A dual-frequency shared power divider using a bandwidth exceeding three times the frequency

Abstract

The present invention discloses a dual-frequency shared power divider with a bandwidth exceeding three times the frequency, and belongs to the field of waveguide technology. It includes an axial multi-frequency shared waveguide, a multi-level sidewall branch waveguide and an H-surface curved waveguide. The axial multi-frequency shared waveguide is a circular transition waveguide. The high-frequency band signal is transmitted along its axial direction, and the low-frequency signal is coupled to the corresponding frequency sidewall waveguide branch through a coupling port. In addition to the high frequency, the low-frequency branch transmission channel presents a four-way symmetrical structure. Each sidewall branch waveguide includes a filter and a step waveguide impedance converter, and the filter is a two-stage filter cascade design. The present invention has the characteristics of large relative bandwidth, low cross-polarization, and low standing wave ratio, and has a compact structure and is easy to process. The present invention solves the problem of frequency separation and power distribution of the feed network system when the antenna is used for multiple frequencies from three times the frequency upwards, can effectively improve the influence of high-order modes on the radiation pattern of the feed system and reduce the level of antenna cross-polarization, and is suitable for engineering promotion.

Description

Technical Field

[0001] The invention relates to the field of waveguide technology, in particular to a dual-frequency shared power distributor with a bandwidth exceeding three times the frequency. Background Art

[0002] In the field of microwave antenna communications, power division networks and power synthesis networks are common passive subsystems in various station-type antenna feeding networks. In order to achieve multiple uses of one station and multiple frequencies, reduce antenna construction costs, and increase antenna usage functions, users are increasingly demanding multi-frequency shared antennas, making the design of microwave devices that include frequency separation and power distribution even more important.

[0003] At present, there are two main forms of multi-frequency shared feed network systems: coaxial wave splitting and common nozzle wave splitting. Among them, coaxial wave splitting has developed to a certain bottleneck period, and the common nozzle wave splitting form is more traditional, but it has more advantages for the comprehensive use indicators of antennas. At the same time, it is well known that the number of high-order mode excitations of multi-frequency co-jet devices increases sharply with the increase of relative bandwidth. These high-order modes directly affect the electrical design indicators of the highest frequency and secondary high frequency bands. The antenna pattern and cross-polarization will be extremely deteriorated. Different high-order modes have different directions and degrees of influence on the feed network system. There are few reports on the control methods of these large numbers of harmful high-order modes. Therefore, there has been no systematic introduction to the design of mature multi-frequency shared power dividers internationally, which has correspondingly curbed the development of multi-frequency co-jet feed networks. Therefore, it is imperative to find a new dual-frequency or multi-frequency shared power divider. Summary of the invention

[0004] The purpose of the present invention is to provide a dual-band common power divider with a bandwidth exceeding three times the frequency, which is used to solve the problems that the existing multi-frequency common power divider with two times the frequency and above has difficulty in suppressing high-order modes, poor antenna cross polarization, and difficulty in meeting engineering use requirements. The power divider has excellent electrical indicators such as large relative bandwidth, low cross polarization, and low standing wave ratio, and has many advantages such as compact structure and easy processing.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A dual-frequency shared power distributor with a bandwidth exceeding three times the frequency is a six-port microwave device, comprising an axial multi-frequency shared waveguide, four side wall branch waveguides and four H-plane bent waveguides; the axial multi-frequency shared waveguide is a circular transition waveguide, and high-frequency band signals are transmitted along its axial direction; the four side wall branch waveguides are symmetrically distributed at 90 degrees along the axial direction of the multi-frequency shared waveguide, and are low-frequency band signal transmission channels; the four side wall branch waveguides each include a filter and a stepped impedance converter.

[0007] Furthermore, the gradual change curve of the circular transition waveguide is a spline fitting curve.

[0008] Furthermore, four rectangular ridged coupling ports are opened on the inner wall of the axial multi-frequency shared waveguide, and are symmetrically distributed at 90° around the axis of the axial multi-frequency shared waveguide. The long sides of the rectangular ridged coupling ports are along the axial direction, and the angle between the end face of the rectangular ridged coupling port and the axis of the axial multi-frequency shared waveguide is 7°.

[0009] Furthermore, the filter of the sidewall branch waveguide is a two-stage filter cascade structure, and both of the two-stage filters are block mode filters; symmetrical metal sawtooth structures are distributed above and below at the entrance of the block mode filter.

[0010] Furthermore, the first-stage filter in the block mode filter adjacent to the axial multi-frequency shared waveguide coupling port has only two rows of metal vertical teeth along the branch waveguide direction, and the second-stage filter also has only two rows of metal vertical teeth along the axial direction of the branch waveguide.

[0011] Furthermore, in the two-stage filter cascade structure, a metal sheet parallel to the wide side of the filter is embedded in the center of the first-stage filter.

[0012] Furthermore, the sidewall branch waveguide ladder impedance transformer is a three-order rectangular waveguide ladder impedance transformer.

[0013] Compared with the background technology, the present invention has the following beneficial effects:

[0014] 1. The present invention has the characteristics of large relative bandwidth, low cross polarization, low standing wave ratio, compact structure and easy processing.

[0015] 2. The present invention solves the problem of frequency separation and power distribution of the feeding network system when the antenna is used in multiple frequencies from triple frequency onwards, can effectively improve the influence of high-order modes on the radiation pattern of the feed system and reduce the level of antenna cross-polarization, and is suitable for engineering promotion.

[0016] 3. The present invention uses a novel branch filter structure and coupling port design to make the coupling of the high-frequency main mode to each high-order mode below -20dB when the maximum relative bandwidth exceeds 3.5 times the frequency, improves the high-frequency channel return loss, reduces the system axial ratio of the circular polarization network and the linear polarization cross-polarization component of the high-frequency channel, and suppresses the high-order harmonics of the low-frequency passband. The simulation results of the feed cascade and the single feed simulation directional diagram are basically consistent. The multi-frequency shared power divider is reasonably designed and can meet the needs of engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a four-wall coupled dual-frequency shared power distributor in an embodiment of the present invention.

[0018] Figure 2It is a three-dimensional assembly schematic diagram of a dual-frequency shared power distributor in an embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of the axial circular transition and side wall coupling oral body in an embodiment of the present invention.

[0020] Figure 4 Schematic diagram of the three-dimensional structure of the sidewall branch waveguide in an embodiment of the present invention.

[0021] Figure 5 4 is a cross-sectional view of a side wall branch waveguide in an embodiment of the present invention.

[0022] Figure 6 It is the return loss frequency response curve of the main mode using frequency band.

[0023] Figure 7 This is the frequency response curve of the main mode and high-order mode coupling in the high-frequency band. In the figure, only the curves of the worst indicators are distinguished, namely S1(7),1(1). It can be seen from the figure that even the worst indicators have good effects.

[0024] Figure 8 This is the frequency response curve of the low-frequency port to high-frequency signal isolation.

[0025] Explanation of the reference numerals: 1—axial multi-frequency shared waveguide, 2—sidewall branch waveguide, 3—H-plane bent waveguide, 4—embedded metal sheet, 5—first-stage filter, 6—second-stage filter, 7—stepped impedance transformer. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0027] A dual-frequency shared power divider with a bandwidth exceeding three times the frequency includes an axial multi-frequency shared waveguide, a multi-stage sidewall branch waveguide and an H-surface bent waveguide. The axial multi-frequency shared waveguide is a circular transition waveguide. The high-frequency band signal is transmitted along its axial direction, and the low-frequency signal is coupled to the corresponding frequency sidewall waveguide branch through a coupling port. In addition to the high frequency, the low-frequency branch transmission channel has a four-way symmetrical structure. Each sidewall branch waveguide includes a filter and a stepped waveguide impedance converter, and the filter is a two-stage filter cascade design.

[0028] Specifically, the dual-frequency shared power divider is a six-port microwave device, including an axial multi-frequency shared waveguide, four side wall branch waveguides and four H-plane bent waveguides. The axial multi-frequency shared waveguide is a circular transition waveguide, and the high-frequency band signal is transmitted along its axial direction; the four side wall branch waveguides are symmetrically distributed at 90° along the axial direction of the multi-frequency shared waveguide, and are low-frequency band signal transmission channels; the side wall branch waveguides all include filters and step impedance converters.

[0029] Wherein, the axial circular transition waveguide gradient curve is designed by spline fitting.

[0030] Four rectangular ridged coupling ports are provided on the inner wall of the axial multi-frequency shared waveguide and are symmetrically distributed at 90° around the axis of the multi-frequency shared waveguide. The long side of the rectangle is along the axis direction, and the angle between the end face of the coupling port and the axis of the multi-frequency shared waveguide is 7°.

[0031] The filter of the sidewall branch waveguide is a block mode filter design, and is a two-stage filter cascade design; the inlet of the block mode filter is a symmetrical metal sawtooth structure distributed up and down, rather than a rectangular cavity structure.

[0032] In the block mode filter, the first-stage filter adjacent to the multi-frequency common waveguide coupling port has only two rows of metal vertical teeth along the branch waveguide direction, and the second-stage filter also has only two rows of metal vertical teeth along the axial direction of the branch waveguide.

[0033] The cascade block mode filter has a metal sheet inlaid in the center of the first filter and parallel to the wide side of the filter.

[0034] The sidewall branch waveguide ladder impedance transformer is a three-order rectangular waveguide ladder impedance transformer.

[0035] The multi-frequency shared power divider has always been the most critical component of the multi-frequency network. From the functional point of view, it needs to complete the high isolation separation of multiple frequency bands, and also realize the orthogonal polarization separation of a single frequency band and the equal power distribution of a single polarization. It can be said that it integrates the main functions of the traditional frequency duplexer and the broadband orthogonal mode coupler. Figure 1 As shown, from a physical point of view, the power divider is a tapered six-port device, and from an electrical point of view, the power divider is an eight-port device with two orthogonal polarizations in the input and output. Specifically, the multi-frequency shared power divider is mainly divided into several design partitions, including circular transition, transition section coupling port, branch filter, and impedance matching from filter to standard waveguide. The core of the design of the multi-frequency shared power divider is the coupling matching of the side wall low-frequency channel and the effective suppression of high-order modes in the high-frequency band. In short, the multi-frequency shared power divider can be designed according to the following steps:

[0036] 1. Determine the diameter size of the circular waveguide transition inlet and outlet according to the waveguide cutoff theory and actual engineering requirements;

[0037] 2. Seek the optimal transition curve and determine the initial size of the low-frequency coupling port;

[0038] 3. Design and optimize low-frequency branch filters at all levels;

[0039] 4. Find the best low-frequency branch coupling port positions at each level and the best short-circuit position for high-order modes, and cascade the optimized filters for dual-frequency simulation optimization and verification;

[0040] 5. Fine-tune the low-frequency filter branch parameters and optimize the impedance transformation section at the tail of the branch waveguide to achieve optimal impedance matching in the low-frequency band. After multiple iterations, the optimal electrical design result of the four-arm coupling system is obtained.

[0041] Further, such as Figure 2 As shown, the dual-band shared power divider includes an axial multi-frequency shared waveguide, four sidewall branch waveguides and four H-surface bent waveguides. Figure 3 As shown, the axial multi-frequency shared waveguide mainly includes two design partitions, namely, a circular transition and a sidewall coupling port. In order to suppress axial high-order mode excitation, the circular transition curve is designed using a spline fitting curve.

[0042] The circular transition curve is provided with four rectangular ridge coupling ports, which are symmetrically distributed at 90° around the axis of the multi-frequency common waveguide, with the long sides of the rectangles along the axis direction, and Figure 1 As shown, the angle between the coupling port end face and the multi-frequency shared waveguide axis is 7°.

[0043] Further, such as Figure 5 As shown, the side wall branch waveguide includes a filter and a step impedance converter. The filter is a block mode filter design, and is a two-stage filter cascade design. The first-stage filter next to the multi-frequency shared waveguide coupling port in the block mode filter has only two rows of metal vertical teeth along the branch waveguide direction, and the second-stage filter has only two rows of metal vertical teeth along the axial direction of the branch waveguide. The step impedance converter is a three-order rectangular waveguide step impedance converter, which eventually converts the branch waveguide to the standard outlet of the corresponding coupling frequency band. Figure 4 As shown, the inlet of the block mode filter is a symmetrical metal sawtooth structure distributed up and down, rather than a rectangular cavity structure.

[0044] Furthermore, the longitudinal slot unit of the block mode filter has a natural suppression characteristic for the higher-order modes of the rectangular waveguide, and has ultra-wide channel and power capacity characteristics. By selecting a reasonable cutoff frequency, it can meet the design requirements of engineering stopband exceeding three times the frequency.

[0045] Further, such as Figure 5 As shown, the cascaded block mode filter has a metal sheet inlaid in the center of the first-stage filter, which is parallel to the wide side of the filter. The metal sheet is perpendicular to the main mode electric field component of the branch waveguide, and can effectively suppress the excitation of the high-order mode of the anti-polarization component in the axial multi-frequency shared waveguide in the coupled branch waveguide, thereby further improving the polarization isolation and improving the high-frequency cross polarization.

[0046] The stepped impedance transformation section is connected to an H-surface curved waveguide behind to connect with other network components at the rear end.

[0047] like Figure 1As shown, the working principle of the dual-band shared power divider is as follows:

[0048] Usually when dual-frequency signals are received simultaneously, when the RF signal transmitted to the multi-frequency shared waveguide passes through the side wall coupling port, the low-frequency signal is coupled and matched by the branch block filter at 0dB, and the high-frequency band is short-circuited and suppressed, and then transmitted to the back-end waveguide routing through the low-frequency step impedance converter; it can be expanded. When more than three frequencies are shared, a coupling port is opened at the coupling position corresponding to the sub-low frequency on the circular transition curve, and the sub-low frequency RF signal is 0dB coupled and matched and transmitted to the sub-low frequency channel. When passing through the filter, the high isolation suppression of the previous low-frequency signal and other high-frequency signals is completed; in this way, the low-frequency signals of each level are coupled and matched one by one when multiple frequencies are shared, and the highest frequency signal is output from the axial channel with low loss. The working principle of multi-frequency signal transmission is opposite, so it will not be repeated.

[0049] For ease of understanding, a typical dual-band shared power distributor is taken as an example below, and the effects of the present invention are auxiliary explained in conjunction with corresponding drawings.

[0050] Embodiment: CKu dual-frequency shared power divider

[0051] The design frequency is C: 3.4GHz~4.2GHz; Ku: 10.7~14.5GHz.

[0052] The dual-frequency shared power distributor is as follows Figure 1 As shown, the corresponding values ​​of the main structural parameters are as follows:

[0053] The diameter of the large round transition opening is D1=62mm; the diameter of the small opening is D2=20mm; the wide side of the C-band filter entrance is W1=50mm, and the width of the rectangular ridge coupling opening is AOH1=25.6mm.

[0054] Figure 6~Figure 8 The figure shows the simulation results of the dual-frequency shared power divider. As can be seen from the figure, the bandwidth is 3.75 times the frequency, and the main mode return loss S in the C and Ku bands is 1(1)1(1) The mutual coupling energy from the main mode to the nth higher-order mode is mainly returned to the common port, with S 1(n)1(1) Indicates that the coupling degree in the Ku band is less than -20dB; the frequency isolation of the main mode to the high frequency band is S 3(1)1(1) It means that the suppression of low frequency band on high frequency band and the suppression of C band on Ku main mode are greater than 78dB.

[0055] In summary, the dual-band shared power distributor of the present invention includes waveguide routing such as axial multi-frequency shared waveguide, multi-level sidewall branch waveguide and H-plane bent waveguide. The axial multi-frequency shared waveguide is a high-frequency signal transmission channel, and the low-frequency sidewall branch waveguide is distributed along the axial direction, and the sidewall branch waveguide corresponding to the low-frequency signal is distributed in four-way symmetrical manner relative to the multi-frequency shared waveguide. The present invention has excellent electrical indicators such as large relative bandwidth, low cross-polarization, and low standing wave ratio, and has many advantages such as compact structure and easy processing. It solves the core problems of frequency separation, polarization separation and power distribution when the antenna is used for multi-frequency co-spraying, and can meet the needs of most multi-frequency broadband fixed stations and vehicle-mounted stations.

[0056] It should be noted that the above description and examples are helpful for those skilled in the art to understand the invention, but they do not limit the protection scope of the invention. Any various deformations, scaling, modifications and / or simplifications that do not deviate from the essence of the invention should fall within the protection scope of the invention.

Claims

1. A dual-frequency shared power divider with a bandwidth exceeding three times the frequency, which is a six-port microwave device, comprising an axial multi-frequency shared waveguide, four sidewall branch waveguides and four H-surface curved waveguides, wherein the H-surface curved waveguides are connected to the sidewall branch waveguides in a one-to-one correspondence; characterized in that: The axial multi-frequency shared waveguide is a circular transition waveguide, and the high-frequency band signal is transmitted along its axial direction; the four side wall branch waveguides are symmetrically distributed at 90° along the axial direction of the multi-frequency shared waveguide, and are low-frequency band signal transmission channels; four rectangular ridged coupling ports are opened on the inner wall of the axial multi-frequency shared waveguide, and the four rectangular ridged coupling ports are symmetrically distributed at 90° around the axis of the axial multi-frequency shared waveguide, and correspond to the four side wall branch waveguides one by one; the four side wall branch waveguides all include filters and step impedance converters; The long side of the rectangular ridged coupling port is along the axial direction, and the angle between the end face of the rectangular ridged coupling port and the axis of the axial multi-frequency shared waveguide is 7°; The filter of the sidewall branch waveguide is a two-stage filter cascade structure, and both of the two-stage filters are block mode filters; symmetrical metal sawtooth structures are distributed above and below the entrance of the block mode filter; The first-stage filter in the block mode filter, which is adjacent to the axial multi-frequency common waveguide coupling port, has only two rows of metal vertical teeth along the branch waveguide direction, and the second-stage filter also has only two rows of metal vertical teeth along the axial direction of the branch waveguide; In the two-stage filter cascade structure, a metal sheet parallel to the wide side of the filter is embedded in the center of the first-stage filter.

2. A dual-frequency shared power divider with a bandwidth exceeding three times the frequency according to claim 1, characterized in that: The gradual change curve of the circular transition waveguide is a spline fitting curve.

3. A dual-frequency shared power divider with a bandwidth exceeding three times the frequency according to claim 1, characterized in that: The sidewall branch waveguide ladder impedance transformer is a three-order rectangular waveguide ladder impedance transformer.

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