TWI524594B - Miniaturized planar multi - frequency antenna - Google Patents

Description

Miniaturized planar multi-frequency antenna

The invention relates to a mobile wireless broadband antenna structure, in particular to a five-frequency specification frequency band operable on a WWAN and covering a low frequency LTE 700 frequency band, and even further comprising a high frequency LTE 2300 and LTE 2500 six frequency specification frequency band to eight A miniaturized planar antenna with a frequency band.

In order to meet the advent of the high-tech era, the concept of the Office of Action has become the trend of the present and the future, and personal mobile communication has become the most important part. A variety of mobile communication products for versatility and convenience, continue to innovate, such as mobile phones, tablets and notebook computers, etc., have gradually become a handy, indispensable personal belongings. At the same time, with the breakthrough of the function of mobile communication products, its inseparable mobile communication system has also developed accordingly.

The evolution of mobile communication systems can be divided into first generation (1G), second generation (2G), third generation (3G) and future fourth generation (4G) mobile communication systems; among them, third generation mobile communication system The center frequency and bandwidth of the low frequency and high frequency application bands combined by the five bands covered are 892 MHz (15.2%) and 1940 MHz (23.7%), respectively. A device with 3G mobile communication system function will be able to construct a Wireless Wide Area Network (WWAN), so that it can wirelessly access the Internet anytime, anywhere.

However, today's facilities such as high-speed railways and fast-moving vehicles, which are commonly used in life, often suffer from poor reception or disconnection in existing 3G systems, so 4G systems that can meet more diverse living needs are The future will be what everyone is looking forward to.

The fourth-generation mobile communication system (4G) will develop a three-band band of Long Term Evolution (LTE) in addition to the five bands containing the existing third-generation mobile communication system; 698~960 MHz and 1710~2690 MHz combined with eight standard bands such as LTE 700 (698~787 MHz), China LTE 2300 (2300~2395 MHz), and European LTE 2500 (2500~2690 MHz) The two application frequency bands have a center frequency and a percentage bandwidth of 829 MHz (31.6%) and 2200 MHz (44.5%), respectively.

The data transmission rate of the communication system entering the 4G era will reach dozens of times of the current 3G network, and even reach the upload speed of 50 Mbps and the downlink transmission speed of 100 Mbps or more, and it has the ability to respond to the movement, and can be applied to the present day. High-speed vehicles to maintain communication quality without interruption. In addition, in the 4G mobile communication system, not only reduces the cost of setting up the base station, but also directly constructs the GSM mobile phone system, as long as the existing 3G/3.5G base station is upgraded to a 4G base station, and any mobile phone base station signal All places can receive high-speed network signals, which is very suitable for the future information industry to pursue the trend of pursuing a high data transmission rate and multi-function service function at the lowest cost. Therefore, it will remove the bottleneck of 3G and enter a 4G era.

Since different countries use different mobile communication systems and operating frequency bands, which will cause unnecessary problems for people around the world, it is necessary to integrate mobile communication devices that can be used in various systems. Among the mobile communication devices, the most popular non-mobile phones and notebooks are the only ones. Compared with the two, although the mobile phone has been widely used in communication, sending and receiving messages, network information and other functions, the notebook computer not only includes the function of mobile communication, but also has the functions of processing work reports and data. For an office worker who is on a business trip or a traveler from all over the world, the notebook computer can provide the instant document processing functions required for the job in addition to the latest information.

As these mobile communication devices continue to evolve in terms of functionality, convenience, lightness in appearance, and portability, the antennas used are also developed from the exposed type to the built-in type, and the size is reduced and thinned. The requirements are becoming more and more demanding, so in the future, how to avoid the influence of peripheral devices and degrade the performance of the antenna in the limited space with almost no thickness, and meet the fourth generation mobile communication (4G) system with higher transmission rate. The operating bandwidth will be a major challenge for future antenna designs. Therefore, how to design a small planar multi-band antenna for notebook computers and to meet future 4G applications has been developed by the industry and academia.

In view of this, the present invention provides a small frequency band that can operate in the WWAN and covers the low frequency LTE 700 band, and even further includes a small frequency band of the HF LTE 2300 and LTE 2500 to the octave band. The planar antenna is the main target.

In order to achieve the above, the miniaturized planar multi-frequency antenna system of the present invention comprises: a substrate, a feed metal microstrip, a cut-off metal microstrip, a resonant metal microstrip, and a spur-shaped metal micro A tape, and an extended metal strip structure; wherein the substrate is a substantially elongated dielectric substrate. The feeding metal microstrip is disposed on the substrate, and sequentially forms a first starting section extending from a middle portion of the leading edge of the substrate toward the inner side of the substrate by a predetermined length, and a turn toward the right side of the substrate The direction extends to the first stretched section of the edge of the substrate. The cut-off loop metal microstrip is disposed on the substrate, and is sequentially formed with a second starting section parallel to the first extended section of the feeding metal microstrip, and one turn from the right side of the substrate The edge extends to a first continuous section of the trailing edge of the substrate, a main section extending along the trailing edge of the substrate to the left edge of the substrate, and a second stretch extending along the left edge of the substrate to the leading edge of the substrate Section. The resonant metal microstrip is disposed on the substrate, and is sequentially formed to extend from the first starting portion of the feeding metal microstrip to the opposite direction of the first extended portion of the feeding metal microstrip. a third starting section, a second successive section extending a predetermined length toward the inner side of the substrate, and a third extension extending in a direction toward the starting point by a predetermined length and parallel to the third starting section Section. The spur-shaped metal microstrip is disposed on the substrate, and sequentially forms a fourth starting segment extending from the middle portion of the third stretched portion of the resonant metal microstrip toward the front edge of the substrate by a predetermined length, and a Transducing a fourth extended section of a predetermined length toward the right side of the substrate; and the horse-shaped metal microstrip forms an increased width class at a near mid-section of the fourth extended section, the class extending to the end of the fourth stretched section The end becomes an extended metal strip structure.

The miniaturized planar multi-frequency antenna of the present invention uses the front end of the first starting section of the feeding metal microstrip as a feeding point, and the end of the second extended section of the cut-off metal microstrip as a grounding point. The original direct feed structure of the cut-off metal microstrip is changed into a coupled feed structure by the feeding of the metal microstrip and the cut-off metal microstrip to excite the low-frequency resonant mode, and the design A set of dual coupled feed structures are used to excite four resonant modes.

And with the Spur-shaped metal microstrip, the inductive impedance of the low frequency band from 800 MHz to 965 MHz can be increased, and the impedance matching of VSWR<3 is achieved at 675~965 MHz. At the same time, not only does the high-frequency second mode (resonance at 2540 MHz) move to 2150 MHz and improves the impedance curve that changes drastically in the vicinity, but also produces a double resonance phenomenon, which enables impedance matching of VSWR<3 at 1670~2900 MHz. Thus, the miniaturized planar multi-frequency antenna of the present invention can cover eight specification bands such as LTE 700/GSM 850/GSM 900/GSM 1800/GSM 1900/UMTS/LTE 2300/LTE 2500.

In particular, the present invention utilizes the above design to achieve a miniaturized planar multi-frequency antenna that is particularly suitable for use in a 4G eight-band planar notebook computer. This miniaturized planar multi-frequency antenna uses only a planar size of 55 x 8 mm ² . The impedance band range of 675~965 MHz and 1670~2900 MHz is available under the VSWR≦3 standard. This operating band range can cover eight specification bands such as LTE 700/GSM 850/GSM 900/GSM 1800/GSM 1900/UMTS/LTE 2300/LTE 2500.

The features of the present invention can be clearly understood by referring to the drawings and the detailed description of the embodiments.

The present invention mainly provides a miniaturized planar antenna that can operate in a five-frequency specification band of a WWAN and that covers a low-frequency LTE 700 band, and even further includes a six-frequency specification band to an eight-frequency specification band of the high-frequency LTE 2300 and LTE 2500. As shown in the first perspective view of the structure of the miniaturized planar antenna of the present invention, the miniaturized planar antenna of the present invention basically comprises: a substrate 10, a feed metal microstrip 20, and a cut-off loop metal microstrip. 30, and a resonant metal microstrip 40; wherein: the substrate 10 is a substantially elongated dielectric substrate, in practice, the substrate 10 can be erected on a grounded metal surface 60; The 10 series may be an FR4 dielectric substrate having an outer dimension of 55 mm × 8 mm × 0.4 mm; thus, the grounded metal surface 60 may be a copper plate having an outer dimension of 260 mm × 200 mm × 0.2 mm; and, the overall antenna The feed signal can be connected by a wire 70 routed along the edge of the grounded metal surface 60.

The feeding metal microstrip 20 is disposed on the substrate 10, and is sequentially formed with a first starting portion 21 extending from a middle portion of the leading edge of the substrate 10 toward the inner side of the substrate 10 by a predetermined length (point A~ Point B), and a first stretched section 22 (point B to point C) extending toward the right side of the substrate 10 in the right direction of the substrate 10.

The cut-off loop metal microstrip 30 is disposed on the substrate 10, and is sequentially formed with a second starting section 31 (D point) substantially parallel to the first extended section 22 of the feeding metal microstrip 20. ~E point), one turn from the right edge of the substrate 10 to the first continuous section 32 (point E to point F) of the trailing edge of the substrate 10, one along the trailing edge of the substrate 10 to the left side of the substrate 10 The main section 33 of the edge (point F to point G) and a second stretched section 34 (point G to point H) extending along the left edge of the substrate 10 to the leading edge of the substrate 10.

The resonant metal microstrip 40 is disposed on the substrate 10, and is sequentially formed from the first starting section 21 of the feeding metal microstrip 20 toward the first extended section 22 of the feeding metal microstrip 20. Conversely, a third starting section 41 (point A to point I) extending a predetermined length, a second connecting section 42 (point I to point J) extending a predetermined length toward the inner side of the substrate 10, and one turn The third extended section 43 (J point - K point) extending a predetermined length toward the starting point and being substantially parallel to the third starting section 41.

Further comprising a spur-shaped metal microstrip 50, the spur-shaped metal microstrip 50 is disposed on the substrate 10, and sequentially formed from the middle portion of the third stretched section 43 of the resonant metal microstrip 40 toward the substrate 10 leading edge extending a predetermined length of the fourth starting section 51 (L point ~ M point), and a fourth extending section 52 (M point ~ N point) extending a predetermined length toward the right side of the substrate 10, and A section of increasing width is formed at a proximal portion of the fourth extended section 52, and the step extends to the end of the fourth extended section 52 to form an extended metal strip structure 53 (N point ~ O point); the extended metal strip structure The increased width of 53 is preferably five-fifths the width of the Spur-shaped metal microstrip 50.

In principle, the miniaturized planar multi-frequency antenna of the present invention adopts the front end of the first starting section 21 of the feeding metal microstrip 20 as a feeding point (point A), and the cut-off loop metal microstrip 30 The end of the second extension section 34 is a ground point (H point), and the original of the cut-off loop metal microstrip 30 is directly fed through the division of the feed metal microstrip 20 and the cut-off loop metal microstrip 30 The structure is changed to a coupled feed structure to excite low frequency resonant modes, and a set of dual coupled feed structures are designed to excite four resonant modes, thereby forming two wide impedance bands to cover the eight of the 4G applications. Specification band.

The development process of the miniaturized planar multi-frequency antenna of the present invention, as shown in the second diagrams (A) to (D), begins with a feed metal microstrip 20 as a starting structure. As shown in the second figure (A), the printed path of the feeding metal microstrip 20 is ABCFGH segment, the line width is 1 mm and the total length is 96 mm; wherein point A is the feeding point and point H is the grounding point. . Feeding the metal microstrip 20 excites two modes (referred to as the high frequency first and second modes, respectively) in the higher frequency specification band (1710~2690 MHz).

To create a new resonant mode (called the low-band first mode) in the lower frequency specification band (698-960 MHz), a cut-off metal microstrip 30 is developed. As shown in the second diagram (B), it is broken at a suitable place in the path of feeding the metal microstrip 20, and the direct feed structure fed into the metal microstrip 20 is designed as a coupled feed structure. The path break (point E) is 3 mm below the point F fed into the CF segment of the path of the metal microstrip 20, and thus extends to the left for a length and then to point D, forming two separations of the ABC segment and the DEFGH segment. Metal microstrip.

To generate a resonant mode (referred to as the low-band second mode) in the lower frequency specification band to cover the required impedance bandwidth of 698 to 960 MHz, which will be subsequently fed into the metal microstrip 20 Developed as a resonant metal microstrip 40. As shown in the second figure (C), the antenna extends to the left at point A on the metal microstrip 20, and then extends upward and right to point J and point K, respectively, to form a mark point BIJK. An inverted U-shaped resonant metal microstrip 40 composed of segments.

Next, a spur-shaped metal microstrip 50 (L-M-N-O line segment) is extended at the point L shown in the second figure (D). At the same time, the N-O segment (the length of the N-O segment is one-half of the length of the spur-shaped structure) in the spike-shaped metal microstrip 50 is widened in a direction perpendicular to the M-O segment such that the width of the N-O segment is wider than the M-N segment. The planar antenna design covering two broadband application bands (698~960 MHz and 1710~2690 MHz) can be achieved by the above design steps.

The third figure is an impedance frequency response diagram obtained by simulating the structures of the second (C) and second (D) processes in the development of the miniaturized planar multi-frequency antenna of the present invention: (a) a reflection loss map; b) real impedance map; (c) imaginary impedance map, from the simulation results, the substrate 10 used in the miniaturized planar multi-frequency antenna of the present invention has a thickness of only 0.4 mm, and the area of the substrate 10 is only It is 55×8 mm ² , so when the antenna is developed to the structure of the second figure (C), the low frequency band can only cover 670~830 MHz, while the high frequency band only covers 1670~2210 MHz and 2530~2770 MHz, which cannot be completely Covers the high frequency application band (1710 MHz ~ 2690 MHz). By the addition of the horse-shaped metal microstrip 50, the structure of the second figure (D) is obtained; that is, the miniaturized planar multi-frequency antenna of the present invention can increase the structure of the second figure (C) at a low frequency of 800 MHz to 965 MHz. The inductive impedance of the band makes it possible to achieve impedance matching of VSWR<3 from 675 to 965 MHz. At the same time, the miniaturized planar multi-frequency antenna of the present invention will also improve the impedance curve of the structure of the second figure (C), which not only makes it move to 2150 MHz but also smoothes the impedance amplitude, resulting in a double resonance phenomenon. The impedance matching of VSWR<3 can be achieved from 1670 to 2900 MHz, so that the miniaturized planar multi-frequency antenna of the present invention can cover LTE 700/GSM 850/GSM 900/GSM 1800/GSM 1900/UMTS/LTE 2300/LTE 2500 Wait for eight gauge bands.

In addition, as shown in the fourth figure, when the miniaturized planar multi-frequency antenna of the present invention has 50 ohm coaxial transmission wires of different lengths, the reflection loss map obtained by measurement and simulation is different from 520 mm and 720 mm, respectively. A 50 ohm coaxial transmission wire of length is fed to the miniaturized planar multi-frequency antenna of the present invention and its characteristics are measured. The feed signal end of the transmission line is connected to the feed point (point A), and the ground woven mesh is soldered to the antenna metal ground plane near the ground point (point H). The 50 ohm coaxial transmission wire will be routed to the right end along the upper edge of the ground plane of the back of the notebook screen, and along the right edge to the lower right corner of the antenna metal ground plane, and then connected to the test end of the network analyzer. As shown in the reflection loss diagram of the fourth graph measurement and simulation, when the transmission wire length is 520 mm or 720 mm, the antenna reflection loss is higher than the simulation result (without 50 ohm coaxial transmission wire). The longer the loss, the better the impedance matching. Nevertheless, both the measured results and the simulation results can cover the impedance matching of the eight frequency specification bands such as the low frequency application band (698~960 MHz) and the high frequency application band (1710~2690 MHz).

In this embodiment, the substrate 10 can also be mounted on a grounded metal surface 60; the substrate 10 can be an FR4 dielectric substrate having an outer dimension of 55 mm × 8 mm × 0.4 mm; The metal surface 60 can be a copper plate having an outer dimension of 260 mm x 200 mm x 0.2 mm; and the feed signal of the integral antenna can be connected by a wire 70 routed along the edge of the grounded metal surface 60.

In particular, the present invention utilizes the above design to achieve a miniaturized planar multi-frequency antenna that is particularly suitable for use in a 4G eight-band planar notebook computer. This miniaturized planar multi-frequency antenna uses only a planar size of 55 x 8 mm ² . The impedance band range of 675~965 MHz and 1670~2900 MHz is available under the VSWR≦3 standard. This operating band range can cover eight specification bands such as LTE 700/GSM 850/GSM 900/GSM 1800/GSM 1900/UMTS/LTE 2300/LTE 2500.

It is worth mentioning that the above-mentioned planar size of 55 × 8 mm ² is not the only possible size limitation of the substrate 10 in the present invention. The gap between the first extended section 22 of the feed metal microstrip 20 and the second starting section 31 of the cut-off loop metal microstrip 30 is maintained at 0.5 mm under other equally feasible planar dimensions; The main section 33 of the cut-off loop metal microstrip 30 is spaced apart from the third extended section 43 of the resonant metal microstrip 40 by 0.5 mm; and the first starting section of the feed metal microstrip 20 It is preferable that the distance between the front end of the 21 and the leading edge of the substrate is maintained at 0.5 mm.

Moreover, when the area of the substrate 10 is a plane size of 55×8 mm ² , the size of each metal microstrip may be designed as follows: the width of the first starting section 21 of the feeding metal microstrip 20 is 1 mm, length 3 mm; the first extended section 22 of the feed metal microstrip 20 has a width of 1 mm and a length of 24 mm; the second starting section 31 of the cut-off loop metal microstrip 30 has a width of 1 mm. The length of the first continuous section 32 of the cut-off loop metal microstrip 30 is 1 mm and the length is 3 mm; the main section 33 of the cut-off loop metal microstrip 30 has a width of 1 mm and a length of 1 mm. 54 mm; the second extended section 34 of the cut-off loop metal microstrip 30 has a width of 1 mm and a length of 7 mm.

In addition, the third starting section 41 of the resonant metal microstrip 40 has a width of 0.5 mm and a length of 24 mm; the second connecting section 42 of the resonant metal microstrip 40 has a width of 1 mm and a length of 6 mm; The third stretch section 43 of the belt 40 has a width of 1 mm and a length of 25.5 mm.

As a result, the fourth starting section 51 of the spur-shaped metal microstrip 50 has a width of 1 mm and a length of 2 mm; the fourth extending section 52 of the spur-shaped metal microstrip 50 has a width of 1 mm and a length of 15 mm; The belt structure 53 has a width of 1.5 mm and a length of 8 mm.

In addition, it should be noted in the antenna design of the present invention that the fourth starting section 51 of the horse-shaped metal microstrip and the second connecting section 42 of the resonant metal microstrip must be kept at an appropriate distance, in order to avoid two The segment metal microstrip is too close to couple the low frequency second modal current distribution directly from the second splicing section 42 to the fourth starting section 51, resulting in an increase in the resonant frequency of the modality, and the present implementation In the example, the distance between the fourth starting section 51 of the horse and the second connecting section 42 is preferably 7 mm.

In summary, the present invention provides a preferred and feasible miniaturized planar multi-frequency antenna, and the invention patent application is provided according to the law; the technical content and technical features of the present invention are disclosed above, but those skilled in the art may still The various alternatives and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be construed as being limited by the scope of the appended claims

10. . . Substrate

20. . . Feeding metal microstrip

twenty one. . . First starting segment

twenty two. . . First stretch section

30. . . Cut-off loop metal microstrip

31. . . Second starting segment

32. . . First continuation section

33. . . Main section

34. . . Second stretch section

40. . . Resonant metal microstrip

41. . . Third starting section

42. . . Second continuation section

43. . . Third stretch section

50. . . Spur-shaped metal microstrip

51. . . Fourth starting segment

52. . . Fourth stretch section

53. . . Extended metal strip structure

60. . . Grounded metal surface

70. . . wire

The first figure is a perspective view of the structure of the miniaturized planar antenna of the present invention.

The second figure is a schematic diagram of the development process of the miniaturized planar antenna of the present invention.

The third figure is an impedance frequency response diagram obtained by simulating the development process of the second (D) plane of the miniaturized planar multi-frequency antenna of the present invention and the structure of the second figure (D).

The fourth figure is a reflection loss diagram obtained by measuring and simulating the miniaturized planar multi-frequency antenna of the present invention.

10. . . Substrate

20. . . Feeding metal microstrip

twenty one. . . First starting segment

twenty two. . . First stretch section

30. . . Cut-off loop metal microstrip

31. . . Second starting segment

32. . . First continuation section

33. . . Main section

34. . . Second stretch section

40. . . Resonant metal microstrip

41. . . Third starting section

42. . . Second continuation section

43. . . Third stretch section

50. . . Spur-shaped metal microstrip

51. . . Fourth starting section

52. . . Fourth stretch section

53. . . Extended metal strip structure

60. . . Grounded metal surface

70. . . wire

Claims (8)

A miniaturized planar multi-frequency antenna system includes: a substrate, which is a substantially elongated medium substrate; and a feed metal microstrip disposed on the substrate, which is sequentially formed from the front of the substrate a first starting section extending a predetermined length toward the inner side of the substrate, and a first extending section extending to the right side of the substrate to the edge of the substrate, wherein the first portion of the metal microstrip is fed The front end of the starting section is a feeding point; a cut-off loop metal microstrip is disposed on the substrate, and sequentially forming a second starting section parallel to the first extending section of the feeding metal microstrip a first continuous section extending from the right edge of the substrate to the trailing edge of the substrate, a main section extending along the trailing edge of the substrate to the left edge of the substrate, and a length along the left edge of the substrate to a second extended section of the leading edge of the substrate, wherein the end of the second extended section of the cut-off metal microstrip is a ground point; a resonant metal microstrip is disposed on the substrate, which is sequentially formed Having a first extension from the first initial section of the feed metal microstrip toward the first extension of the metal microstrip a third starting section extending backward by a predetermined length, a second connecting section extending a predetermined length toward the inner side of the substrate, and a direction extending toward the starting point by a predetermined length and a third starting zone a third extending section parallel to the segment; a spur-shaped metal microstrip disposed on the substrate, sequentially formed with a predetermined length extending from a middle portion of the third stretched portion of the resonant metal microstrip toward the leading edge of the substrate a fourth starting section, and a fourth extending section extending a predetermined length toward the right side of the substrate; and the horse-shaped metal microstrip forms a width-increasing class at a near-middle section of the fourth extending section thereof, The extension of the class system to the end of the fourth extension section becomes a delay Stretched metal strip structure. The miniaturized planar multi-frequency antenna of claim 1, wherein the extended metal strip structure has a width that is five-fifths the width of the spur-shaped metal microstrip. The miniaturized planar multi-frequency antenna according to claim 1 or 2, wherein the first extended section of the metal microstrip and the second starting zone of the cut-off metal microstrip The segment spacing is 0.5 mm, and the main section of the cut-off loop metal microstrip is spaced apart from the third extension section of the resonant metal microstrip by 0.5 mm, and the front end of the first starting section of the metal microstrip is fed with the base The leading edge distance of the material is 0.5mm. The miniaturized planar multi-frequency antenna according to claim 1 or 2, wherein the substrate is mounted on a grounded metal surface, and the feed signal of the integral antenna is routed along an edge of the grounded metal surface. Wire connection. The miniaturized planar multi-frequency antenna according to claim 1 or 2, wherein the substrate has an area of 55×8 mm ² ; the first starting section of the fed metal microstrip has a width of 1 mm and a length. 3mm; the first stretched section of the feed metal microstrip has a width of 1 mm and a length of 24 mm; the second starting section of the cut-off loop metal microstrip has a width of 1 mm and a length of 15 mm; The first continuous section of the metal loop of the loop metal has a width of 1 mm and a length of 3 mm; the main section of the cut-off metal microstrip has a width of 1 mm and a length of 54 mm; the cut-off metal microstrip The second extended section has a width of 1 mm and a length of 7 mm; the third starting section of the resonant metal microstrip has a width of 0.5 mm and a length of 24 mm; and the second connecting section of the resonant metal microstrip has a width of 1 mm. The length is 6 mm; the third stretched section of the resonant metal microstrip has a width of 1 mm and a length of 25.5 mm. The miniaturized planar multi-frequency antenna according to claim 5, wherein the fourth starting section of the spur-shaped metal microstrip has a width of 1 mm and a length of 2mm; the fourth stretched section of the horse-shaped metal microstrip has a width of 1 mm and a length of 15 mm; and the extended metal strip structure has a width of 1.5 mm and a length of 8 mm. The miniaturized planar multi-frequency antenna according to claim 1 or 2, wherein a distance between a fourth starting section of the horse-shaped metal microstrip and a second connecting section of the resonant metal microstrip It is 7mm. The miniaturized planar multi-frequency antenna according to claim 1 or 2, wherein the substrate may be an FR4 substrate having a relative dielectric constant of 4.4.