ANT-418-CW-QW
Data Sheet
Product Description
CW Series ¼-wave antennas deliver outstanding
performance in a rugged and cosmetically
attractive package. These antennas are available
with standard SMA or FCC Part 15 compliant
RP-SMA connectors. RP-SMA connectors allow
for easy field replacement while complying with
FCC requirements. A wide variety of matching
connectors permit numerous mounting options.
7.8 mm
(0.31")
by
13.0 mm
(0.51")
Features
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Low cost
Excellent performance
Omni-directional pattern
Wide bandwidth
Very low VSWR
Fully weatherized
Flexible main shaft
Rugged & damage-resistant
SMA or Part 15 compliant RP-SMA connector
Use with plastic* or metal enclosures
178.0 mm
(7.01")
6.0 mm
(0.24")
14.5 mm
(0.57")
*Requires proximity ground plane
Electrical Specifications
Center Frequency:
Recom. Freq. Range:
Wavelength:
Peak Gain:
VSWR:
Impedance:
Connector:
Oper. Temp. Range:
418MHz
380–450MHz
¼-wave
2.9dBi
<1.9 typ. at center
50-ohms
RP-SMA or SMA
–40°C to +90°C
52.0 mm
(2.05")
6.4 mm
(0.25")
End
View
4.5 mm
(0.18")
Electrical specifications and plots measured on 10.16 cm x
10.16 cm (4.00” x 4.00”) reference ground plane
Ordering Information
ANT-418-CW-QW (with RP-SMA connector)
ANT-418-CW-QW-SMA (with SMA connector)
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Revised 12/9/13
Counterpoise
Quarter-wave or monopole antennas require an associated ground plane
counterpoise for proper operation. The size and location of the ground
plate relative to the antenna will affect the overall performance of the
antenna in the final design. When used in conjunction with a ground
plane smaller than that used to tune the antenna, the center frequency
typically will shift higher in frequency and the bandwidth will decrease.
The proximity of other circuit elements and packaging near the antenna
will also affect the final performance. For further discussion and guidance
on the importance of the ground plane counterpoise, please refer to Linx
Application Note AN-00501: Understanding Antenna Specifications and
Operation.
VSWR Graph
VSWR
3:1
1.158
Reflected Power
25%
2:1
11%
1:1
318MHz
418MHz
0%
518MHz
What is VSWR?
The Voltage Standing Wave Ratio (VSWR) is a measurement of how well
an antenna is matched to a source impedance, typically 50-ohms. It is
calculated by measuring the voltage wave that is headed toward the load
versus the voltage wave that is reflected back from the load. A perfect
match will have a VSWR of 1:1. The higher the first number, the worse the
match, and the more inefficient the system. Since a perfect match cannot
ever be obtained, some benchmark for performance needs to be set. In
the case of antenna VSWR, this is usually 2:1. At this point, 88.9% of the
energy sent to the antenna by the transmitter is radiated into free space
and 11.1% is either reflected back into the source or lost as heat on
the structure of the antenna. In the other direction, 88.9% of the energy
recovered by the antenna is transferred into the receiver. As a side note,
since the “:1” is always implied, many data sheets will remove it and just
display the first number.
How to Read a VSWR Graph
VSWR is usually displayed graphically versus frequency. The lowest point
on the graph is the antenna’s operational center frequency. In most cases,
this will be different than the designed center frequency due to fabrication
tolerances. The VSWR at that point denotes how close to 50-ohms the
antenna gets. Linx specifies the recommended bandwidth as the range
where the typical antenna VSWR is less than 2:1.
159 Ort Lane, Merlin, OR, US 97532
Phone: +1 541 471 6256
Fax: +1 541 471 6251
www.linxtechnologies.com
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Data Sheet ANT-418-CW-QW
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