TWI643407B - Antenna structure - Google Patents

Abstract

An antenna structure includes a ground element and a metal loop. The metal ring includes a main radiation portion and a floating radiation portion. The main radiating part has a feeding point, a first short-circuit point, and a second short-circuit point, wherein the first short-circuit point and the second short-circuit point are both coupled to the ground element, and the feeding point is approximately between the first Between the short-circuit point and the second short-circuit point. The floating radiation part is adjacent to the main radiation part, and is separated from the grounding element and the main radiation part. The ground element is substantially surrounded by the metal ring.

Description

Antenna structure

The present invention relates to an antenna structure, and more particularly to an antenna structure that can cover a mobile communication frequency band.

With the development of mobile communication technology, mobile devices have become more and more common in recent years. Common examples include: portable computers, mobile phones, multimedia players, and other portable electronic devices with mixed functions. In order to meet people's needs, mobile devices usually have the function of wireless communication. Some cover long-range wireless communication ranges, for example: mobile phones use 2G, 3G, LTE (Long Term Evolution) systems and the 700MHz, 850MHz, 900MHz, 1800MHz, 1900MHz, 2100MHz, 2300MHz, and 2500MHz frequency bands to communicate, and Some cover short-range wireless communication ranges, such as: Wi-Fi, Bluetooth systems use the 2.4GHz, 5.2GHz, and 5.8GHz bands for communication.

According to the research directions of major brands, the next-generation emerging mobile device is likely to be a "Wearable Device". For example, watches, glasses, and even any carry-on items have the opportunity to have wireless communication capabilities in the future. However, the internal space of a wearable device is very small and is often not enough to accommodate antennas for wireless communication. Therefore, how to design a small-sized, wide-band antenna structure will become a major challenge for designers.

In a preferred embodiment, the present invention provides an antenna structure including: a ground element; and a metal ring including: a main radiating portion having a feeding point, a first short-circuit point, and a second short-circuit Point, wherein the first short-circuit point and the second short-circuit point are both coupled to the ground element, and wherein the feeding point is approximately between the first short-circuit point and the second short-circuit point; and a floating connection The radiating part is adjacent to the main radiating part and separated from the ground element and the main radiating part; wherein the ground element is substantially surrounded by the metal ring.

In some embodiments, the main radiating portion has a first end and a second end remote from each other, the first short-circuit point is located at the first end of the main radiating portion, and the second short-circuit point is located at the first The second end of the main radiation portion.

In some embodiments, the floating radiation portion has a first end and a second end remote from each other, and a first end is formed between the first end of the floating radiation portion and the first end of the main radiation portion. A coupling gap, and a second coupling gap is formed between the second end of the floating radiation part and the second end of the main radiation part.

In some embodiments, the antenna structure covers an operating frequency band, and the operating frequency band is between 2403 MHz and 2483.5 MHz.

In some embodiments, the main radiating portion includes a radiating branch and an adjusting branch, the radiating branch is between the feeding point and the second short-circuit point, and the adjusting branch is between the feeding point Between the entry point and the first short-circuit point, the radiating branch system serves as one of the main resonance paths of the antenna structure, and the adjusting branch system is used to fine-tune the impedance matching of the antenna structure.

In some embodiments, the radiation branch is extended along an edge of the ground element, so that a slot area is formed between the radiation branch and the ground element.

In some embodiments, the length of the slot area is approximately equal to a wavelength of 1 times the center frequency of the operating frequency band.

In some embodiments, the length of the adjustment branch is less than 0.25 times the wavelength of the center frequency of the operating frequency band.

In some embodiments, the floating radiation part is used as a director of the main radiation part, so that the antenna structure can provide an approximately omnidirectional radiation field pattern.

In another preferred embodiment, the present invention provides an antenna structure including: a ground element; and a metal ring having a feeding point and a short-circuit point, wherein the short-circuit point is coupled to the ground element; The ground element is substantially surrounded by the metal ring.

In some embodiments, when the antenna structure is excited, a current zero will be generated on the metal loop.

In some embodiments, the metal ring includes a radiating branch and an adjustment branch, the radiating branch is between the feeding point and the current zero, and the adjusting branch is between the feeding point Between the short-circuit point and the short-circuit point, the radiating branch system serves as one of the main resonance paths of the antenna structure, and the adjusting branch system is used to fine-tune the impedance matching of the antenna structure.

100, 200, 300, 400‧‧‧ antenna structure

110, 210, 310, 410‧‧‧ grounding elements

111‧‧‧Edge of Grounding Element

120, 220, 320, 420‧‧‧ metal rings

130, 230, 330‧‧‧ Main Radiation Department

131, 231, 331‧‧‧ the first end of the main radiation department

132, 232, 332‧‧‧ the second end of the main radiation department

133, 233, 333, 433‧‧‧ radiation branch

134, 234, 334, 434 ‧ ‧ ‧ adjusted branch road

135, 235, 335‧‧‧ slot area

140, 240, 340‧‧‧Floating Radiation Department

141‧‧‧The first end of the floating radiation part

142‧‧‧The second end of the floating radiation department

190‧‧‧Signal Source

436‧‧‧The rest of the metal ring

FP‧‧‧feed point

GC1‧‧‧first coupling gap

GC2‧‧‧Second coupling gap

GP‧‧‧short-circuit point

GP1‧‧‧First short-circuit point

GP2‧‧‧Second short-circuit point

L1, L2, L3, L4, L5‧‧‧ length

NP‧‧‧Current zero

W1‧‧‧Width

X‧‧‧X axis

Y‧‧‧Y axis

Z‧‧‧Z axis

FIG. 1 is a schematic diagram showing an antenna structure according to an embodiment of the present invention; FIG. 2 is a schematic diagram showing an antenna structure according to an embodiment of the present invention; FIG. 3 is a schematic diagram showing an antenna structure according to an embodiment of the present invention; and FIG. 4 is a schematic diagram showing an antenna structure according to an embodiment of the present invention.

In order to make the objects, features, and advantages of the present invention more comprehensible, specific embodiments of the present invention are specifically listed below, and described in detail with the accompanying drawings.

Certain terms are used in the description and the scope of patent applications to refer to specific elements. Those skilled in the art will understand that hardware manufacturers may use different terms to refer to the same component. The scope of this specification and the patent application does not use the difference in names as a way to distinguish components, but rather uses the difference in functions of components as a criterion for distinguishing components. The terms "including" and "including" mentioned throughout the specification and the scope of patent applications are open-ended terms and should be interpreted as "including but not limited to." The term "approximately" means that within the acceptable error range, those skilled in the art can solve the technical problem within a certain error range and achieve the basic technical effect. In addition, the term "coupled" includes any direct and indirect electrical connection means in this specification. Therefore, if a first device is described as being coupled to a second device, it means that the first device can be electrically connected directly to the second device, or indirectly electrically connected to the first device via other devices or connection means.二 装置。 Two devices.

FIG. 1 is a schematic diagram showing an antenna structure 100 according to an embodiment of the present invention. The antenna structure 100 can be applied to a mobile device, a wearable device, or a portable device. In some embodiments, the antenna structure 100 is combined with a key ring, so that the key ring has the function of wireless communication, but the present invention is not limited to this. In other embodiments, the antenna structure 100 can also be combined with any small items to make it part of an Internet of Things (IOT). As shown in FIG. 1, the antenna structure 100 includes a ground element 110 and a metal loop 120. The ground element 110 is substantially surrounded by the metal loop 120. For example, the grounding element 110 may be a ground copper on a printed circuit board (PCB), and the metal ring 120 may be an appearance element. The characteristics help to modify and beautify the appearance of the applied device.

The metal ring 120 includes a main radiation element 130 and a floating radiation element 140. The main radiation element 130 and the floating radiation element 140 both extend along the ground element 110. The main radiation part 130 has a feeding point FP, a first shorting point GP1, and a second shorting point GP2. The feeding point FP is coupled to a signal source 190. For example, the signal source 190 may be a radio frequency (RF) module, which may be used to generate a transmitted signal or process a received signal. A positive electrode of the signal source 190 may be coupled to the feeding point FP, and a negative electrode of the signal source 190 may be coupled to the ground element 110. Both the first short-circuit point GP1 and the second short-circuit point GP2 are directly coupled to the ground element 110. The feeding point FP is approximately between the first short-circuit point GP1 and the second short-circuit point GP2. The floating radiation portion 140 is adjacent to the ground element 110 and the main radiation portion 130 and is completely separated from the ground element 110 and the main radiation portion 130.

In detail, the main radiation portion 130 has a first end far from each other. 131 and a second end 132, wherein the first short-circuit point GP1 may be located at the first end 131 of the main radiation part 130, and the second short-circuit point GP2 may be located at the second end 132 of the main radiation part 130. The floating radiation part 140 also has a first end 141 and a second end 142 far from each other, wherein the first end 141 of the floating radiation part 140 and the first end 131 of the main radiation part 130 form a first A coupling gap GC1, and a second coupling gap GC2 may be formed between the second end 142 of the floating radiation portion 140 and the second end 132 of the main radiation portion 130. In order to enhance the coupling effect between the components, the width of the first coupling gap GC1 and the width of the second coupling gap GC2 must be less than 20 mm.

In the embodiment of FIG. 1, the grounding element 110 is substantially a square metal plate, but its four corners are modified into arc-shaped corners. Correspondingly, the metal ring 120 is substantially a hollow square frame, and its four corners are also modified into arc-shaped corners. In detail, the main radiation portion 130 may be substantially a long U-shape, and the floating radiation portion 140 may be substantially a short U-shape. That is, the total length of the main radiation portion 130 may be larger than the total length of the floating radiation portion 140. However, the present invention is not limited to this. In other embodiments, the ground element 110 and the metal ring 120 may be changed to other different corresponding shapes. For example, the ground element 110 may be a substantially rectangular metal plate, but its four corners are all kept in a right-angled shape; and the metal ring 120 may be substantially a hollow rectangular frame, and its four corners are also kept in a right-angled shape. In other embodiments, at least one of the corners of the ground element 110 may form a truncated angle.

According to actual measurement results, when the antenna structure 100 is excited, the antenna structure 100 may cover an operating frequency band, wherein the operating frequency band may be between 2403 MHz and 2483.5 MHz. Therefore, the antenna structure 100 will support at least the Mobile Communication band using Bluetooth or Wi-Fi. Frequency Band).

In detail, the main radiation section 130 includes a radiation branch 133 and a tuning branch 134, where the radiation branch 133 is between the feeding point FP and the second short-circuit point GP2. The adjustment branch 134 is between the feeding point FP and the first short-circuit point GP1. The radiation branch 133 may be substantially C-shaped. The adjustment branch 134 may be substantially straight. The radiation branch 133 extends along one edge 111 of the ground element 110, so that a slot region 135 is formed between the radiation branch 133 and the ground element 110. The slot region 135 is a metal-free headroom region. , Which will not be equipped with any metal components.

In terms of antenna principles, the radiating branch 133 is the higher part of the current density of the antenna structure 100, and is used as one of the main resonance paths of the antenna structure 100. The adjusting branch 134 is used to provide Inductance is used to fine-tune the impedance matching of the antenna structure 100. One end of the radiating branch 133 is a feeding point FP, and the other end is a first short-circuit point GP1 coupled to the grounding element 110. Therefore, a combination of the radiating branch 133 and the grounding element 110 can be regarded as a loop antenna. . In addition, the slot area 135 between the radiation branch 133 and the ground element 110 can be regarded as a slot antenna. Under this design, the antenna structure 100 can be used as a hybrid antenna including a loop antenna and a slot antenna. By integrating two different antenna types, the antenna structure 100 can enjoy the better radiation of the slot antenna. Field pattern (Radiation Pattern), also has a larger operating bandwidth (Operation Bandwidth) of the loop antenna. On the other hand, the floating radiation portion 140 can be used as a director of the main radiation portion 130 to modify the radiation field pattern of the antenna structure 100. For example, when the main radiation directions of the antenna structure 100 are front and rear In the direction (such as + Z axis, -Z axis direction in the first figure), the floating radiation portion 140 can be excited by the coupling of the main radiation portion 130, and the coupling current on it can generate radiation in the side direction (such as toward the first direction). (+ X axis, -X axis direction in the figure), so that the antenna structure 100 can provide an approximately omnidirectional radiation field pattern. Therefore, the antenna structure 100 can easily receive and transmit wireless signals in various directions.

In terms of component size, the length L1 of the slot area 135 is approximately equal to one wavelength (1λ) of the center frequency of the operating frequency band of the antenna structure 100, and the width W1 of the slot area 135 is greater than or equal to 2 mm. The aforementioned limitation of the length L1 and the width W1 helps to maintain the broadband characteristics of the antenna structure 100 (for example, if the width W1 of the slot area 135 is insufficient, the slot antenna's bandwidth will become narrower). Because the radiation branch 133 is closely attached to the slot area 135, the length L2 of the radiation branch 133 is almost equal to (or slightly larger than) the length L1 of the slot area 135. In order to provide sufficient inductance characteristics, the length L3 of the adjustment branch 134 must be less than 0.25 times the wavelength (0.25λ) of the center frequency of the operating frequency band of the antenna structure 100. The above size range is summarized according to the results of multiple experiments, which can optimize the operating frequency band and impedance matching of the antenna structure 100.

It must be understood that the shapes of the ground element 110 and the metal ring 120 of the antenna structure 100 are not a limitation of the present invention, and they can be adjusted according to different appearance requirements. The following embodiments will exemplify the design of antenna structures of different shapes, but the operating principles are substantially the same as those of the antenna structure 100 in FIG. 1.

FIG. 2 is a schematic diagram showing an antenna structure 200 according to an embodiment of the present invention. Figure 2 is similar to Figure 1. In the embodiment of FIG. 2, one grounding element 210 of the antenna structure 200 is substantially a circular metal plate, and one metal ring 220 of the antenna structure 200 is approximately a hollow circular frame to correspondingly accommodate a circular shape. The grounding element 210. The remaining features of the antenna structure 200 in FIG. 2 are similar to those of the antenna structure 100 in FIG. 1. Therefore, the two embodiments can achieve similar operating effects.

FIG. 3 is a schematic diagram showing an antenna structure 300 according to an embodiment of the present invention. Figure 3 is similar to Figure 1. In the embodiment of FIG. 3, one grounding element 310 of the antenna structure 300 is substantially a triangular metal plate, and one metal ring 320 of the antenna structure 300 is substantially a hollow triangular frame to correspondingly receive the triangular grounding element 310. . The remaining features of the antenna structure 300 in FIG. 3 are similar to the antenna structure 100 in FIG. 1, and thus the two embodiments can achieve similar operating effects.

FIG. 4 is a schematic diagram showing an antenna structure 400 according to an embodiment of the present invention. The antenna structure 400 can be regarded as a simplified version of the antenna structure 100 in FIG. 1, but it can also provide similar operating characteristics. For example, the antenna structure 400 may cover an operating frequency band, and the operating frequency band may be between 2403 MHz and 2483.5 MHz. In the embodiment shown in FIG. 4, the antenna structure 400 includes a ground element 410 and a metal ring 420. The ground element 410 is substantially surrounded by the metal ring 420. It must be noted that there is no disconnection or coupling gap on the metal ring 420, but it has a complete loop shape, which further reduces the manufacturing complexity of the antenna structure 400. The metal ring 420 has a feed point FP and a short-circuit point GP. The feed point FP is coupled to a signal source 190, and the short-circuit point GP is coupled to the ground element 410. When the antenna structure 400 is excited, a current null NP will be generated on the metal ring 420. The current density at the current null NP is almost 0, which can be regarded as a virtual short-circuit point. In detail, the metal ring 420 includes a radiating branch 433 and an adjusting branch 434, where the radiating branch 433 is between the feeding point FP and the current zero NP, and the adjusting branch 434 is between the feeding point Between the entry point FP and the short-circuit point GP. The total length of the radiation branch 433 is much larger than the total length of the adjustment branch 434. For example, the total length of the radiation branch 433 may be at least three times the total length of the adjustment branch 434. In terms of antenna principles, the radiating branch 433 is the higher current density part of the antenna structure 400 as one of the main resonance paths of the antenna structure 400; and the adjusting branch 434 is used to provide inductance characteristics to fine-tune the antenna structure 400. Impedance matching. It should be noted that the current density on the remaining portion 436 of the metal ring 420 is relatively low, so it has little effect on the radiation characteristics of the antenna structure 400. In terms of component size, the length L4 of the radiating branch 433 may be approximately equal to one wavelength of the center frequency of the operating frequency band of the antenna structure 400, and the length L5 of the adjusting branch 434 may be less than 0.25 of the center frequency of the operating frequency band of the antenna structure 400. Times the wavelength. The remaining features of the antenna structure 400 in FIG. 4 are similar to those of the antenna structure 100 in FIG. 1. Therefore, the two embodiments can achieve similar operating effects.

The invention proposes a novel antenna structure. Compared with the traditional design, the invention has the advantages of at least small size, wide frequency band, low cost, low manufacturing complexity, and the like. In addition, the antenna structure of the present invention can be integrated with the metal appearance elements of the device, so it also has the effect of beautifying the appearance of the device and improving the fashion sense of the device. The present invention is very suitable for being applied to various personal belongings or wearable devices.

It is worth noting that the above-mentioned component size, component shape, and frequency range are not the limiting conditions of the present invention. The antenna designer can adjust these settings according to different needs. The antenna structure of the present invention is not limited to the state illustrated in FIGS. 1-4. The invention may include only any one or more features of any one or more of the embodiments of FIGS. 1-4. In other words, not all the illustrated features must be implemented in the antenna structure of the present invention at the same time.

The ordinal numbers in this specification and the scope of patent application, such as "first", "second", "third", etc., do not have a sequential relationship with each other, they are only used to indicate that two have the same Different components of the name.

Although the present invention is disclosed as above with a preferred embodiment, it is not intended to limit the scope of the present invention. Any person skilled in the art can make some modifications and decorations without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims (7)

An antenna structure includes: a grounding element; and a metal loop including: a main radiating portion having a feeding point, a first short-circuit point, and a second short-circuit point, wherein the first short-circuit point and the The second short-circuit points are all coupled to the ground element, and the feeding point is substantially between the first short-circuit point and the second short-circuit point; and a floating radiation portion is adjacent to the main radiation portion, And is separated from the ground element and the main radiating part; wherein the ground element is substantially surrounded by the metal ring; wherein the main radiating part has a first end and a second end far from each other, and the first short circuit The point is located at the first end of the main radiating portion, and the second short-circuit point is located at the second end of the main radiating portion; wherein the antenna structure covers an operating frequency band; wherein the main radiating portion includes an adjustment branch , The adjustment branch is between the feeding point and the first short-circuit point, and the adjustment branch is used to fine-tune the impedance matching of the antenna structure; wherein the length of the adjustment branch is smaller than that of the operating frequency band Wavelength of 0.25 times the center frequency. The antenna structure according to item 1 of the scope of patent application, wherein the floating radiation portion has a first end and a second end far from each other, the first end of the floating radiation portion and the first end of the main radiation portion A first coupling gap is formed between the first ends, and a second coupling gap is formed between the second end of the floating radiation part and the second end of the main radiation part. The antenna structure according to item 1 of the patent application range, wherein the operating frequency band is between 2403 MHz and 2483.5 MHz. The antenna structure according to item 3 of the patent application scope, wherein the main radiating section further includes a radiating branch, the radiating branch is between the feeding point and the second short-circuit point, and the radiating branch is As one of the main resonance paths of the antenna structure. The antenna structure according to item 4 of the scope of patent application, wherein the radiating branch is extended along an edge of the ground element, so that a slot area is formed between the radiating branch and the ground element. The antenna structure according to item 5 of the scope of patent application, wherein the length of the slot area is approximately equal to the wavelength of the center frequency of the operating frequency band. The antenna structure according to item 1 of the scope of the patent application, wherein the floating radiation part serves as a director of the main radiation part, so that the antenna structure can provide an approximately omnidirectional radiation field type.