SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
1
Product Description
Built on patented PowerHelix® fi ltering
antenna technology, the SL1250 GPS antenna
provides high performance in diffi cult GPS applications
using a quadrafi lar helix design. The SL1250 antenna is
ideal in applications where:
• the device is handheld, body-worn, or otherwise surrounded by
high-dielectric materials that would de-tune conventional antennas;
• the antenna is tightly integrated with other antennas, e.g., Bluetooth®/GPS
receivers or GPS/GSM mobile phones;
• there are tight constraints on the size of the device or the amount of space
allocated to ground planes;
• the orientation of the device is random; or
• the antenna will be embedded in the device.
The SL1250 antenna is balanced, which isolates it from the device and enables the
antenna to reject common mode noise resident on the device ground plane. The construction
and materials of the antenna constrain its near-fi eld to a very small volume, therefore materials
near the antenna have negligible de-tuning effects and the antenna maintains its pattern and
effi ciency in the presence of dielectric loading. As a dielectrically-loaded antenna, the SL1250
acts as its own fi lter, attenuating signals from common GSM and ISM frequencies by as much as 30dB with-
out external fi ltering.
The SL1250 is similar in size to the SL1200, using the same ceramic element, but has a number of enhance-
ments over the SL1200. These include:
Improved antenna ruggedness. The new feed system requires less mechanical support and is capable of
withstanding higher stresses
Simplifi ed interconnection system. Antenna can be connected using either simple contacts or hot air
soldered to the product board
Specifi cations
Minimum Typical Maximum Unit
Part Number SL1251 (Embedded) or SL1252 (Low Frequency) Each
TypeQuadrafi lar Helix
Embedded Frequency 1575.42 MHz
Polarization Right-hand circular polarized
Integrated Gain(on PCB-see page 4) -3.0dBic dBic @ zenith
Beamwidth >135 Degrees
Bandwidth (3dB) 15 MHz
Axial Ratio(Free Space) <1.5 @Zenith
VSWR <2.0:1 2.3:1
Impedance 50 Ω
Operating Temperature -40 +20 +85 °C
Element Dimensions 10 (diameter) x 17.75 (length) mm
Weight 7.0 grams
•
•
SL1250 GeoHelix®
Passive GPS Antenna
v5 Iss 12-12 © Sarantel Ltd. 2012
Sarantel UK
info@sarantel.com
www.sarantel.com Specifi cations subject to change
SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
2
Radiating
Section
Balun
Gnd Gnd
RF(50Ω)
Styron Sleeve for
Embedding
The SL1250 GPS antenna provides similar
performance to the SL1200 (GeoHelix-P2)
antenna, with typical peak gain of ≈-3dBic,
excellent beamwidth and strong circular
polarization.
The strength of the PowerHelix antenna
technology is its immunity to de-tuning in the
presence of dielectric loading, like human
tissues. GeoHelix antennas retains effi ciency and
polarization near the human body. Conventional
antennas lose 5-10dB of gain in similar
circumstances.
Though it will not electrically couple with a ground
plane, the SL1250 antenna can be expected to
increase effi ciency by up to 30% when mounted
over a ground plane due to near-fi eld signal
refl ections. Confi guration and orientation of the
ground plane with respect to the antenna will vary
results, but effi ciency will not decrease.
The SL1250 antenna is optimized for 50Ω
impedance to simplify the matching process.
The Smith chart showing a typical impedance
plot of the antenna has been normalized to 1.
The resonant frequency of the antenna is shown
at the marker, and the bandwidth of the antenna
is shown by the dimensions of the loop. The
red circle shows the VSWR<=2.3:1 impedance
mask.
As with the pattern chart, it is important to note
the immunity of the antenna to loading factors
in close proximity. It can be seen that the
impedance of the antenna changes very little
until a phantom hand is placed inside a radius of
10mm from the antenna.
Radiation Pattern (dBic)
Typical Impedance
SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
3
Return Loss
Immunity from bio-loading effects can
be demonstrated effectively through the
S11 plot. While some change in match
is observed as a phantom hand is
moved closer to the radiating section of
the antenna, minimal de-tuning occurs.
The SL1250 antenna also demonstrates
a sharp fi ltering response in bands near
the desired resonant frequency.
Filtering Response
SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
4
Embedding Information
The SL1250 antenna is available with two frequency
options, the SL1251 with a free space frequency of
1603.5MHz and the SL1252 with a free space frequency
of 1593.5MHz, to suit various embedding requirements.
The SL1251 antenna is typically designed to be embedded
in a device with the plastic tuning sleeve to ensure on-
frequency performance. Ground planes within 5mm of the
antenna radiating section can affect the performance of
the antenna.
The SL1252 antenna is designed to be typically mounted
externally either with the radome available from Sarantel
or within the customers own radome.
See the Ordering Guide section of this document for details
on which version of the antenna should be ordered to
suit specifi c requirements. Additional mechanical support
should be provided to hold the antenna in place.
For further information on embedding either the SL1251
or SL1252 antennas please refer to the Mechanical
Integration Guideline documents available on the Sarantel
website
Ordering Guide for the SL1250 antenna
Part Number Description MOQ Pack Size
SL1251 GeoHelix® P2.5 Emb Ant 800 400
SL1251SF GeoHelix® P2.5 Emb Ant+Sleeve 800 400
SL1252 GeoHelix® P2.5 LF Ant 800 400
SL1252SF GeoHelix® P2.5 LF Ant+Sleeve 800 400
SL1252R GeoHelix® P2.5 LF Ant+Radome 800 400
Notes
1. Orders placed for below MOQ or not in multiples of pack quantities will be subject to a $50
handling fee
2. For further guidance on selecting the correct part number please contact Sarantel distributors or
info@sarantel.com
SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
5
Mechanical Drawings - SL1250
SARANTEL CONFIDENTIAL
FIRST ANGLE
PROJECTION
REMOVE ALL BURRS
AND SHARP EDGES
MATERIAL FINISH TOLERANCES
DIMENSIONS WITH NO DECIMAL PLACE ±0.5
DIMENSIONS WITH ONE DECIMAL PLACE ±0.1
DIMENSIONS WITH TWO DECIMAL PLACES ±0.05
OTHER TOLERANCES TO BE STATED ON DRAWING
ALL DIMENSIONS IN MILLIMETRES
SARANTEL
2 RYLE DRIVE
PARK FARM IND EST
WELLINGBOROUGH
NN8 6BA
TEL +44 01933 670560
FAX +44 01933 401155
USED ON TITLE
DRN
DATE
SCALE
DRG No. ISSUE
ENG.CHECK
ENG.APPROVE
PROD.APPROVE DATE
DATE
DATE
SHEET
1
DRG No. THIS DRAWING, INCLUDING ANY PATENTED OR PATENTABLE FEATURES IS COPYRIGHT
AND SHALL NOT BE LENT, COPIED OR IN ANY WAY REPRODUCED WITHOUT THE WRITTEN
PERMISSION OF SARANTEL LTD. DO NOT SCALE. IF IN DOUBT - ASK
DATEDETAILREV 125110300
SL1251 ANTENNA
125110300
19/06/2012
L.HARDY
2:1
A4
SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
6
Mechanical Drawings - 2010055 Sleeve
SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
7
Mechanical Drawings - 120421202 Radome
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SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
8
RoHS Compliance Statement
SL1250 Product Specifi cation v5 Iss 12-12
Sarantel Propriety Information
9
About Sarantel
Sarantel designs and manufactures dielectrically
loaded antennas based on patented PowerHelix®
fi l tering antenna technology. Sarantel’s antennas
are ideal for applications in which the radio device
is small, handheld, or body-worn, or in devices
with multiple transceivers and high levels of
common mode noise. Sarantel antennas can be
mounted externally or easily embedded within a
device.
GeoHelix®, PowerHelix®, and the Sarantel logo
are registered trademarks of Sarantel Ltd.
Contact Sarantel
Sarantel Ltd. (HQ)
2 Ryle Drive, Park Farm South
Wellingborough, NN8 6BA
United Kingdom
Ph: +44 1933 670564
Fax: +44 1933 401155
Email: info@sarantel.com
Web: www.sarantel.com
Global Distributors & Representatives
www.sarantel.com/wheretobuy
Application Support
Sarantel are committed to our customers’ success, and so
offer a variety of support options for customers designing RF
products.
Check the Sarantel Applications Centre for the latest
production specifi cations, technical notes, and application
guides for solutions to the most common antenna integration
issues.
https://applicationcentre.sarantel.com
Contact our applications support group by email at info@
sarantel.com for detailed product specifi cations, including
mechanical drawings, surface mount pad layout, embedding
recommendations, and other application questions not
answered in the technical literature.
For further support options, please contact your local sales
representative at www.sarantel.com/wheretobuy.
Sarantel strongly believes in the value of intellectual property and the right of entrepreneurs to protect what they have created. Sarantel dem-
onstrates its commitment to this principle by continuously developing its technology and then fi ling patents in a number of regions around the
world. Additionally, Sarantel is constantly fi ling new patent applications and has a substantial portfolio of pending applications.
A list of Sarantel’s granted patents;
Australia; 707488, 716542, 720873, 769570, 2004223229 Austria; 0791978 Brazil; PI9508769-9 Canada; 2198318, 2198375, 2245882, 2250790,
2272389, 2357041, 2373941, 2521493 China; ZL00136656.4, ZL00803562.8, ZL00808144.1, ZL95195772.4, ZL97181567.4, ZL97193099.6,
ZL97194742.2, ZL99816387.2 Denmark; 0777922, 1088367 Finland; 0791978, 0876688, 0935826, 0941557, 1088367, 1098392, 1147571, 1153458,
1196963, 1609213 France; 0777922, 0791978, 0876688, 0935826, 0941557, 1081787, 1088367, 1098392, 1147571, 1153458, 1196963, 1609213
Germany; 60003157.8-0, 60029538.9-08, 60034042.2-08, 602004010085.4-08, 69535431.0-08, 69722590.9-0, 69723093.7-0, 69726177.8-0,
69730369.1-08, 69923558.8-08, 69930407.5-08 India; 193515, 193751, 193929, 195085, 206740 Italy; 0777922, 0791978, 0876688, 0935826, 1081787,
1088367, 1153458, 1196963 Japan; 3489684, 3489775, 3923530, 3946955, 4052800, 4057612, 4077197, 4099309, 4147260, 4159749, 4188412
Malaysia; MY-112473-A, MY-119077-A, MY-119465-A, MY-123075-A Mexico; 199890, 205239, 213947, 220048, 213633, 232437, 232438, 231633,
259577 Netherlands; 0791978, 1081787 New Zealand; 291852, 334614 Philippines; 1-1995-51169, 1-1997-55284, 1-1997-55978, 1-1997-58557, 1-
1999-03167 Russia; 2173009, 2210146, 2339131 Singapore; 37745, 54891, 56480, 116791, 131698 South Korea; 348441, 366071, 446790, 458310,
523092, 625638, 650620, 650621, 650622, 663873, 667216, 667221, 709688, 767329 Spain; 0777922, 0791978, 1088367, 1196963 Sweden; 0777922,
0791978, 0876688, 0935826, 0941557, 1081787, 1088367, 1098392, 1147571, 1153458, 1196963, 1609213 Switzerland; 0791978, 1081787, 1196963
Taiwan; 094978, 108488, 123671, 144801, 156702, 285980, M 312023 Thailand; 17812, 19360, 19570, 23745 United Kingdom; 1081787, 1147571,
2292257, 2292638, 2309592, 2310543, 2311675, 2321785, 2326532, 2326533, 2338605, 2351850, 2356086, 2367429, 2383901, 2399948, 2419037
USA; 5854608, 5859621, 5945963, 5963180, 6181297, 6184845, 6300917, 6369776, 6424316, 6552693, 6690336, 6886237, 6914580, 7256752,
7372427, 7408515
