TWI621305B - Open slot antenna - Google Patents

Abstract

A slotted antenna comprising a substrate, a ground plane, and a signal feed network. The grounding plate is disposed on a surface of the substrate and has a slotted hole extending from one of the long sides of the grounding plate to the inside of the grounding plate. The signal feed network is disposed on the other surface of the substrate, and includes first to third feed portions. The first feed portion spans the slotted hole in the direction of the plane of the vertical substrate. The second feeding portion has a first branch, a second branch, and a capacitor element, wherein the first branch is located in the slotted hole in the direction of the plane of the vertical substrate and intersects the first feed portion, and the second branch is short-circuited to the ground plate, and The capacitive element connects the first and second branches. The third feed portion is partially located in the slotted hole in the direction of the plane of the vertical substrate, and one end thereof is connected to the first feed portion.

Description

Slotted antenna

The present invention relates to a slotted antenna, and more particularly to a slotted antenna for a mobile communication device having multiple operating bands.

With the rapid development of communication technologies, commercial mobile communication systems have been developed to the fourth generation of mobile communication systems, which can provide high-speed data transmission in high-speed mobile environments, and provide Internet service providers with a variety of services, such as multimedia. Video services that require huge amounts of data transmission, such as video streaming, instant traffic reporting and driving navigation, and instant network communications. The Long Term Evolution (LTE) system is the mainstream of the international fourth-generation mobile communication system. The mobile communication device can achieve downlink and uplink data transmission rates of 100Mbps and 50Mbps respectively under its mobile. However, the fourth generation mobile communication system differs from the operating band of its prior mobile communication system. In Taiwan, the Global System for Mobile Communications (GSM) system operates at 850MHz, 900MHz, 1800MHz and 1900MHz, Universal Mobile Telecommunications System (Universal Mobile Telecommunications System; The operating frequency of the UMTS system includes 2100 MHz, while the operating frequency of the LTE system includes 700 MHz, 2300 MHz, and 2500 MHz.

On the other hand, antennas commonly used in mobile communication devices are mainly monopole antennas, loop antennas, and inverted F antennas. However, these antennas occupy a certain space in the mobile communication device, which is not conducive to the thinning of the mobile communication device. If the housing of the mobile phone and the mobile device designed for the mobile communication device can be integrated, the thinning of the mobile communication device can be promoted.

Therefore, how to design an antenna for a mobile communication device can make the mobile communication device thinner and lighter, and the mobile communication device can operate on the LTE/Wireless Wide Area Network (WWAN) band and has good performance. The wireless signal transmission effect has been one of the goals that the industry is committed to.

It is an object of the present invention to provide a slotted antenna that utilizes a single slotted hole, a single capacitive component, and a signal feed network having multiple branches to excite the slotted hole to enable the slotted antenna. The mobile communication device can realize wireless signal transmission in a low frequency band of 698 MHz to 960 MHz and a high frequency band of 1710 MHz to 2690 MHz, and can have good radiation characteristics.

In accordance with the above objects of the present invention, a slotted antenna is provided that includes a substrate, a ground plane, and a signal feed network. The substrate has a first surface and a second surface opposite to each other. The grounding plate is disposed on the first surface and has a slotted hole extending from the long side of the grounding plate to The inside of the grounding plate. The signal feeding network is disposed on the second surface, and includes a first feeding portion, a second feeding portion and a third feeding portion. The first feed portion has a signal feed point and it spans the slotted hole in the direction of the plane of the vertical substrate. The second feeding portion has a first branch, a second branch, and a capacitor element, wherein the first branch is located in the slotted hole in the direction of the plane of the vertical substrate and intersects the first feed portion, and the second branch is short-circuited to the ground plate, and The capacitive element is located in the interval between the first branch and the second branch and connects the first branch and the second branch. The third feeding portion is partially located in the slotted hole in the direction of the plane of the vertical substrate, and one end of the third feeding portion is connected to the first feeding portion.

According to a further embodiment of the invention, the capacitive element is at least partially located in the slotted opening in the direction of the plane of the vertical substrate.

According to still another embodiment of the present invention, the capacitance element has a capacitance of about 1.5 picofarad (pF).

According to still another embodiment of the present invention, the first feeding portion is a microstrip metal wire having an impedance of 50 ohms.

According to still another embodiment of the present invention, the third feeding portion is a secondary bent microstrip metal wire, wherein one of the bends is located outside the slotted hole in the direction of the plane of the vertical substrate, and the other bend is Located in the slotted hole in the direction of the plane of the vertical substrate.

According to still another embodiment of the present invention, the slotted antenna further includes a metal plate connected to the short side of the ground plate and extending from the first surface of the substrate toward the second surface of the substrate, and on the substrate A portion outside the second surface is bent toward the signal feed network.

According to still another embodiment of the present invention, the metal plate partially overlaps the first feed portion in a direction of a plane of the vertical substrate.

According to still another embodiment of the present invention, the capacitive element is a wafer capacitor.

According to still another embodiment of the present invention, the substrate is a glass fiber substrate.

100‧‧‧Slotted antenna

110‧‧‧Substrate

112‧‧‧ first surface

114‧‧‧ second surface

120‧‧‧ Grounding plate

122‧‧‧ slotted hole

130‧‧‧ Signal feed into the network

132‧‧‧First Feeding Department

132A‧‧‧ signal feed point

134‧‧‧Second Feeding Department

First branch of 134A‧‧

134B‧‧‧Second branch

134C‧‧‧Capacitive components

136‧‧‧ Third Feeding Department

136A, 136B‧‧‧ bends

140‧‧‧Metal plates

D1, D2‧‧‧ plane distance

H ₁₄₀ ‧‧‧ Height

L ₁₁₀ , L ₁₂₂ , L ₁₃₂ , L ₁₃₄ , L ₁₃₆ , L _136-1 , L _136-2 ‧‧‧ Length

Mode 1‧‧‧first mode

Mode 2‧‧‧second mode

Mode 3‧‧‧ third mode

Mode 4‧‧‧fourth mode

T ₁₁₀ ‧‧‧thickness

W ₁₁₀ , W ₁₂₂ , W ₁₄₀ ‧ ‧ width

For a more complete understanding of the embodiments and the advantages thereof, the following description is made with reference to the accompanying drawings, wherein: FIG. 1A is a perspective view showing a slotted antenna according to an embodiment of the present invention; [FIG. 1B] FIG. 2 is a plan view showing a slotted antenna of FIG. 1A; FIG. 2 is a schematic diagram of measurement and simulated return loss of a slotted antenna according to an embodiment of the present invention; FIG. 3A is an embodiment of the present invention. Schematic diagram of the simulated resistance values of the slot antenna and the slotted antenna of the comparative example; [Fig. 3B] is a schematic diagram showing the simulated reactance values of the slotted antenna of the embodiment of the present invention and the slotted antenna of the comparative example; [Fig. 4] FIG. 5 is a schematic diagram of simulated return loss of a slotted antenna having different capacitances according to an embodiment of the present invention; FIG. 6 is a schematic diagram of antenna efficiency of a slotted antenna according to an embodiment of the present invention.

Embodiments of the invention are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable concepts that can be implemented in a wide variety of specific content. The examples discussed and disclosed are illustrative only and are not intended to limit the scope of the invention.

1A and FIG. 1B, FIG. 1A is a perspective view of a slotted antenna 100 according to an embodiment of the present invention, and FIG. 1B is a plan view of the slotted antenna 100. The slotted antenna 100 is disposed in a mobile communication device, and the mobile communication device may be, for example, a smart phone, a tablet, or a wearable device, but is not limited thereto. In particular, the slotted antenna 100 can be integrated with a housing (eg, a back cover) of a mobile communication device. The slotted antenna 100 includes a substrate 110, a ground plane 120, a signal feed network 130, and a metal plate 140. The substrate 110 has a first surface 112 and a second surface 114 opposite to each other, and the ground plate 120 and the signal feed network 130 are disposed on the first surface 112 and the second surface 114, respectively. The substrate 110 may be a fiberglass substrate, a ceramic substrate, or other similar substrate.

The ground plane 120 acts as a system ground plane in the mobile communication device that can be integrated with the housing of the mobile communication device. The material of the ground plate 120 may be a metal such as copper, silver, gold or the like. As shown in FIGS. 1A and 1B, the ground plate 120 has a slotted hole 122 that extends from the long side of the ground plate 110 to the inside of the ground plate 110.

The material of the ground plate 130 may also be a metal such as copper, silver or gold. As shown in FIG. 1B, the signal feed network 130 includes a first feed portion 132, a second feed portion 134, and a third feed portion 136. The first feeding portion 132 is perpendicular to the slotted hole 122 and perpendicular to the slotted hole 122 in the direction of the plane of the vertical substrate 110, and the first feeding portion 132 has a signal feeding point 132A for electrically connecting the mobile communication device. Circuit. In some embodiments, the first feed portion 132 is a microstrip metal wire having an impedance of 50 ohms.

The second feeding portion 134 has a first branch 134A, a second branch 134B, and a capacitive element 134C. The first branch 134A is located in the slotted hole 122 in the direction of the plane of the vertical substrate 110 and perpendicularly intersects the first feed portion 132, and the second branch 134B is short-circuited to the ground plate 120. The second branch 134B may be located outside or partially in the slotted opening 122 in the direction of the plane of the vertical substrate 110. The capacitive element 134C is located in the space between the first branch 134A and the second branch 134B and connects the first branch 134A and the second branch 134B, and the capacitive element 134C is located in the slotted hole 122 in the direction of the plane of the vertical substrate 110. Capacitor element 134C can be a wafer capacitor or other similar capacitive element. In other embodiments, the capacitive element 134C may be located outside or partially within the slotted aperture 122 in the direction of the plane of the vertical substrate 110.

The third feeding portion 136 is partially located in the slotted hole 122 in the direction of the plane of the vertical substrate 110, and one end of the third feeding portion 136 is connected to the first feeding portion 132. As shown in FIG. 1B, the third feeding portion 136 is a secondary bent metal wire, wherein the bent portion 136A is located in the slotted hole 122 in the direction of the plane of the vertical substrate 110, and the other bent portion 136B is in the vertical direction. Flattening of the substrate 110 The direction of the face is outside the slotted opening 122. Further, the connection of the third feeding portion 136 and the first feeding portion 132 is located outside the slotted hole 122 in the direction of the plane of the vertical substrate 110.

The metal plate 140 is connected to the short side of the ground plate 120 and extends from the first surface 112 of the substrate 110 toward the second surface 114 of the substrate 110. As shown in FIG. 1A, the metal plate 140 is bent toward the signal feed network 130 at a position outside the second surface 114 of the substrate 110, and partially overlaps the first feed portion 132 in the direction of the plane of the vertical substrate 110. . In other embodiments, the metal plate 140 can be removed from the slotted antenna 100.

In the following description, the physical properties of the components in the slotted antenna 100 of the embodiment of the present invention are as follows: the substrate 110 is a glass fiber substrate having a relative permittivity of 4.4 and a loss tangent of 0.02 ( FR4 substrate), the length L ₁₁₀ , the width W ₁₁₀ and the thickness T ₁₁₀ are 75 mm, 140 mm and 0.8 mm, respectively; the length L ₁₂₂ and the width W _{122 of} the slotted hole 122 are 66 mm and 2 mm, respectively, and the top end of the slotted hole 122 The plane distance D1 from the top end of the substrate 110 is 9 mm; the first feed line 132 is a microstrip metal wire having an impedance of 50 ohms, the length L ₁₃₂ is 10 mm, and the top end of the first feed line 132 and the slotted hole 122 The plane distance D2 between the top ends is 7 mm; the length L ₁₃₄ of the second feed line 134 is 50 mm, wherein the first branch 134A and the second branch 134B have a line width of 1 mm, and the capacitive element 134C has a capacitance of 1.5 pF. The chip capacitor; the total length of the third feed line 136 is 32.3 mm, wherein the branch lengths L _136-1 and L _136-2 are 16 mm and 1.9 mm, respectively, and the intersection with the first feed line 132 to the bend 136B The line width is 0.5mm, and the line width from the bend 136B to the end is 0.8mm; the metal plate The height H ₁₄₀ and the width W _{140 of 140} are 6 mm and 7 mm, respectively. However, it should be noted that the physical properties such as the length, the width and the thickness of each of the above components may be adjusted according to the design requirements of the mobile communication device, and are not limited to the above.

2 is a schematic diagram of return loss of a slotted antenna according to an embodiment of the present invention. It can be seen from Figure 2 that the trend of the return loss results of the measurement and simulation is similar. Based on the return loss of 5 dB, the measurement bandwidth of the slotted antenna of the embodiment of the present invention includes both 626 MHz to 1012 MHz and 1692 MHz to 2734 MHz, which covers the operating frequency of the GSM system of 850/900/1800/1900 MHz, 2100MHz UMTS system operating frequency and 700/2300/2500MHz LTE system operating frequency. Therefore, the slotted antenna of the embodiment of the present invention is suitable for a mobile communication device operating at eight frequencies.

3A and FIG. 3B are respectively schematic diagrams showing simulated resistance values and reactance values of the slotted antenna and the slotted antenna of Comparative Examples 1 and 2 according to an embodiment of the present invention, and FIG. 4 is a slotted antenna of the embodiment of the present invention. A schematic diagram of the simulated return loss of the slotted antenna of Comparative Examples 1 and 2, wherein the comparative example 1 is that the signal feed network 130 of FIG. 1A includes only the slotted antenna of the first feed line 132, and Comparative Example 2 is FIG. 1A. The signal feed network 130 includes only slotted antennas of the first feed line 132 and the third feed line 136. 3A, FIG. 3B and FIG. 4, the first feed line 132 of Comparative Example 1 excites a fundamental frequency mode at a frequency of about 720 MHz and at a frequency of about 2350 MHz (ie, mode 1 of FIG. 3A; The first mode) and a higher-order mode (ie, mode 4 of FIG. 3A; hereinafter referred to as the fourth mode), and the fourth mode of the first mode has operating ranges of 648 MHz to 710 MHz and 1895 MHz to 2455 MHz, respectively. , Its bandwidth is relatively narrow. The third feed line 136 of Comparative Example 2 can additionally excite a mode at a frequency of about 1730 MHz (ie, mode 3 of FIG. 3A; hereinafter referred to as a third mode), and affects the first mode and the fourth mode. Not much. At the same time, the high frequency band formed by the third mode and the fourth mode is increased to 1755 MHz to 2630 MHz, but the low frequency band formed by the first mode still does not cover the operating bands of 850 MHz and 900 MHz. The slotted antenna of the embodiment of the present invention has a second feed line 134, which can additionally excite a mode at a frequency of about 1010 MHz (ie, mode 2 of FIG. 3A; hereinafter referred to as a second mode), and for the first mode The state, the third mode, and the fourth mode have little effect. The low frequency band formed by the first mode and the second mode is increased to 627 MHz to 1005 MHz, and the high frequency band formed by the third mode and the fourth mode is increased to 1693 MHz to 3000 MHz. Therefore, the slotted antenna of the embodiment of the present invention can perform impedance matching in the eight frequency band of the LTE/WWAN.

5 is a schematic diagram of simulated return loss of a capacitive element 134C of a slotted antenna according to an embodiment of the present invention with different capacitances (including 0.5 pF, 1 pF, 1.5 pF, and 2.5 pF). As can be seen from Figure 5, the change in capacitance of the capacitive element has a significant effect on the operation of the second mode (i.e., mode 2 of Figure 5). As the capacitance of the capacitive element increases, the operating frequency of the second mode shifts to a low frequency; when the capacitance of the capacitive element is 1.5 pF, the frequency of the second mode is about 1010 MHz, and the second mode at this time It can be combined with the first mode as a broadband operating mode with an optimal low band operating bandwidth.

6 is a schematic diagram showing antenna efficiency of a slotted antenna in a low frequency band of 700 MHz to 960 MHz and a high frequency band of 1710 MHz to 2690 MHz according to an embodiment of the present invention. As can be seen from FIG. 6, the slotted hole of the embodiment of the present invention The simulation results of the antenna in the two frequency bands are similar to those of the measurement results, wherein the measured antenna efficiency is between 64% and 73% in the frequency band of 700MHz to 960MHz, and is approximately in the frequency band of 1710MHz to 2690MHz. Between 41% and 79%. Since the antenna efficiencies in the above two frequency bands are all greater than 40%, it can be confirmed that the slotted antenna of the embodiment of the present invention can be applied to a communication product for transmitting and receiving signals on the operation bandwidth of the LTE/WWAN.

As can be seen from the above experimental results, the slotted antenna of the present invention is suitable for dual wideband operation covering a low frequency band of 698 MHz to 960 MHz and a high frequency band of 1710 MHz to 2690 MHz, and has good radiation characteristics. Furthermore, the structure of the slotted antenna of the present invention can increase the bandwidth of the low frequency band by arranging only one capacitive element, and does not need to be additionally configured with other circuits, so that it has the advantages of easy fabrication and low cost. In addition, since the slotted hole in the structure of the slotted antenna is elongated and has a width of only 2 mm, it has the advantage of simple structure. Applying the slotted antenna of the present invention to a mobile communication device can make the mobile communication device thinner and lighter, and is advantageous for the housing design of the mobile communication device.

In summary, the slotted antenna of the present invention can be applied to wireless signal transmission and reception in the LTE/WWAN frequency band, and has good radiation characteristics, and can be integrated with the mobile communication device housing to make the mobile communication device more It is light and thin.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

Claims (9)

A slotted antenna includes: a substrate having a first surface and a second surface opposite to each other; a grounding plate disposed on the first surface, the grounding plate having a slotted hole, the slotted The hole extends from the long side of the ground plate to the inside of the ground plate; and a signal feeding network is disposed on the second surface, the signal feeding network includes: a first feeding portion, the first a feed portion traverses the slotted hole in a direction perpendicular to a plane of the substrate, and the first feed portion has a signal feed point; and a second feed portion has a first branch, a second branch, and a a capacitor element, the first branch is located in the slotted hole in a direction perpendicular to a plane of the substrate and intersects the first feed portion, the second branch is short-circuited to the ground plate, and the capacitor element is located at the first branch And connecting the first branch and the second branch in the interval between the second branches; and a third feeding portion, the third feeding portion is partially located in the slotted hole in a direction perpendicular to a plane of the substrate, And one end of the third feeding portion is connected to the first The feeding portion. The slotted antenna of claim 1, wherein the capacitive element is at least partially located in the slotted hole in a direction perpendicular to a plane of the substrate. The slotted antenna of claim 1, wherein the capacitive element has a capacitance of about 1.5 picofarad (pF). The slotted antenna of claim 1, wherein the first feed portion is a microstrip metal wire having an impedance of 50 ohms. The slotted antenna of claim 1, wherein the third feed portion is a second bent metal wire, and the first bend of the third feed portion is perpendicular to a plane of the substrate. The direction is outside the slotted hole, and the second bend of one of the third feedthroughs is located in the slotted hole in a direction perpendicular to the plane of the substrate. The slotted antenna of claim 1, further comprising: a metal plate connected to a short side of the ground plate, the metal plate being from the first surface of the substrate to the second surface of the substrate The direction extends and is bent toward the signal feed network at a location outside the second surface of the substrate. The slotted antenna of claim 6, wherein the metal plate partially overlaps the first feed portion in a direction perpendicular to a plane of the substrate. The slotted antenna of claim 1, wherein the capacitive component is a chip capacitor. The slotted antenna of claim 1, wherein the substrate is a fiberglass substrate.