CN103873008B - Antenna assembly - Google Patents

Abstract

The invention discloses an antenna device, which includes: a feed point (hereinafter referred to as a single feed point), a transmission antenna, a low-pass filter with an impedance converter of 50 to 100 ohms, a low-frequency matching network, A high-pass filter with an impedance converter of 50 to 100 ohms, a high-frequency matching network, and a single-pole single-throw switch. The single-pole single-throw switch is turned on when the antenna device is in the high-band matching state, and when the antenna device is in the low-band matching state off. The antenna device proposed by the present invention uses the structure of the switch matching network to effectively match the high frequency and low frequency to 50 ohms, and at the same time, it avoids the switch's own impedance in the low frequency band and makes the original, usually due to its own impedance not The echo loss caused by the good is worse.

Description

Antenna device

technical field

The invention relates to the technical field of antennas for mobile phones and handheld devices, in particular to an antenna device capable of impedance matching in high and low frequency bands.

Background technique

With the rapid development of electronic communication technology, mobile communication devices such as mobile phones are becoming more and more portable. Antennas in mobile communication devices are also miniaturized accordingly. Typically, when designing miniaturized antennas in larger mobile phones, the antenna's own impedance is far from 50 ohms even though the transmit antenna's bandwidth potential is good, and the return loss of the circuit's own impedance at low frequencies tends to be Return loss greater than the self-impedance of a high-frequency circuit. Passive matching components can often be used to obtain a bandwidth with a return loss less than the industry-recognized 6-dB in the low frequency band. In the high frequency band, the corresponding bandwidth can also be achieved through the matching of passive components, but high and low frequencies cannot be achieved at the same time. match. The accepted way is to use switches to solve this problem. The problem is that even in a 50 ohm environment where the insertion loss of the switch is very small, the direct connection of the switch to the transmitting unit will cause a lot of loss, especially at low frequency, this loss leads to a large return loss. In order to reduce its own loss and improve the quality and efficiency of communication, it is more effective to bypass the switch with the low-frequency circuit to reduce the return loss.

Contents of the invention

The present invention aims to solve one of the above-mentioned technical problems in the prior art at least to a certain extent.

Therefore, an object of the embodiments of the present invention is to provide an antenna device that can perform impedance matching in high and low frequency bands, and can reduce switching loss and return loss, thereby improving communication quality.

In order to achieve the above object, the embodiment of the present invention proposes an antenna device, including: a single feed point, a transmission antenna, a low-pass filter with a 50 to 100 ohm impedance converter, a low-frequency matching network, and a 50 to 100 ohm impedance converter. 100 ohm impedance converter high pass filter, high band matching network and single pole single throw switch. Wherein, the single feed point is respectively connected to one end of the low-pass filter with an impedance converter of 50 to 100 ohms and one end of the high-pass filter with an impedance converter of 50 to 100 ohms; The other end of the low-pass filter with an impedance converter of 50 to 100 ohms is connected to one end of the low-frequency band matching network, and then connected to the transmission antenna through the low-frequency band matching network; The other end of the high-pass filter with an impedance converter of 50 to 100 ohms is connected to one end of the high-frequency band matching network, and the other end of the high-frequency band matching network is connected to one end of the single-pole single-throw switch, so The other end of the single pole single throw switch is connected to the transmission antenna. The single pole single throw switch is turned on when the antenna is in a high frequency band matching state, and is turned off when the antenna device is in a low frequency band matching state.

Preferably, the low-pass filter with an impedance converter of 50 to 100 ohms specifically includes: a low-pass filter inductor, one end of the low-pass filter inductor is connected to the single feed point, and the low-pass filter inductor The other end of the low-pass filter capacitor is connected to the low-frequency band matching network; and a low-pass filter capacitor, one end of the low-pass filter capacitor is connected to one end of the low-pass filter inductor, and the other end of the low-pass filter capacitor is grounded.

Preferably, the low-frequency matching network with an impedance converter of 50 to 100 ohms specifically includes: a first low-frequency matching inductor, one end of the first low-frequency matching inductor is connected to the low-pass filter inductor; Two low-frequency matching inductors, one end of the second low-frequency matching inductor is connected to the other end of the first low-frequency matching inductor, and the other end of the second low-frequency matching inductor is connected to the transmission antenna; the first A low-frequency matching capacitor, one end of the first low-frequency matching capacitor is connected to one end of the first low-frequency matching inductor, and the other end of the first low-frequency matching capacitor is grounded; and a second low-frequency matching capacitor, the One end of the second low-frequency matching capacitor is connected to one end of the second low-frequency matching inductor, and the other end of the second low-frequency matching capacitor is grounded.

Preferably, the high-pass filter with an impedance converter of 50 to 100 ohms specifically includes: a high-pass filter capacitor, one end of the high-pass filter capacitor is connected to the single feed point, and the other end of the high-pass filter capacitor is connected to the The high-frequency band matching network is connected; and a high-pass filter inductor, one end of the high-pass filter inductor is connected to one end of the high-pass filter capacitor, and the other end of the high-pass filter inductor is grounded.

In addition, the high-frequency matching network specifically includes: a high-frequency matching inductor, one end of the high-frequency matching inductor is connected to the high-pass filter capacitor, and the other end of the high-frequency matching inductor is connected to a switch; the first high-frequency A matching capacitor, one end of the first high-frequency band matching capacitor is connected to one end of the high-frequency band matching inductor, and the other end of the first high-frequency band matching capacitor is grounded; and a second high-frequency band matching capacitor, the second high-band matching capacitor One end of the frequency band matching capacitor is connected to the other end of the high frequency band matching inductor, and the other end of the second high frequency band matching capacitor is grounded.

Compared with the prior art, the embodiment of the present invention proposes an antenna device. The antenna device utilizes the structure of a switch matching network to effectively match the high frequency and low frequency to 50 ohms while avoiding the low frequency band. Switching the self-impedance makes the original return loss worse due to the bad self-impedance, which improves the antenna efficiency and ensures the communication quality.

Description of drawings

FIG. 1 is a schematic diagram of a topological structure of an antenna device according to an embodiment of the present invention;

2 is a schematic circuit diagram of an antenna device according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a single-feed return loss value of an antenna device according to an embodiment of the present invention;

FIG. 4 is a Smith diagram of the single-fed low-band insertion loss of the antenna device according to an embodiment of the present invention; and

FIG. 5 is a Smith diagram of the single-fed high-band insertion loss of the antenna device according to an embodiment of the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

In the present invention, terms such as "installation", "connection", "connection" and "fixed" should be interpreted in a broad sense unless otherwise clearly specified and limited, for example, they can be fixedly connected or detachably connected , or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

An antenna device according to an embodiment of the present invention is described below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of an antenna device according to an embodiment of the present invention. As shown in Figure 1, the antenna device includes: a single feed point 10, a low-pass filter 20 with a 50 to 100 ohm impedance converter, a low-frequency band matching network 30, and a 50 to 100 ohm impedance converter High-pass filter 40 , high-band matching network 50 , single-pole single-throw switch 60 and transmission antenna 70 .

Wherein, the single feed point 10 for signal transmission is connected to one end of the low-pass filter 20 with an impedance converter of 50 to 100 ohms and one end of the high-pass filter 40 with an impedance converter of 50 to 100 ohms respectively; The other end of the low-pass filter 20 with the impedance converter of 50 to 100 ohms is connected with one end of the low frequency band matching network 30, and then is connected with the transmission antenna 70 through the low frequency band matching network 30; The other end of the high-pass filter 40 of the impedance converter is connected with one end of the high frequency band matching network 50, the other end of the high frequency band matching network 50 is connected with one end of the SPST switch 60, and the other end of the SPST switch 60 Connected to the transmission antenna 70.

Wherein, the single pole single throw switch 60 is turned on when the antenna device is in the high frequency band matching state, and is turned off when the antenna device is in the low frequency band matching state.

In the embodiment of the present invention, as shown in FIG. 2 , when the switch 60 is turned on in the high frequency band matching state, the high and low frequency band circuits can work simultaneously, thereby achieving the effect of high frequency band impedance matching. At the same time, when the switch 60 is turned off in the low-band matching state, the influence of the high-band network received by the low-band network will be reduced to a small level, so that it can be ignored, thereby achieving the effect of low-band impedance matching . By ensuring that the antenna device can perform impedance matching in both the high frequency band and the low frequency band, the quality of communication is guaranteed. At the same time, because the single pole single throw switch 60 is only installed in the high frequency band circuit and no control switch is installed in the low frequency band circuit , thereby eliminating the switching impedance of the low-frequency circuit, thereby reducing the impedance of the entire device and reducing power loss.

Further, according to an embodiment of the present invention, as shown in FIG. 2 , the low-pass filter 20 with an impedance converter of 50 to 100 ohms specifically includes: a low-pass filter inductor 201, one end of the low-pass filter inductor 201 and A single feed point 10 is connected, and the other end of the low-pass filter inductor 201 is connected to the low-frequency band matching network 30; a low-pass filter capacitor 202, one end of the low-pass filter capacitor 202 is connected to one end of the low-pass filter inductor 201, and the low-pass filter capacitor The other end of 202 is grounded.

In this embodiment of the present invention, as shown in FIG. 2 , the low-frequency band matching network 30 specifically includes: a low-pass filter inductor 201, one end of the low-pass filter inductor 201 is connected to a single feed point 10, and the low-pass filter inductor 201 The other end is connected to the low-frequency band matching network 30 ; and a low-pass filter capacitor 202 , one end of the low-pass filter capacitor 202 is connected to one end of the low-pass filter inductor 201 , and the other end of the low-pass filter capacitor 202 is grounded.

Preferably, the low-frequency matching network 30 specifically includes: a first low-frequency matching inductor 301, one end of the first low-frequency matching inductor 301 is connected to the low-pass filter inductor 201; a second low-frequency matching inductor 302, the second low-frequency matching One end of the inductor 302 is connected to the other end of the first low-frequency band matching inductor 301, and the other end of the second low-frequency band matching inductor 302 is connected to the transmission antenna 70; the first low-frequency band matching capacitor 303 is connected to one end of the first low-frequency band matching capacitor 303 One end of the first low frequency band matching inductor 301 is connected, the other end of the first low frequency band matching capacitor 303 is grounded; and the second low frequency band matching capacitor 304, one end of the second low frequency band matching capacitor 304 is matched with the second low frequency band One end of the inductor 302 is connected, and the other end of the second low frequency band matching capacitor 304 is grounded.

Preferably, the high-pass filter 40 with an impedance converter of 50 to 100 ohms specifically includes: a high-pass filter capacitor 401, one end of the high-pass filter capacitor 401 is connected to the single feed point 10, and the other end of the high-pass filter capacitor 402 matches the high-frequency band connected to the network 50 ; and a high-pass filter inductor 402 , one end of the high-pass filter inductor 402 is connected to one end of the high-pass filter capacitor 401 , and the other end of the high-pass filter inductor 402 is grounded.

In addition, the high-frequency matching network 50 specifically includes: a high-frequency matching inductor 501, one end of the high-frequency matching inductor 501 is connected to the high-pass filter capacitor 401, and the other end of the high-frequency matching inductor 501 is connected to the switch 60; the first high-frequency A matching capacitor 502, one end of the first high-frequency band matching capacitor 502 is connected to one end of the high-frequency band matching inductor 501, and the other end of the first high-frequency band matching capacitor 502 is grounded; and a second high-frequency band matching capacitor 503, the second high-band matching capacitor One end of the second high frequency band matching capacitor 503 is connected to the other end of the high frequency band matching inductor 501, and the other end of the second high frequency band matching capacitor 503 is grounded.

Specifically, in this embodiment of the present invention, the inductance value of the low-pass filter inductor 201 is 3-4nH, the capacitance value of the low-pass filter capacitor 202 is 1-2pF, and the inductance value of the first low-frequency band matching inductor 301 is 2 -3nH, the inductance value of the second low frequency band matching inductor 302 is 9-10nH, the capacitance value of the first low frequency band matching capacitor 303 is 18-19pF, the capacitance value of the second low frequency band matching capacitor 304 is 38-40pF, high-pass filtering The capacitance value of the capacitor 401 is 1-2pF, the inductance value of the high-pass filter inductor 402 is 21-22nH, the inductance value of the high-frequency matching inductor 501 is 3-4nH, and the capacitance value of the first high-frequency matching capacitor 502 is 1-2pF , the capacitance value of the second high frequency band matching capacitor 503 is 7-8pF. According to the above component values, the effect of reducing the switch impedance and ensuring the communication quality of the present invention can be achieved in this embodiment. It should be understood that the component values of the present invention can be adjusted according to specific conditions, and are not limited to the above component values.

FIG. 3 , FIG. 4 and FIG. 5 are schematic diagrams showing the effect of the antenna device according to the embodiment of the present invention.

Fig. 3 is a schematic diagram of the return loss value of the single-feed loop of the antenna device according to the embodiment of the present invention, wherein the four curves are respectively, DB (︱S(1,1)︱) is the return loss of the low-frequency circuit, DB (︱S(2,2)︱) is the return loss of the high-frequency circuit, and DB(︱S(3,1)︱) is the insertion loss through the low-frequency matching circuit. DB(︱S(4,2)︱) is the insertion loss through the high frequency band matching circuit.

In one embodiment of the present invention, the GSM850 frequency band commonly used by mobile phones starts at 824 MHz and ends at 894 MHz. It can be seen from the figure that the return loss in this band is less than the required 6 decibels, which meets the general performance standard in the industry, and the insertion loss of this frequency band and the matching circuit through the high frequency band is basically zero.

FIG. 4 is a Smith diagram of the single-fed low-band insertion loss of the antenna device according to an embodiment of the present invention, and FIG. 5 is a Smith diagram of the single-fed high-band insertion loss of the antenna device according to an embodiment of the present invention. As shown in Figure 4 and Figure 5, the insertion loss of the low-frequency band and the insertion loss of the high-frequency band, that is, the curves S(1,1) and S(2,2) are close to 0, so the device of the present invention can be very good The reduction of insertion loss caused by switch embedding.

To sum up, according to the antenna device proposed by the embodiment of the present invention, the antenna device uses the structure of the switch matching network to effectively match the high frequency and low frequency to 50 ohms, and at the same time avoid the switch itself in the low frequency band. Impedance makes the original, usually the return loss caused by poor own impedance worse, to ensure communication quality and reduce power consumption.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (6)

1. An antenna device, characterized in that it comprises: a single feed point, a transmission antenna, a low-pass filter with an impedance converter of 50 to 100 ohms, a low-frequency band matching network, and an impedance of 50 to 100 ohms The converter's high-pass filter, high-band matching network, and single-pole single-throw switch, where The single feed point is respectively connected to one end of the low-pass filter with an impedance converter of 50 to 100 ohms and one end of the high-pass filter with an impedance converter of 50 to 100 ohms; The other end of the low-pass filter with an impedance converter of 50 to 100 ohms is connected to one end of the low-frequency band matching network, and then connected to the transmission antenna through the low-frequency band matching network; The other end of the high-pass filter with an impedance converter of 50 to 100 ohms is connected to one end of the high-frequency band matching network, and the other end of the high-frequency band matching network is connected to one end of the single-pole single-throw switch , the other end of the SPST switch is connected to the transmission antenna, the SPST switch is turned on when the antenna device is in a high frequency band matching state, and is turned off when the antenna device is in a low frequency band matching state. 2. The antenna device according to claim 1, wherein the low-pass filter with an impedance converter of 50 to 100 ohms specifically comprises: A low-pass filter inductor, one end of the low-pass filter inductor is connected to the single feed point, and the other end of the low-pass filter inductor is connected to the low-frequency band matching network; and A low-pass filter capacitor, one end of the low-pass filter capacitor is connected to one end of the low-pass filter inductor, and the other end of the low-pass filter capacitor is grounded. 3. The antenna device according to claim 2, wherein the low-frequency band matching network specifically comprises: A first low-frequency band matching inductor, one end of the first low-frequency band matching inductor is connected to the low-pass filter inductor; A second low-frequency matching inductor, one end of the second low-frequency matching inductor is connected to the other end of the first low-frequency matching inductor, and the other end of the second low-frequency matching inductor is connected to the transmission antenna; A first low-frequency matching capacitor, one end of the first low-frequency matching capacitor is connected to one end of the first low-frequency matching inductor, and the other end of the first low-frequency matching capacitor is grounded; and A second low-frequency matching capacitor, one end of the second low-frequency matching capacitor is connected to one end of the second low-frequency matching inductor, and the other end of the second low-frequency matching capacitor is grounded. 4. The antenna device according to claim 1, wherein the high-pass filter with an impedance converter of 50 to 100 ohms specifically comprises: A high-pass filter capacitor, one end of the high-pass filter capacitor is connected to the single feed point, and the other end of the high-pass filter capacitor is connected to the high-frequency band matching network; and A high-pass filter inductor, one end of the high-pass filter inductor is connected to one end of the high-pass filter capacitor, and the other end of the high-pass filter inductor is grounded. 5. The antenna device according to claim 4, wherein the high-frequency band matching network specifically comprises: A high-frequency band matching inductor, one end of the high-frequency band matching inductor is connected to the high-pass filter capacitor, and the other end of the high-frequency band matching inductor is connected to a switch; A first high-frequency band matching capacitor, one end of the first high-frequency band matching capacitor is connected to one end of the high-frequency band matching inductor, and the other end of the first high-frequency band matching capacitor is grounded; and A second high-frequency matching capacitor, one end of the second high-frequency matching capacitor is connected to the other end of the high-frequency matching inductor, and the other end of the second high-frequency matching capacitor is grounded. 6. A mobile terminal, comprising the antenna device according to any one of claims 1-5.