JP2003037418A - Multi-band antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna that can operate at a plurality of frequency bands. SOLUTION: The antenna is suitable for operation in a plurality of frequency bands and consists of first and second antenna elements for transmitting and receiving signals of first and second frequency bands, respectively. The first antenna element has a substantially slender conductor with a specific first pitch, and is connected to a feeding point. The second antenna element has a substantially winding coil with a specific second pitch and is connected to the feeding point. The substantially winding coil includes a plurality of first portions, that surround at least one portion of the first antenna element and is formed into a winding shape, and a plurality of second portions that are formed in a straight line shape. The first portion is extended to the next second portion which follows in the axial direction of the second antenna element starting from the upper end of the second portion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates generally to antennas adapted to operate in multiple frequency bands, and more particularly to multi-band antennas used in wireless communication systems such as cellular telephone systems.

[0002]

BACKGROUND OF THE INVENTION Wireless communication systems, such as cellular telephone systems, are typically based on radio frequency (RF) waves. There are analog and digital standards used in various parts of the world that have been created to provide an acceptable level of compatibility for wireless communication systems, ie, to standardize the design criteria for cellular telephone devices. The standards differ significantly in their operating frequency ranges from each other. For example, GSM (Global Sy)
system for Mobile communica
is a digital standard that operates in a low frequency band such as 880 MHz to 960 MHz, while AMPS (Advanced Mobile Ph).
One System) is generally 824 MHz to 8
It is an analog standard that operates in the frequency band of 94 MHz. In addition, the widely used digital standard is 1
DCS in the high frequency band of 710 MHz to 1880 MHz
(Digital Communication Sy
PCS (Personal Communic) with an operating frequency of 1850 MHz to 1990 MHz.
system), DCS and PCS
Are both based on GSM.

Cellular telephone devices used in wireless communication systems are inevitably the widely used monopoles.
Included are antennas, such as antennas, for receiving and transmitting radio frequency signals. The resonance frequency of the antenna is RF
An antenna can only be used in a certain frequency range, since it depends on the length of the antenna in a known relationship that depends on the wavelength of the wave. However, since there are various standards, it is desirable that these cellular telephone devices can operate in a plurality of widely separated frequency bands in order to use two or more standards. Therefore, what is needed is an antenna that is adapted to operate in multiple frequency bands.

Further, cellular telephone devices are becoming smaller and smaller in order to meet the convenience requirements of customers. As a result, the antennas utilized by such devices must also be made smaller and lighter. However, as the antenna becomes smaller, the frequency band in which the antenna can operate becomes narrower. Therefore, spiral antennas are often used in cellular telephone devices operating in multiple frequency bands. Helical antennas typically include a spirally wound conductor member. Since the radiating element of the spiral antenna is wound around the axis, the axial length of the spiral antenna can be significantly shorter than the length of an equivalent monopole antenna. Therefore, if the length of the monopole antenna is too long, a spiral antenna can be used.

Therefore, the size is relatively compact and G
There is a need for antennas that can operate in multiple widely separated frequency bands, such as SM and PCS.
Small multi-band antennas are known which provide sufficient bandwidth in at least two frequency bands.

For example, US Pat. No. 6,075,488 to Hope discloses a centrally located high frequency radiating element surrounded by a dielectric support element and wrapped around the dielectric support element. A broadband antenna is disclosed that includes a linear radiating element in the form of a wire that extends over substantially the entire length of the centrally located high frequency radiating element to form a lap spiral coil. The length of the linear radiating element is sized to facilitate resonance at low frequencies. Such antennas are capable of resonating at two widely separated frequencies and are therefore configured for dual frequency band operation.

Further, US Pat. No. 6,127,979 to Zhou et al. Discloses a multiband antenna including fixed whip antenna elements and spiral coil antenna elements connected to a single feed point. It is disclosed.
This antenna is reduced in size by mounting a disc at the end of the whip antenna element while at the same time reducing the pitch of the spiral coil antenna element. A dielectric material surrounds the whip antenna and supports the spiral coil antenna element.

[0008]

A pre-determined, constant distance between the top of the whip antenna element and the corresponding end of the spiral coil antenna element is of great importance for antenna performance. There was found. However, attachment of the spiral coil antenna element often causes variations in this distance. Such variations are difficult to control due to the elasticity of the spiral coil antenna element. Furthermore, because the production cost is reduced,
Helical coil antenna elements are usually manufactured with large tolerances. Therefore, the pitch of the spiral coil antenna elements will be inaccurate.

[0009]

According to the invention, a first antenna element adapted to operate in a plurality of frequency bands and for receiving and transmitting signals in a first frequency band,
A second for receiving and transmitting a signal in a second frequency band
An antenna composed of the antenna elements of
The first antenna element is a predetermined first antenna element connected to the feeding point.
Of substantially elongated conductors of pitch. The second antenna element comprises a substantially serpentine coil of a predetermined second pitch connected to the feed point. The substantially serpentine coil includes a plurality of first portions having a winding shape and surrounding at least a portion of the first antenna element, and further, a plurality of second portions having a linear shape. There is. The first part extends from the upper end of said second part to the lower end of the next second part which extends axially of the second antenna element.

According to a preferred embodiment of the present invention, the second
The portion of can extend parallel to the elongated conductor of the first antenna element. The first portion can also extend coaxially with the elongated conductor of the first antenna element. The first portion and the second portion are preferably orthogonal.

Further in accordance with a preferred embodiment of the present invention, one of the first portions is located on top of the second antenna element and the other first portion is of the second antenna element. It can be placed at the bottom. Furthermore, the first part, which is arranged below the second antenna element, can be formed as a closed ring.

Further, according to a preferred embodiment of the present invention, the first antenna may be a fixed whip antenna. The first antenna element may preferably comprise a disc on top of the substantially elongated conductor.

According to another embodiment of the present invention, the antenna may include an RF matching network that matches the first antenna element and the second antenna element.

In accordance with a preferred embodiment of the present invention, the antenna includes a dielectric material surrounding the first antenna element and the substantially serpentine coil of the second antenna element is a dielectric material. Supported by the material.

Preferably, the second antenna element can be made from stamped metal plate or copper plated molded plastic. Further, according to a preferred embodiment of the present invention, the second frequency band is GSM and AM.
One of the PS bands, the first frequency band is D
One of the CS and PCS bands.

The antenna according to the invention is particularly suitable for operation within a wireless communication system, such as a cellular telephone system, which utilizes a plurality of widely separated frequency bands. further,
The small size of the antenna according to the invention allows it to be used in very small communication devices. Further, the second antenna element having a substantially meandering coil shape includes a plurality of first portions having a winding shape and a plurality of second portions having a linear shape, and the first portion. Extends from the upper end of the second portion to the lower end of the subsequent second portion that continues axially of the second antenna element,
The antenna according to the present invention can be manufactured so as to exhibit stable performance. The reason for this is that the second antenna element according to the invention is stiffer and can be manufactured with a more precise pitch than conventional spiral antenna elements. As a result, the distance between the upper part of the first high-frequency antenna element and the corresponding end of the second low-frequency antenna element can easily be kept constant. Various features and advantages of the invention will be apparent from the following description in conjunction with the accompanying drawings. In the drawings, the same reference numerals
Similar components are shown.

[0017]

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, a dual band antenna 1 constructed and operative in accordance with the present invention is illustrated. As shown in FIGS. 1 and 9, the antenna 1 includes an outer housing or overmold 2 that protects and houses the entire antenna structure. Antenna 1
A first antenna element 3 for receiving and transmitting a signal in a high frequency band, that is, a DCS band is provided in the overmold 2 that also forms the appearance of. The first antenna element 3 comprises a substantially elongate conductor or monopole with a predetermined pitch, which elongate conductor forms a fixed whip antenna and is connected to the feed point 4. The feeding point 4 extends to a connection portion 5 electrically connected to the RF matching network 15 as shown in FIG.
The RF matching network 15 is used to match the impedance of the antenna 1 with the impedance of the T / R switch (transmission / reception switch) 16, and includes several capacitors and inductors. A similar RF matching network 16 operation is described in US Pat. No. 6,12.
No. 7,979, which is incorporated herein by reference.

The antenna 1 further comprises a dielectric material 6 such as santoprene or polypropylene surrounding the first antenna element 3 and for receiving and transmitting signals in the low frequency band, ie the GSM band. The second antenna element 7 of is included. Both the first antenna element 3 and the second antenna element 7 are connected to the feeding point 4. The second antenna element 7 comprises a substantially serpentine predetermined pitch coil supported by a dielectric material 6. The dielectric material 6 carries the elongated conductors of the first antenna element 3, which ensures the coaxiality of the elongated conductors in the substantially meandering coil of the second antenna element 7. In addition, the dielectric material 6 shortens the overall length of the antenna 1 so that the disk 8 fixed on top of the substantially elongated conductor.
Holding In contrast to the teaching of US Pat. No. 6,127,979, the dielectric material 6 is no longer needed to fix the distance between the top of the second antenna element 7 and the disk 8. The reason for this is that the rigidity of the second antenna element 7 is obtained with a substantially meandering coil.

Referring now to FIGS. 2 and 3, there are shown two substantially serpentine coil variations of the second antenna element 7 according to a preferred embodiment of the present invention.

According to a first embodiment of the present invention, the substantially serpentine coil illustrated in FIG. 2 includes a plurality of first portions 7a and a plurality of second portions 7b.
The first portion 7a has a winding shape that coaxially surrounds the elongated conductor of the first antenna element 3 in the assembled position of the antenna 1. Since FIG. 2 is a plan view, the winding shape of the first portion 7a cannot be seen.
In contrast to the first part 7a, the second part 7b has a linear shape, and the first part 7a has a first shape in the assembled position of the antenna 1.
Of the antenna element 3 extends parallel to the elongated conductor. Since the first portion 7a surrounds the elongated conductor so as to be coaxial with the elongated conductor, the first portion 7a and the second portion
Is orthogonal to the portion 7b. As clearly shown in FIG. 2, the second part 7b is a single first part 7a.
From the upper end of the second portion 7b to the second antenna element 7
It is configured to extend to the lower end of the next second portion 7b continuing in the axial direction.

FIG. 3 shows a substantially meandering coil according to the second embodiment of the invention, similar to the second antenna element 7 described above. FIG. 3 shows the first part 7
It is the perspective view which showed clearly that a has the winding shape which partially surrounds the elongate conductor of the 1st antenna element 3. The substantially serpentine coil of FIG.
First part 7 arranged on top of the second antenna element 7.
a and another first portion 7a arranged underneath the second antenna element 7. Since the first part 7a is arranged on the upper part and the lower part of the second antenna element 7, it becomes possible to easily obtain a precise pitch of the substantially winding coil. Further, the first portion 7a arranged under the second antenna element 7 is
It is formed as a closed ring. The inner diameter of the ring is the first
Corresponding to the diameter of the elongated conductor or monopole of the antenna element 3 of
The antenna element 7 can be centered.

Referring to FIGS. 4 and 5, the second aspect of the present invention is described.
A modification of the embodiment of FIG. The second antenna element 7 according to FIGS. 4 and 5 comprises a first portion 7a at both the upper and lower portions of the substantially serpentine coil. Contrary to the second antenna element 7 of FIG. 3, the substantially serpentine coil first part 7a has a substantially perfect closed ring shape. Therefore, the first portion 7a is
It surrounds the elongated conductor of the first antenna element 3 almost completely. The substantially serpentine coil of FIGS. 4 and 5 can be easily manufactured from a metal sheet by appropriate stamping and bending. The thickness of the metal plate ensures a satisfactory rigidity of the second antenna element 7. Alternatively, the substantially serpentine coil can be manufactured from molded plastic plated with copper or any suitable metal.

In FIG. 4, the components of the antenna 1 are illustrated in exploded view. FIG. 5 shows the components of FIG. 4 in the assembled position of the antenna 1, but the dielectric material 6 and the overmold 2 are not shown. As is apparent from FIG. 4, the antenna 1 has both the first antenna element 3 and the second antenna element 7 inserted into the appropriate recesses 9 and 10 of the feeding point 4 so that the first antenna element 3 is It can be easily assembled by fixing and aligning the elongate conductor and the substantially meandering coil of the second antenna element 7. Furthermore, the dielectric material 6 ensures the reliability and durability in the matching of the first antenna element 3 and the second antenna element 7. Thus, the cylindrical dielectric material 6 comprises a hole 11 for accommodating the elongated conductor or monopole of the first antenna element 3, a support surface 12 for supporting the disk 8 of the first antenna element 3, and It has an outer diameter that substantially matches the inner diameter of the meandering coil. As a result, the first antenna element 3, the second antenna element 7, and the cylindrical dielectric material 6 are securely fixed in the recess 9 of the feeding point 4 and further frictionally connected.

Referring now to FIG. 6, there is shown a third embodiment of the present invention. As shown in FIG. 6, the substantially meandering coil of the second antenna element 7 comprises a plurality of first portions 7a and a plurality of second portions 7b. In contrast to the first and second embodiments of the present invention, the second antenna element 7 illustrated in FIG. 6 comprises a first antenna element 3 or a dielectric material 6 surrounding the first antenna element 3. A flexible foil that can be wrapped around,
It is composed of a flexible PCB.

Referring to FIG. 7, a graph illustrating return loss R as a function of frequency f in steps of 2 dB is illustrated. As can be seen in this figure, the antenna according to the present invention comprises GSM, AMPS, DCS and PCS.
830 MHz to about 96, including a wide range of standards
0 MHz and about 1710 MHz to about 1990 MHz
Handles signals in the frequency band of. In this example, the high frequency band and the low frequency band are described as being the DCS and GSM bands, respectively, but those skilled in the art will recognize that without departing from the spirit and scope of the present invention, By modifying the lengths of the first antenna element 3 and the second antenna element 7, it is possible to introduce frequency bands with other combinations. For example, other possible combinations of low and high frequency bands include GS
It may include M + PCS, AMPS + DCS, AMPS + PCS, or any other combination of one or more lower and higher frequency bands of known standards.

FIG. 9 shows a three-dimensional perspective view of how the antenna 1 can interface with the system. It forms part of the antenna feed mechanism for the transceiver. That is, the connection part 5
Is the housing 14 of the system to which the antenna 1 is connected
It is connected to mechanical and electrical contacts 13 located therein. The antenna 1 is connected to the respective networks in the system via mechanical and electrical contacts 13.

In summary, according to the preferred embodiment, the antenna 1 described above functions like a prior art dual band antenna over a wide frequency range and is relatively small in size. Therefore, the antenna 1 is particularly suitable for operation in a wireless communication system, such as a cellular telephone device. However, in the antenna 1 of the present invention, the production efficiency is also improved in relation to the stable performance of the antenna. The reason is that the structure of the first portion 7a and the second portion 7b according to the present invention increases the rigidity of the second antenna element 7 and manufactures it with a more accurate pitch than the conventional spiral antenna element. Because it becomes possible. As a result, it is easy to keep the distance between the disk 8 on top of the elongated conductor of the first antenna element 7 and the adjacent end of the first portion 7a located substantially above the meandering coil constant. become.

Although the above is the embodiments of the present invention, these embodiments do not limit the present invention. While some of the exemplary embodiments of the invention have been described, it will be readily apparent to those skilled in the art that the exemplary embodiments may be embodied without departing from the novel teachings and advantages of the invention. Many modifications are possible. Accordingly, all such modifications are intended to be included within the scope of this invention as claimed. Therefore, the above description should not be construed as limiting the present invention, but should be construed as being limited to the particular embodiments disclosed, as well as modifications to the disclosed embodiments, as well as other embodiments. Is intended to be included within the scope of. The present invention is defined by the appended claims, and equivalents thereof are also included in the present invention.

[0029]

The present invention provides an antenna capable of operating in a plurality of frequency bands by being configured as above.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an antenna adapted to receive and transmit signals in multiple frequency bands.

FIG. 2 is a plan view showing a low frequency antenna element according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a low frequency antenna element according to a second embodiment of the present invention.

FIG. 4 is an exploded view showing components of an antenna according to a second modified embodiment of the invention.

5 is a perspective view of the partially assembled component according to FIG. 4; FIG.

FIG. 6 is a schematic diagram showing a low frequency antenna element according to a third embodiment of the present invention.

FIG. 7 is a graph showing the frequency response of an antenna according to the present invention.

FIG. 8 is a schematic block diagram showing an interface between an antenna and an RF matching network according to the present invention.

FIG. 9 is a perspective view showing how an antenna according to the present invention can be connected to an RF matching network.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01Q 9/32 H01Q 9/32 9/42 9/42 21/30 21/30 (72) Inventor Huang Von Tan Singapore 530 220, Number 08-60, Hogan Street 21, Block 220 (72) Inventor Ben Thiek Yap Singapore 100058, Number 09-39, Telok Blancer Heights, Block 58 F Term (reference) 5J021 AA02 AB02 GA08 HA05 JA07 5J046 AA02 AA04 AA07 AA13 AB06 PA02 PA04 QA02 5J047 AA02 AA04 AA07 AA13 AB06 FD01

Claims (12)

[Claims] 1. An antenna operating in a plurality of frequency bands, comprising a substantially elongated conductor of a predetermined first pitch connected to a feeding point, for receiving and transmitting signals in the first frequency band. For receiving and transmitting a signal in a second frequency band, having a first antenna element and a substantially meandering coil of a predetermined second pitch connected to the feeding point, A plurality of first portions having a winding shape surrounding at least a part of the first antenna element, and a plurality of linear elements. A second portion, the first portion extending from an upper end of the second portion to a lower end of a second portion of the second antenna element extending axially of the second antenna element. . 2. The antenna of claim 1, wherein the second portion extends parallel to the elongated conductor of the first antenna element. 3. The antenna of claim 1 or 2, wherein the first portion extends coaxially with the elongated conductor of the first antenna element. 4. The antenna of claim 1, wherein the first portion and the second portion are orthogonal. 5. The antenna of claim 1, wherein one of the first portions is located on top of the second antenna element and another of the first portions is located on the bottom. 6. The antenna as claimed in claim 5, wherein the first part arranged below the second antenna element is formed as a closed ring. 7. The first antenna element is a fixed whip
The antenna of claim 1, which is an antenna. 8. The antenna of claim 1, wherein the first antenna element has a disk on top of the substantially elongated conductor. 9. An RF matching network for providing the first
2. The antenna of claim 1, wherein the antenna element of and the second antenna element are matched. 10. The antenna of claim 1, further comprising a dielectric material surrounding the first antenna element, wherein the substantially serpentine coil of the second antenna element is supported by the dielectric material. . 11. The antenna of claim 1, wherein the second antenna element is made from stamped metal sheet or copper-plated molded plastic. 12. The antenna of claim 1, wherein the second frequency band is one of a GSM band and an AMPS band and the first frequency band is one of a DCS band and a PCS band.