LNA Assembly
The LNA board inside the antenna assembly filters the received signals
from the antenna, thereby rejecting any chance of interference
degrading the GPS signals. A Low Noise Amplifier section providing
a gain of 23 dB and a noise figure of 3.0 dB follows. An RF cable
connects this amplified signal to the TNC connector for the external
connection to the receiver board. This connector is sealed against the
side to the mounting plate with an environmental gasket. The
connector feeds the GPS signals to the GPS Receiver while accepting
4.5 Vdc to power the LNA circuitry.
Mounting Plate
The mounting plate provides:
• A platform to attach the radiator element and the LNA board
• A mount for the TNC connector
• With the radome, provides environmental protection for the
internal circuits
• A 5/8" coarse threaded hole in the base for a tripod mount
• Holes threaded for #6-32 screws for alternative mounting
The antenna can be mounted on a common surveying tripod using the
5/8" tripod threaded hole. Four extra mounting holes threaded for #6-
32 screws are provided under the mounting plate for alternative
mounting configurations. Another set of six threaded holes for #6-32
screws is provided directly under the antenna to allow mounting of
large ground planes for additional multipath rejection.
GPSAntenna
Model 501
Mounting plate
(botto m vi ew)
#6-32 UNC (6 places)
Ground Plane mounting
#6-32 UNC (4 places)
Platform mounting
5/8" UNC
Tripod mount

Figure 3 GPSAntenna Base

Radome
The radome is attached to the mounting plate and protects the radiator
from performance degradation in outside environments. The low loss
material ensures that the received signals are not attenuated.
Installation

Selecting a site

For best reception, choose an antenna location that has a clear view of
the sky down to the horizon in all directions. This will ensure that all
satellites in view can be tracked without obstruction. In some cases it
may be required to mount the antenna on an elevated structure to
ensure unobstructed reception.
It is important to note that large structures near the antenna may block
reception of satellite signals, and metallic structures could cause
multipath reception.
NovAtel’s GPSAntenna is designed to minimize the effects of
multipath reception. However, if additional multipath reduction is
required, the GPSAntenna can be mounted onto a flat ground plane or
the optional GPSAntenna Choke Ring ground plane.
Tripod Mounting
Refer to Figure 4 for mounting onto a standard surveyor’s tripod.
Ensure that the tripod platform is level before mounting the
GPSAntenna. It may be necessary to secure the tripod legs to weights
if you are surveying in a windy environment or if it will be left
standing for an extended period of time.
• Connect the coaxial cable TNC-male connector to the
GPSAntenna
TNC-female connector; screw on finger-tight.
• Set the GPSAntenna onto the tripod platform.
• Secure the GPSAntenna to the platform with the standard
5/8" mounting bolt.
3 4