TWI467853B - Dual band antenna and wireless communication device using the same - Google Patents

Description

Dual-frequency antenna and wireless communication device using the same

The present invention relates to an antenna, and more particularly to a dual frequency antenna and a wireless communication device using the same.

In wireless communication devices such as mobile phones and personal digital assistants (PDAs), the antenna is the most important component of the wireless communication device as its component for transmitting and receiving radio waves to transmit and exchange radio signals. One. At present, wireless communication devices generally need to have the function of communicating in dual frequency bands or more frequency bands, and therefore antenna devices generally use dual-frequency or multi-frequency antennas.

Referring to FIG. 1 , a conventional dual-frequency antenna 1 generally has a first radiating element 11 and a second radiating element 12 . One end of the second radiating element 12 is electrically connected to the first radiating unit 11 , and the first radiating unit 11 is divided into a first radiating portion 111 and a second radiating portion 112 according to the second radiating unit 12 . . The other end of the second radiating element 12 is a ground end. In the dual-frequency antenna 1, the first radiating portion 111 and the second radiating unit 12 generate high-frequency resonance to operate in a high-frequency band. The second radiating portion 112 and the second radiating portion 12 generate low frequency resonance and operate in a low frequency band.

Although the above dual-band antenna 1 can operate in two frequency bands, since the two radiating elements 11 and 12 of the dual-frequency antenna 1 share a ground terminal, and the high frequency band and the low frequency band are common. The second radiating element 12, so the antenna length required for the operating frequency band of the dual-frequency antenna 1 is directly reflected on the lengths of the first radiating portion 111 and the second radiating portion 112, if the size parameter of the antenna radiator of one of the frequency bands is performed Adjustment will affect the performance of another frequency band. In this way, not only will the design workload of the dual-frequency antenna be increased, but also it is difficult to make the two frequency bands have independent resonance frequency and bandwidth adjustment performance independent of each other.

In view of this, it is necessary to provide a dual-frequency antenna that is simple in structure and can independently adjust the bandwidth.

In addition, it is also necessary to provide a wireless communication device to which the dual frequency antenna is applied.

A dual-frequency antenna includes a first antenna portion and a second antenna portion coupled to the first antenna portion for receiving and transmitting electromagnetic wave signals of different frequency bands. Two slots are formed on one side of the second antenna portion adjacent to the first antenna portion, and two adjacent ends of the two slots extend in a direction away from the first antenna portion to form two slots until the second antenna portion is Opening, the two slots are in communication with the slot, and the second antenna portion is divided into two ground planes and a feed end, and the two ground planes and slots are related to the feed end Symmetrically, one end of the first antenna portion is perpendicular to a side of the second antenna portion adjacent to the slot, the first antenna portion includes a first radiator and a second radiator, the first radiation The body and the second radiator are both L-shaped sheets, and are symmetrically disposed about the feeding end, and the feeding end is electrically connected to the first radiator and the second radiator, and is used for An antenna unit inputs or outputs an RF signal.

A wireless communication device includes a circuit substrate having a signal transmission end for receiving and transmitting electromagnetic wave signals. The wireless communication device further includes a dual frequency antenna disposed on the circuit substrate, including a first antenna portion and a second antenna portion coupled to the first antenna portion for receiving and transmitting electromagnetic wave signals of different frequency bands. Two slots are formed on one side of the second antenna portion adjacent to the first antenna portion, and two adjacent ends of the two slots extend in a direction away from the first antenna portion to form two slots until the second antenna portion is Opening, the two slots are in communication with the slot, and the second antenna portion is divided into two ground planes and a feed end, and the two ground planes and slots are related to the feed end Symmetrically, one end of the first antenna portion is perpendicular to a side of the second antenna portion adjacent to the slot, the first antenna portion includes a first radiator and a second radiator, the first radiation The body and the second radiator are both L-shaped sheets, and are symmetrically arranged with respect to a line in the feeding end, and the feeding end is electrically connected to the first radiator and the second radiator, and the signal output is The terminal is electrically connected to the feeding end for inputting or outputting an RF signal to the dual-frequency antenna.

Compared with the prior art, the dual-frequency antenna utilizes the coupling effect between the first antenna portion and the second antenna portion to enhance the effect of the first antenna portion on the low-band radiation. In addition, the electric field directions of the first antenna portion and the second antenna portion are perpendicular to each other, so that when the dual-frequency antenna forms two bands of high and low, the two frequency bands respectively have respective resonance frequencies and independent bandwidths. The performance is adjusted so that when the resonant frequency or bandwidth of a single frequency band is optimized, the resonant frequency or bandwidth of the other frequency band is not affected by the change of the respective parameters. In this way, the design complexity of the antenna is reduced, which is beneficial to reduce workload and cost.

1, 100‧‧‧Double-band antenna

11‧‧‧First Radiation Unit

111‧‧‧First Radiation Department

112‧‧‧Second Radiation Department

12‧‧‧second radiation unit

10‧‧‧First antenna unit

12‧‧‧First radiator

122‧‧‧The first piece

124‧‧‧Second body

14‧‧‧Second radiator

142‧‧‧ third body

144‧‧‧fourth body

30‧‧‧second antenna unit

31‧‧‧Slots

32‧‧‧ gap

33‧‧‧ Ground plane

35‧‧‧Feeding end

40‧‧‧ adjustment line

50‧‧‧Feeding line

90‧‧‧Substrate

92‧‧‧ Signal transmission end

94‧‧‧ Grounding

1 is a schematic diagram of a conventional dual frequency antenna.

2 is a schematic diagram of a dual frequency antenna according to a preferred embodiment of the present invention.

3 is a diagram showing the use state of a dual-frequency antenna connected to a substrate according to a preferred embodiment of the present invention; intention.

4 is a schematic view showing the size ratio of the dual-frequency antenna shown in FIG. 2.

FIG. 5 is a return loss test diagram of a dual band antenna according to a preferred embodiment of the present invention.

Referring to FIG. 2 and FIG. 3, there is shown a dual-band antenna 100 suitable for use in a wireless communication device such as a mobile phone or a PDA according to a preferred embodiment of the present invention. The dual-band antenna 100 is a dual-frequency coplanar waveguide fed hybrid antenna, which is a combination of a coplanar waveguide inductive slot antenna and a dual "L" shaped monopole antenna, thereby providing dual-band performance. The dual-band antenna 100 is mounted on a substrate 90 in a wireless communication device and electrically connected to the substrate 90. The substrate 90 is a printed circuit board (PCB) disposed in the wireless communication device, and a metal portion thereof provides grounding for the dual-frequency antenna 100. The substrate 90 has a substantially rectangular plate shape, and a signal transmitting end 92 and a grounding end 94 are disposed thereon. The signal transmitting end 92 is configured to receive the RF signal received by the dual-band antenna 100 and transmit the RF signal transmitted by the dual-frequency antenna 100. The grounding end 94 is a conductive portion on the substrate 90, and is used for The dual frequency antenna 100 is grounded.

The dual-frequency antenna 100 is fabricated from a metal having good electrical conductivity, such as a copper alloy, and includes a first antenna portion 10 and a second antenna portion 30 for transmitting and receiving wireless signals. It is integrally formed, and the coupling effect is generated by mutual inductance between the two.

The first antenna portion 10 is a monopole antenna, and its resonant frequency is set to 2.4 GHz, which can be used for transmitting and receiving low frequency communication electromagnetic wave signals. The first antenna portion 10 adopts a double "L" shape design, and includes a first radiator 12 and a second radiator 14, the two radiators 12, 14 are identical in shape and Symmetrical settings. The first radiator 12 includes a first body 122 and a second body 124, which are vertically connected and have the same width. The second radiator 14 includes a third body 142 and a fourth body 144 which are vertically connected and have the same width. The length of the second piece 124 and the third piece 142 is greater than the height of the first piece 122 and the fourth piece 144. The first body 122 and the fourth body 144 are connected to the second antenna portion 30 in parallel with each other, and perpendicular to the second antenna portion 30, the second body 124 and the The third sheets 142 are on the same straight line and extend away from each other in a direction parallel to the second antenna portion 30. The sum of the height of the first sheet 122 and the length and width of the second sheet 124 is approximately equal to one quarter of the low frequency wavelength, the height of the fourth sheet 144 and the sum of the length and width of the third sheet 142. Also equal to about one quarter of the low frequency wavelength, the first radiator 12 and the second radiator 14 are used to radiate to generate the low frequency resonance frequency of the dual frequency antenna 100.

The second antenna portion 30 is a coplanar waveguide inductive slot antenna having a substantially rectangular shape and a resonant frequency of 5.4 GHz, which can be used for transmitting and receiving high frequency communication electromagnetic wave signals. Two slots 31 are defined in the second antenna portion 30 adjacent to one side of the first antenna portion 10, and two adjacent ends of the two slots 31 extend in a direction away from the first antenna portion 10 to form two The slit 32 is opened until the second antenna portion 30 is opened, thereby dividing the second antenna portion 30 into two ground planes 33 and a feed end 35.

The two slots 31 are substantially rectangular and are adjacent to the ground plane 33 and are in communication with the two slots 32 and are symmetrical about the feed end 35. When the RF signal is transmitted or received, the current intensity around the rectangular slot 31 is large, and the resonant frequency of the high frequency band is radiated by the slot 31. The long side of the slot 31 is parallel to the second body 124, and the length of the long side of the slot 31 is about one-half of a high frequency wavelength, which length determines the high frequency resonant frequency of the dual-frequency antenna 100.

The two ground planes 33 are substantially rectangular in shape, and are symmetric with respect to the feed end 35, and are connected to a ground end (not shown) of the substrate 90 inside the wireless communication device. The two ground planes 33 are connected to each other by a plurality of bonding wires 40. The alignment wires 40 are connected to the two ground planes 33 across the feed terminals 35, so that the two ground planes 33 have the same potential.

The feeding end 35 is substantially in the shape of a rectangular sheet, and is electrically connected to the two radiators 12 and 14 of the first antenna portion 10 and perpendicular to the second sheet 124 and the third sheet 142. The feed end 35 is located between the two slits 32 and adjacent to the two ground planes 33. The feed end 35 is electrically connected to the signal transmission end 92 of the internal substrate 90 of the wireless communication device by a feed line 50 having a resistance of 50 Ω for input to the first antenna portion 10 and the second antenna portion 30. Microwave RF signal. The dual frequency antenna 100 shares the ground plane 33 and the feed end 35.

Referring to FIG. 4, in the embodiment, the first piece 122 of the first antenna portion 10 and the fourth piece 144 are equal in height, and are both set to H=4 mm, the first antenna. The second piece 124 of the portion 10 and the third piece 142 are equal in length, and are each set to L1=15 mm, and the widths of the first piece 122, the second piece 124, the third piece 142, and the fourth piece 144 are wide. Equally, both are set to W1=2 mm, wherein the height H of the first sheet 122 and the third sheet 142, the length L1 and the width W1 of the second sheet 124 and the fourth sheet 144 determine the resonance frequency of the low frequency. The slot L1 of the second antenna portion 30 has a length L2 of 17 mm and a width W2 of 4 mm. The slot 31 of the second antenna portion 30 is known according to the nature of the coplanar waveguide inductive slot antenna. The length L2 is about half the wavelength of the high frequency microwave. The feed end 35 has a width W3 of 4 mm and the slit 32 has a width G of 0.4 mm.

When the dual-frequency antenna 100 is in operation, after the signal enters from the feed-in terminal 35, the different propagations are obtained along the first antenna portion 10 and the second antenna portion 30 of the dual-band antenna 100, respectively. a path, and a strong current at the slot 35 and the first antenna portion 10, respectively, such that the first antenna portion 10 and the second antenna portion 30 respectively generate different operating frequencies, so that the dual-band antenna 100 can Satisfied with the requirements of working at 2.4 GHz and 5.4 GHz respectively. Further, since the slot 35 and the second sheet 124 are parallel at an appropriate distance, mutual inductance can be formed to further generate a coupling effect, thereby enhancing the radiation effect of the first antenna portion 10.

The reflection coefficient of the antenna can be used to measure the bandwidth of the working band of the antenna. The horizontal axis of the reflection coefficient of the antenna is expressed as the frequency, and the vertical axis is represented as the return loss (Return Loss). The reflection loss varies with the frequency. . Generally, the voltage standing wave ratio (VSWR) of the antenna is 2:1 as the frequency band used by the antenna, where the reflection loss value is equal to -10 decibels (dB), so the reflection loss value is less than or equal to -10 dB. The frequency range can be used as the frequency band for the antenna to operate. Referring to FIG. 4, the graph of the reflection loss of the dual-band antenna 100 shown in this embodiment as a function of frequency shows that when the VSWR=2, the dual-frequency antenna 100 operates in the 2.4 GHz and 5.4 GHz bands. The values are less than -10dB, which meets the application requirements of the dual-band antenna, and can realize the function of receiving and transmitting signals of different frequencies.

The dual band antenna 100 utilizes a coupling effect between the first antenna portion 10 and the second antenna portion 30 to enhance the effect of the first antenna portion 10 on low frequency band radiation. In addition, the electric field directions of the first antenna portion 10 and the second antenna portion 30 are perpendicular to each other, so that when the dual-frequency antenna 100 forms two bands of high and low, the two frequency bands have respective resonance frequencies and bandwidths. Independently adjusted, when the resonant frequency or bandwidth of a single frequency band is optimized, the resonant frequency or bandwidth of the other frequency band is not affected by the change of the respective parameters. This will reduce the design difficulty of the antenna.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. but The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above embodiments, and equivalent modifications or changes made by those skilled in the art to the spirit of the present invention should be It is covered by the following patent application.

100‧‧‧Double frequency antenna

10‧‧‧First antenna unit

12‧‧‧First radiator

122‧‧‧The first piece

124‧‧‧Second body

14‧‧‧Second radiator

142‧‧‧ third body

144‧‧‧fourth body

30‧‧‧second antenna unit

31‧‧‧Slots

32‧‧‧ gap

33‧‧‧ Ground plane

35‧‧‧Feeding end

40‧‧‧ adjustment line

50‧‧‧Feeding line

90‧‧‧Substrate

92‧‧‧ Signal transmission end

94‧‧‧ Grounding

Claims (8)

A dual-frequency antenna includes a first antenna portion and a second antenna portion coupled to the first antenna portion, and the two are configured to receive and transmit electromagnetic wave signals of different frequency bands, and the improvement is: Two slots are formed on a side of the second antenna portion adjacent to the first antenna portion, and two adjacent ends of the two slots extend in a direction away from the first antenna portion to form two slots until the second antenna portion is opened. The two slots are in communication with the slot, and the second antenna portion is divided into two ground planes and a feed end, and the two ground planes and slots are symmetric about the feed end One end of the first antenna portion is perpendicular to one side of the second antenna portion adjacent to the slot, the first antenna portion includes a first radiator and a second radiator, and the first radiator And the second radiator is an L-shaped sheet body, and is symmetrically arranged with respect to a line in the feeding end, and the feeding end is electrically connected to the first radiator and the second radiator, and is used for the first The antenna unit inputs or outputs an RF signal. The dual-frequency antenna according to claim 1, wherein the first radiator includes a first body having the same width and a second body perpendicularly connected to one end of the first body, the The second radiator includes a third body having the same width and a fourth body perpendicularly connected to one end of the third body, wherein the length of the second body and the third body is greater than the first body and the first a height of the four-piece body, the first body and the fourth body are connected to each other in parallel with the second antenna portion adjacent to the slot, and perpendicular to the second antenna portion, the second body and the second body The three bodies are on the same straight line and extend away from each other in a direction parallel to the second antenna portion. The dual-frequency antenna according to claim 1, wherein the first antenna portion and the second antenna portion are integrally formed. The dual-frequency antenna of claim 1, wherein the two ground planes are rectangular plate-shaped bodies, the two slots are rectangular holes, and the two ground planes are symmetric about the feed end, the two The slot is symmetrical about the feed end, the first antenna and the second antenna share the ground plane and feed end. The dual-frequency antenna according to claim 1, wherein a height of the first body and a length and a width of the second body determine a low-frequency resonance frequency, and the slot is used to radiate a high-frequency resonance. The frequency, the length of the slot determines the high frequency resonant frequency. A wireless communication device includes a circuit substrate having a signal transmission end, the signal transmission end is configured to receive and transmit electromagnetic wave signals, and the wireless communication device further includes a circuit substrate disposed on the circuit substrate a dual-frequency antenna comprising a first antenna portion and a second antenna portion coupled to the first antenna portion for receiving and transmitting electromagnetic wave signals of different frequency bands, the improvement being: Two slots are formed on a side of the second antenna portion adjacent to the first antenna portion, and two adjacent ends of the two slots extend in a direction away from the first antenna portion to form two slots until the second antenna portion is opened. The two slots are in communication with the slot, and the second antenna portion is divided into two ground planes and a feed end, and the two ground planes and slots are symmetric about the feed end One end of the first antenna portion is perpendicular to one side of the second antenna portion adjacent to the slot, the first antenna portion includes a first radiator and a second radiator, and the first radiator And the second radiator is an L-shaped sheet body, and is related to the feeding end a line-symmetric arrangement, the feeding end is electrically connected to the first radiator and the second radiator, and the signal output end is electrically connected to the feeding end for inputting to the dual-frequency antenna or Output RF signal. The wireless communication device of claim 6, wherein the first antenna portion is a low frequency antenna, and the resonant frequency of the low frequency band is generated by the first radiator and the second radiator; The second antenna portion is a high frequency antenna, and the resonant frequency of the high frequency band is generated by the slot radiation. The wireless communication device of claim 6, wherein the wireless communication device comprises a plurality of adjustment lines, wherein the adjustment lines are used to connect the two ground planes such that the potentials of the two ground planes are equal.