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The present invention relates to an antenna according to the pre-characterizing
clause of claim 1.
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In modem information-oriented society, it is desirable that information is
accessible at anytime and at anyplace. Wireless communication equipment is capable
of transmitting signals without the use of cables or optical fibers making wireless
communication undoubtedly the best way to transmit information. As technology
develops, various kinds of wireless communication devices, such as mobile phones
and personal digital assistants (PDAs), have become an important means of
communicating due to their compactness and portability.
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In the field of wireless communication equipment, antennas, which are used to
transmit and receive radio waves in order to transfer and exchange data signals, are
unquestionably one of the most important devices. Especially in modem portable
wireless communication devices, antennas are required to be compact and must be
designed to occupy less space in order to match pace with the miniaturization trend of
portable wireless devices. In addition, as the bit rate of radio data signals (sometimes
measured in units of bits/second) increases, antenna bandwidth requirements increase
as well.
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State-of-the-art planar inverted F antennas (PIFAs) are limited in application. For
example, these antennas are usually positioned on a circuit board having a radiator
being parallel to the circuit board. The height of the antenna cannot be reduced to fit
bandwidth requirements, as material is required due to support feeding and ground
plates. Prior art antennas such as this are not conducive to use in compact wireless
products.
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This in mind, the present invention aims at providing an antenna that is
perpendicularly installed above or to the side of the circuit board in a space efficient
manner.
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This is achieved by an antenna according to claim 1. The dependent claims
pertain to corresponding further developments and improvements.
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As will be seen more clearly from the detailed description following below; the
claimed antenna includes a radiator that is perpendicular to a ground plane of a circuit
board, and further, feeding and ground plate structures to support such a radiator.
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In the following, the invention is further illustrated by way of example, taking
reference to the accompanying drawings. Thereof
- Fig.1 is a diagram of a planar inverted F antenna positioned on a circuit board
according to the prior art,
- Fig.2 is a block diagram of an application of the present invention on a PDA,
- Fig.3 is a diagram of the perpendicularly-oriented inverted F antenna according
to the first embodiment of the present invention,
- Fig.4 is a diagram of an antenna with a feeding plate connected to the upper edge,
and a ground plate connected to the lower edge of the radiator,
- Fig.5 is a schematic diagram of a perpendicularly-oriented inverted F antenna
according to the second embodiment to the present invention, and
- Fig.6 is a schematic diagram of a perpendicularly-oriented inverted F antenna
according to the third embodiment of the present invention.
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Please refer to Fig.1. Fig.1 is a schematic diagram of a planar inverted F antenna
(PIFA) 10 positioned on a circuit board 12 according to the prior art. The antenna 10
is a PIFA connected to the circuit board 12, which includes a radiator 14 for receiving
and transmitting radio frequency (RF) signals, a feeding plate 16 stretching out from
the radiator 14 and connected perpendicularly to a feed pad 18 for transmitting RF
signals, and a ground plate 20 stretching out from the radiator 14 and connected
perpendicularly to the ground plane 22 on the circuit board 12. The antenna 10 is a
single-frequency antenna, which transmits and receives RF signals through the
resonance of the radiator 14. The length of the antenna 14 decides the operation
frequency for transmitting and receiving of RF signals. The transmission of RF signals
between the antenna 10 and the circuit board 12 depends on the connection of the
feeding plate 16 of the antenna 10 and the feed pad 18 of the circuit board 12.
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However, the antenna 10 according to the prior art is limited in application. For
example, because the antenna 10 is positioned on the circuit board 12, the radiator 14
is parallel to the circuit board 12, and furthermore the height of the antenna 10 cannot
be shortened to fit the bandwidth requirements; an additional height is required due to
the existence of the feeding plate 16 and the ground plate 20, that accordingly
influences the size of the antenna 10. Therefore, it is difficult to utilize the antenna 10
according to the prior art when designing compact wireless products.
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Please refer to Fig.2. Fig.2 is a block diagram of an application of the present
invention on a PDA 2. The PDA 2 includes a processing module 3 for controlling the
operation of the PDA 2, a memory 4 to store data of the PDA 2. The memory 4 can be
any kind of storage media, such as CF, SD or MMC flash memories. In order to
implement wireless communication, the PDA 2 further includes a wireless
communication module 5, which includes a baseband circuit 6, an RF circuit 7, and an
antenna 8. The processing module 3 can read out and process the data in the memory 4,
then transmit the processed communication signals to the baseband circuit 6. The
baseband circuit 6 can encode the communication signals from the processing module
3 into baseband signals, then transmit them to the RF circuit 7. The RF circuit 7
modulates the baseband signals into RF signals and transmits them through the
antenna 8. The RF circuit 7 can also receive RF signals through the antenna 8 and
demodulate them into baseband signals. The baseband circuit 6 then decodes them
into communication signals and transmits them to the processing module 3. The
processing module 3 can process the transmitted communication signals and store
them into the memory 4.
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As for the application of the POIFA according to the present invention, please
refer to Fig.3. Fig.3 is a diagram of the perpendicularly-oriented inverted F antenna 24
according to the first embodiment of the present invention. The antenna 24 is
connected to a printed circuit board (PCB) 26. The antenna 24 includes a radiator 28
installed off the PCB 26 for receiving and transmitting RF signals, and a feeding plate
30 stretching out of the radiator 28 and connected to the feed pad 32 on the PCB 26
for transmitting RF signals. The feed pad 32 can receive RF signals from the RF
circuit 7 of the wireless communication device and then transfer them to the antenna
24 for transmission, or receive RF signals from the antenna 24 and transfer them to the
RF circuit 7 of the wireless communication device for demodulation. The antenna 24
further includes a ground plate 34 stretching out from the radiator 28. The ground
plate 34 is connected to a ground plane 36 of the PCB 26. The antenna 24 is a
single-frequency antenna, which transmits and receives RF signals through the
resonance of the radiator 28. The length of the radiator 28 decides the operation
frequency of transmission and reception of RF signals. For example if the antenna 24
is a 1/4 wavelength antenna, the length of the radiator 28 is approximately 1/4 the
wavelength of the transmitted RF signals. The antenna 24 further includes an
expanding plate 38 stretching out from a side of the radiator 28 for capacitive loading,
which can shorten the necessary length of the radiator 28 for receiving RF signals with
a specific frequency. For example, if the expanding plate 38 is attached to the 1/4
wavelength antenna, the length of the radiator 28 can be less than 1/4 of the
wavelength, so that the length of the antenna can be shortened. The transmission of
RF signals in the antenna 24 depends on the connection of the feeding plate 30 of the
antenna 24 and the feed pad 32 of the PCB 26.
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The first embodiment of the present invention can be the application in bluetooth
technology or WLAN(802.11b), and the applied frequency band is between
2400-2483.5MHz. However, this antenna design also can be applied to other
commercial products with 802.11a, GPS and GPRS applications. In Fig.3, the radiator
28 is perpendicular to the ground plane 36 of the PCB 26, for bluetooth or 802.11b
application, the length L1 of the radiator 28 is approximately 26mm, and the width d3
is approximately 1-6mm, which corresponds to a frequency of radio signals
transmittable and receivable by the antenna 24. The distance d1 between the radiator
28 and the PCB 26 is 0.5-2.5mm. The reason for keeping a distance between the
radiator 28 and the PCB 26 is to avoid contact and the electric short that would result,
and additionally to obtain a necessary bandwidth by adjusting the distance d1. The
distance d2 between the feeding plate 30 and the ground plate 34 is 2.5-4.0mm. The
impedance match can be adjusted through adjusting the distance d2. The feeding plate
30 and the ground plate 34 both stretch out from the lower edge of the radiator 28, and
are located on the same side and connected to the PCB 26. The feeding plate 30 and
the ground plate 34 can also be connected to the lower or the upper edge of the
radiator 28 separately. Please refer to Fig.4. Fig.4 is a schematic diagram of an
antenna with a feeding plate 31 connected to the upper edge, and a ground plate 34
connected to the lower edge of the radiator 28. Fig.4 shows one of the variations of
setting the feeding plate 31 and the ground plate 34. The feeding plate 31 and the
ground plate 34 can be installed on the same side or different sides, descriptions of the
other variations are hereby omitted.
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In this embodiment, since the radiator 28 of the antenna 24 is located off of the
PCB 26, and the radiator 28 is perpendicular to the PCB 26, additional PCB 26 space
is saved because the space next to the radiator 28 on the PCB 26 is free for other
devices.
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Please refer to Fig.5. Fig.5 is a diagram of a perpendicularly-oriented inverted F
antenna 40 according to the second embodiment of the present invention. Because the
components of the second embodiment are practically the same to those in the first
embodiment, the numbering used in Fig.3 is also used in Fig.5. The antenna 40 is
connected to a PCB 26, and includes a radiator 28 installed off the PCB 26 for
receiving and transmitting RF signals, a feeding plate 30 stretching out from the
radiator 28 and connected to a feed pad 32 of the PCB 26 for transmitting RF signals,
and a ground plate 34 stretching out from the radiator 28 and connected to a ground
plane 36 of the PCB 26.
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The functions of the components in the second embodiment are the same to those
in the first embodiment; therefore function descriptions are hereby omitted. The only
difference between the two embodiments is that the feeding plate 30 and the ground
plate 34 according to the second embodiment both stretch out from the upper edge of
the radiator 28, instead of the lower edge as according to the first embodiment.
Therefore the radiator 28 according to the second embodiment is located off the PCB
26 and positioned along the PCB 26 edge, instead of being located above the PCB 26
as according to the first embodiment. Again, a distance d1 is maintained between the
radiator 28 and the PCB 26 in order to avoid contact and the resulting electrical short.
Additionally, to obtain a necessary bandwidth, the distance d1 can be adjusted. The
arrangement according to the second embodiment avoids the size increase due to the
height of the radiator 28.
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Please refer to Fig.6. Fig.6 is a schematic diagram of a perpendicularly-oriented
inverted F antenna 42 according to the third embodiment of the present invention. The
antenna 42 is connected to a PCB 26, and includes a radiator 28 installed above the
PCB 26 for receiving and transmitting RF signals, a feeding plate 44 stretching out
from the radiator 28 and connected to a feed pad 32 of the PCB 26 for transmitting RF
signals, and a ground plate 46 stretching out from the radiator 28 and connected to a
ground plane 36 of the PCB 26.
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The functions of the devices in the third embodiment are the same as those in the
first embodiment, therefore functional descriptions are hereby omitted. The difference
between the two embodiments is that the antenna 42 is installed above the PCB 26,
and the feeding plate 44 and the ground plate 46 both stretch out from the lower edge
of the radiator 28 according to the third embodiment. However, the feeding plate 44
and the ground plate 46 can be bent over, and the height d3 is kept in order to avoid
contact between the feeding plate 44 and the ground plane 36, thus resulting in
electrical short. Additionally, to obtain the necessary bandwidth, the distance d3 can
be adjusted. The arrangement according to the third embodiment can be used when
there is no space available on the side of the PCB 26.
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In contrast to the prior art, the radiator of the antenna is perpendicularly installed
above or to the side of the circuit board according to the present invention. This
arrangement is capable of saving space on the circuit board for other devices.
Therefore, the present invention shows a more practical and better way to utilize the
antenna in compact wireless mobile communication devices.
