• When you use any cellular antennas such as 3G UMTS, 4G/LTE, 4G/LTEA (LTE Advanced) with a
modular router and a pluggable module, try to mount the antenna a certain distance away from the router.
For example, in indoor deployments, an appropriate extension cable and antenna stand can be utilized.
For outdoor installations, choose a suitable outdoor antenna, and mount it away from obstructions that
ideally have a direct view of the cellular tower. The antenna performance, and therefore that of the router,
will not be optimal if mounted directly on a pluggable module. Primary reasons for possible degradation
of performance include:
• Obstruction of the router antenna view of the cellular base station tower by Ethernet cables, power
cables, USB cables, and walls.
• Possible coupling of digital noise from inside the router to the antenna when unshielded Ethernet
cables are used.
• Keep antennas away from electrical and signal cable clutter. Metal conductors inside cables may block
antenna view of the base station. Additionally, unshielded (and even shielded cables in some cases) may
radiate signals that interfere with RF signal reception.
• It is recommended that all cellular antennas for the IR1800 are oriented vertically to ensure polarization
match. While polarization of the signal may change as it is reflected from obstructions, when the view
is unobstructed - vertical polarization is optimal.
• When installing the IR1800 the following note is important:
When cellular FDD Band 5 is deployed with 3G WCDMA, 4G/LTE or 4G/LTEA C/A, such as with P-LTE-US
or P-LTEA-EA pluggable modules on certain carriers, ensure that both Main and Aux cellular antennas are
physically separated from the IR1800 chassis by a minimum of 5 feet (1.5 meters). This note only affects
P-LTE-xx receiver operation in Band 5 in a narrow 875 MHz frequency range. No significant effect on the
P-LTE-xx cellular Band 5 receiver has been measured when antennas are separated from the chassis by more
than 5 feet (1.5 meters). This note does not apply when the receive signal does not overlap 875 MHz, such as
when operating on other bands, or other frequencies within FDD Band 5.
Note
• For optimal MIMO performance, space cellular Main and Aux antennas apart by at least 17 inches (43
cm). At the lowest LTE frequency of 700 MHz, 17 inches represents 1 wavelength. Spacing of half (or
0.5) wavelength or 8.5 inch (22.5cm) results in good MIMO performance.
• Spacing Main and Aux LTE antennas less than 8.5 inches may result in significantly reduced MIMO
performance.
• Spacing antennas too close to each other (e.g. 3 inches) results in antennas significantly detuning from
their original designed performance due to antenna coupling.
• Wherever possible, mount the IR1800 router with the pluggable LTE module and antenna where the
cellular base station or tower are within sight and without physical obstructions. Barriers along the line
of sight between the router and the local base station will degrade the wireless radio signals. Install the
IR1800, pluggable modules and antennas above floor level in office environments or near the ceiling for
better performance because most obstructions tend to be near the floor level.
• The density of the materials used in a building's construction determines the number of walls the signal
must pass through while still maintaining adequate coverage. Consider the following before choosing
the location for installing the antenna:
• Paper and vinyl walls have very little effect on signal penetration.
• Solid and precast concrete walls limit signal penetration to one or two walls without degradation of
coverage.
• Concrete and wood block walls limit signal penetration to three or four walls.
• A signal can penetrate five or six walls constructed of drywall or wood.
Cisco Catalyst IR1800 Rugged Series Router Hardware Installation Guide
40
Antenna Selection and Installation
Antenna Installation Best Practices
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