Follow these guidelines to ensure the best possible performance:
• When you use cellular antennas such as 4G/LTE, 4G/LTEA (LTE Advanced), and 5G NR FR1 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 IR8340 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 cellular FDD Band 5 is deployed with 4G/LTE or 4G/LTEA C/A, such as
with P-LTEA-EA pluggable modules on certain carriers, ensure that both Main
and Aux cellular antennas are physically separated from the IR8340 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, set the cellular Main and Aux antennas apart by at least 20 inches (50
cm). At the lowest LTE frequency of 617 MHz, 20 inches represents 1 wavelength. Spacing of half (or
0.5) wavelength or 10 inch (25 cm) results in good MIMO performance.
• Spacing Main and Aux LTE antennas less than 10 inches may result in significantly reduced MIMO
performance.
• Spacing antennas too close to each other, for example, 3 inches, results in antennas significantly detuning
from their original designed performance due to antenna coupling.
• Wherever possible, mount the IR8340 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
IR8340, 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.
Cisco Catalyst IR8340 Rugged Series Router Hardware Installation Guide
54
Antenna Selection and Installation
Antenna Installation Best Practices