Compact Antenna for Bluetooth "SF2450"

1.

INTRODUCTION

Along with the recent development of the Bluetooth market, we frequently hear the release news of electronicequipment provided with the Bluetooth functions including
notebook PCs, mobile phones, digital cameras and headsets. In order for the Bluetooth system to be enhanced in
the convenience, it is essential that the system beinstalled in a number of equipment of diversified areas,
sharing varieties of application software within the network. For such wide acceptance of the Bluetooth equipment in the marketplace, the components have to be not
only compact in size and low in cost but also provided withsatisfactory characteristics to ensure its availability in a
multitude of environments.
In an effort to meet such requirements mentioned
above, Furukawa Electric has developed a compact
antenna --one of the key devices of the Bluetooth system-- based on our proprietary technology. See Photo 1.
The features and specifications of the antenna "SF2450"
will be described below.

Photo 1

Appearance of SF2450.

2,90,7FEATURES

8,82.

80,41,40,70,7

Figure 1

Outer dimensions of SF2450.

32.8
2.6
2.4VSWR

1) Ultra-compact and Ultra-slim Package
Figure 1 shows the outer dimensions. We have beensuccessful in making the antenna small in size and low in
profile by utilizing our proprietary technology of radiating
element configuration as well as using a dielectric materialof high dielectric constant. The product is tape mounted
for automatic loading enabling surface mounting.
2) Wide Bandwidth
Although downsizing of antennas ordinarily results inlimited bandwidth, we have been successful, based on ourproprietary technology of antenna radiator configuration,in achieving an antenna bandwidth that is twice as much
as is required for the Bluetooth equipment irrespective of
the small size mentioned above. See Figure 2.
3) High Efficiency
High radiation efficiency has been attained by configuring the antenna radiators of proprietary shape using acopper alloy of high electrical conductivity, followed bymolding the product using a dielectric material of low dissipation factor. Figure 3 shows a typical radiation pattern.

0,4

1,45

2.2
2
1.8
1.6
1.4
1.2
1
2.25

2.3

2.35

2.4

2.45

2.5

2.55

2.62.65

Frequency (MHz)Figure 2

Input impedance of SF2450.

1xy-plane (dBi)

10Eθ
Max. Gain = 2.40
Ave. Gain = 0.17-10-30

ZEθ
Eφ-50
YXEφMax. Gain = -7.49
Ave. Gain = -14.27

SF2450
GND

Figure 3

X

Typical radiation pattern of SF2450.

4) Low Cost
A manufacturing method has been established in which
the radiator conductor is stamped by a press, inserted intoa die, and is subsequently injection molded. This method
is suited for continuous manufacturing of automatic operation, contributing to the reduction of costs. Moreover, theadoption of such high-precision manufacturing methods
as stamping and injection molding has resulted in a stabilized standard of product quality, suppressing the variationin product performance.
As described above, SF2450 has a number of features.
It is ultra compact and ultra slim, so that it permits installation in compact equipment of high packing density withlimited space for mounting. It has a wide bandwidth, sothat it allows for ensuring required bandwidths in case of
frequency shift occurrence due to the environment. Thus,
it is applicable to a variety of Bluetooth equipment.

3.

IN CONCLUSION

With its outstanding features, the product is expected todemonstrate its capability in various Bluetooth equipment.
However, it is known that an antenna is likely to change its
characteristics under the influence of grounding conditions, the position of mounting and other components
mounted around it. So it is recommended to make final
evaluation using actual equipment.
For more information, please contact:
Marketing Promotion Department
TEL: +81-3-3286-3204
FAX: +81-3-3286-3928

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Furukawa Review, No. 222002