ANT-433-CW-RH
Data Sheet
Product Description
The RH Series utilizes a helical element to greatly
reduce the physical length of the antenna housing.
They are ideal for small products where cosmetic
or functional requirements dictate a compact,
aesthetically pleasing antenna package. Despite
their tiny size, RH Series antennas are ruggedly
constructed and able to withstand punishing
environments just like our larger whips. RH Series
antennas attach via an SMA or Part 15 compliant
RP-SMA connector.
8.0 mm
(0.31")
by
51.0 mm
(2.00")
Features
•
•
•
•
•
•
•
•
•
Reduced-height helical whip
Excellent performance
Omni-directional pattern
Low VSWR
Fully weatherized
Rugged & damage-resistant
SMA or Part 15 compliant RP-SMA connector
Available in black or custom colors
Use with plastic* or metal enclosures
3.8 mm
(0.15")
10.0 mm
(0.39")
8.5 mm
(0.33")
* Requires proximity ground plane
Electrical Specifications
Center Frequency:
Recom. Freq. Range:
Wavelength:
VSWR:
Peak Gain:
Impedance:
Oper. Temp. Range:
Connector:
433MHz
425–440MHz
¼-wave
< 1.9 typical at center
–5.6dBi
50-ohms
–40°C to +90°C
RP-SMA or SMA
3.6 mm
(0.14")
Electrical specifications and plots measured on 10.16 cm x
10.16 cm (4.00" x 4.00”) reference ground plane
Ordering Information
ANT-433-CW-RH (with RP-SMA connector)
ANT-433-CW-RH-SMA (with SMA connector)
–
1
–
Revised 12/5/13
Counterpoise
Quarter-wave or monopole antennas require an associated ground plane
counterpoise for proper operation. The size and location of the ground
plane 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
1.861
Reflected Power
25%
2:1
11%
1:1
395.5MHz
433MHz
0%
470.5MHz
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.
–2
–
Data Sheet ANT-433-CW-RH
by
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