Patent Description:
This application relates to the technical field of wireless local area networks, in particular to a dual-frequency antenna.

The current antennas usually achieves dual-frequency resonance through multi-branch wires. Wiring of the antenna with this structure occupies a larger space on a PCB (Printed Circuit Board), which causes the overall size of antenna to be too large to satisfy the miniaturization design. Further, it is difficult to adjust the resonance frequency band of the antennas whose dual-frequency resonance is achieved through the multi-branch wires.

Also, in the art are known some methods or devices as described in their respective documents.

For example, <CIT> discloses a ground radiation antenna. Herein, the ground radiation antenna provides a ground radiator inducing resonance by using the inductance of a ground. Since the ground radiator efficiently uses the inductance of the ground, the ground radiator may operate as a radiator of the ground radiation antenna by using a simple structure of combining a capacitive element with the ground. As described above, by providing an antenna radiator having a remarkably simple structure, the fabrication cost for the antenna may be decreased, and the size of the antenna may also be largely reduced.

<CIT> discloses an antenna and a mobile terminal with the antenna including a first radiator and a first capacitor structure. A first end of the first radiator is electrically connected to a signal feed end of a printed circuit board by means of the first capacitor structure, and a second end of the first radiator is electrically connected to a ground end of the printed circuit board. The first radiator, the first capacitor structure, the signal feed end, and the ground end form a first antenna, configured to generate a first resonance frequency. An electrical length of the first radiator is less than or equal to one eighth of a wavelength corresponding to the first resonance frequency.

<CIT> discloses an antenna device capable of being applied to a portable radio terminal and showing a good antenna characteristic regardless of the direction, and a portable radio terminal provided with the antenna device. The antenna device applied to a portable radio terminal whose housing length is equal to or more than λ/<NUM> with respect to the wavelength λ of transmission-reception signals comprises an antenna element disposed on one end of the housing in the longitudinal direction in which at least one point of one end is connected to a signal wiring pattern on a substrate and the other end is an open end, and a parasitic element disposed on the same side of the housing as the antenna element in which one point of one end is connected to a ground wiring on the substrate and the other end is an open end, wherein the open end of the antenna element and the open end of the parasitic element are approximated to each other and capacity coupled.

<CIT> discloses an antenna device including a line-shaped or belt-shaped first conductor having an electrically half length of a wave-length of a first resonant frequency, a feed point to which an end of the first conductor is connected, a plate-shaped second conductor on which the feed point is located and on which another end of the first conductor is grounded, an impedance element is loaded halfway on the first conductor and which varies the first resonant frequency, a second resonant frequency, or both the first resonant frequency and the second resonant frequency. Accordingly, a compact antenna device can therefore be constituted so that an impedance matching between the first conductor and the feed point may be readily obtained. In addition, the antenna device can be commonly used with respect to a multi-frequency operation.

Accordingly, it is highly desirable to optimize the design of the dual-frequency antenna to provide a dual-frequency antenna with a small size and with a resonant frequency band easy to adjust.

An object of an embodiment of the present application is to provide a dual-frequency antenna, which can achieve dual-frequency resonance merely by means of one metal conduction band on which capacitors are connected in series, and can solve the problems that the space occupied by a multi-branch multi-path structure is large, its size is relatively large and its resonant frequency band is difficult to adjust. The specific technical solutions are as follows:
An embodiment of the present application provides a dual-frequency antenna, which includes:.

Optionally, the dual-frequency antenna includes a plurality of capacitors connected in series on the single-path metal conduction band.

Optionally, the clearance area is arranged at an edge of the PCB, and the terminal end and the excitation end of the single-path metal conduction band are located near an opening side of the clearance area.

Optionally, the dual-frequency antenna further includes a microstrip line which is disposed in the non-clearance area and to which the excitation end of the single-path metal conduction band is electrically connected.

Optionally, the dual-frequency antenna further includes:
a test connector connected in series with the capacitor on the single-path metal conduction band and arranged close to the excitation end of the single-path metal conduction band.

Optionally, the test connector is a resistor which is connected in series on the single-path metal conduction band and whose resistance value is zero.

The single-path metal conduction band is arranged within the clearance area in a stacked reciprocating manner.

It can be seen that, based on the above-mentioned embodiments, a dual-frequency antenna includes a PCB, a single-path metal conduction band, and a capacitor. The PCB is provided with a clearance area and a non-clearance area, wherein the clearance area is formed in an area without metal or wires and the like on the PCB, and the non-clearance area is located outside the clearance. The single-path metal conduction band refers to one metal conduction band which only forms one path without branches. The single-path metal conduction band is arranged within the clearance area, and a terminal end of the single-path metal conduction band is electrically connected to a ground end of the PCB to form a loop antenna, so that high-frequency resonance of the dual-frequency antenna can be realized. The capacitor is connected between an excitation end and the terminal end of the single-path metal conduction band, so that low-frequency resonance of the dual-frequency antenna can be realized.

Compared with a dual-frequency antenna realized though a multi-branch metal conduction band, the dual-frequency antenna can realize dual-frequency resonance through the single-path metal conduction band and capacitors, which is simple in structure and can adjust the high-frequency resonance by adjusting the length of the single-path metal conduction band and the area of the clearance area, and can adjust the low-frequency resonance by adjusting the capacitance value of the capacitor, which effectively simplifies the resonance adjustment of the antenna.

In order to illustrate the embodiments of the present application and the technical solutions of the prior art more clearly, the drawings used in the embodiments and the prior art are briefly described below. It is obvious that the drawings in the following description are merely some embodiments of the present application, and other drawings can be obtained by those skilled in the art based on to the drawings without creative efforts.

Reference signs: <NUM>- PCB, <NUM>- a single-path metal conduction band, <NUM>- terminal end, <NUM>- an excitation end, <NUM>- a capacitor, <NUM>- a microstrip line, 1a- a clearance area, 2a- a non-clearance area.

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described in more details with reference to the accompanying drawings and embodiments below. It should be apparent that the described embodiments are only some of the embodiments of the present application instead of all of them.

In order to describe a dual-frequency antenna provided in the present application in detail, the structure and operation principle of the dual-frequency antenna will be described in detail below with reference to the accompanying drawings.

As shown in <FIG>, which is a schematic structural diagram of a dual-frequency antenna according to a specific embodiment of the present application.

In a specific embodiment, the present application provides a dual-frequency antenna comprising a PCB <NUM>, a single-path metal conduction band <NUM> and a capacitor <NUM>. As shown in <FIG>, the PCB <NUM> is provided with a clearance area 1a and a non-clearance area 2a, wherein the clearance area 1a is formed in an area without metal or wires and the like on the PCB <NUM>, and the non-clearance area 2a is outside the clearance area. The single-path metal conduction band <NUM> refers to one metal conduction band which only forms one path without branches. The single-path metal conduction band <NUM> is arranged within the clearance area 1a, and a terminal end of the single-path metal conduction band <NUM> is electrically connected to a ground end of the PCB <NUM> to form a loop antenna, so that high-frequency resonance of the dual-frequency antenna can be realized. The capacitor <NUM> is connected between an excitation end and the terminal end of the single-path metal conduction band <NUM>, so that low-frequency resonance of the dual-frequency antenna can be realized.

Compared with a dual-frequency antenna realized though a multi-branch metal conduction band, the dual-frequency antenna can realize dual-frequency resonance through the single-path metal conduction band <NUM> and the capacitor <NUM>, which is simple in structure.

The high-frequency resonance can be adjusted by adjusting the length of the single-path metal conduction band <NUM> and the area of the clearance area 1a. Specifically, the high-frequency resonance can be adjusted by increasing the length of the single-path metal conduction band <NUM> with the area of the clearance area 1a unchanged. For example, in the case that the terminal end <NUM> and the excitation end <NUM> of the single-path metal conduction band <NUM> are kept unchanged, the high-frequency resonance can be adjusted by increasing the length of the single-path metal conduction band <NUM>, in which the single-path metal conduction band <NUM> is disposed within the clearance area 1a in a wave shape or in a stacked reciprocating manner.

The low-frequency resonance can be adjusted by adjusting the capacitance value of the capacitor <NUM>, and the capacitance value of the capacitor <NUM> is set according to the required low-frequency resonance point in order to meet the requirements of different low-frequency resonance points, which effectively simplifies the resonance adjustment of the antenna.

Further, the dual-frequency antenna includes a plurality of capacitors <NUM>, which are connected in series on the single-path metal conduction band <NUM>.

In a specific embodiment, three capacitors <NUM> are connected in series on the single-path metal conduction band <NUM>, as shown in <FIG>. Preferably, a plurality of capacitors <NUM> are connected in series, so that the low-frequency resonance can be accurately adjusted, fine adjustments can be reliably realized, and the requirements on a low-frequency resonance point can be fully met.

As shown in <FIG>, the clearance area 1a is arranged at an edge of the PCB <NUM>, and the terminal end and the excitation end of the single-path metal conduction band <NUM> are located near an opening side of the clearance area 1a, so that a distance between the single-path metal conduction band <NUM> and the non-clearance area 2a in a direction perpendicular to the opening side can be increased, thereby the single-path metal conduction band <NUM> is located far away from the metal, further optimizing the operating performance of the antenna.

<FIG> only shows one specific shape of the clearance area 1a, and the shape of the clearance area 1a is not limited to the square shape in the figure, and can also be a semicircular shape, an irregular shape, etc., as long as the PCB <NUM> can be fully utilized and the utilization rate of the clearance area 1a can be optimized.

Further, as shown in <FIG>, the dual-frequency antenna further includes a microstrip line <NUM> disposed in the non-clearance area 2a. The excitation end of the single-path metal conduction band <NUM> is electrically connected to the microstrip line <NUM>, so as to be connected to a radio frequency chip or other devices through the microstrip line <NUM>.

Based on the above embodiments, the dual-frequency antenna further includes a test connector, which is connected in series with the capacitor <NUM> on the single-path metal conduction band <NUM> and is arranged close to the excitation end of the single-path metal conduction band <NUM>.

In a specific embodiment, the test connector is a resistor with a resistance value of zero. The resistor is used to form the connection end for testing the dual-frequency antenna.

Based on the above structure, the dual-frequency antenna can achieve dual-frequency resonance merely by means of a metal conduction band on which capacitors <NUM> are connected in series, and can solve the problems in the prior art that the space occupied by a multi-branch multi-path structure is large, its size is relatively large, and its resonant frequency band is difficult to adjust.

The performance of the dual-frequency antenna in the specific embodiment of the present invention is described below with reference to <FIG> and <FIG>. <FIG> is a return loss curve of the dual-frequency antenna in the specific embodiment of the present invention, and <FIG> is a schematic diagram illustrating the efficiency of a dual-frequency antenna in an specific embodiment of the present application.

As shown in <FIG>, the dual-frequency antenna with the above structure can achieve good electrical performance in a frequency band of <NUM>-<NUM> and a frequency band of <NUM>-<NUM>. As shown in <FIG>, the efficiency of the dual-frequency antenna according to the present application can reach more than <NUM>% in the frequency band of <NUM>-<NUM>, and more than <NUM>% in the frequency band of <NUM>-<NUM>.

Claim 1:
A dual-frequency antenna, comprising:
a PCB (<NUM>) provided with a clearance area (1a) and a non-clearance area (2a);
a single-path metal conduction band (<NUM>) which is arranged within the clearance area (1a) and a terminal end of which is electrically connected to a ground end of the PCB (<NUM>); and
a capacitor (<NUM>) connected between an excitation end and the terminal end of the single-path metal conduction band (<NUM>);
wherein the single-path metal conduction band (<NUM>) is one metal conduction band which only forms one path without branches, characterized in that the single-path metal conduction band (<NUM>) is arranged within the clearance area (1a) in a stacked reciprocating manner.