Dual-band feed source and base station antenna

Abstract

The invention provides a dual-band feed source and a base station antenna, the dual-band feed source comprises a feed source horn, a circular waveguide, a waveguide transition piece and a four-ridge feed network, the feed source horn is used for receiving or radiating signals; one end of the circular waveguide is connected with one end of the feed source horn, the other end of the circular waveguide is connected with the first end of the waveguide transition piece, and the circular waveguide is used for transmitting signals between the feed source horn and the waveguide transition piece; the waveguide transition piece is arranged to be transited from the circular waveguide to the four-ridge waveguide along the direction from the first end to the second end of the waveguide transition piece, and is used for transmitting signals between the circular waveguide and the four-ridge feed network; and the four-ridge feed network is used for separating or combining the signal with the horizontal polarization signal and the vertical polarization signal of each of the two different frequency bands.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a dual-band feed source and a base station antenna. Background Art

[0002] With the rapid development of communication technology, the performance requirements for microwave antenna systems are increasing, especially in terms of data transmission rate, spectrum efficiency and system capacity. As a key component in wireless communication systems, the design of microwave antennas is directly related to the quality and reliability of communication links. At present, the antennas widely used in microwave communication systems are mostly single-band antennas, which limits the effective use of spectrum resources and increases system complexity.

[0003] In order to overcome the limitations of existing technologies, the industry is gradually moving towards dual-band or even multi-band microwave antenna systems. Such antennas can work in two or more frequency bands simultaneously on the same hardware platform, thereby improving spectrum utilization and simplifying system design. However, existing microwave antennas that achieve dual-band operation generally have problems such as complex structure, high cost, difficult processing, and dielectric loss. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art, and proposes a dual-band feed and base station antenna, which can solve the problems of complex antenna structure, high cost, great processing difficulty and dielectric loss in the prior art.

[0005] To achieve the above-mentioned object, an embodiment of the present application provides a dual-band feed, comprising: a feed horn, a circular waveguide, a waveguide transition piece, and a four-ridge feed network, wherein the feed horn is used to receive or radiate a signal;

[0006] One end of the circular waveguide is connected to one end of the feed horn, and the other end of the circular waveguide is connected to the first end of the waveguide transition piece, and the circular waveguide is used to transmit signals between the feed horn and the waveguide transition piece;

[0007] The waveguide transition piece is configured to transition from a circular waveguide to a quad-ridged waveguide in a direction from a first end thereof to a second end thereof for transmitting signals between the circular waveguide and the quad-ridged feed network;

[0008] The quad-ridge feed network is used to separate or combine the signal with horizontally polarized signals and vertically polarized signals for each of two different frequency bands.

[0009] In some embodiments, the waveguide transition piece includes a circular waveguide segment, a tapered four-ridged waveguide segment, and a four-ridged waveguide segment connected in sequence along a direction from its first end to its second end, wherein the radial cross-sectional profile size of the first end of the tapered four-ridged waveguide segment is the same as the radial cross-sectional profile size of the circular waveguide segment; the radial cross-sectional profile size of the second end of the tapered four-ridged waveguide segment is the same as the radial cross-sectional profile size of the four-ridged waveguide segment; and the radial cross-sectional profile size of the tapered four-ridged waveguide segment decreases along a direction from its first end to its second end.

[0010] In some embodiments, the waveguide transition piece includes a circular waveguide segment, at least two step four-ridged waveguide segments and a four-ridged waveguide segment connected in sequence along a direction from its first end to its second end, wherein one end of the step four-ridged waveguide segment adjacent to the circular waveguide segment has the same radial cross-sectional profile size as the circular waveguide segment, one end of the step four-ridged waveguide segment adjacent to the four-ridged waveguide segment has the same radial cross-sectional profile size as the four-ridged waveguide segment, and the radial cross-sectional profile sizes of the at least two step four-ridged waveguide segments decrease in sequence along a direction from the circular waveguide segment to the four-ridged waveguide segment.

[0011] In some embodiments, the total length of the waveguide transition piece along the direction from the first end to the second end is greater than or equal to four times the wavelength of the electromagnetic wave corresponding to the lowest frequency value in the operating frequency range in free space.

[0012] In some embodiments, the quad-ridge feed network includes a quad-ridge splitter and four ridge waveguide duplexers, wherein the quad-ridge splitter is used to separate or synthesize the signal from two horizontally polarized signals and two vertically polarized signals; the quad-ridge splitter has a common port, and the common port is connected to the second end of the waveguide transition piece;

[0013] Two of the ridge waveguide duplexers are used to separate or synthesize the horizontal polarization signal from the first frequency band horizontal polarization signal and the second frequency band horizontal polarization signal, and are synthesized with a first transmission port and a second transmission port, which are used to output or input the first frequency band horizontal polarization signal and the second frequency band horizontal polarization signal respectively; the other two ridge waveguide duplexers are used to separate or synthesize the vertical polarization signal from the first frequency band vertical polarization signal and the second frequency band vertical polarization signal, and are synthesized with a third transmission port and a fourth transmission port, which are used to output or input the first frequency band vertical polarization signal and the second frequency band vertical polarization signal respectively.

[0014] In some embodiments, the quad-ridge splitter has at least one truncated cone, at least one of the truncated cones is disposed at the common port and is coaxially disposed with the waveguide transition piece;

[0015] When there are multiple truncated cones, the multiple truncated cones are coaxially stacked in sequence along the axial direction of the waveguide transition piece, and the diameters of the multiple truncated cones increase in sequence in a direction away from the waveguide transition piece.

[0016] In some embodiments, the total length of the at least one truncated cone along the signal propagation direction of the waveguide transition piece is greater than or equal to 0.1 to 0.2 times the wavelength of the electromagnetic wave in free space corresponding to the lowest frequency value within the operating frequency range.

[0017] In some embodiments, the first frequency band is a standard backhaul frequency band; and the second frequency band is an E-band.

[0018] In some embodiments, the inner circumferential surface of the feed horn is provided with a corrugated structure, and the corrugated structure includes a plurality of first annular grooves sequentially arranged along the axial direction of the feed horn.

[0019] As another technical solution, the present application also provides a base station antenna, including:

[0020] The above-mentioned dual-band feed provided by this application;

[0021] A secondary reflector, disposed on a side of the feed horn away from the circular waveguide and having a secondary reflector surface facing the circular waveguide;

[0022] The main reflector is arranged between the waveguide transition piece and the four-ridge feed network, and the waveguide transition piece passes through the main reflector and is connected to the four-ridge feed network; the main reflector has a main reflection surface facing away from the four-ridge feed network.

[0023] In some embodiments, a central plane and a plurality of concentric annular surfaces surrounding the central plane are arranged in the central area of ​​the secondary reflector, and the central plane and the plurality of annular surfaces constitute a continuous surface; the orthographic projections of the central plane and the plurality of annular surfaces on a preset cross section constitute a plurality of line segments connected in series, and the preset cross section is parallel to the central axis and radial straight line of the secondary reflector.

[0024] In some embodiments, a plurality of concentric second annular grooves are provided in the edge region of the secondary reflective surface.

[0025] In some embodiments, a plurality of concentric annular surfaces are arranged in the edge area of ​​the secondary reflector, and the plurality of annular surfaces constitute a continuous surface; the orthographic projections of the plurality of annular surfaces on a preset cross section constitute a plurality of serially connected line segments, and the preset cross section is parallel to the central axis and radial straight line of the secondary reflector.

[0026] In some embodiments, a plurality of concentric second annular grooves are disposed in a central region of the secondary reflective surface.

[0027] Other objects and features of the present application will become clear by reading the specification, claims and drawings of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0029] Figure 1 is a structural exploded perspective view of a base station antenna provided in an embodiment of the present application;

[0030] Figure 2 is an installation diagram of a dual-band feed and a sub-reflector provided in an embodiment of the present application;

[0031] Figure 3 is a structural diagram of a waveguide transition piece used in an embodiment of the present application;

[0032] Figure 4 is a perspective view of a four-ridge feed network and a waveguide transition piece used in an embodiment of the present application;

[0033] Figure 5 is a perspective view of a quad-ridge splitter used in an embodiment of the present application;

[0034] Figure 6 is a top view of a quad-ridge splitter used in an embodiment of the present application;

[0035] Figure 7 is a perspective view of a ridge waveguide duplexer used in an embodiment of the present application;

[0036] Figure 8 is a schematic diagram of a ridge waveguide duplexer used in an embodiment of the present application;

[0037] Fig. 9 is a transmission diagram of horizontal and vertical polarized signals in two frequency bands in an embodiment of the present application;

[0038] Fig.10 is a structural diagram of a feed horn used in an embodiment of the present application;

[0039] Fig.11 is a structural diagram of a secondary reflective surface of a secondary reflector used in an embodiment of the present application;

[0040] Fig.12 is a standing wave ratio curve of the dual-band feed used in the embodiment of the present application in the conventional return frequency band;

[0041] Fig.13 is a standing wave ratio curve of the dual-band feed used in the embodiment of the present application in the E-BAND band;

[0042] Fig.14is the gain pattern of the base station antenna used in the embodiment of the present application in the conventional backhaul frequency band;

[0043] Fig.15 It is the gain pattern of the base station antenna used in the embodiment of the present application in the E-BAND frequency band.

[0044] Description of main component symbols:

[0045] 100, dual-band feed; 2, feed horn; 21, first annular groove; 3, fixing bracket; 4, circular waveguide; 5, waveguide transition piece; 5a, first end; 5b, second end; 51, circular waveguide section; 52, gradient quad-ridge waveguide section; 521, first end; 522, second end; 53, quad-ridge waveguide section; 7, quad-ridge feed network; 71, quad-ridge splitter; 711a, common port; 711b, ridge waveguide port; 721a, common port; 7 21b, first frequency band port; 721c, second frequency band port; 72a, first ridge waveguide duplexer; 72b, second ridge waveguide duplexer; 72c, third ridge waveguide duplexer; 72d, fourth ridge waveguide duplexer; 722a, first transmission port; 722b, second transmission port; 722c, third transmission port; 722d, fourth transmission port; 723, rectangular waveguide; 724, step ridge transition structure; 725, metal ridge; 73, truncated cone;

[0046] 200, antenna; 1, secondary reflector; 11, annular surface; 111, line segment; 12, center surface; 13, second annular groove; 6, primary reflector; 61, primary reflective surface; 62, metal frame;

[0047] X1, first direction; X2, second direction. DETAILED DESCRIPTION

[0048] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0049] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0050] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "certain embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0053] Please also read Figure 1 and Figure 2 The present application embodiment provides a dual-band feed source 100, which is used, for example, in Figure 1 The point-to-point microwave communication antenna shown is an antenna used in a point-to-point (PtP) microwave communication system. This antenna is designed to establish a direct wireless communication link between two fixed locations. However, the dual-band feed 100 provided in the embodiment of the present application can also be applied to 5G, 6G communications, satellite communications and other communication scenarios with high data rates and broadband spectrum requirements. The dual-band feed 100 provided in the embodiment of the present application can be shared at the same time, allowing one antenna to work simultaneously on two different frequency bands (such as a conventional backhaul band and an E-BAND band), instead of using two independent antennas separately. This can significantly improve the utilization efficiency of spectrum resources while reducing the number of antennas and system complexity. On this basis, the dual-band feed 100 provided in the embodiment of the present application does not involve a medium, which not only avoids medium loss and achieves optimal transmission efficiency; moreover, compared with the coaxial nested waveguide structure adopted in the prior art (the high-frequency transmission waveguide is nested inside the low-frequency transmission waveguide), when the dual bands are shared, the dual-band feed 100 provided in the embodiment of the present application has a simpler structure, thereby reducing the processing difficulty and cost while maintaining high performance.

[0054] Specifically, the dual-band feed 100 provided in the embodiment of the present application includes: a feed horn 2, a circular waveguide 4, a waveguide transition piece 5 and a four-ridge feed network 7, wherein the feed horn 2 is used to receive or radiate signals. Specifically, the feed horn 2 is used to receive electromagnetic wave signals in free space in a receiving mode; in a radiating mode, the signal from the circular waveguide 4 is radiated into free space. One end of the circular waveguide 4 is connected to one end of the feed horn 2, and the other end of the circular waveguide 4 is connected to the first end 5a (such as the first end 5b of the waveguide transition piece 5) of the waveguide transition piece 5. Figure 3The circular waveguide 4 is connected to the feed horn 2 and the waveguide transition piece 5, and is used to transmit signals between the feed horn 2 and the waveguide transition piece 5. Specifically, the radial cross section of the circular waveguide 4 is circular, and is used to transmit the signal from the feed horn 2 to the waveguide transition piece 5 in the receiving mode, and transmit the signal from the waveguide transition piece 5 to the feed horn 2 in the radiation mode. The circular waveguide 4 is generally used to transmit a specific electromagnetic wave mode, such as the TE11 mode.

[0055] See also Figure 3 The waveguide transition piece 5 is arranged in a direction from its first end 5a to its second end 5b (ie Figure 3 The radial cross-section of the waveguide transition piece 5 is configured to transition from a circular waveguide to a quad-ridged waveguide in the vertical direction of the circular waveguide 4 and the quad-ridged feeding network 7 to transmit signals between the circular waveguide 4 and the quad-ridged feeding network 7. The radial cross-section of the first end 5a of the waveguide transition piece 5 is circular, and the radial cross-section of the second end 5b thereof is a quad-ridged shape, that is, a central shape (such as a circle, a quadrilateral, etc.) surrounded by four ridges (or fins). The radial cross-sectional shape of the waveguide transition piece 5 is configured to transition from a circle to the quad-ridged shape to facilitate smooth conversion of electromagnetic wave modes and reduce reflections and high-order mode excitations. The waveguide transition piece 5 is used to achieve effective conversion between different waveguide modes, thereby facilitating optimization of impedance matching, reducing signal reflections and high-order mode excitations, and thereby improving signal transmission efficiency and antenna performance. On this basis, the waveguide transition piece 5 does not involve a medium, for example, it is an all-metal structure, which not only avoids dielectric loss and achieves optimal transmission efficiency; moreover, compared with the coaxial nested waveguide structure adopted in the prior art (the high-frequency transmission waveguide is nested inside the low-frequency transmission waveguide), the structure of the waveguide transition piece 5 is simpler, thereby reducing processing difficulty and cost while maintaining high performance.

[0056] In some embodiments, the length of the waveguide transition piece 5 should ensure good impedance matching and mode control within the required frequency range. To achieve this purpose, preferably, the total length of the waveguide transition piece 5 along the direction from its first end 5a to its second end 5b is greater than or equal to four times the wavelength of the electromagnetic wave in free space corresponding to the lowest frequency value within the operating frequency range. By satisfying the above range, the total length can ensure good impedance matching in the conventional return frequency band and the E-BAND frequency band, avoid high-order mode excitation, and ensure stable signal transmission. Of course, in actual applications, the above total length of the waveguide transition piece 5 can be obtained according to specific electromagnetic simulation and optimization processes.

[0057] The four-ridge feed network 7 is used to separate or synthesize the horizontal polarization signal and the vertical polarization signal of each of the two different frequency bands. With the help of the four-ridge feed network 7, dual-band (such as conventional backhaul band and E-BAND band) and dual polarization (such as horizontal and vertical polarization) operations can be achieved to improve spectrum efficiency and system capacity. On this basis, by combining the waveguide transition piece 5 and the four-ridge feed network 7, the working bandwidth of each device in the feed network can be expanded (for example, the ratio of high frequency to low frequency is about 2:1). Compared with the coaxial nested waveguide structure used in the prior art, it is difficult to achieve a large ratio of high frequency to low frequency (for example, 10:1). The embodiment of the present application allows each device in the feed network to operate within a wider frequency range, thereby supporting electromagnetic wave propagation in multiple modes, thereby covering a wider frequency range. Moreover, the waveguide transition piece 5 and the four-ridge feed network 7 can both be all-metal structures, which can overcome the defects of dielectric loss, high processing difficulty, and high cost caused by the need to use a dielectric in the prior art.

[0058] The radial cross-sectional shape of the waveguide transition piece 5 is configured to transition from a circular shape to the four-ridge shape, which can be implemented in a variety of ways. In one example, Figure 3 As shown, the waveguide transition piece 5 includes a circular waveguide segment 51, a gradient four-ridge waveguide segment 52 and a four-ridge waveguide segment 53 connected in sequence along the direction from the first end 5a to the second end 5b, wherein the radial cross-sectional profiles of the circular waveguide segment 51 at different axial positions are all circular, and the size can be the same everywhere, or it can decrease in the direction away from the circular waveguide 4. In practical applications, it can be set according to specific needs to achieve a good impedance matching effect. The radial cross-sectional profiles of the four-ridge waveguide segment 53 at different axial positions are all four-ridged, and the size can be the same everywhere, or it can decrease in the direction away from the circular waveguide 4. In practical applications, it can be set according to specific needs to achieve a good impedance matching effect. The radial cross-sectional profile size of the first end 521 of the tapered quad-ridged waveguide segment 52 is the same as the radial cross-sectional profile size of the circular waveguide segment 51 (this size is a fixed value or a minimum value); the radial cross-sectional profile size of the second end 522 of the tapered quad-ridged waveguide segment 52 is the same as the radial cross-sectional profile size of the quad-ridged waveguide segment 53 (this size is a fixed value or a maximum value); the radial cross-sectional profile size of the tapered quad-ridged waveguide segment 52 decreases in the direction from its first end 521 to its second end 522. By adopting a gradual transition from a circular waveguide to a quad-ridged waveguide, not only can the structure be simplified, but it is also easier to process, reducing costs while maintaining high performance.

[0059] In another example, the waveguide transition piece 5 includes a circular waveguide segment 51, at least two stepped four-ridged waveguide segments 53 and a four-ridged waveguide segment 53 connected in sequence along the direction from the first end 5a thereof to the second end 5b thereof, wherein the shapes and structures of the circular waveguide segment 51 and the four-ridged waveguide segment 53 are the same as those in the above examples and are not described in detail herein. One end of the stepped four-ridged waveguide segment 53 adjacent to the circular waveguide segment 51 has the same radial cross-sectional profile size as the circular waveguide segment 51, and one end of the stepped four-ridged waveguide segment 53 adjacent to the four-ridged waveguide segment 53 has the same radial cross-sectional profile size as the four-ridged waveguide segment 53, and the radial cross-sectional profile sizes of at least two stepped four-ridged waveguide segments 53 decrease in sequence along the direction from the circular waveguide segment 51 to the four-ridged waveguide segment 53. Such a step-by-step change in the radial cross-sectional profile size can also achieve a transition from a circular waveguide to a four-ridged waveguide.

[0060] See also Figure 4 and Fig. 9 The four-ridge feed network 7 for achieving the above effect includes, for example, a four-ridge splitter 71 and four ridge waveguide duplexers, namely, a first ridge waveguide duplexer 72a, a second ridge waveguide duplexer 72b, a third ridge waveguide duplexer 72c and a fourth ridge waveguide duplexer 72d, wherein the four-ridge splitter 71 is used to separate or synthesize the signal from two horizontally polarized signals and two vertically polarized signals. For details, please refer to Figure 5 The quad-ridge splitter 71 has a common port 711a and four ridge waveguide ports 711b, wherein, in one example, the combination Figure 3 and Figure 5 As shown, the waveguide transition piece 5 is connected to the quad-ridged wave splitter 71 through the quad-ridged waveguide section 53. That is, the quad-ridged waveguide section 53 is a common part for connecting the waveguide transition piece 5 and the quad-ridged wave splitter 71. In this case, the quad-ridged waveguide section 53 is Figure 5 The upper end of the waveguide is used as a common port 711a, which is connected to the second end 522 of the tapered quad-ridged waveguide segment 52 of the waveguide transition piece 5, so that the signal can be transmitted between the waveguide transition piece 5 and the quad-ridged wave splitter 71. However, the embodiment of the present application is not limited to this. In another example, the quad-ridged waveguide segment 53 can also adopt a split structure, that is, the quad-ridged waveguide segment 53 is composed of two sub-quad-ridged waveguide segments connected in sequence, and one of the sub-quad-ridged waveguide segments belongs to the waveguide transition piece 5, and the other sub-quad-ridged waveguide segment belongs to the quad-ridged wave splitter 71.

[0061] like Figure 6As shown, the four ridge waveguide ports 711b of the quad-ridge splitter 71 are oriented in four different directions, wherein two ridge waveguide ports 711b are oriented in two opposite directions along the first direction X1, respectively; the other two ridge waveguide ports 711b are oriented in two opposite directions along the second direction X2, respectively, and the first direction X1 and the second direction X2 are perpendicular to each other. The quad-ridge splitter 71 is used to separate the signal from the waveguide transition piece 5 into two horizontally polarized signals and two vertically polarized signals, and to synthesize the received horizontally polarized signals and vertically polarized signals and transmit them to the waveguide transition piece 5. The two horizontally polarized signals can be input or output respectively from the two ridge waveguide ports 711b oriented in the direction along the first direction X1, and the two vertically polarized signals can be input or output respectively from the two ridge waveguide ports 711b oriented in the second direction X2.

[0062] See also Figure 7 Taking the first ridge waveguide duplexer 72a as an example, each of the first ridge waveguide duplexer 72a, the second ridge waveguide duplexer 72b, the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d has a common port 721a, a first frequency band port 721b and a second frequency band port 721c, wherein, in combination with Figure 4 The common port 721a of the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b are respectively connected to the two ridge waveguide ports 711b of the quad-ridge wave splitter 71 along the first direction X1, and the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b are used to separate or synthesize the horizontal polarization signal from the first frequency band horizontal polarization signal and the second frequency band horizontal polarization signal, and the first transmission port 722a and the second transmission port 722b are synthesized to output or input the first frequency band horizontal polarization signal and the second frequency band horizontal polarization signal, respectively, as shown in FIG. Figure 4As shown, the first frequency band port 721b and the second frequency band port 721c of the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b are respectively combined into a first transmission port 722a and a second transmission port 722b through two rectangular waveguides 723. Specifically, the ridge waveguide ports 711b facing two opposite directions along the first direction X1 respectively transmit two horizontally polarized signals to the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b through the common port 721a of the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b, and the two horizontally polarized signals are respectively separated into a first frequency band horizontally polarized signal and a second frequency band horizontally polarized signal by the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b, and the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b transmit the two horizontally polarized signals to the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b. The first frequency band port 721b and the second frequency band port 721c of the waveguide duplexer 72b are output, and then the first frequency band horizontal polarization signal output by the first frequency band port 721b of the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b is output through the first transmission port 722a synthesized by a rectangular waveguide 723; the second frequency band horizontal polarization signal output by the second frequency band port 721c of the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b is output through the second transmission port 722b synthesized by another rectangular waveguide 723. It is easy to understand that the function of each rectangular waveguide 723 is to synthesize the two signals output by the first frequency band port 721b or the second frequency band port 721c of the first ridge waveguide duplexer 72a and the second ridge waveguide duplexer 72b, and then output from the first transmission port 722a or the second transmission port 722b. The first transmission port 722a and the second transmission port 722b are formed in the rectangular waveguide 723.

[0063] Similarly, the common ports 721a of the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d are respectively connected to the two ridge waveguide ports 711b of the quad-ridge wave splitter 71 along the second direction X2, and the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d are used to separate or synthesize the vertical polarization signal from the first frequency band vertical polarization signal and the second frequency band vertical polarization signal, and are synthesized with a third transmission port 722c and a fourth transmission port 722d, which are used to output or input the first frequency band vertical polarization signal and the second frequency band vertical polarization signal, respectively, as shown in FIG. Figure 4As shown, the first frequency band port 721b and the second frequency band port 721c of the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d are respectively synthesized into a third transmission port 722c and a fourth transmission port 722d through two rectangular waveguides 723. Specifically, the ridge waveguide ports 711b facing two opposite directions along the second direction X2 respectively transmit two vertically polarized signals to the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d via the common port 721a of the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d, and the two vertically polarized signals are respectively separated into a first frequency band vertically polarized signal and a second frequency band vertically polarized signal by the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d, and the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d are respectively transmitted to the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d. The first frequency band port 721b and the second frequency band port 721c of the waveguide duplexer 72d are output, and then the first frequency band vertical polarization signal output by the first frequency band port 721b of the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d is output through the third transmission port 722c synthesized by a rectangular waveguide 723; the second frequency band vertical polarization signal output by the second frequency band port 721c of the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d is output through the fourth transmission port 722d synthesized by another rectangular waveguide 723. It is easy to understand that the function of each rectangular waveguide 723 is to synthesize the two signals output by the first frequency band port 721b or the second frequency band port 721c of the third ridge waveguide duplexer 72c and the fourth ridge waveguide duplexer 72d, and then output from the corresponding third transmission port 722c or the fourth transmission port 722d. The third transmission port 722c and the fourth transmission port 722d are formed in the rectangular waveguide 723.

[0064] The above-mentioned ridge waveguide duplexer adopts, for example, a multi-stage coupling structure to separate the horizontal or vertical polarization signal into a horizontal or vertical polarization signal of a first frequency band and a horizontal or vertical polarization signal of a second frequency band.

[0065] In some embodiments, the first frequency band is, for example, a standard backhaul frequency band; and the second frequency band is an E-band (ie, an E-BAND frequency band).

[0066] In some embodiments, Figure 8 As shown, the ridge waveguide duplexer is composed of two independently designed frequency band filters (i.e., a high-pass filter and a low-pass filter) and connected through a T-junction. The impedance of the ridge waveguide duplexer at the common port, the first frequency band port, and the second frequency band port is Z 0 That is to say, the ridge waveguide duplexer can be integrated with a filtering structure, for example, to efficiently separate signals in two frequency bands. Figure 7As shown, the high-pass filter is realized by changing the size of the ridge waveguide and utilizing its low-frequency cutoff characteristics, and its matching characteristics are realized by the transition structure 724 of the stepped ridge; the width of the metal ridge 725 of the low-pass filter remains unchanged, but the height is changed, and the metal ridges of different heights are combined together to achieve high and low impedance, thereby generating low-pass characteristics. The grooves and teeth of the metal ridge 725 of the low-pass filter are generally 6 to 10 groups, for example, 8 groups.

[0067] This is achieved by loading ridges of the same width and unequal height as the ridges at the common end of the ridge waveguide duplexer. Specifically, by adjusting the height of the ridges inside the ridge waveguide, the impedance characteristics can be changed, thereby affecting the propagation characteristics of the electromagnetic wave. Based on this, the ridge waveguide duplexer achieves matching with the low-pass filter by loading ridges of unequal heights at its common end. In this way, the effect of the change in ridge height on the impedance characteristics can be utilized, so that good impedance matching can be achieved within the operating frequency band of the low-pass filter, thereby not only improving the signal transmission efficiency and reducing signal reflection and loss, but also by selectively passing low-frequency signals while suppressing high-frequency signals by frequency, achieving effective frequency separation, meeting the needs of specific communication systems, and improving the performance and efficiency of the overall system. Of course, in practical applications, the ridge width of the ridge waveguide duplexer can also be variable. Figure 7 The specific structure of the ridge waveguide duplexer is shown. According to the simulation results, the reflection coefficient in the dual frequency bands (i.e., the first frequency band and the second frequency band mentioned above) is less than -18dB, the transmission coefficient is about -0.1dB, and the isolation is better than -40dB, ensuring that the two frequency band signals are output at the common port of the two ridge waveguide duplexers and synthesized without intermodulation interference.

[0068] In some embodiments, to adjust impedance matching, such as Figure 5 and Figure 6 As shown, the quad-ridge wave splitter 71 has at least one truncated cone 73, and at least one truncated cone 73 is arranged at the common port 711a of the quad-ridge wave splitter 71, and is coaxially arranged with the waveguide transition piece 5. Further, in some embodiments, when there are multiple truncated cones 73, the multiple truncated cones 73 are coaxially stacked in sequence along the axial direction of the waveguide transition piece 5, and the diameters of the multiple truncated cones 73 are successively increased in the direction away from the waveguide transition piece 5. In practical applications, according to the impedance matching characteristics adapted to the specific situation, the number of truncated cones 73 can be one or more. For example, simulation with two truncated cones 73 can obtain the following impedance matching effect: the reflection coefficients in the dual bands (for example, the standard return band and the E-BAND band) are all less than -29dB, the transmission coefficient is close to 0dB, and the high-order modulus level is less than -50dB in the E-BAND band.

[0069] Furthermore, in some embodiments, in order to achieve good impedance matching, the total length of at least one truncated cone 73 along the signal propagation direction of the waveguide transition piece 5 is greater than or equal to 0.1 to 0.2 times the wavelength of the electromagnetic wave in free space corresponding to the lowest frequency value within the operating frequency range.

[0070] In some embodiments, Fig.10 As shown, the inner circumference of the feed horn 2 is provided with a corrugated structure, and the corrugated structure includes a plurality of first annular grooves 21 arranged in sequence along the axial direction of the feed horn 2. The diameter of the inner circumference of the feed horn 2 gradually decreases in the direction close to the circular waveguide 4. In this case, the inner diameters of the plurality of first annular grooves 21 decrease one by one in the direction close to the circular waveguide 4; each adjacent two first annular grooves 21 are arranged at intervals in the radial direction. The first annular grooves 21 are used to control the radiation mode, reduce unnecessary radiation (such as side lobes), and ensure good rotational symmetry and stable phase center in the main radiation area of ​​the dual-band, improve the uniformity of radiated electromagnetic waves in all directions, and thus improve the performance of the antenna. The first annular grooves 21 are, for example, 3 to 5. In a specific embodiment, there are four first annular grooves 21, each of which has a radial width of about 0.9 mm, and each adjacent two first annular grooves 21 are arranged at intervals, and the interval is about 0.6 mm.

[0071] As another technical solution, see Figure 1 The embodiment of the present application also provides an antenna 200, comprising: a dual-band feed 100, a sub-reflector 1 and a main reflector 6, wherein the dual-band feed 100 adopts the above antenna provided in the embodiment of the present application. The sub-reflector 1 is arranged on the side of the feed horn 2 away from the circular waveguide 4 through a fixing bracket 3, and has a sub-reflector surface facing the circular waveguide 4; the main reflector 6 is arranged between the waveguide transition piece 5 and the four-ridge feed network 7, and the waveguide transition piece 5 passes through the main reflector 6 and is connected to the four-ridge feed network 7; the main reflector 6 has a main reflector surface 61 facing away from the four-ridge feed network 7.

[0072] The sub-reflection surface of the sub-reflector 1 is a reflection surface that is smaller than the main reflection surface, is located in front of the main reflection surface 61, and faces the circular waveguide 4. The main function of the sub-reflection surface is to assist in focusing the electromagnetic waves emitted by the feed source onto the main reflection surface 61, thereby improving the directivity and gain of the antenna. The sub-reflector 1 can be fixed to the feed horn 2 by a fixing bracket 3 (for example, including multiple support rods).

[0073] The main reflector 61 adopts a ring-focus parabolic structure, for example, which can effectively focus the electromagnetic waves radiated by the feed source to form a plane wave, thereby ensuring high gain and low sidelobe performance in two frequency bands (such as the conventional return frequency band and the E-BAND frequency band). The aperture of the main reflector 61 is about 0.6m, and the main reflector 6 can be provided with a metal frame 62 around the main reflector to enhance structural stability and anti-interference performance.

[0074] The antennas in the prior art that can cover two frequency bands do not consider the sidelobe envelope problem of the antenna pattern, that is, they do not optimize the performance of the sidelobe envelope. The sidelobe envelope refers to the maximum radiation intensity distribution of the sidelobe in the antenna pattern. If the sidelobe level is too high, the antenna may interfere with signals in other directions or receive interference signals in other directions, thereby causing the antenna to fail to meet the requirements of the ETSI standard and thus be difficult to use in point-to-point microwave communication systems that have strict requirements on high directivity and low interference. In order to solve this problem, Fig.11 As shown, a central plane 12 and a plurality of concentric annular surfaces 11 surrounding the central plane 12 are arranged in the central region of the secondary reflector used in the embodiment of the present application, and the central plane 12 and the plurality of annular surfaces 11 constitute a continuous surface; the orthographic projections of the central plane 12 and the plurality of annular surfaces 11 on a preset cross section constitute a plurality of line segments 111 connected in series, and the preset cross section is parallel to the central axis and the radial straight line of the secondary reflector, that is, the line segments 111 extend radially along the annular surface 11. In a specific embodiment, there are 8 line segments formed by the orthographic projections of the central plane 12 and the plurality of annular surfaces 11 on the preset cross section, and the endpoints of each adjacent two line segments 111 are connected to form a node, and there are 7 nodes in total. The positions of the 7 nodes (for example, the coordinate positions in the axial direction) are adjustable to control the reflection path of the electromagnetic wave, thereby controlling the distribution of the aperture field of the main reflector.

[0075] According to the principle of geometric optics, when the shape of the sub-reflector changes, the energy scattered after the feed source irradiates the sub-reflector will also change accordingly, and then form a different aperture field distribution after irradiating the main reflector 61, thereby changing the antenna radiation pattern. Based on this, by adjusting the number of concentric annular surfaces 11, the shape and length of the line segment 111, the shape of the sub-reflector can be controlled, so that the distribution of the aperture field of the main reflector (that is, the distribution of electromagnetic waves on the main reflector) can be controlled, thereby optimizing the antenna's pattern, reducing the level of the side lobes, and increasing the gain of the main lobe, etc., so that the performance of the antenna can be flexibly adjusted to meet different communication needs and standards. It is easy to understand that adjusting the shape and length of the line segment 111, for example, includes adjusting the position of the node connecting each two adjacent line segments 111 (that is, the end point of each line segment 111) to change the geometric structure of the entire multi-segment shape. Compared with the main reflector or sub-reflector of the traditional ring focus or Cassegrain parabola, the sub-reflector of the present application adopts a plurality of concentric annular surfaces 11, and by adjusting the number of concentric annular surfaces 11, the shape and length of the line segments, the directional pattern of the antenna 200 can be optimized, such as reducing the side lobe level, improving the main lobe shape, or adjusting the beam pointing, etc. In practical applications, the optimal positions of these nodes can be determined according to the operating frequency band of the antenna 200, the required radiation characteristics, and the communication standards to be met (such as ETSI standards). In addition, these line segments 111 can be straight segments, curved segments, or other shapes to achieve specific electromagnetic wave reflection and radiation characteristics.

[0076] It should be noted that the above-mentioned line segment 111 is a virtual line used to represent the characteristics or structure of the annular surface 11 during the design process of the annular surface 11. In actual applications, the secondary reflection surface is composed of a continuous metal surface, which is composed of multiple concentric annular surfaces 11. The orthographic projections of these annular surfaces 11 on the preset cross-section include the line segment 111.

[0077] Further, in some embodiments, in order to increase the structural strength and control the reflection characteristics of electromagnetic waves, a plurality of concentric second annular grooves 13 are provided in the edge region of the sub-reflecting surface. Side lobes are radiation lobes other than the main lobe in the antenna pattern, which may cause signal interference and reduced spectral efficiency. The second annular groove 13 (for example, by adjusting its depth) can affect the formation of the side lobe, and by changing the reflection and propagation mode of the electromagnetic wave on the sub-reflecting surface, the strength of the side lobe is reduced, thereby improving the antenna pattern characteristics. In addition, the second annular groove 13 can enhance the structural rigidity of the sub-reflecting surface, making it more solid and able to withstand various forces that may be encountered during installation, transportation or use, such as wind force, dead weight, etc. In addition, the design of the second annular groove 13 helps to control the propagation path of the electromagnetic wave, reduce diffraction, and make the electromagnetic energy propagate more concentratedly in a predetermined direction. In order to achieve this effect, the depth of the second annular groove 13 is, for example, one-fourth of the wavelength of the electromagnetic wave in free space corresponding to the lowest frequency value in the operating frequency range.

[0078] These second annular grooves 13 are distributed around the above-mentioned multiple annular surfaces 11, but the embodiments of the present application are not limited to this. In other embodiments, the above-mentioned multiple annular surfaces 11 may also be distributed around these second annular grooves 13. That is, multiple concentric annular surfaces are arranged in the edge area of ​​the secondary reflector, and the multiple annular surfaces constitute a continuous surface; the orthographic projections of the multiple annular surfaces on the preset cross section constitute multiple line segments connected in series, and the preset cross section is parallel to the central axis and radial straight line of the secondary reflector. Multiple concentric second annular grooves 13 are arranged in the central area of ​​the secondary reflector. Of course, in practical applications, the second annular grooves 13 can also be omitted, and multiple concentric annular surfaces are arranged only in the central area and / or edge area of ​​the secondary reflector.

[0079] The assembly steps of the antenna provided in the embodiment of the present application are as follows: the secondary reflector is connected to the feed horn 2 through a plurality of support rods. One end of the circular waveguide 4 is connected to one end of the feed horn 2, and the two ends of the waveguide transition piece 5 (i.e., the first end 5a and the second end 5b) are respectively connected to the other end of the circular waveguide 4 and the four-ridge feed network 7. The four-ridge feed network 7 adopts a metal laminate structure, which can be further assembled with the main reflector. After the installation is completed, the gain and coverage of the antenna can be further optimized by fine-tuning the angle of each support rod.

[0080] like Fig.12 and Fig.13 As shown, the vertical axis in these two figures represents the voltage standing wave ratio (VSWR), and the horizontal axis represents the frequency (in GHz). The black curve and the gray curve in these two figures correspond to horizontal polarization and vertical polarization respectively. The dual-band feed 100 in the embodiment of the present application achieves a standing wave ratio of less than 1.65 (such as Fig.12 As shown in Figure 2), the VSWR achieved in E-BAND is less than 1.52 (as shown in Figure 2 Fig.13 The smaller standing wave ratio indicates that the feed source of the present application and its feeding system have achieved good impedance matching and high transmission efficiency.

[0081] like Fig.14 and Fig.15 As shown, the vertical axis in these two figures represents gain (Gain, unit is dBi), and the horizontal axis represents angle (unit is deg). The black curve and gray curve in these two figures correspond to horizontal polarization and vertical polarization respectively. The antenna in the embodiment of the present application is in the conventional return frequency band f1 (such as Fig.14 as shown) and E-BAND (as Fig.15 The gain pattern test result diagram (as shown) basically meets the standard requirements of ETSI antenna radiation characteristics.

[0082] In summary, the antenna 200 provided in the embodiment of the present application can be an all-metal structure by adopting the dual-band feed 100 provided in the embodiment of the present application, and can work in dual bands (such as conventional return band / E-BAND), and does not involve a medium, which not only avoids dielectric loss, but also achieves optimal transmission efficiency; and, compared with the coaxial nested waveguide structure (high-frequency transmission waveguide nested inside the low-frequency transmission waveguide) used in the prior art, the dual-band feed 100 provided in the embodiment of the present application has a simpler structure, thereby reducing the processing difficulty and cost, while maintaining high performance. The secondary reflector can improve the sidelobe characteristics of the antenna system pattern by adjusting the number of concentric annular surfaces, the shape and length of the radial line segment, and the depth of the second annular groove 13 to meet the ETSI requirements.

[0083] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present application, but the present application is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of the present application, and these modifications and improvements are also considered to be within the scope of protection of the present application.

Claims

1. A dual-band feed, characterized in that: include: A feed horn, a circular waveguide, a waveguide transition piece, and a four-ridge feed network, wherein the feed horn is used to receive or radiate a signal; One end of the circular waveguide is connected to one end of the feed horn, and the other end of the circular waveguide is connected to the first end of the waveguide transition piece, and the circular waveguide is used to transmit signals between the feed horn and the waveguide transition piece; The waveguide transition piece is configured to transition from a circular waveguide to a quad-ridged waveguide in a direction from a first end thereof to a second end thereof for transmitting signals between the circular waveguide and the quad-ridged feed network; The quad-ridge feed network is used to separate or combine the signal with horizontally polarized signals and vertically polarized signals for each of two different frequency bands.

2. The dual-band feed according to claim 1, characterized in that: The waveguide transition piece comprises a circular waveguide segment, a tapered four-ridged waveguide segment and a four-ridged waveguide segment which are sequentially connected along a direction from a first end thereof to a second end thereof, wherein a radial cross-sectional profile dimension of a first end portion of the tapered four-ridged waveguide segment is the same as a radial cross-sectional profile dimension of the circular waveguide segment; a radial cross-sectional profile dimension of a second end portion of the tapered four-ridged waveguide segment is the same as a radial cross-sectional profile dimension of the four-ridged waveguide segment; and a radial cross-sectional profile dimension of the tapered four-ridged waveguide segment decreases along a direction from a first end portion thereof to a second end portion thereof.

3. The dual-band feed according to claim 1, characterized in that: The waveguide transition piece includes a circular waveguide segment, at least two stepped four-ridged waveguide segments and a four-ridged waveguide segment which are sequentially connected along a direction from a first end thereof to a second end thereof, wherein one end of the stepped four-ridged waveguide segment adjacent to the circular waveguide segment has the same radial cross-sectional profile size as that of the circular waveguide segment, one end of the stepped four-ridged waveguide segment adjacent to the four-ridged waveguide segment has the same radial cross-sectional profile size as that of the four-ridged waveguide segment, and the radial cross-sectional profile sizes of the at least two stepped four-ridged waveguide segments decrease sequentially along a direction from the circular waveguide segment to the four-ridged waveguide segment.

4. The dual-band feed according to any one of claims 1 to 3, characterized in that: The total length of the waveguide transition piece along the direction from the first end to the second end is greater than or equal to four times the wavelength of the electromagnetic wave corresponding to the lowest frequency value in the working frequency range in the free space.

5. The dual-band feed according to claim 1, characterized in that: The quad-ridge feed network comprises a quad-ridge splitter and four ridge waveguide duplexers, wherein the quad-ridge splitter is used to separate or synthesize the signal from two horizontally polarized signals and two vertically polarized signals; the quad-ridge splitter has a common port, and the common port is connected to the second end of the waveguide transition piece; Two of the ridge waveguide duplexers are used to separate or synthesize the horizontal polarization signal from the first frequency band horizontal polarization signal and the second frequency band horizontal polarization signal, and are synthesized with a first transmission port and a second transmission port, which are used to output or input the first frequency band horizontal polarization signal and the second frequency band horizontal polarization signal respectively; the other two ridge waveguide duplexers are used to separate or synthesize the vertical polarization signal from the first frequency band vertical polarization signal and the second frequency band vertical polarization signal, and are synthesized with a third transmission port and a fourth transmission port, which are used to output or input the first frequency band vertical polarization signal and the second frequency band vertical polarization signal respectively.

6. The dual-band feed according to claim 5, characterized in that: The quad-ridge wave splitter has at least one truncated cone, at least one of the truncated cones is disposed at the common port and is coaxially disposed with the waveguide transition piece; When there are multiple truncated cones, the multiple truncated cones are coaxially stacked in sequence along the axial direction of the waveguide transition piece, and the diameters of the multiple truncated cones increase in sequence in a direction away from the waveguide transition piece.

7. The dual-band feed according to claim 6, characterized in that: The total length of the at least one truncated cone along the signal propagation direction of the waveguide transition piece is greater than or equal to 0.1 times to 0.2 times the wavelength of the electromagnetic wave corresponding to the lowest frequency value in the operating frequency range in free space.

8. The dual-band feed according to claim 5, characterized in that: The first frequency band is a standard backhaul frequency band; the second frequency band is an E band.

9. The dual-band feed according to claim 1, characterized in that: The inner circumferential surface of the feed horn is provided with a corrugated structure, and the corrugated structure includes a plurality of first annular grooves sequentially arranged along the axial direction of the feed horn.

10. A base station antenna, characterized in that: include: The dual-band feed as claimed in any one of claims 1 to 9; A secondary reflector, disposed on a side of the feed horn away from the circular waveguide and having a secondary reflector surface facing the circular waveguide; The main reflector is arranged between the waveguide transition piece and the four-ridge feed network, and the waveguide transition piece passes through the main reflector and is connected to the four-ridge feed network; the main reflector has a main reflective surface facing away from the four-ridge feed network.

11. The base station antenna according to claim 10, characterized in that: A central plane and a plurality of concentric annular surfaces surrounding the central plane are arranged in the central area of ​​the secondary reflector, and the central plane and the plurality of annular surfaces constitute a continuous surface; the orthographic projections of the central plane and the plurality of annular surfaces on a preset cross section constitute a plurality of line segments connected in series, and the preset cross section is parallel to the central axis and radial straight line of the secondary reflector.

12. The base station antenna according to claim 11, characterized in that: A plurality of concentric second annular grooves are arranged in the edge region of the secondary reflective surface.

13. The base station antenna according to claim 10, characterized in that: A plurality of concentric annular surfaces are arranged in the edge region of the secondary reflector, and the plurality of annular surfaces constitute a continuous surface; the orthographic projections of the plurality of annular surfaces on a preset cross section constitute a plurality of line segments connected in series, and the preset cross section is parallel to the central axis and radial straight line of the secondary reflector.

14. The base station antenna according to claim 13, characterized in that: A plurality of concentric second annular grooves are arranged in the central area of ​​the secondary reflecting surface.

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