Base station antenna

Abstract

The application provides a base station antenna. The base station antenna comprises a feed network, a cable and a switching structure. The feed network comprises a cavity and an internal structure in the cavity. The switching structure comprises a first transmission line. One end of the first transmission line is electrically connected to the internal structure, and the other end is electrically connected to the cable. The first transmission line is used for transmitting a radio frequency signal, and is at least partially located outside the cavity. In the application, the feed network is connected to the cable through the switching structure. The impedance matching with the cable is realized by adjusting the characteristic impedance of the transmission line of the switching structure, so as to expand the matching space of the feed network, improve the continuity of the radio frequency signal transmission, and make the electrical performance of the base station antenna better.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, in particular to a base station antenna. BACKGROUND

[0002] A base station antenna is composed of a cable, a feed network, a radiating unit and other components, and the modules are connected through a medium. With the development of mobile communication systems towards multi-frequency and multi-system, base station antennas also need to be multi-frequency and multi-polarization. However, the frequency bands of multi-frequency base station antennas are many, which leads to very complex connection of the feed network, thereby increasing the discontinuity of radio frequency signal transmission and affecting the electrical performance of the base station antenna. SUMMARY

[0003] The present application provides a base station antenna. The feed network in the base station antenna connects the cable through an adapter structure, and impedance matching with the cable is achieved by adjusting the characteristic impedance of the transmission line of the adapter structure, so as to expand the matching space of the feed network, improve the continuity of radio frequency signal transmission, and make the electrical performance of the base station antenna better.

[0004] In a possible implementation, the base station antenna includes a feed network, a cable and an adapter structure, the feed network includes a cavity and an internal structure located in the cavity, the adapter structure includes a first transmission line, one end of the first transmission line is electrically connected with the internal structure, and the other end is electrically connected with the cable, the first transmission line is used for transmitting radio frequency signals, and the first transmission line is at least partially located outside the cavity.

[0005] In the present implementation, the characteristic impedance of the first transmission line is easy to adjust, and the internal loss of the radio frequency signal is smaller than that of the cable. The adapter between the feed network and the cable through the first transmission line can achieve impedance matching with the cable by adjusting the characteristic impedance of the first transmission line, thereby expanding the matching space of the feed network. In the traditional scheme, the cable is directly connected with the feed network, and in the present application, part of the cable is replaced by the first transmission line. Since the loss of the radio frequency signal caused by the first transmission line is lower than that of the cable of the same length, the impedance of the radio frequency signal transmission line is reduced, the loss is reduced, and the antenna gain is improved.

[0006] In a possible implementation, one end of the first transmission line extends into the cavity to connect the internal structure, which can expand the matching space of the feed network and reduce the assembly and design difficulty.

[0007] In a possible implementation, the first transmission line is entirely located outside the cavity, and the adapter structure further includes a second transmission line, one end of the second transmission line is connected with the first transmission line, and the other end extends into the cavity to connect the internal structure.

[0008] In the present embodiment, the connection of the first transmission line to the internal structure of the feeding network can be more flexible by the transition through the second transmission line. In addition, the characteristic impedance of the first transmission line and the second transmission line can be designed respectively to achieve impedance matching with the cable, improve the flexibility of the design, and expand the matching space of the feeding network.

[0009] In a possible implementation, the first transmission line and the second transmission line adopt the same transmission line structure, so that the connection mode of the second transmission line to the first transmission line is simple and the assembly difficulty is reduced. The transmission line structure is a suspended strip line, a microstrip line, or a strip line.

[0010] In a possible implementation, the first transmission line and the second transmission line adopt different transmission line structures, which can achieve different transmission modes, thereby achieving the purpose of converting the radio frequency transmission mode. The transmission line structure is a suspended strip line, a microstrip line, or a strip line.

[0011] In a possible implementation, the feeding network includes a phase shifter and a power divider, and the power divider is electrically connected to the phase shifter. The power divider receives the radio frequency signal from the cable through the phase shifting network of the phase shifter, then divides the radio frequency signal into multiple output signals according to the actual application requirements, and sends the output signals to the radiating unit through multiple output ports. The radiating unit converts the electrical signal into an electromagnetic wave, which is finally received by a terminal such as a mobile phone.

[0012] In a possible implementation, the first transmission line is a suspended strip line, and the suspended strip line includes a metal strip. The suspended strip line can also include a metal cavity and a dielectric substrate. The dielectric substrate is suspended in the metal cavity, and the metal strip is fixedly connected to the dielectric substrate. By adjusting the structure of the metal strip and the width and length of the metal cavity, the resonant frequency and the high-order mode frequency of the suspended strip line can be improved so that they do not fall within the working frequency and can be applied to higher frequency application scenarios.

[0013] In the present embodiment, the metal cavity includes two metal side walls arranged oppositely, and the two metal side walls are each provided with a groove, the opening of the groove facing the inner side of the metal cavity, and the dielectric substrate is embedded in the two grooves. The dielectric substrate is grounded through the two metal cavity walls, so that the dielectric substrate can be designed as a circuit on both sides.

[0014] In the present embodiment, the suspended strip line includes two metal strips, and the two metal strips are oppositely arranged on both sides of the dielectric substrate. The double-sided circuit formed by the two metal strips has a strong coupling characteristic compared with a single-layer circuit, and is more convenient to connect to other types of transmission lines, such as slot lines, coplanar waveguides, etc.

[0015] In a possible implementation, the first transmission line is a strip line, the strip line includes a dielectric and a conductor strip arranged in the dielectric, and the dielectric is arranged between two conductive planes, and the two conductive planes are both grounded. The characteristic impedance of the strip line can be controlled by adjusting the thickness and width of the conductor strip, the relative dielectric constant of the dielectric, and the distance between the two conductive planes. In addition, because the conductor strip of the strip line is embedded between the two conductive planes, the impedance of the strip line is easy to control. Moreover, when the radio frequency signal is transmitted in the strip line, the electric field of the radio frequency signal is distributed between the two conductive planes, and cannot be radiated to the outside of the strip line, so that the shielding capability is good; and the radio frequency signal cannot be interfered by external radiation, so that the anti-interference capability is strong.

[0016] In a possible implementation, the first transmission line is a microstrip line, the microstrip line includes a dielectric substrate and a metal conductor strip, and the metal conductor strip is fixedly connected to the dielectric substrate. The characteristic impedance of the microstrip line can be controlled by adjusting the thickness and width of the conductor strip and the thickness of the dielectric substrate. In addition, because one side of the conductor strip of the microstrip line is a dielectric (the dielectric substrate) and the other side is air, and the relative dielectric constant of the dielectric can be greater than that of the air, the transmission speed of the radio frequency signal in the microstrip line is fast, which is beneficial to transmitting signals with high speed requirements. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic diagram of a base station provided by the present application in some embodiments;

[0018] Figure 2 is an internal structural schematic diagram of a base station antenna provided by the present application in some embodiments;

[0019] Figure 3 is Figure 2 is a partial structural schematic diagram of the base station antenna shown in some embodiments;

[0020] Figure 4 is Figure 3 is an internal structural schematic diagram of the base station antenna shown;

[0021] Figure 5 is an internal structural schematic diagram of a microstrip line provided by the present application in some embodiments;

[0022] Figure 6 is an internal structural schematic diagram of a strip line provided by the present application in some embodiments;

[0023] Figure 7 is an internal structural schematic diagram of a suspended strip line provided by the present application in some embodiments. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described below with reference to the accompanying drawings. In the description of the embodiments of the present application, "a plurality of" means two or more than two, unless otherwise specified.

[0025] Please refer to Figure 1 , Figure 1 is a structural schematic diagram of a base station 100 in some embodiments provided by the present application. The base station 100 can also be referred to as a public mobile communication base station, which refers to a radio transmitting and receiving station that transmits and receives information between a mobile communication switching center and a terminal such as a mobile phone in a certain radio coverage area. As shown in Figure 1 , the base station 100 can include a tower 1, a base station antenna 2, and a feeder 3. The bottom of the tower 1 is fixed to the ground, and the bottom is larger than the top to provide stable support. It can be understood that the orientation words such as "top", "bottom", "upper", and "lower" involved in the present application are described with reference to the orientation of the attached drawings, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0026] The base station antenna 2 is installed at the top of the tower 1. The base station antenna 2 is used for transmitting and receiving radio frequency signals. The feeder 3 extends from the bottom to the top of the tower 1 and is electrically connected to the base station antenna 2. The electrical connection includes coupling connection and connection through a conductor. The feeder 3 is used to transmit radio frequency signals, which can transmit the radio frequency signals emitted by the transmitter to the input end of the base station antenna 2, radiate the radio frequency signals through the base station antenna 2, and be received by a terminal device such as a mobile phone; or the radio frequency signals received by the base station antenna 2 can be transmitted to the input end of the receiver.

[0027] Among them, the transmitter is used to modulate the useful low-frequency signal, change the low-frequency signal into a radio frequency signal with a certain center frequency and a certain bandwidth suitable for transmission through the antenna, and transmit the radio frequency signal to the input end of the base station antenna 2. The receiver can receive the radio frequency signal from the base station antenna 2, select the required frequency component from the numerous radio frequency signals, suppress or filter out the signals or noise and interference signals that are not required, and obtain the useful information.

[0028] In some embodiments, please refer to Figure 2 , Figure 2 is a structural schematic diagram of a base station antenna 2 in some embodiments provided by the present application. The base station antenna 2 is used to convert the guided electromagnetic wave fed by the transmitter into spatial electromagnetic wave, or convert the electromagnetic wave into guided electromagnetic wave and deliver it to the receiver. Among them, the electromagnetic wave propagating along a certain path (such as cable, transmission line) is guided electromagnetic wave. The modulated electromagnetic wave with a certain transmission frequency is a radio frequency signal.

[0029] The base station antenna 2 can include a radome, a radiating element, a feed network and an antenna connector. The radome can be a shell, and a cavity can be provided inside the shell for accommodating the radiating element and the feed network. The radiating element, also referred to as a vibrator or an antenna vibrator, can effectively radiate or receive radio frequency signals. The radiating element is electrically connected to the feed network, and receives or transmits radio frequency signals through the feed network. The antenna connector is located on the outside of the radome, and is electrically connected to the feed network in the cavity of the radome through a cable. Please refer to Figure 1 and Figure 2 The other end of the antenna connector can be electrically connected to the feeder 3. The feed network receives radio frequency signals from the feeder 3 through the antenna connector, and transmits the radio frequency signals to the radiating element, so that the radio frequency signals are radiated by the radiating element and received by a terminal device such as a mobile phone. In addition, the base station antenna 2 can also receive radio frequency signals, and transmit the received radio frequency signals to the input end of the receiver through the feeder 3, so as to realize signal transmission.

[0030] For example, the radiating element can be a half-wave vibrator or a full-wave vibrator, and the embodiments of the present application are not limited in this regard. In some embodiments, as shown in Figure 2 The base station antenna 2 can also include a reflector plate. The radiating element can be fixedly connected to the reflector plate. The reflector plate can also be referred to as a bottom plate, an antenna panel or a metal reflector. The reflector plate is used to improve the sensitivity of the radiating element in receiving antenna signals, and reflects and concentrates the antenna signals on the signal receiving point. The reflector plate can be made of metal material, which not only greatly enhances the ability of the radiating element to receive or radiate signals, but also blocks and shields other electric waves from the side opposite to the radiating element, thereby preventing the signals from being disturbed.

[0031] For example, the base station antenna 2 can include a plurality of radiating arrays, and the plurality of radiating arrays can be fixedly connected to one reflector plate to form one radiating array. In other embodiments, the plurality of radiating arrays can be fixedly connected to a plurality of reflector plates to form a plurality of radiating arrays, so as to realize multi-frequency and multi-polarization of the antenna, and the embodiments of the present application are not limited in this regard.

[0032] In some embodiments, the base station antenna 2 can include one radiating element array. In other embodiments, the base station antenna 2 can include a plurality of radiating element arrays. The base station antenna 2 can also include a plurality of feed networks. Each radiating element array can correspond to a different feed network, and the plurality of radiating element arrays can receive or transmit radio frequency signals through the respective feed networks, so as to realize multi-frequency and multi-polarization of the base station antenna 2.

[0033] The radome is used to protect the base station antenna system from the external environment. In some embodiments, the radome can be made of non-metallic materials, so that the radome has good electromagnetic wave penetration characteristics in electrical performance, avoids causing loss to the radio frequency signal, and improves the antenna gain. At the same time, the radome can resist the external harsh environment in mechanical performance, so that the base station antenna system inside the radome can avoid being affected by the external environment, thereby improving the service life of the base station antenna.

[0034] In some embodiments, the feed network can be composed of controlled impedance transmission lines. The feed network is used to realize the energy transmission from the antenna junction to the radiating elements, and also to realize the amplitude and phase distribution of the radio frequency signal between the radiating elements, and to realize the impedance matching with the cable. In this application, the load impedance connected by the cable terminal is equal to the characteristic impedance of the cable, which is called "impedance matching with the cable". The feed network can include a phase shifter, for example. In some embodiments, the feed network can also include power dividers, combiners, filters and other devices.

[0035] In some embodiments, the phase shifter (Phaser) can be used to adjust the phase of the radio frequency signal, and the phase adjustment can be realized by digital phase shift and / or RC phase shift. The digital phase shift can be realized by A / D and D / A conversion, and the RC phase shift can be realized by changing the power frequency and circuit parameters, for example.

[0036] In some embodiments, the power divider can be used to distribute the energy of the input signal, and adjust the signal energy in different output directions according to the demand, so as to improve the utilization rate of energy. The power divider can realize energy distribution by dividing the input signal into two or more paths. The energy carried by each path of signal can be equal or at least the energy of two paths can be unequal, which is not limited in the embodiments of the application.

[0037] In some embodiments, the combiner is used to combine multiple frequency signals together and output them through one transmission line, which can simplify the structure of the feed network and avoid the process of switching different frequency band radiating elements. The combiner can be used in the antenna transmitting end to combine two or more radio frequency signals from different transmitters into one path and sent to the radiating element, while avoiding the mutual influence between the signals of each port. In other embodiments, the combiner can also be used in the antenna receiving end to combine the radio frequency signals received by the antenna into one path and sent to the receiver for subsequent processing, which is not limited in the embodiments of the application.

[0038] In some embodiments, the filter is used to screen the radio frequency signal of the desired frequency, to filter out the interference noise or to analyze the spectrum. For example, the filter can be a frequency selection circuit composed of a capacitor, an inductor and a resistor, which can pass the signal with a specific frequency in the radio frequency signal, thereby greatly attenuating the signal with other frequencies. The filter can effectively filter out the specific frequency to obtain the radio frequency signal without the specific frequency, or effectively filter out the frequencies other than the specific frequency to obtain the radio frequency signal with the specific frequency, which is not limited in the embodiments of the application.

[0039] For example, as shown in Figure 2 , the feed network can further include a transmission component or a calibration network electrically connected with the phase shifter. The feed network can realize the pointing of different radiation beams through the transmission component, and adjust the phase shifter through the motor driving the transmission component, so as to adjust the down angle of the vertical pattern of the antenna. In addition, the feed network can be connected with the calibration network to obtain the required calibration signal. The calibration network extracts a part of the radio frequency signal input to each radiation port, and monitors the extracted signal, so as to ensure that the beamforming formed by the baseband signal processing can be accurately distributed to the antenna radiator, and the signal amplitude and phase input to each radiation port are stable.

[0040] In the present application, as shown in Figure 2 , after the radio frequency signal enters the feed network, the signal is first combined or frequency-selected through the combiner or the filter, and then transmitted to the phase shifter. Then, the phase of the signal is adjusted through the phase shift network, and the signal can be further processed through the transmission component or the calibration network to form the radio frequency signal to be transmitted outward. Finally, the radio frequency signal processed by the feed network is transmitted to the radiation unit, and is radiated out through the radiation unit and received by the terminal device such as a mobile phone.

[0041] For example, the feed network can be electrically connected with the antenna connector through a cable, so as to realize the transmission of the radio frequency signal from the feeder 3 to the feed network.

[0042] In the embodiments of the present application, as shown in Figure 3 , Figure 3 is a partial structure diagram of the base station antenna 2 shown in Figure 2 .

[0043] The feeding network 21 can be electrically connected with the cable 23 through the adapter structure 22. The feeding network 21 comprises an end cover 211 and a cavity 212 fixedly connected with the end cover 211. The cavity 212 comprises a bottom plate 2121 opposite to the end cover 211 and two side plates 2122 and 2123 located on both sides of the bottom plate 2121 and fixedly connected with the bottom plate 2121. The two side plates 2122 and 2123 can be connected to the inner side of the edge of the end cover 211 and fixedly connected with the end cover 211. The feeding network 21 further comprises an internal structure (not shown in the figure), and the cavity 212 is used for accommodating the internal structure of the feeding network 21.

[0044] The adapter structure 22 can comprise a first transmission line 221 used for transmitting the radio frequency signal. One end of the first transmission line 221 is electrically connected with the internal structure of the feeding network 21, and the other end is electrically connected with the cable 23. The first transmission line 221 is located on the side of the end cover 211 away from the cavity 212. Exemplarily, the first transmission line 221 can be located outside the cavity 212. In other embodiments, the first transmission line 221 can also be partially located outside the cavity 212, as long as the first transmission line 221 is at least partially located outside the cavity 212, which is not limited in the embodiments of the present application. The first transmission line 221 can be a microstrip line, a strip line or a suspended strip line.

[0045] In the embodiments, the characteristic impedance of the first transmission line 221 is easy to adjust, and the internal loss of the radio frequency signal is smaller than that of the cable 23. In the present application, the adapter structure 22 is used to connect the feeding network 21 and the cable 23, which can realize the impedance matching with the cable 23 by adjusting the characteristic impedance of the first transmission line 221, thereby expanding the matching space of the feeding network 21. In the traditional scheme, the cable 23 is directly connected with the feeding network 21, while in the present application, part of the cable 23 is replaced by the first transmission line 221. Since the loss of the radio frequency signal caused by the first transmission line 221 is lower than that of the cable 23 with the same length, the impedance of the radio frequency signal transmission line is reduced, the loss is reduced, and the antenna gain is improved.

[0046] Exemplarily, the adapter structure 22 further comprises a cover 222 covering the first transmission line 221. The cover 222 comprises a top plate away from the end cover and side plates located on both sides of the top plate. The two side plates are oppositely arranged and one end is fixedly connected with the top plate, and the other end is fixedly connected with the end cover. The top plate and the two side plates jointly enclose an inner cavity of the cover. The first transmission line 221 is at least partially located in the inner cavity of the cover. The cover is used for protecting the first transmission line 221 from the external environment. The cover can be made of metal material to shield the electromagnetic radiation of the transmission line and reduce the influence of the external electromagnetic environment on the transmitted radio frequency signal.

[0047] The cable 23 is used to transmit and distribute radio frequency signals. The cable 23 has a multi-layer structure, for example, three layers. The cable 23 includes a wire core 231, an insulation layer 232 wrapped outside the wire core 231, and a protective layer 233 wrapped outside the insulation layer 232. The wire core 231 is the conductive part of the power cable, which is used to transmit electric energy. The insulation layer 232 electrically isolates the wire core 231 from the ground, ensuring the transmission of electric energy. In some embodiments, the cable can include multiple wire cores 231, for example, two or three. In this case, the insulation layer 232 can electrically isolate the wire core 231 from the ground and different wire cores 231. The protective layer 233 protects the cable 23 from external impurities and moisture, and prevents external forces from directly damaging the cable 23.

[0048] The end cover 211 can be provided with a through hole 2111. The internal structure of the feed network 21 can be connected to the first transmission line 221 through the through hole 2111. For example, the first transmission line 221 can extend into the cavity through the through hole 2111, or the first transmission line 221 can be connected to the internal structure through an intermediate connecting structure (not shown in the figure) extending into the cavity 212, as long as at least part of the first transmission line 221 is located outside the cavity 212. In some embodiments, the cavity 212 can be a semi-open structure. In other embodiments, the cavity 212 can also be a closed structure, which can better avoid the interference of external radiation while not affecting the radiation unit, and the present application does not limit this.

[0049] Please refer to Figure 4 , Figure 4 is Figure 3 the internal structure of the base station antenna 2. The internal structure of the feed network includes a power divider 213, a phase shift network 214, and a plurality of output ports 215 and 216. The adapter structure 22 is electrically connected to one end of the phase shift network 214 and transmits radio frequency signals, and the power divider 213 can be electrically connected to the other end of the phase shift network 214 and can also be electrically connected to a plurality of output ports 215 and 216. The output ports 215 and 216 can be electrically connected to the radiation unit. The power divider 213 is used to divide one input signal into two or more output signals, and the energy of the multiple output signals can be equal to each other or at least two of them can be unequal, and the present application does not limit this. Specifically, the power divider 213 receives radio frequency signals from the cable 23 through the phase shift network 214 of the phase shifter, then divides the radio frequency signals into multiple output signals according to the actual application requirements, and sends the output signals to the radiation unit through the multiple output ports 215 and 216. The radiation unit converts the electrical signals into electromagnetic waves, which are finally received by terminals such as mobile phones.

[0050] For example, please refer to Figure 3 andFigure 4 The transition structure 22 includes a second transmission line 223 extending into the cavity. The first transmission line 221 can be connected to the internal structure through the second transmission line 223. For example, the second transmission line 223 includes a first segment 2231 and a second segment 2232, one end of the second segment 2232 is connected to one end of the first segment 2231, and the second segment 2232 is bent relative to the first segment 2231. For example, the second transmission line 223 can be L-shaped. The first segment 2231 can be fixedly connected to the phase shift network 214, and the second segment 2232 is fixedly connected to the first transmission line 221. For example, the first segment 2231 can be fixedly connected to the phase shift network 214 by means of fasteners, welding or the like. The second segment 2232 can be fixedly connected to the first transmission line 221 by means of welding or coupling, and the embodiments of the present application are not limited thereto. The transition through the second transmission line 223 can make the connection of the first transmission line 221 to the internal structure of the feed network 21 more flexible. In addition, the characteristic impedances of the first transmission line 221 and the second transmission line 223 can also be designed respectively to achieve impedance matching with the cable 23, improve the flexibility of the design, and expand the matching space of the feed network 21.

[0051] In some embodiments, the second transmission line 223 can have the same transmission line structure as the first transmission line 221, so that the connection mode of the second transmission line 223 and the first transmission line 221 is simple and convenient, and the assembly difficulty is reduced. In other embodiments, the second transmission line 223 can have a different transmission line structure from the first transmission line 221, which can achieve different transmission modes, thereby achieving the purpose of converting the radio frequency transmission mode. For example, the transmission line structure can include a strip line, a microstrip line or a suspended strip line. In other embodiments, the transmission line can also be other devices with radio frequency transmission function, and the embodiments of the present application are not limited thereto.

[0052] For example, the plurality of output ports can include a first output port 215 and a second output port 216. In some embodiments, the power divider 213 can be directly electrically connected to the first output port 215 and connected to the second output port 216 through a wire 217. The wire 217 can be a suspended strip line structure. The suspended strip line has good electromagnetic shielding property and will not cause electromagnetic interference to other devices in the cavity 212; at the same time, the electromagnetic influence of other devices is also very small, which is conducive to ensuring the stability and continuity of radio frequency signal transmission. In other embodiments, the wire 217 can also be other devices with radio frequency transmission function, such as a microstrip line and a strip line, and the embodiments of the present application are not limited thereto.

[0053] Exemplarily, there can be a mode conversion between the adapter structure 22 and the feed network 21. For example, the conversion can be between TEM (Transverse Electromagnetic Wave), TE (Transverse electric wave), quasi-TEM and all other radio frequency transmission modes. Specifically, when an electromagnetic wave propagates in free space, the propagation direction is not limited, so it is TEM; when it propagates in a transmission line, the electromagnetic wave is one-dimensionally limited, and at this time, a mode distribution is generated in the limited direction. The propagation mode of an electromagnetic wave is a certain electromagnetic field distribution rule that can exist independently. The propagation mode of an electromagnetic wave is related to the cross-sectional shape and size of the transmission line. For example, a rectangular transmission line usually only transmits electromagnetic waves of the TE10 mode, and a coaxial line and a strip line only transmit electromagnetic waves of the TEM mode. In addition, by adjusting the size of the transmission line, single-mode transmission and multi-mode transmission of the transmission line can also be controlled. For an electromagnetic wave of a certain frequency, by appropriately selecting the size of the transmission line to make the high-order mode be cut off and only the main mode be transmitted, that is, single-mode transmission. The main mode and one or more high-order modes are allowed to be transmitted at the same time, which is multi-mode transmission.

[0054] Exemplarily, the feed network 21 further includes a medium 218, which determines the equivalent dielectric constant of the transmission path of the radio frequency signal. The transmission path refers to the transmission section between the signal input end and the signal output end. By adjusting the equivalent dielectric constant of the medium 218 in the transmission path, the power and phase of the signal output from the signal output end can be controlled. For transmission lines without metal cavities, such as strip lines and microstrip lines, the medium 218 in the cavity includes a medium 218 substrate stacked on the transmission line and air around the transmission line.

[0055] Exemplarily, the transmission line structure can be a microstrip line. Please refer to Figure 5 , Figure 5 is a schematic diagram of the internal structure of the microstrip line 5 in some embodiments provided by the present application. The microstrip line 5 is a radio frequency transmission line composed of a dielectric substrate 51 and a conductor strip 52 fixedly connected to the dielectric substrate 51, and the side of the dielectric substrate 51 away from the conductor strip 52 is grounded. By adjusting the thickness and width of the conductor strip 52 and the thickness of the dielectric substrate 51, the characteristic impedance of the microstrip line 5 can be controlled.

[0056] In addition, since one side of the conductor strip 52 of the microstrip line 5 is a dielectric (dielectric substrate 51) and the other side is air, and the relative dielectric constant of the dielectric can be greater than that of air, the transmission speed of the radio frequency signal in the microstrip line 5 is fast, which is beneficial to the transmission of signals with high speed requirements. However, since part of the electric field formed in the microstrip line 5 is distributed in the dielectric substrate 51 and the other part is distributed in the air, the microstrip line 5 is easily affected by the surrounding radiation, and therefore the anti-interference ability of the microstrip line 5 is poor. In addition, the conductor strip 52 of the microstrip line 5 can have an increased width, thereby reducing the loss of the transmitted signal and improving the antenna gain.

[0057] For example, the transmission line structure can be a strip line. Please refer to Figure 6 , Figure 6 is a schematic diagram of the internal structure of the strip line 6 provided by the present application in some embodiments. The strip line 6 includes a dielectric 61 and a conductor strip 62 disposed in the dielectric 61. The dielectric 61 is disposed between two conductive planes 63, and both of the two conductive planes 63 are grounded. By adjusting the thickness and width of the conductor strip 62, the relative dielectric constant of the dielectric 61, and the distance between the two conductive planes 63, the characteristic impedance of the strip line 6 can be controlled.

[0058] In addition, since the conductor strip 62 of the strip line 6 is embedded between the two conductive planes 63, the impedance of the strip line 6 is easy to control. In addition, when the radio frequency signal is transmitted in the strip line 6, the electric field of the radio frequency signal is distributed between the conductive planes 63, and does not radiate outwardly, so the shielding ability is good; at the same time, it is not affected by external radiation, so the anti-interference ability is strong. However, since the conductor strip 62 is surrounded by the dielectric 61, and the dielectric constant of the dielectric 61 can be greater than that of air, the transmission speed of the signal in the strip line 6 is slower than that in the microstrip line, which affects the transmission efficiency of the radio frequency signal.

[0059] For example, the transmission line structure can be a suspended strip line. Please refer to Figure 7 , Figure 7 is a schematic diagram of the internal structure of the suspended strip line 7 provided by the present application in some embodiments. The suspended strip line 7 is a special strip line structure, which has the characteristics of low temperature drift and high power capacity. The suspended strip line 7 includes a metal cavity 71, a dielectric substrate 72, and a metal conductor strip 73, the dielectric substrate 72 is suspended in the metal cavity 71, and the metal conductor strip 73 is fixedly connected to the dielectric substrate 72. The suspended strip line 7 can include two metal conductor strips 73, which are oppositely located on both sides of the dielectric substrate 72, or one metal conductor strip 73.

[0060] Exemplarily, the two side metal cavity walls of the metal cavity 71 are oppositely provided with grooves, and the dielectric substrate 72 is embedded in the two grooves to be suspended in the metal cavity 71. The dielectric substrate 72 is grounded through the two side metal cavity walls, and thus the dielectric substrate 72 can be designed with circuits on both sides. In addition, the metal conductor strip 73 can be designed with circuits, and the metal conductor strip 73 on both sides of the dielectric substrate 72 can form double-sided circuits, which have strong coupling characteristics compared with single-layer circuits and are more convenient to be connected with other types of transmission lines, such as slot lines, coplanar waveguides, etc. The dielectric substrate 72 has an air cavity above and below, and the air cavities are filled with air.

[0061] Compared with the microstrip line, the internal electromagnetic field of the suspended strip line 7 is mostly distributed in the air cavities above and below, and less in the dielectric substrate 72, so that the relative permittivity of the suspended strip line 7 is close to the relative permittivity of air, effectively reducing the internal loss.

[0062] In addition, the air cavities produce a closed effect, and in combination with the shielding effect of the metal cavity 71 on the outside of the dielectric substrate 72 on electromagnetic radiation, the electromagnetic shielding property of the transmission line is good, and the transmission line can withstand high power and can be applied in high-power devices and systems. Correspondingly, the metal conductor strip 73 inside the metal cavity 71 is also less affected by the electromagnetic radiation outside the metal cavity 71, thereby ensuring the accuracy of the radio frequency signal in the transmission process.

[0063] Exemplarily, by adjusting the structure of the metal conductor strip 73 and the width and length of the metal cavity 71, the resonant frequency and high-order mode frequency of the suspended strip line 7 can be improved, so that they do not fall within the working frequency and can be applied to higher frequency application scenarios.

[0064] Exemplarily, please refer to Figure 3 When the first transmission line 221 is the suspended strip line 7, that is, the suspended strip line 7 is at least partially located outside the cavity 212, the suspended strip line 7 can include a dielectric substrate or can not include a dielectric substrate, which is not limited in the embodiments of the present application.

[0065] The above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application; in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A base station antenna, characterized in that, It includes a power supply network, cables, and a switching structure, wherein the power supply network includes a cavity and an internal structure located within the cavity; The adapter structure includes a first transmission line and a second transmission line. One end of the first transmission line is connected to one end of the second transmission line, and the other end of the first transmission line is electrically connected to the cable. The first transmission line is entirely located outside the cavity. One end of the second transmission line is connected to the first transmission line, and the other end extends into the cavity to connect to the internal structure. The first transmission line and the second transmission line are used to transmit radio frequency signals. The first transmission line adopts a transmission line structure of suspended stripline, microstrip line or stripline, and the second transmission line adopts a transmission line structure of suspended stripline, microstrip line or stripline; The adapter structure also includes a cover that covers the first transmission line.

2. The base station antenna as described in claim 1, characterized in that, The first transmission line and the second transmission line use the same transmission line structure.

3. The base station antenna as described in claim 1, characterized in that, The first transmission line and the second transmission line use different transmission line structures.

4. The base station antenna as described in any one of claims 1 to 3, characterized in that, The power supply network is electrically connected to the antenna connector via the cable.

5. The base station antenna as described in any one of claims 1 to 4, characterized in that, The second transmission line includes a first segment and a second segment. One end of the first segment is connected to the internal structure, and the other end of the first segment is connected to the second segment. One end of the second segment is connected to the first segment, and the other end of the second segment is connected to the first transmission line.

6. The base station antenna as described in claim 5, characterized in that, The second transmission line is L-shaped.

7. The base station antenna as described in any one of claims 1 to 6, characterized in that, The power supply network includes a phase shifter and a power divider, with the power divider electrically connected to the phase shifter.

8. The base station antenna as described in any one of claims 1 to 7, characterized in that, The suspension cable includes a metal conductor.

9. The base station antenna as described in claim 8, characterized in that, The suspended cable also includes a metal cavity and a dielectric substrate. The dielectric substrate is suspended in the metal cavity, and the metal guide strip is fixedly connected to the dielectric substrate. The metal cavity includes two metal sidewalls arranged opposite each other. Both metal sidewalls are provided with grooves, and the openings of the grooves face the inner side of the metal cavity. The dielectric substrate is embedded in the two grooves.

10. The base station antenna as described in claim 9, characterized in that, The suspended wire includes two metal conductors, which are located opposite each other on both sides of the dielectric substrate.

11. The base station antenna as described in any one of claims 1 to 7, characterized in that, The stripline includes a dielectric and a conductor strip placed in the middle of the dielectric, the dielectric being placed between two conductive planes, both of which are grounded.

12. The base station antenna as described in any one of claims 1 to 7, characterized in that, The microstrip line includes a dielectric substrate and a metal conductor strip, with the metal conductor strip fixedly connected to the dielectric substrate.

13. The base station antenna as described in any one of claims 1 to 12, characterized in that, The cover includes a top plate with an end cap facing away from the cavity and two side plates located on both sides of the top plate, wherein the two side plates are arranged opposite to each other, one end of the two side plates is fixedly connected to the top plate and the other end is fixedly connected to the end cap.

14. The base station antenna as described in claim 13, characterized in that, The cover is made of metal.

15. The base station antenna as described in any one of claims 1 to 14, characterized in that, The end cap of the cavity is provided with a through hole, through which the second transmission line extends into the cavity.

16. A base station, characterized in that, The base station antenna includes any one of claims 1 to 15.

17. A communication system, characterized in that, Including the base station as described in claim 16.

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