ANT-433- SP
Data Sheet
Product Description
The µSplatch™ uses a grounded-line technique
to achieve outstanding performance from a tiny
surface-mount element. This unique antenna is
designed for hand or reflow-mounting directly to a
product’s circuit board. Its low cost makes it ideal
for volume applications. Unlike many compact
antennas, the µSplatch™ exhibits good proximity
performance, making it an appropriate choice for
handheld applications such as remote controls,
pagers and alert devices.
0.5"
(12.70)
by
0.36"
(9.14)
0.103"
(2.62)
0.20"
(5.1)
0.05"
(1.27)
Features
•
•
•
•
•
•
•
Very low-cost
Ultra-compact package
Direct PCB attachment
Ideal for concealed / internal mounting
Perfect for compact portable devices
Suitable for hand or reflow-assembly
Resistant to proximity effects
Recommended Footprint
0.20"
0.10"
0.08"
Recommended Mounting
Electrical Specifications
Center frequency:
Bandwidth:
Wavelength:
VSWR:
Peak gain:
Impedance:
Connection:
433MHz
7MHz
¼-wave
≤
2.0 typical at center
–9.8dBi
50-ohms
Surface-mount
0.280”
(7.11)
0.415”
(10.54)
No ground plane or traces
under the antenna
PCB pads for the
µSplatch
Vias to ground plane
Ground plane on bottom
layer for counterpoise
50-ohm microstrip line
(0.21” minimum)
1.590”
(40.37)
Electrical specifications and plots measured with a 1.53" x
3.145" reference ground plane.
Ordering Information
ANT-433-USP (supplied in tubes of 63 pieces)
3.615”
(91.82)
3.145”
(79.88)
0.030”
(7.62)
1.530”
(38.86)
0.030”
(7.62)
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Revised 12/28/12
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
1.65
Reflected Power
25%
2:1
11%
1:1
383MHz
433MHz
0%
483MHz
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.
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Data Sheet ANT-433-µSP
by
Gain Plots
E / Vertical Gain
H / Horizontal Gain
Total Gain
XZ-Plane Gain
YZ-Plane Gain
XY-Plane Gain
About Gain Plots
The true measure of the effectiveness of an antenna in any given applica-
tion is determined by the gain and radiation pattern measurement. For
antennas gain is typically measured relative to a perfect (isotropic) radia-
tor having the same source power as the antenna under test, the units of
gain in this case will be decibels isotropic (dBi). The radiation pattern is a
graphical representation of signal strength measured at fixed distance from
the antenna.
Gain when applied to antennas is a measure of how the antenna radiates
and focuses the energy received into free space. Much like a flashlight
focuses light from a bulb into a specific direction, antennas can focus RF
energy into specific directions. Gain in this sense refers to an increase in
energy in one direction over others.
It should also be understood that gain is not “free”, gain above 0dBi in one
direction means that there must be less gain in another direction. Pictori-
ally this can be pictured as shown in the figures to the right. The orange
pattern represents the radiation pattern for a perfect dipole antenna,
which is shaped like a donut. The pattern for an omnidirectional antenna
with gain is shown in blue. The gain antenna is able to work with a device
located further from the center along the axis of the pattern, but not with
devices closer to the center when they are off the axis – the donut has
been squished.
Gain is also related to the overall physical size of the antenna, as well as
surrounding materials. As the geometry of the antenna is reduced below
the effective wavelength (considered an electrically small antenna) the gain
will decrease. As well, the relative distance between an electrically small
antenna and its associated ground will impact antenna gain.
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-433-µSP
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