Swarm M138 - Antenna Characteristics

6.2.1 Antenna Characteristics
The Modem is certified with the following antenna as described in Table 15. No power reduction
compensation is required for use with this antenna.
Swarm Coiled ¼ Wave Antenna
Parameter
Value
Length
22 cm
Diameter (Connector)
11.2 mm
Diameter (along major length)
7.6 mm
Weight
31.5 g
Operating Temperature
-55 °C to +130 °C
Operating Humidity
0-100% humidity, condensable
Impedance
50 Ohms nominal
Polarization
Linearly Polarized
VSWR
< 5
Gain
2.0 dBi
Frequency
137.000-138.000 MHz (Rx)
148.000-150.000 MHz (Tx)
Connector
SMA male (U.FL to SMA female cable
required)
Antenna Ground Plane
Required, see section 6.2.2
Antenna Height Requirement
1m above the ground/solid surfaces
Antenna Classification
Mobile, Fixed
Minimum separation distance from body
29cm
Table 15: Antenna characteristics for Swarm Coiled ¼ Wave Antenna.
November 2021 Swarm M138 Modem Manual - Rev 1.00 28/77