Patent ID: 12224496

10, substrate;20, BT antenna;30, WLAN antenna;40, circuit ground;41, circuit board;50, first WLAN antenna RF ground;60, second WLAN antenna RF ground;70, first dividing slit;80, the second dividing slit;90, microstrip transmission line.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In order to make the objections, technical solutions, and effects of the present disclosure clearer and clearer, the present disclosure will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present disclosure, but not to limit the present disclosure.

An existing BT antenna is provided on one broad side edge of a substrate, and two branches of WLAN antennas are arranged on another broad side edge of the substrate, so the BT antenna and the WLAN antennas are distanced to a maximum extent; an antenna module needs to be placed as close to an edge as possible when it is placed on a terminal board to have a better effect of transmitting signals of an antenna; however, antennas in the prior art are distributed on two side edges, and the antenna on one side edge must be farther from an edge, affecting data transmission. The present disclosure solves this problem; in the present disclosure, all BT antenna and WLAN antennas are provided on a same side edge of the substrate, so that when the signal transmission apparatus is installed on the terminal board, the side edge where the BT antenna and the WLAN antennas are installed is assembled to the edge, thereby facilitating signal transmission.

Please refer toFIG.1andFIG.2, a signal transmission apparatus provided in the present disclosure comprises: a substrate10, and a BT antenna20and WLAN antennas30provided on the substrate10; the BT antenna20and the WLAN antennas30are provided on a same side edge of the substrate10. At least two branches of WLAN antennas30are provided, and the BT antenna20and the WLAN antennas30are provided at intervals. The BT antenna20is arranged between the WLAN antennas30. If more than two of the WLAN antennas30are provided, for example, three of the WLAN antennas30are provided, then one of the WLAN antennas30is provided on one side of the BT antenna20, and two of the WLAN antennas30are provided on another side of the BT antenna20. Two adjacent WLAN antennas30are also arranged at intervals to improve an isolation degree.

Specifically, the substrate10is a hollow cuboid, the BT antenna20and the WLAN antennas30are arranged in the substrate10and are close to a same long side edge. In this way, the antennas of the signal transmission apparatus can be arranged on an edge of the terminal board, thereby facilitating signal transmission and solving the problem in the prior art that the BT antenna and the WLAN antennas are respectively provided on two side edges of the substrate, which affects data transmission. Moreover, in the present disclosure, all the antennas are arranged on the long side edge of the substrate, compared with all the antennas arranged on the broad side edge of the substrate, which is advantageous to isolation between the antennas in terms of the distance.

Further, in a field of the antennas, a certain isolation degree is often required between multiple antennas. However, when multiple antenna systems are integrated into one module, a spatial distance of the antennas is small, and it is very difficult to improve the isolation degree. In a design that the WLAN antennas and the BLUETOOTH (BT) antenna share a same module and are integrated, the isolation degree between individual antennas is often achieved by distancing the antennas. For example, considering that a requirement of the isolation degree between the WLAN antennas and the BT antenna is high, while a requirement of isolation degree between the WLAN antennas is relatively low, the BT antenna is placed on one side edge of the substrate, and the two WLAN antennas are placed on another side edge of a circuit board to distance to a maximum extent.

When the above methods are actually used, a target isolation state cannot be achieved between the individual antennas. A main reason is that a shortest wavelength of an antenna carrier signal is 12 cm, and co-frequency isolation must reach more than −30 dB, and a spatial distance must reach more than two wavelengths. Completely adopting a spatial isolation method will increase a volume of the integrated antenna module, and it is difficult to realize a miniaturization of the antenna module.

In addition, the spatial isolation method is currently WLAN used to improve the isolation degree; when arranging, the two WLAN antennas are basically arranged in parallel, while an orientation of the BT antenna is orthogonal to the WLAN antennas, in order to achieve polarization orthogonal isolation. However, because the three antennas share a same circuit ground, antenna radiation is not only the antenna itself, but also the circuit board connected thereto, so a polarization isolation effect is also limited.

A fundamental reason for above isolation results is that the antennas used in the existing multiple antenna modules are all current source antennas, that is, the existing BT antenna and the WLAN antennas are all current source antennas. Then, it is difficult to realize orthogonal polarization between the two types of the antennas, thereby realizing the polarization isolation.

Therefore, the BT antenna20is arranged as a magnetic current source BT antenna in the present disclosure, and the WLAN antennas30are arranged as current source WLAN antennas. A radiation source of the magnetic current source BT antenna is a magnetic current source, and a radiation source of the current source WLAN antennas is a current source, and both are arranged at intervals; that is, the magnetic current source BT antenna is always arranged between the current source WLAN antennas. In this way, the orthogonal polarization is achieved by using the antennas with different radiation sources in an interaction direction, thereby achieving polarization isolation. At the same time, an RF ground of the BT antenna20has an isolation function, and the isolation degree between the WLAN antennas30is also significantly improved. That is to say, an RF ground of the magnetic current source is arranged between the WLAN antennas to achieve isolation between the WLAN antennas. The isolation degree between the WLAN antennas can be significantly improved, thereby reducing a possibility of using spatial isolation and meeting a requirement of module miniaturization.

In an embodiment, two branches of the WLAN antennas30are provided, which are a first WLAN antenna and a second WLAN antenna, and the BT antenna20is arranged between the first WLAN antenna and the second WLAN antenna. Specifically, in the present disclosure, a magnetic current source antenna is provided as the BT antenna20, two current source vertical polarization antennas are provided as the WLAN antennas30, and the two WLAN antennas30are located on both sides of the BT antenna20to realize the polarization isolation between the BT antenna20and the WLAN antennas30. At the same time, an RF ground of the magnetic current source antenna has an isolation effect on RF grounds of the two WLAN antennas30, and the isolation degree between the two WLAN antennas30can be significantly improved.

Since the two WLAN antennas30and the one BT antenna20in the prior art are arranged on the circuit board, all the RF grounds of the three antennas are the circuit ground40; that is, the two WLAN antennas30and the one BT antenna20have the common RF ground, which greatly reduces effects of various isolation methods. In order to solve the above problems, the present disclosure no longer only arranges the circuit ground in the substrate10, the circuit ground is a PCB board, but arranges the circuit ground40, a first WLAN antenna RF ground50, and a second WLAN antenna RF ground60in the substrate10. The BT antenna20is arranged on the circuit ground40, the first WLAN antenna is arranged on the first WLAN antenna RF ground50, and the second WLAN antenna is arranged on the second WLAN antenna RF ground60to prevent the two WLAN antennas30and the one BT antenna20from having the same RF ground to reduce the isolation degree.

Further, a first dividing slit70is defined between the circuit ground40and the first WLAN antenna RF ground50, and a second dividing slit80is defined between the circuit ground40and the second WLAN antenna RF ground60. That is to say, the circuit ground40, the first WLAN antenna RF ground50, and the second WLAN antenna RF ground60are independently arranged. Specifically, the RF grounds where the WLAN antennas30are located in the present disclosure separate the first WLAN antenna RF ground50and the second WLAN antenna RF ground60from the circuit ground40by etching slits on the PCB board. The isolation of the slits of the antenna RF ground causes the multiple antennas share the same circuit board but does not share the same ground. By controlling a direction of an RF current, polarization characteristics of radiation are controlled. That is to say, the first WLAN antenna RF ground50and the second WLAN antenna RF ground60are both separated from the circuit ground40with the dividing slits, so that the three grounds have no direct connection among them, and there is no possibility of indirect coupling, which overcomes a problem that the effects of various isolation methods are greatly reduced due to the common RF ground among the multiple antennas. When more than two of the WLAN antennas30are provided, for example, three of the WLAN antennas30are provided, then one of the WLAN antennas30is provided on one side of the BT antenna20, and two of the WLAN antennas30are provided on another side of the BT antenna20. A dividing slit is also defined between the RF grounds of two adjacent WLAN antennas30to improve the isolation degree.

Further, widths of the first dividing slit70and the second dividing slit80are greater than or equal to 0.1 mm. In an embodiment, the widths of the first dividing slit70and the second dividing slit80are configured to be about 1 mm. That is to say, each of the first WLAN antenna RF ground50and the second WLAN antenna RF ground60has a slit of about 1 mm from the circuit ground40. Specifically, each of the widths of the first dividing slit70and the second dividing slit80is configured to be 1 mm.

Further, a microstrip transmission line90is arranged in the substrate10, a circuit module is arranged on the circuit ground40, and both the first WLAN antenna30and the second WLAN antenna30are connected to the circuit module through the microstrip transmission line90, thereby performing data transmission.

Further, a routing mode of the microstrip transmission line90is vertical routing or parallel routing. That is to say, the microstrip transmission line90(i.e., an RF transmission line) is an orthogonal routing layout, and an orthogonal layout of the vertical routing and the horizontal routing are arranged to ensure that a polarization mode of the antenna is not affected, thereby ensuring that the orthogonal polarization isolation is not affected by routing and deteriorates. The routing of the microstrip transmission line90comprises two ways as shown inFIG.1andFIG.2.

In an embodiment, the microstrip transmission line90is a CPW transmission line. That is to say, both the first WLAN antenna and the second WLAN antenna are connected to the circuit module through the CPW transmission line, so as to realize the data transmission of the WLAN antennas30.

In an embodiment, the BT antenna20is a microstrip BT antenna and has a radiation slit. Specifically, the microstrip BT antenna has only one radiation slit. Further, a length of the radiation slit can be particularly lengthened, so that the length of the radiation slit is greater than a half of a wavelength of a medium.

Further, the WLAN antennas30are arranged as the current source vertical polarization antennas; the substrate10is an FR4 substrate. Preferably, the substrate10adopts a low-loss high-frequency board FR4 base material.

The present disclosure realizes the orthogonal polarization by using the antennas with the different radiation sources, thereby realizing the polarization isolation, and arranges the RF ground of the magnetic current source between the WLAN antennas to realize the isolation between the WLAN antennas, and does not need to completely utilize spatial isolation and meets the requirement of the module miniaturization. By the isolation method of the present disclosure, the isolation degree of the WLAN antennas can reach −16 dB, and the isolation degree between the WLAN and BT antennas can reach more than −40 dB, as shown inFIG.3. The WLAN antennas achieve omnidirectional horizontal radiation as shown inFIG.4, and a radiation diagram of the BT antenna is shown inFIG.5, and forward gain and reverse gain exceed-10 dB. Voltage standing wave ratio (VSWR) characteristics of the three antennas are shown inFIG.6. Therefore, the forward gain is significantly improved, the WLAN antennas achieve omnidirectional no-blind area in a horizontal plane, transmission is smooth, and a throughput rate is approximately doubled in all directions. Therefore, the present disclosure improves the isolation degree between the antennas under a condition of multiple antennas, thereby improving the throughput rate of WLAN and an electromagnetic compatibility of BT & WLAN.

In summary, the signal transmission apparatus provided in the present disclosure comprises: the substrate, and the BT antenna and the WLAN antennas which are provided on the same side edge of the substrate. At least two branches of the WLAN antennas are provided, and the BT antenna and the WLAN antennas are provided at intervals. According to the present disclosure, the BT antenna and the WLAN antennas are provided on the same side edge of the substrate, and the BT antenna and the WLAN antennas are provided at intervals, so that all the antennas of the signal transmission apparatus are provided at the edge of the terminal board, thereby facilitating signal transmission, and solving the problem in the prior art that the BT antenna and the WLAN antennas are respectively provided on two side edges of the substrate, affecting the data transmission.