dual-band AIR-ANT2451NV which is a single unit suitable for the 1250 and 1260. It has six RP-TNC pig-tails.
Just be wary of the following rule-of-thumbs:
Antennas transmit and receive radio signals which are susceptible to RF obstructions and common sources of interference that can reduce throughput and range of the device to which they are connected. Follow these guidelines to ensure the best possible performance:
•Keep the antenna away from metal obstructions such as heating and air-conditioning ducts, large ceiling trusses, building superstructures, and major power cabling runs. If necessary, use a rigid conduit to lower the antenna away from these obstructions.
•The density of the materials used in a building’s construction determines the number of walls the signal can pass through and still maintain adequate signal strength. Consider the following before choosing the location for your antenna:
–Signals penetrate paper and vinyl walls with little change to signal strength.
–Signals penetrate only one or two solid and pre-cast concrete walls without degrading signal strength.
–Signals penetrate three or four concrete and wood block walls without degrading signal strength.
–Signals penetrate five or six walls constructed of drywall or wood without degrading signal strength.
–Signals will likely reflect off a thick metal wall and may not penetrate it at all.
–Signals will likely reflect off a chain link fence or wire mesh spaced between 1 and 1 1/2 in. (2.5 and 3.8 cm). The fence acts as a harmonic reflector that blocks the signal.
•Install the antenna away from microwave ovens and 2-GHz cordless phones. These products can cause signal interference because they operate in the same frequency range as the device to which your antenna is connected.
Don be tempted to use signal/radio boosters. The APs and antennaes weren designed for that scenario.
5.0Ghz was designed for high bandwidth but small "footprint" or range but 2.4Ghz has a larger range. So you may want to consider this.
If you are really looking at directional antennae just make sure look at the horizontal and vertical radiation patterns found in the "Cisco Aironet Antennas and Accessories Reference Guide".
Hope this helps.
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