ANT-315-SP Datasheet by Linx Technologies Inc.

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Anienna Lih‘x Splatchw AntennaFackox ANTJS‘W 55F: *1“ axr—w
1 Revised 1/3/2017
Recommended Footprint
Recommended Mounting
38.86 mm
(1.53 in)
6.32 mm
(0.25 in)
No ground plane or traces
under the antenna
Ground plane on bottom
layer for counterpoise
50-ohm microstrip line
Vias to ground plane
PCB pads for the Splatch
15.48 mm
(0.57 in)
37.85 mm
(1.49 in)
98.55 mm
(3.88 in)
83.57 mm
(3.29 in)
0.51 mm
(0.02 in)
0.51 mm
(0.02 in)
Product Description
The Splatch 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 Splatch exhibits good proximity
performance, making it an appropriate choice for
handheld applications such as remote controls,
pagers and alert devices.
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
Electrical Specifications
Center Frequency: 315MHz
Recom. Freq. Range: 312–317MHz
Bandwidth: 5MHz
Wavelength: ¼-wave
VSWR: 1.9 typ. at center
Impedance: 50-ohms
Connection: Surface-mount
Oper. Temp. Range: –40°C to +130°C
Electrical specifications and plots measured on 3.8 cm x 8.4 cm
(1.50” x 3.30”) reference ground plane.
Ordering Information
ANT-315-SP (supplied in tubes of 20 pieces)
ANT-315-SP-T (Tape and reel of 500 pieces)
ANT-315-SP
Data Sheet by
27.94 mm
(1.10")
1.5 mm
(0.06")
13.7 mm
(0.54")
5.1 mm
(0.20")
1.27 mm
(0.05")
2.03 mm
(0.08")
5.1 mm
(0.20")
2.54 mm
(0.10")
Please see AN-00502 for more details on PCB layout.
VSWR V1558 Reflected Power 277.5MHZ 315MHz 352.5MHZ AniennaFactor Lir'Ix
2
Copyright © 2017 Linx Technologies
159 Ort Lane, Merlin, OR 97532
Phone: +1 541 471 6256
Fax: +1 541 471 6251
www.linxtechnologies.com
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
by
ANT-315-SP Data Sheet
3:1
2:1
1:1
277.5MHz 315MHz 352.5MHz
VSWR 1.558
25%
11%
0%
Reflected Powe
r
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 has 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 is 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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