Cisco Aironet 1700 Deployment Manual page 38

Remember, the best antenna placement is the one where the antenna is physically closest to the actual users. If you are mounting
multiple single package dual band antennas externally, such as dipoles, spacing is not critical but try to space them as far apart
as practical (with "A" and "B" as the furthest apart).
Figure 51 Antenna Placement- Avoid Spacing Antennas Further than 10 Ft (Antennas Should be in the Same RF
Coverage Area)
Avoid using single band (single radiating element antennas) such as those used with earlier 3500 series
Note
AP products because they are not fully compatible with the newer 1600/2600 and 3600 Series APs.
Antennas for the 1260 and 3500 series are single radiating element antennas made for each individual
band. The 3600, 2600, and 1600 APs use dual band - dual radiating element antennas and are branded
with an orange marking see
Cisco Aironet Series 3700 Access Point
Figure 49
Cisco Aironet Series 1700/2700/3700 Access Point Deployment Guide
3
and Figure 50.