Waveguide power combiner based on E-plane T-junction

Abstract

The invention relates to a waveguide power combiner based on an E-surface T-type junction, which comprises a plurality of stages of E-surface T-type one-to-two rectangular waveguide unit structures based on discrete film resistors, and Chebyshev gradual change waveguide transition structures are adopted among the stages of the one-to-two rectangular waveguide unit structures, the ceramic substrate is located in the rectangular waveguide; the gradient metal partition plates are located on the two faces of the ceramic substrate respectively, one end of the rectangular waveguide is divided into two E-face half-height standard waveguides, the two E-face half-height standard waveguides are gradually changed into the rectangular waveguide to form a T-shaped structure, and a plurality of discrete thin-film resistors are distributed on the portion, not covered by the gradient metal partition plates, of the ceramic substrate. Compared with the prior art, the power synthesis efficiency can be more than 91% at 8.2-12GHz, the return loss is less than-20dB, and the isolation degree of each port is less than-19.5 dB.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave communications, and in particular to an E-plane T-type waveguide power combiner. Background Art

[0002] With the rapid development of industrial electronics, various passive and active RF circuits and devices have been proposed and studied. In recent years, the growth of civilian radar, navigation, and communications applications has placed higher demands on high-power amplifiers (HPAs) operating in the microwave frequency band. Ideal power dividers and combiners must provide low RF loss, high isolation, and broadband matching.

[0003] Various power combiners have been proposed for multi-channel power combining, including radial power combiners, traveling-wave power combiners, and multi-stage cascaded two-stage power combiners. However, as the number of input ports increases, radial power combiners often suffer from poor port return loss. Similar to radial power combiners, traveling-wave power combiners are typically larger. Multi-stage cascaded two-stage power combiners utilize multiple 3dB dividers / combiners in cascade to achieve the desired power division / combination on a binary scale. This solution offers high design flexibility and overall performance.

[0004] However, existing planar power combiners are unable to handle kilowatt-level power, nor can they meet the requirements of broadband, high isolation, low reflection, low insertion loss, high efficiency, and high power capacity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a waveguide power combiner based on an E-plane T-junction to solve or partially solve the problems of broadband matching and unsatisfactory power capacity of planar power combiners.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a waveguide power combiner based on an E-plane T-junction, characterized in that it includes multiple stages of E-plane T-type one-to-two rectangular waveguide unit structures based on discrete thin film resistors, wherein the one-to-two rectangular waveguide unit structures use a Chebyshev gradient waveguide transition structure between the stages. For any E-plane T-type one-to-two rectangular waveguide unit structure, it includes:

[0008] a ceramic substrate, located within a rectangular waveguide;

[0009] A pair of gradient metal partitions are respectively located on the two surfaces of the ceramic substrate, dividing one end of the rectangular waveguide into two E-plane half-height standard waveguides, and gradiently transitioning to the interior of the rectangular waveguide to form a T-shaped structure. A plurality of discrete thin film resistors are distributed on the portion of the ceramic substrate not covered by the gradient metal partition.

[0010] As a preferred technical solution, the ceramic substrate is rectangular, the pair of gradient metal partitions are of the same shape and are isosceles triangles, and the bottom edge of the gradient metal partition coincides with one edge of the ceramic substrate.

[0011] As a preferred technical solution, the plurality of discrete thin film resistors are distributed at equal intervals along a direction perpendicular to the bottom edge of the gradient metal partition and have the same resistivity.

[0012] As a preferred technical solution, it includes at least one complete discrete thin film resistor that is not covered by the gradient metal partition.

[0013] As an optimal technical solution, it includes seven E-plane T-type one-to-two rectangular waveguide unit structures, which are divided into three-level binary power combiners in the manner of 1, 2, and 4. A half-height standard rectangular waveguide to standard rectangular waveguide transition matching structure based on the Chebyshev function is used between each level of power combiner to form an eight-way binary waveguide power combiner.

[0014] As a preferred technical solution, the output port of the first stage of the eight-way binary waveguide power combiner is located on one side, and the eight input ports of the third stage transition to the standard waveguide through the gradient waveguide transition structure and are located on both sides of the structure, and the waveguide is symmetrical on the left and right, and the electrical length from the eight input ports to the output ports is the same.

[0015] As a preferred technical solution, the first and second level connections and the second and third level connections include a 90-degree turning structure with a chamfer.

[0016] As a preferred technical solution, the narrow side of the rectangular waveguide includes a groove matching the ceramic substrate.

[0017] As an optimal technical solution, in the one-to-two rectangular waveguide unit structure, when the signal power is input at the standard rectangular waveguide end, the two E-plane half-height standard waveguides with equal height waveguide symmetry achieve 3dB equal power distribution, the amplitude and phase are balanced, the resistance layer does not dissipate power, the current density of the upper resistance layer is equal to the current density of the lower resistance layer and the phase is opposite, and the total net current density of the discrete thin film resistor is zero; when the input signal uses a half-height standard waveguide, the amplitude or phase difference between the signals of the two E-plane half-height standard waveguides generates a net current density on the resistance layer, and the discrete thin film resistor dissipates the power related to the unbalanced mode, thereby achieving isolation between the two ports.

[0018] As a preferred technical solution, the equivalent length and resistivity of the discrete thin film resistor are calculated using the following formula:

[0019]

[0020] Among them, Rs is the resistivity of the discrete resistor film, l r is the equivalent resistance length, f c is the cutoff frequency, f is the frequency, a and b are the length and bandwidth of the rectangular waveguide.

[0021] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0022] (1) While achieving high isolation characteristics, it reduces insertion loss and improves power combination efficiency: The E-plane T-type one-to-two rectangular waveguide unit structure provided by the present invention adopts an E-plane T-type junction, which can achieve good broadband matching and high power capacity. The rectangular waveguide structure adds discrete thin film resistors on both sides of the gradient metal partition. When the power of the two output ports is balanced, there is no dissipated current on the resistor and no power attenuation. When the power of the two output ports is unbalanced, the dissipated current consumes the unbalanced power, reducing the power coupling between the two ports, thereby achieving high isolation characteristics while reducing insertion loss and improving power combination efficiency.

[0023] (2) Achieving matching within a broadband range: The eight-way power combiner of the present invention is composed of a cascade of three-stage waveguide unit structures. By using a Chebyshev gradient waveguide to achieve a transition from a half-height standard rectangular waveguide to a standard rectangular waveguide, good matching within a broadband range is achieved. The transition matching of each stage of the gradient waveguide increases the power capacity.

[0024] (3) Equivalent length and resistivity of discrete thin film resistors: Currently, the resistor film in the waveguide is mainly a wide-edge full-coverage resistor film. The present invention uses a discrete resistor film, which can achieve the same function while reducing the area of ​​the resistor film. The calculation formula can be expanded to realize the design of resistor films of different shapes based on equivalent resistance and length. In addition, the discrete thin film resistor film can reduce the additional power attenuation and improve the power synthesis efficiency compared with the full-coverage resistor film. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 2. It is a three-dimensional schematic diagram of a one-to-two rectangular waveguide unit structure in an embodiment;

[0026] Figure 2 It is a front view of the one-to-two rectangular waveguide unit structure in the embodiment;

[0027] Figure 3 A side view of a one-to-two rectangular waveguide unit structure in an embodiment;

[0028] Figure 4 A three-dimensional assembly diagram of a one-to-two rectangular waveguide unit structure in an embodiment;

[0029] Figure 5 A three-dimensional schematic diagram of a Chebyshev gradient waveguide transition structure in an embodiment;

[0030] Figure 6 2. A three-dimensional schematic diagram of an eight-way binary waveguide power combiner in an embodiment;

[0031] Figure 7 is a top view of an eight-way binary waveguide power combiner in an embodiment;

[0032] Figure 8 is a side view of an eight-way binary waveguide power combiner in an embodiment;

[0033] Figure 9 Schematic diagram of reflection parameters of each port obtained by simulation of an eight-way binary waveguide power combiner in an embodiment;

[0034] Figure 10 Schematic diagram of the transmission coefficient obtained by simulation of the eight-way binary waveguide power combiner in the embodiment;

[0035] Figure 11 Schematic diagram of the isolation obtained by simulation of the eight-way binary waveguide power combiner in the embodiment, wherein: 1. rectangular waveguide; 2. ceramic substrate; 3. gradient metal partition; 4. discrete thin film resistor. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and simplify the description, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0038] In response to the problems existing in the aforementioned prior art, this embodiment provides a waveguide power combiner based on an E-plane T-junction, aiming to obtain a broadband, high-isolation, and high-efficiency eight-way waveguide power combiner, including seven E-plane T-type one-to-two rectangular waveguide unit structures, which are divided into three-level binary power combiners in the manner of 1, 2, and 4. A half-height standard rectangular waveguide to standard rectangular waveguide transition matching structure based on the Chebyshev function is used between each level of power combiner to form an eight-way binary waveguide power combiner.

[0039] See also Figure 1-4 This is a schematic diagram of a single E-plane T-type one-to-two rectangular waveguide unit structure, comprising a rectangular waveguide 1, a ceramic substrate 2, a pair of gradient metal partitions 3 located on either side of the ceramic substrate 2, and several discrete thin-film resistors 4 attached to the ceramic substrate 2, forming a two-way power combiner. The discrete thin-film resistors 4 have the same resistivity but different lengths. The ceramic substrate 2 is mounted and fixed via grooves located directly in the middle of the narrow walls of the rectangular waveguide 1. The gradient metal partitions 3 in the rectangular waveguide 1 are printed on both sides of the ceramic substrate 2, dividing one end of the waveguide into two half-height standard waveguides and gradiently transitioning into the interior of the waveguide. Discrete thin-film resistors 4 of the same resistivity are evenly spaced on either side of the gradient metal partition 3, extending from the sides of the gradient metal partition 3 to the narrow wall of the waveguide.

[0040] The two E-plane half-height standard waveguides in rectangular waveguide 1 guarantee 3dB power distribution at all operating frequencies, with their bandwidth limited only by the frequency of the TE10 mode. Discrete thin-film resistors 4 attenuate unbalanced power, achieving high isolation between ports. When signal power is input to the standard rectangular waveguide, the symmetrical structure of the equal-height waveguides naturally achieves 3dB equal power distribution, with balanced amplitude and phase. The resistor layer dissipates no power, and the current density in the upper resistor layer is equal in magnitude and opposite in phase to that in the lower resistor layer. Therefore, the total net current density in the resistor layer is zero. When the input signal uses the half-height standard waveguide, any amplitude or phase difference between the signals in the two half-height standard waveguides generates a net current density in the resistor layer. Therefore, the resistor layer dissipates the power associated with the unbalanced mode, thereby improving isolation between the two ports.

[0041] Considering the reciprocity of the power divider, the transmission coefficient from a standard rectangular waveguide to a half-height standard waveguide is the same as the transmission coefficient from a half-height standard waveguide to a standard rectangular waveguide. The power at the half-height standard waveguide port is four times the power at the combined port of the two half-height standard waveguides, and the combined power is equal. Therefore, the attenuation power of the resistor layer should be half of the input power of the half-height standard waveguide. Based on this attenuation power, the resistivity and area of ​​the discrete resistor layer are designed. The equivalent length and resistivity of the discrete resistor layer (i.e., discrete thin-film resistor 4) can be used as initial design values ​​using the following equations, which are then used for optimization.

[0042]

[0043] Where R s is the resistivity of the discrete resistor film, l r is the equivalent resistance length, f c is the cutoff frequency, f is the frequency, a and b are the length and bandwidth of the standard rectangular waveguide.

[0044] See also Figure 5 The eight-way power combiner of this embodiment uses a Chebyshev gradient waveguide transition structure between each level of the power combiner, see Figure 6-8 The first-stage output port of the eight-way power combiner is located on one side. The eight input ports of the third stage transition to standard waveguides via a tapered waveguide transition structure, located on both sides of the structure. The waveguides are symmetrical, and the electrical length from the eight input ports to the output ports is the same. There are 90-degree turns with chamfers in the connections between the first and second stages and the second and third stages.

[0045] The operating frequency range of the waveguide power combiner of this embodiment is 8.2 to 12 GHz. The reflection coefficient of each port is less than -20 dB, the isolation between ports is less than -19.5 dB, and the combining efficiency is greater than 91%. To verify the effectiveness, the following simulation is performed:

[0046] See also Figures 1-4 The standard rectangular waveguide uses BJ100, with an inner cross-section width dimension a = 22.86mm, an inner cross-section height dimension b = 10.16mm, an outer cross-section width dimension A = 24.13mm, an outer cross-section height dimension B = 11.43mm, and a waveguide length l1 = 60mm. The ceramic substrate is made of beryllium oxide, with a length x = 37mm, a thickness t1 = 0.105mm, a width a2 = 23.86mm, and a groove depth of 0.5mm on each side. The gradient metal partition has a length x1 = 35mm, a thickness t2 = 0.01mm, and a width that gradually changes from a wide side of 22.86mm to 0. The discrete resistor film uses tantalum nitride with a resistivity R s =100Ω·m, thickness t3 =0.013mm, width a3 =2mm, and the length extends from the edge of the gradient metal partition to the narrow wall of the waveguide.

[0047] like Figure 5 As shown, the length of the Chebyshev graded metal waveguide is l2 = 78.26 mm, the width of the ports on both sides is a = 22.86 mm, the height of one side connected to the half-height standard rectangular waveguide is b1 = 4.97 mm, and the height of one side connected to the standard rectangular waveguide is b2 = 10.07 mm. One side uses a straight wall and the other side wall uses a Chebyshev impedance matching function.

[0048] like Figure 6 、 Figure 7 and Figure 8As shown, seven one-to-two rectangular waveguide unit structures are connected through a Chebyshev graded metal waveguide and a 90° turn structure to form a three-level eight-way power combiner structure. The overall structure has a length of l0 = 418.62 mm, a width of w0 = 320.29 mm, and a height of h0 = 41.4 mm.

[0049] Figure 9 The reflection parameters of each port are obtained by simulating the eight-way power combiner. Figure 9 It can be seen that within the operating frequency bandwidth of 8.2 to 12 GHz, the reflection coefficient of each port is below -20 dB, and the ports are well matched.

[0050] Figure 10 The transmission coefficient obtained by simulating the eight-way power combiner. Figure 10 It can be seen that within the working frequency bandwidth of 8.2 to 12 GHz, the transmission coefficient is above -9.4 dB, the synthesis efficiency reaches above 91%, the device insertion loss is small, and the synthesis efficiency is high.

[0051] Figure 11 This is the isolation obtained by simulating the eight-way power combiner. Figure 11 It can be seen that within the operating frequency bandwidth of 8.2 to 12 GHz, the isolation of each port is below -19.5 dB, and the port isolation performance is good.

[0052] In summary, the rectangular waveguide unit structure provided by the present invention adopts an E-plane T-junction, which can achieve good broadband matching in practical applications and achieve higher power capacity. The rectangular waveguide structure adds discrete thin film resistors on both sides of the gradient metal partition. When the power of the two output ports is balanced, there is no dissipated current on the resistor and no power attenuation; when the power of the two output ports is unbalanced, the dissipated current consumes the unbalanced power, reducing the power coupling between the two ports, thereby achieving high isolation characteristics while reducing insertion loss and improving power synthesis efficiency. The eight-way power combiner is composed of a cascade of three-stage waveguide unit structures. By using the Chebyshev gradient waveguide to achieve the transition from half-height standard rectangular waveguide to standard rectangular waveguide, good matching within a broadband range is achieved, and the transition matching of each stage of gradient waveguide increases power capacity. The Chebyshev gradient transition can achieve a smoother transition than the step transition. Since it is based on the Chebyshev impedance matching formula, a wider bandwidth matching is achieved, and the reflection coefficient is smoother within the required bandwidth, providing conditions for achieving broadband design.

[0053] The eight-way waveguide power combiner of the present invention has good matching performance, high combining efficiency, high isolation, and uses a waveguide structure and a continuous gradient metal waveguide to achieve waveguide height transformation, thereby improving the device's power capacity. By adopting a waveguide structure and a discrete resistor film to dissipate power, it avoids energy attenuation caused by structures with dielectric loss such as microstrip lines, thereby improving the combining efficiency, which can reach over 90%, achieving high-efficiency combining.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A waveguide power combiner based on an E-plane T-junction, characterized in that: The invention comprises a multi-stage E-plane T-type one-to-two rectangular waveguide unit structure based on discrete thin film resistors, wherein a Chebyshev gradient waveguide transition structure is adopted between the stages of the one-to-two rectangular waveguide unit structure. For any E-plane T-type one-to-two rectangular waveguide unit structure, the invention comprises: A ceramic substrate (2) is located inside the rectangular waveguide (1); A pair of gradient metal partitions (3) are respectively located on two surfaces of the ceramic substrate (2), dividing one end of the rectangular waveguide (1) into two E-plane half-height standard waveguides, and gradiently changing to the inside of the rectangular waveguide (1) to form a T-shaped structure. A plurality of discrete thin film resistors (4) are distributed on the portion of the ceramic substrate (2) not covered by the gradient metal partition (3).

2. The waveguide power combiner based on an E-plane T-junction according to claim 1, characterized in that: The ceramic substrate (2) is rectangular, the pair of gradient metal partitions (3) are of the same shape and are isosceles triangles, and the bottom edge of the gradient metal partition (3) coincides with one edge of the ceramic substrate (2).

3. The waveguide power combiner based on an E-plane T-junction according to claim 2, characterized in that: The plurality of discrete thin film resistors (4) are distributed at equal intervals along a direction perpendicular to the bottom edge of the gradient metal partition (3) and have the same resistivity.

4. The waveguide power combiner based on an E-plane T-junction according to claim 1, characterized in that: The invention comprises at least one complete discrete thin film resistor (4) which is not covered by the gradient metal spacer (3).

5. The waveguide power combiner based on an E-plane T-junction according to claim 1, characterized in that: It includes seven E-plane T-type one-to-two rectangular waveguide unit structures, which are divided into three-level binary power combiners in the manner of 1, 2, and 4. A half-height standard rectangular waveguide to standard rectangular waveguide transition matching structure based on the Chebyshev function is used between each level of power combiner to form an eight-way binary waveguide power combiner.

6. The waveguide power combiner based on an E-plane T-junction according to claim 5, characterized in that: The output port of the first stage of the eight-way binary waveguide power combiner is located on one side, and the eight input ports of the third stage transition to the standard waveguide through the gradient waveguide transition structure and are located on both sides of the structure. The waveguide is symmetrical on the left and right, and the electrical length from the eight input ports to the output ports is the same.

7. The waveguide power combiner based on an E-plane T-junction according to claim 5, characterized in that: The first and second level connections and the second and third level connection positions include a 90-degree turning structure with a chamfer.

8. The waveguide power combiner based on an E-plane T-junction according to claim 1, characterized in that: The narrow side of the rectangular waveguide (1) comprises a groove matching the ceramic substrate (2).

9. The waveguide power combiner based on an E-plane T-junction according to claim 1, characterized in that: In the one-to-two rectangular waveguide unit structure, when the signal power is input at the standard rectangular waveguide end, the two E-plane half-height standard waveguides with equal height waveguide symmetry realize 3dB equal power distribution, the amplitude and phase are balanced, the resistance layer does not dissipate power, the current density of the upper resistance layer is equal to the current density of the lower resistance layer and the phase is opposite, and the total net current density of the discrete thin film resistor (4) is zero; when the input signal uses the half-height standard waveguide, the amplitude or phase difference between the signals of the two E-plane half-height standard waveguides generates a net current density on the resistance layer, the discrete thin film resistor (4) dissipates the power related to the unbalanced mode, and realizes isolation between the two ports.

10. The waveguide power combiner based on an E-plane T-junction according to claim 1, characterized in that: The equivalent length and resistivity of the discrete thin film resistor (4) are calculated using the following formula: Among them, R s is the resistivity of the discrete resistor film, l r is the equivalent resistance length, f c is the cutoff frequency, f is the frequency, a and b are the length and bandwidth of the rectangular waveguide (1).

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