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Matching Impedance of Bluetooth Antenna

Matching Impedance of Bluetooth Antenna
Abstract— Bluetooth is a well-known, short-range
technology for Wireless Personal Area Networks (WPAN).
Starting from a headset cable replacement it has been
extended to support flexible ad-hoc networks. The
purpose of this thesis was to demonstrate and
study Bluetooth technology
and Bluetooth application
Keywords—Bluetooth, WPAN, Ad-hoc network, Bluetooth
application and technology, headset cable.
Antenna matching is an important aspect of any RF
system. A properly designed and matched antenna increases
the operating distance of the wireless product. Well matched
antennas can transmit more power from the radio – therefore
transmit over longer distances. Likewise, a well matched
antenna allows the maximum transfer of energy from the
receiving antenna to the receiver front end. Thus, allowing
better receive characteristics for the system. Antenna
matching becomes critical as antennas are reduced in size and
placed in small modules that can experience wide temperature
ranges and potentially have foreign objects in proximity. This
paper discusses one class of intermediate Q capacitors used
for SMT antenna matching.
Bluetooth Technology. Bluetooth is
technology standard invented by Ericsson in 1994 for
exchanging data over short distances using short-wavelength
UHF radio waves (Range: 2.4 to 2.485 GHz) from fixed and
mobile devices..
Because the typical Bluetooth radio is part of a mobile
device, a Bluetooth device must be able to dynamically locate
devices within the area. A Bluetooth device must also be able
to determine what services are on the devices found. The
Bluetooth specification separates discovery of devices and
discovery of services into separate processes. In the device
discovery process, the local Bluetooth device finds the other
Bluetooth devices in the area. In the service discovery process,
the Bluetooth device determines which services the other
devices have running on them.
In Bluetooth terms, device discovery is known as inquiry.
When a Bluetooth device issues an inquiry, the other devices
in the area respond to the inquiry requests depending on their
discoverable mode. These devices respond with their
Bluetooth address and class of device record. The Bluetooth
address is a 6-byte unique identifier assigned to every
Bluetooth device by the manufacturer. The class of device
record describes the type of Bluetooth device and provides a
general indication of the types of services available on the
At the time of publication, the Bluetooth SIG had defined
two type of inquiries: general and limited. A general
inquiry is used to find all the Bluetooth devices in an area.
A limited inquiry is used to find all devices in an area that
are discoverable for only a limited length of time. A
general inquiry is similar to asking all people in a room to
say their names. A limited inquiry is similar to asking all
people in a room to say their names only if they are
accountants. Which devices respond to an inquiry request
depends on the discoverable mode of the device. A
Bluetooth device can be general, limited, or not
discoverable. A general discoverable device responds only
to general inquiries. Limited discoverable devices respond
to general and limited inquiries. A device cannot respond
to any inquiries if it is not discoverable.
Any structure that is resonant at 2.45 GHz with bandwidth
more than 100 MHz and efficiency >50% can be considered a
Bluetooth antenna. Therefore, a countless variety of antennas
can be used, and they are application-specific.
 Wire Monopole — This consists of a simple wire
soldered at one end from which it is fed against a
ground plane. It is trimmed to be resonant at 2.45 GHz
and provides good performance and high efficiency.
The disadvantage of this antenna is that it is not low
profile because it projects above the PCB.
 PIFA — The Printed Inverted F Antenna is like a
monopole printed on a PCB, but it has a ground point
and feed point along the main resonant structure.
 Helix — Similar to the wire monopole, except that it is
coiled around a central core (usually air) making the
physical dimensions smaller. It provides excellent
performance, but projects above the PCB.
 Ceramic — Surface mount dielectric antennas are the
smallest types of antennas available, because they are
printed on a high-dk ceramic slab, which makes the
electric field concentrated allowing the antenna to be
made small while keeping a high resonant frequency.
A. Survey for Bluetooth
SMT antenna
This paper discusses one
class of intermediate Q
capacitors used
6-byte unique
The format is a welldefined sequence of 32
hex digits grouped into
chunks of 8-4-4-4-12.
This gives us 2^128 or
about 10^38 numbers.
Bluetooth Low Energy is a proper name according
to the Bluetooth Core Specification.
It is written capitalized by the Bluetooth
The same is true for the Mesh Profile (it is written
capitalized throughout the Mesh Profile
B. Some Common Mistakes for Bluetooth
The Problems include failing to pair, audio hiccups, and
recurring dropped connections, The situation usually involves
a Few Bluetooth devices – say a phone a smartwatch, and a
car stereo, trying to get along. Sometimes the conflict is
between a phone, a fitness tracker, and Bluetooth headphones.
D. Figures and Tables
A brief list of the Bluetooth Antenna methods that need
to be implemented is given in Table 1.
Fig. 1.
Brief Description
Ad-hoc Network
Composed of individual
devices communicating
with each other directly.
It avoids interference from other wireless
It has lower power consumption.
It is easily upgradable.
It has range better than infrared communication.
The Bluetooth is used for voice and data transfer.
Bluetooth devices are available at very cheap
No line sight hence can connect through any
Free to use if the device is installed with
The technology is adopted in many products such
as head set, in car system, printer, web cam, Gps
system, Keyboard and mouse.
https://www.sciencedirect.com/topics/computerscience/bluetooth-radio - Ease of use for Bluetooth (activate)
https://www.avx.com/docs/techinfo/whitepapers/AVX-WhitepaperBluetooth-AntennaMatching.pdf - Bluetooth Antenna matching PDF.
Introduction for Bluetooth Antenna
X - Survey for Bluetooth Matching Impedance. (activate)
- IEEE Reference example pdf
https://thewirecutter.com/blog/understanding-bluetooth-pairingproblems/ Some common problems/mistakes ‘bout Bluetooth Antenna
https://www.polytechnichub.com/advantages-disadvantagesbluetooth/ - Advantages and Disadvantages of Bluetooth Antenna
Public Member Fuctions
The are some important advantages of Bluetooth are given
C. Backgroud forBluetooth Antenna
Many applications are driven into small size modules for
cost and ease of system integration. An example of this is
automotive Bluetooth modules. In this case, the use of SMT
chip antennas offers a very good solution to designers. SMT
chip antennas take up minimal PCB area and offer reasonable
performance across frequency. However, the use of chip
antennas typically increases the BOM and assembly expense
over PCB and wire antennas. Additionally, SMT antennas
performance is very relative to the ground plane they are
placed upon. Unlike PCB and wire antennas – they cannot be
trimmed to accomplish tuning. Therefore, external
components are required for tuning and impedance matching.
The goal of impedance matching is to match the module’s
output to the 50 ohm load of the antenna. Once this is
accomplished most of the power from the RF source is
delivered to the load in the transmit mode, and most energy is
transferred from the antenna to the receiver front end in the
receive mode. The exact circuit for matching an antenna and
module will depend upon the antenna type, RF module used,
ground plane, and system specifics etc. Regardless of the exact
system details – inductors and capacitors will be used in a
variety of configurations to accomplish the necessary
impedance transformation to accomplish matching. An
example of one type of matching network is shown below.
To include all necessary
parts for a functioning
system as well as basc
compotents and
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with each other directly.
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