CN114069184A

CN114069184A - Millimeter wave filtering power divider with arbitrary power dividing ratio

Info

Publication number: CN114069184A
Application number: CN202111407408.7A
Authority: CN
Inventors: 陈建新; 闫玉星; 于玮; 秦伟; 杨永杰
Original assignee: Nantong University
Current assignee: Hubei Shenglian Photoelectric Communication Co ltd
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-02-18
Anticipated expiration: 2041-11-24
Also published as: CN114069184B

Abstract

The invention relates to a millimeter-wave filter power divider with an arbitrary power division ratio, which is composed of N -1 TE ₁₀₁ modes and a TE _{n 01} mode resonator, the TE _{n 01} mode resonator divides energy into n equal parts, and then Correspondingly, n output ports are drawn out on the resonant cavity for power distribution. The present invention utilizes the characteristic of dividing the energy into equal parts by the high-order mode resonant cavity, and only needs to simulate any output port to obtain a standardized output window size-external quality factor graph, and based on the standardized graph, each output port is By adjusting the window, the filter power divider design of any power division ratio can be completed, which makes the filter design method simple and flexible, shortens the design time of the device, and improves the research and development efficiency.

Description

Millimeter wave filtering power divider with arbitrary power dividing ratio

Technical Field

The invention belongs to the technical field of radio frequency communication, and relates to a millimeter wave multi-port substrate integrated waveguide filtering power divider with any power dividing ratio.

Background

With the rapid development of modern wireless communication technology, fifth generation (5G) communication is receiving more and more attention. In order to achieve higher transmission rates, many researchers have recently begun exploring the millimeter wave band. Filters and power dividers are indispensable components in the antenna array feed network. They usually employ a conventional cascade design method, which always occupies a large area and results in high insertion loss. The filtering power divider which integrates two adjacent functional devices (a filter and a power divider) into a circuit and is designed in a fusion mode is a research hotspot in recent years, so that the overall size of the circuit can be reduced, and the cascade loss can be avoided.

Microstrip-line based filtering power dividers typically implement the filtering response by coupling lines or stub-loaded transmission lines instead of quarter-wave transformers. In the millimeter wave band, microstrip designs will suffer considerable losses and deteriorate with increasing frequency. The traditional metal waveguide filtering power divider has low loss, but is heavy in volume and not suitable for being integrated with a planar circuit due to a three-dimensional structure. The substrate integrated waveguide combines the advantages of a planar microstrip transmission line and a low-loss waveguide, and is very suitable for millimeter wave application. Therefore, the filtering power divider based on the substrate integrated waveguide has attracted extensive research interest.

In the past years, a great deal of research on two-way filtering power dividers has been conducted by some reported filtering power dividers. However, a multiple power splitter is one of the basic elements of an antenna array feed network. The specific unequal power distribution ratio of the array can enable the array to obtain better directional performance in a beam forming system. In order to meet the requirement of multipath in future wireless communication systems, there are some reports of multi-port filtering power dividers. The tree topology is widely used, however, since only one output port is led out from each resonator of the last stage, the volume of the circuit is rapidly increased as the number of ports is increased. Meanwhile, in order to reduce the antenna array side lobe, a filter power divider with unequal power ratio is generally required. However, few filtering power dividers based on substrate integrated waveguide can simultaneously provide multi-output and unequal power division ratio, especially in millimeter wave frequency band.

Disclosure of Invention

The present invention is directed to solve the above-mentioned deficiencies in the prior art, and to provide a millimeter wave filter power divider with a simple structure and an arbitrary power dividing ratio.

In order to achieve the purpose of the invention, the millimeter wave filtering power divider with any power dividing ratio provided by the invention is characterized in that: cascaded N-1 TEs comprising 1 input port and N output ports₁₀₁Mode-substrate integrated waveguide resonant cavity and 1 TE_n01A mode substrate integrated waveguide resonant cavity, the TE_n01The mode substrate integrated waveguide resonant cavity divides energy into N equal parts uniformly along the long side direction, N is the order of the filter, N is the number of output ends, i is 1,2 … N, the input port is arranged at the level 1 TE₁₀₁Signal input side of a mode-substrate integrated waveguide resonator, the TE_n01The mode substrate integrated waveguide resonant cavity outputs energy from n output ports through n coupling windows respectively, and the ratio of external quality factors of the output ports is equal to the ratio of reciprocal powers of the output ports.

The input port is connected with the first-stage TE through the grounded coplanar waveguide₁₀₁The mode-substrate integrated waveguide resonant cavity connection feeds energy into the first stage TE₁₀₁A mode substrate is integrated with a waveguide resonant cavity.

In addition, the invention also provides a design method of the millimeter wave filtering power divider with any power dividing ratio, which is characterized by comprising the following steps:

step 1, calculating low-pass prototype lumped parameters according to performance indexes required by a pass band of a filtering power divider, calculating external quality factors of input ports according to the low-pass prototype lumped parameters, determining the order N of a filter, the coupling coefficients of adjacent resonators and the number N of output ports, and preliminarily assuming that the filtering power divider is a filtering power divider with N equal power divisions;

step 2, establishing a model of the millimeter wave filtering power divider with any power dividing ratio as claimed in claim 1 according to the parameters determined in the step 1, and adjusting the size of a coupling window between adjacent resonators to enable the coupling degree between the adjacent resonators to meet the coupling coefficient calculated in the step 1;

step 3, adjusting load on level 1 TE₁₀₁The width and depth of the slots on the two sides of the input feeder of the mode substrate integrated waveguide resonant cavity are ensured to meet the requirementsCalculating the external quality factor of the input port obtained in the step 1;

step 4, through simulation extraction of external quality factors corresponding to any one output port of the power divider model with equal power division filtering in the step 2 under different window sizes, a graph of output window size-external quality factor is obtained;

step 5, calculating the external quality factor of each output port according to the output power distribution ratio of the output port required by the design, and adjusting the TE according to the window size-external quality factor curve chart in the step 4_n01And the size of the coupling window of the output port of the mode substrate integrated waveguide resonant cavity is made to meet the external quality factor of the output port required by design.

The invention provides a single-layer millimeter wave multi-port substrate integrated waveguide filtering power divider with any power dividing ratio and a design method thereof. The filtering power divider consists of N-1 TEs₁₀₁Die and a TE_n01The mode cavity, the last cavity (TE)_n01Mode) divides the energy into equal n parts, and then correspondingly leads out n output ports on the resonant cavity for power distribution.

Assuming that the multiport network is lossless, P and P_i(i-1, 2 … n) each represents TE₁₀₁Input power and TE of mode substrate integrated waveguide resonant cavity_n01The dissipation power output by the mode substrate integrated waveguide resonant cavity can obtain P ═ P₁+P₂+…+P_nFor convenience of expression of the following formula, the power division ratio may be set to α_iExpressed, defined as follows:

P₁:P₂:…:P_n＝α₁:α₂:…:α_n (1)

the output power versus input power for each output port may then be expressed as

According to an external quality factor (Q)_e) Definition of (1), input Q_esAnd of each outputQ_eLiCan be expressed as

Wherein W_aAnd ω₀Respectively, the average energy storage and the resonance frequency of the resonator used. From this we can get each output Q_eLi

From equation (5), it can be seen that the power splitting ratio required for the three outputs is only determined by their external Q_eRatio determination, each output port L_iQ of (2)_eThe ratio of which is equal to the ratio of the inverse powers of the output ports. Q of n ports since energy is divided into equal n parts_eThe variation being referenced to Q of one of the output ports_e. Therefore, the invention simplifies the design method and can easily obtain the filtering power divider with any power division ratio.

The invention skillfully puts TE into contact with₁₀₁The mode resonant cavity and the higher-order mode resonant cavity are cascaded, and the characteristic that the higher-order mode resonant cavity equally divides energy is utilized, so that a standardized output window size-external quality factor curve graph can be obtained only by simulating any one output port, and the design of the filtering power divider with any power dividing ratio can be completed by adjusting the window of each output port based on the standardized curve graph. Therefore, the method is simple and flexible to realize, the design time of the device is shortened, and the research and development efficiency is improved.

Drawings

The invention will be further described with reference to the accompanying drawings;

fig. 1 is a top view of an N-th order multiport filter power divider of the present invention.

Fig. 2 is a perspective view of the three-way substrate integrated waveguide filter power divider of the present invention.

Fig. 3 is a top view of a three-way substrate integrated waveguide filter power splitter of the present invention.

Fig. 4 is a graph of the output window size-external quality factor of the three-way substrate integrated waveguide filter power divider of the present invention.

Fig. 5 is a diagram showing simulation results of a three-way substrate integrated waveguide filter power divider for equal power division according to a simulation example of the present invention.

Fig. 6 is a phase response diagram of the output of a three-way sbw filter power divider according to an example of the present invention.

Fig. 7 is a diagram of simulation results of a three-way substrate integrated waveguide filter power divider with unequal power division according to a simulation example of the present invention.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

FIG. 1 shows the planar geometry of an N-th order multiport filter power divider, where S₁And L_i(i-1, 2 … N) represents input and output (N represents the order and N represents the number of outputs), respectively, and R represents₁…R_N-1Are all TE₁₀₁Mode cavity, R_NRepresents TE_n01A mode cavity. The N-order multiport millimeter wave filtering power divider comprises 1 input port S₁And n output ports L_iCascaded N-1 TEs₁₀₁Mode-substrate integrated waveguide resonant cavity and 1 TE_n01The mode substrate integrated waveguide resonant cavity has an input port S₁Set in level 1 TE₁₀₁The signal input side of the mode substrate integrated waveguide resonant cavity, in the invention, the input port S₁By grounding coplanar waveguide to first stage TE₁₀₁The mode-substrate integrated waveguide resonant cavity connection feeds energy into the first stage TE₁₀₁A mode substrate is integrated with a waveguide resonant cavity. As can be seen in the figure, the last resonator (TE)_n01Mode substrate integrated waveguide resonant cavity) to divide the energy into n equal parts uniformly along the long side direction, and then correspondingly leading out n output ports L on the resonant cavity_iPerforming power distribution and outputting, each outputPort L_iIs equal to the ratio of the inverse powers of the output ports. The coupling coefficient and the external quality factor are among the two most important parameters for constructing the pass band and determining the power distribution. The number of ports and the filter response may be independent of each other, since the energy is divided into equal n, Q of n ports_eThe variation being referenced to Q of one of the output ports_eThis provides a simple design method for the overall design of any order and number of loads of the filter power divider resonator. And TE_n01The larger the windowing size of the mode substrate integrated waveguide resonant cavity at the side of the output port is, the smaller the external quality factor of the output port is, and the higher the obtained energy distribution proportion is.

The design method of the millimeter wave filtering power divider with any power dividing ratio is characterized by comprising the following steps:

step 3, adjusting load on level 1 TE₁₀₁The width and the depth of the slots on the two sides of the input feeder of the mode substrate integrated waveguide resonant cavity meet the external quality factor of the input port calculated in the step 1;

step 4, extracting any output port L of the power divider model of the power division filtering in the step 2 through simulation_iObtaining external quality factors corresponding to different window sizes to obtain an output window size-external quality factor curve graph;

step 5, calculating the external quality factors of the output ports according to the output power distribution ratio of the output ports required by the design,adjusting TE according to the window size-external figure of merit graph in step 4_n01Output port L of mode substrate integrated waveguide resonant cavity_iTo meet the design requirements of the output port L_iThe external figure of merit of (1).

Fig. 2 and 3 show the solid and planar geometry of a three-way substrate integrated waveguide filter power divider with a predetermined power division ratio (N ═ 2, N ═ 3), respectively, which is composed of two coupled substrate integrated waveguide cavities (resonant cavity 1 and resonant cavity 2). Port 1 represents the input and

ports

2,3 and 4 represent the outputs. Excitation of TE in the resonant cavity 1 using a 50-omega microstrip connection grounded coplanar waveguide (GCPW) feed₁₀₁Mode(s). The filter power divider is designed on a single layer PCB (Rogers RT/Duroid 5880) with a relative dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.508 mm.

The adopted substrate integrated waveguide

resonant cavities

1 and 2 are respectively designed to be at TE₁₀₁And TE₃₀₁Resonates in the mode. The coupling of two adjacent substrate integrated waveguide cavities is achieved by an intermediate coupling window, and when a signal is injected from the input port 1, a predetermined output power ratio can be achieved between the

ports

2,3,4 by controlling the Q ratio of the

output ports

2,3, 4. The energy generated by the cavity 1 is converted by the TE in the cavity 2₃₀₁The pattern is divided equally into three parts. All three outputs are at TE₃₀₁The position where the mode electric field is strongest, therefore, TE is adopted₁₀₁Die cavity and TE₃₀₁The scheme of cavity coupling can realize power distribution and filter response simultaneously. From TE₃₀₁The electric field distribution of the mode can be obtained as TE₃₀₁The phase in the middle of the mode is opposite to the two sides. The physical dimensions of the substrate integrated waveguide cavity are determined by classical formulas. The unequal power division ratio filter power divider designed herein has the diameter d of the through hole equal to 0.3mm, and the pitch p of the adjacent through holes equal to 0.5 mm.

The invention is verified by designing two examples with predetermined power ratios.

Simulation example one

The simulation example is a three-path substrate integrated waveguide filtering power divider with the power ratio of 1:1:1, the device structure is shown in fig. 2 and fig. 3, and the description is not repeated here.

According to the proposed filter power divider with different coupling window widths W_kThe value of K for the lower simulation can be seen as follows W_kThe coupling becomes stronger. To satisfy the K value required for calculation, W_kA suitable value for this is 2.07 mm. Generally speaking, Q_eIs reflected by the coupling strength between the resonator and the feed line. When the feed line is located at a position where the electric field of the resonant cavity is strong, the coupling is stronger (i.e., Q)_eWould be smaller). At the same time, coupling becomes weaker when the feed slot depth and slot width are smaller (i.e., Q)_eWould be larger). From input Q when other parameters are fixed_eRelative to L₁And W₁It can be seen that when L is₁Or W₁When increasing, Q_eAnd decreases. In other words, when the coupling strength between the resonant cavity 1 and the feed line increases, Q is increased_eThe value decreases. Q according to output (port 3)_eExtraction, where the port 3 is located in the middle of the cavity 2. Q can be seen from the output window size-external figure of merit plot of FIG. 4_eIs as follows W_j2Is increased and decreased. Due to TE₃₀₁The three parts of the mode are equal in energy, so that only one output Q is provided_eExtraction is required in this design, where the Q of the output, located in the center of the SIW chamber 2, and the other two outputs (port 2 and port 4) are extracted_eThe value can be referenced to port 3Q_eThe extraction of (1). In the case of equal power division, three output coupling windows (W)₂、W₃And W₄) Are equal. Fig. 5 is a simulation result, which verifies that this simple design method is effective. Fig. 7 is the phase response of the output, illustrating that port 2 and port 4 are in phase, and port 3 is in anti-phase. This also verifies that the design method is independent of the output phase of the filtering power divider.

Simulation example two

To further prove, the second simulation example designs a filtering power divider with a power division ratio of 1:3:1, which is used as a feed network of a filter antenna array to realize low sidelobe. This FPD has the same filter index as the first example above. The following table gives specific dimensions for a 1:3:1 filtering power divider.

Parameter(s)	W₅₀	W_k	W_slot	W₁	W₂	W₃	W₄
								Value (mm)	1.48	2.07	0.2	1.08	2.23	2.86	2.23
Parameter(s)	L₁	d	p	a₁	a₂	b₁	b₂
								Value (mm)	16.3	4.84	4.9	18.0	5.43	4.33	0.3

To verify the proposed design method, this example simulates two filtered power divider prototypes with a center frequency of 27.2 GHz. The circuit size of the filter power divider is 17.5mm multiplied by 10.5 mm.

As shown in fig. 7, the simulated reflection coefficient (| S) of the three-way filtering power divider with the power distribution ratio preset to 1:3:1₁₁|) better than 20dB in the passband, and a three-way insertion loss of about 1.2dB (excluding the loss of 1:3:1 power distribution). It is ideal for S₂₁、S₃₁、S₄₁Respectively-6.99 dB, -2.22dB and-6.99 dB. Simulation results show that the filter power divider centered at 27.2GHz has a 3-dB fractional bandwidth of 2.24%. The phase response of the output is shown in fig. 7 and will not be repeated here.

In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.

Claims

1. A millimeter-wave filter power divider with an arbitrary power division ratio, characterized in that: comprising 1 input port ( S ₁ ) and n output ports ( L _i ), cascaded N -1 TE ₁₀₁ mode The substrate-integrated waveguide resonator and one TE _{n 01} mode substrate-integrated waveguide resonator, the TE _{n 01} -mode substrate-integrated waveguide resonator evenly divides the energy into n equal parts along its long side, where N is the filter The order of , n is the number of output _terminals , i ₌ 1,2 _... The chip-integrated waveguide resonator outputs energy from n output ports ( L _i ) respectively through n coupling windows, and the ratio of the external quality factor of each output port ( L _i ) is equal to the ratio of the power reciprocal of each output port.

2. The millimeter-wave filter power divider with any power division ratio according to claim 1, characterized in that: the larger the window size of the TE _{n 01} -mode substrate-integrated waveguide resonator on the output port side, the greater the The smaller the external quality factor of the output port, the higher the energy distribution ratio obtained.

3 . The millimeter-wave filter power divider with any power division ratio according to claim 1 , wherein the input port ( S ₁ ) is integrated with a first-stage TE ₁₀₁ -mode substrate through a grounded coplanar waveguide. The resonator is connected to feed energy into the first stage TE ₁₀₁ mode substrate integrated waveguide resonator.

4. The design method of the millimeter-wave filter power divider with any power division ratio is characterized in that the steps are as follows:

Step 1. Calculate the lumped parameter of the low-pass prototype according to the performance index required by the passband of the filter power divider, and calculate the external quality factor of the input port accordingly, determine the order N of the filter, the coupling coefficient of the adjacent resonator and the output The number of ports is n , and it is preliminarily assumed that the filter power divider is a filter power divider with n equal power divisions;

Step 2. Establish a model of the millimeter-wave filter power divider with any power division ratio as claimed in claim 1 according to the parameters determined in step 1, and adjust the size of the coupling window between adjacent resonators, so that the size of the coupling window between adjacent resonators is adjusted. The coupling degree of satisfies the coupling coefficient calculated in step 1;

Step 3. Adjust the width and depth of the slot on both sides of the input feeder loaded on the first-level TE ₁₀₁ -mode substrate integrated waveguide resonator cavity so that it meets the external quality factor of the input port calculated in step 1;

Step 4, extracting the external quality factor corresponding to any output port ( L _i ) of the intermediate power division filter power divider model in step 2 under different window sizes through simulation, and obtain the output window size-external quality factor curve graph;

Step 5. Calculate the external quality factor of each output port according to the output power distribution ratio of the output ports required by the design, and adjust the output port of the TE _{n 01} mode substrate integrated waveguide resonator cavity according to the output window size-external quality factor curve graph in step 4 ( L _i ) the size of the coupling window such that it meets the external quality factor of the output port ( L _i ) required by the design.

5. The method for designing a millimeter-wave filter power divider with an arbitrary power division ratio according to claim 4, wherein the window size of the TE _{n 01} mode substrate-integrated waveguide resonator on the output port side is larger. Larger, the smaller the external quality factor of the output port, the higher the energy distribution ratio obtained.

6 . The method for designing a millimeter-wave filter power divider with an arbitrary power division ratio according to claim 4 , wherein the power distribution ratio of the output port is equal to the ratio of the inverse of the external quality factor of the output port. 7 .