Can you refer me to
technical documentation that discusses the Smart "DART" antenna connector and
the maximum distance the secondary antenna can be placed from 2800/3800 "E"
I would recommend
that customers keep all antenna cables as short as possible.
Let's examine how the
RF system works on the models with external antenna connectors known as the "E"
Figure 1. XOR radio is
defaulted to 2.4 GHz until detection of a smart antenna
If a Smart connector
is not used, the "E" Series Access Point operates much like an AP-2700e / 3700e
in conventional 2.4 and 5 GHz mode.
Dual 5 GHz is not
supported until the XOR radio detects the insertion of a Smart antenna or Smart
antenna to RP-TNC adapter.
Figure 2. Smart antenna
connector "DART" and DART to RP-TNC adapter
Operation of the
Smart antenna connector can enable the XOR radio to function in either band
known as SRE or "single radiating Element mode" enabling single band antennas
to be used with the XOR radio. If the XOR is not servicing clients but rather
in a monitor mode, it will serially scanning 2.4 and 5 GHz and a DRE "dual
radiating element" (orange label antenna) should be used.
If monitor mode,
the XOR radio cannot service clients and only the 5 GHz primary radio on the
TOP of the AP will be active for client use.
Figure 3. Understanding
radio roles DRE and SRE
When using the Smart
antenna connector, in dual 5 GHz mode, you should avoid co-locating them next
to each other it at all possible.
Let's talk a bit
about directional and omni-Directional antennas.
Figure 4. Directionals
are often used in warehouse and stadium deployments
In the case of dual
Directional, face the energy away from each other - If the antenna has
sufficient null behind the antenna you may be able to place them "back to
Avoid using dual Omni
antennas unless you are using the XOR in 2.4 GHz.
Figure 5. Using 5 GHz
Omni (dipoles) indoors and mounting 2.4 GHz Omni Outdoors
If dual 5 GHz were
used, again directional are best or you could use Omni antennas if you were to
run the XOR in very low power (creating a Micro cell) while the AP antennas
(ideally also remoted away) in Macro cell mode.
Most Cisco external
antennas have a cable length of 3 Ft so it is possible using external antennas
to get approximately 7-8 Ft of separation as there is some additional cable
length in the smart antenna adapter.
Avoid extending the
antenna cables it at all possible.
If you choose to use
longer cables, be aware there is significant loss (attenuation) in cable and
different types of cable has different loss ratings. This loss affects both the
ability to receive (decode) the signal as well as reducing the transmitter
power as well.
Additional cable and
RF connectors also introduce potential points of failure and reduce overall
MTBF. So use additional cable only when needed. Consider relocating the device
closer to the user or antenna source.
Figure 6. Cables come in
different sizes and have different loss characteristics
Try to keep cable
lengths to 15 Ft or less when possible. If further distance is needed and
relocating the AP is not possible then look at LMR-600 or better as it has less
Figure 7. Popular coaxial