NAL Research Corporation (TN2009-25-V1.0)
10
4.0 ANTENNA CONNECTOR
The A3LA-XM modem uses a single TNC female 50-ohm connector for both transmit and receive. Cable
loss between the modem and the antenna is critical and must be kept less than 2dB at the operating
frequency of 1616 to 1626.5 MHz. The minimum link margin of 13.1 dB must also be maintained. General
RF parameters are listed in the table below.
NAL Research offers several types of antennas for use with the A3LA-XM modem. These antennas
include the fixed mast, mobile magnetic/permanent mount and portable auxiliary. For low-cost and
applications where small form-factor and light-weight are required, NAL Research highly recommends model
SYN7391-C as shown in Figure 5.
If the specific application requires a custom antenna, it must meet the specifications in the following
table.
It should be noted that the A3LA-XM power transmission profiles may vary for a number of reasons.
Users are reminded to optimize their setup to attain the lowest possible power transmission by the A3LA-
XM. Some of the setup parameters to be carefully observed include:
1.
Have a clear view of the sky for the antenna—poor visibility of the sky is when a clear line-of-sight
is not available between the A3LA-XM‘s antenna and the satellites.
TYPE
DESCRIPTION
Frequency Range
1616 to 1626.5 MHz
Input/Output Impedance
50 Ohms
Oscillator Stability
1.5ppm
PARAMETER
VALUE
Operating Temperature Range
–40
o
C/+85
o
C without loss of function
Measurement Frequency Range
1616 to 1626.5 MHz
Return Loss (Minimum)
9.5 dB (<2:1 VSWR)
Gain
0.0 dBic (weighted average minimum)
Minimum ‗Horizon‘ Gain
–2.0 dBic (82
o
conic average)
Nominal Impedance
50 Ohms
Polarization
Right Hand Circular (RHCP)
Basic Pattern
Omni directional and hemispherical
Figure 5.
NAL Research‘s Antenna SYN7391-C.
