AL3A-RM User Guide Version B
Document Number: 451-93156-002B
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3
A
NTENNA
C
ONNECTOR
The A3LA-RM modem uses a single Threaded Neill–Concelman (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 3 dB at the operating frequency of 1616 to 1626.5 MHz. The minimum
link margin of 12 dB must also be maintained. General RF parameters are listed in the table
below.
Table 2: General RF Parameters
Type
Description
Frequency Range
1616 to 1626.5 MHz
Input/Output Impedance 50 Ohms
Oscillator Stability
±1.5 ppm
NAL Research offers several types of antennas for use with the A3LA-RM 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 recommends model SYN7391-C. If the specific application requires a custom antenna,
it must meet the specifications below.
Table 3: Custom Antenna Specifications
Parameter
Value
Operating Temperature Range
–40°C/+85°C without loss of function
Measurement Frequency Range 1616 to 1626.5 MHz
VSWR
< 1.5 : 1
Maximum Gain
3 dBic
Nominal Impedance
50 Ohms
Polarization
Right-handed circular polarization (RHCP)
Basic Pattern
Omnidirectional and hemispherical
