CN114069184B - Millimeter wave filtering power divider with arbitrary power dividing ratio - Google Patents
Millimeter wave filtering power divider with arbitrary power dividing ratio Download PDFInfo
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Abstract
The invention relates to a millimeter wave filtering power divider with any power dividing ratio, comprisingN-1 TE 101 Die and a TE n01 Formation of a mode-resonant cavity, TE n01 Mode harmonicThe vibration cavity divides energy intonAre divided into equal parts, and then are correspondingly led out from the resonant cavitynThe output ports perform power distribution. The invention utilizes the characteristic that the higher-order mode resonant cavity equally divides energy, can obtain a standardized output window size-external quality factor curve chart only by simulating any one output port, and can complete the design of the filtering power divider with any power dividing ratio by adjusting the window of each output port based on the standardized curve chart, thereby ensuring that the design method of the filter is simple and flexible, shortening the design time of devices and improving the research and development efficiency.
Description
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 ports 101 Mode-substrate integrated waveguide resonant cavity and 1 TE n01 A mode substrate integrated waveguide resonant cavity, the TE n01 The 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 TE 101 Signal input side of a mode-substrate integrated waveguide resonator, the TE n01 The 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 waveguide 101 Mode substrate integrated waveA resonant cavity for feeding energy into the first stage of TE 101 A 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 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 n01 And 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 TEs 101 Die and a TE n01 The mode resonant cavity, the last resonant cavity (TE) n01 Mode) divides the energy into equal n parts, then at harmonicAnd n output ports are correspondingly led out from the vibration cavity for power distribution.
Assuming that the multiport network is lossless, P and P i (i-1, 2 … n) each represents TE 101 Input power and TE of mode substrate integrated waveguide resonant cavity n01 The dissipation power output by the mode substrate integrated waveguide resonant cavity can obtain P ═ P 1 +P 2 +…+P n For convenience of expression of the following formula, the power division ratio may be set to α i Expressed, defined as follows:
P 1 :P 2 :…:P n ＝α 1 :α 2 :…: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 es And Q of each output eLi Can be expressed as
Wherein W a And ω 0 Respectively, 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 e Ratio determination, each output port L i Q of (2) e Ratio of (A) to (B) being equal toThe ratio of the reciprocal of the power at each output port. Q of n ports since energy is divided into equal n parts e The 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 with 101 The 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 an N-order multiport filter power dividerA planar geometry of (2), wherein S 1 And L i (i is 1,2 … N) represents input and output (N represents order, N represents number of outputs), respectively, R 1 …R N-1 Are all TE 101 Mode cavity, R N Represents TE n01 A mode cavity. The N-order multiport millimeter wave filtering power divider comprises 1 input port S 1 And n output ports L i Cascaded N-1 TEs 101 Mode-substrate integrated waveguide resonant cavity and 1 TE n01 The mode substrate integrated waveguide resonant cavity has an input port S 1 Set in level 1 TE 101 The signal input side of the mode substrate integrated waveguide resonant cavity, in the invention, the input port S 1 By grounding the coplanar waveguide to the first stage TE 101 The mode-substrate integrated waveguide resonant cavity connection feeds energy into the first stage TE 101 A mode substrate is integrated with a waveguide resonant cavity. As can be seen in the figure, the last resonator (TE) n01 Mode 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 i Performs power distribution and output, each output port L i Is 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 e The variation being referenced to Q of one of the output ports e This provides a simple design method for the overall design of any order and number of loads of the filter power divider resonator. And TE n01 The 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 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 n01 Output port L of mode substrate integrated waveguide resonant cavity i To meet the design requirements of the output port L i The 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) feed 101 Mode(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 TE 101 And TE 301 Resonates in the mode. The coupling of two adjacent substrate integrated waveguide cavities is realized by an intermediate couplingAnd combining windows to achieve a predetermined output power ratio between ports 2,3,4 by controlling the Q ratio of output ports 2,3,4 when a signal is injected from input port 1. The energy generated by the cavity 1 is converted by the TE in the cavity 2 301 The pattern is divided equally into three parts. All three outputs are at TE 301 The position where the mode electric field is strongest, therefore, TE is adopted 101 Die cavity and TE 301 The scheme of cavity coupling can realize power distribution and filter response simultaneously. From TE 301 The electric field distribution of the mode can be obtained as TE 301 The 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 k The value of K for the lower simulation can be seen as follows W k The coupling becomes stronger. To satisfy the K value required for calculation, W k A suitable value for this is 2.07 mm. Generally speaking, Q e Is 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) e Would be smaller). At the same time, coupling becomes weaker when the feed slot depth and slot width are smaller (i.e., Q) e Would be larger). From input Q when other parameters are fixed e Relative to L 1 And W 1 It can be seen that when L is 1 Or W 1 When increasing, Q e And decreases. In other words, when the coupling strength between the resonant cavity 1 and the feed line increases, Q is increased e The value decreases. Q according to output (port 3) e Extraction, 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 e Is as follows W j2 Is increased and decreased. Due to TE 301 The three parts of the mode are equal in energy, so that only one output Q is provided e Extraction 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 e The value can be referenced to port 3Q e The extraction of (1). In the case of equal power division, three output coupling windows (W) 2 、W 3 And W 4 ) 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) | W 50 | W k | W slot | W 1 | W 2 | W 3 | W 4 |
| Value (mm) | 1.48 | 2.07 | 0.2 | 1.08 | 2.23 | 2.86 | 2.23 |
| Parameter(s) | L 1 | d | p | a 1 | a 2 | b 1 | b 2 |
| 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 1:3:1 11 I) within the pass bandThe three-way insertion loss is about 1.2dB (excluding the loss of 1:3:1 power splitting) better than 20 dB. It is ideal for S 21 、S 31 、S 41 Respectively-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 (6)
1. The utility model provides a millimeter wave filtering power divider with arbitrary power ratio which characterized in that: comprises 1 input port (S 1 ) Andnan output port (L i ) In cascade, ofN-1 TE 101 Mode-substrate integrated waveguide resonator, 1 TE n01 A mode substrate integrated waveguide resonant cavity, the TE n01 The mode substrate integrated waveguide resonant cavity divides energy into two parts uniformly along the long side direction thereofnThe equal parts are evenly distributed on the surface of the steel plate,Nfor the order of the filter, the filter is,nin order to be able to count the number of output terminals,i=1,2…ninput port (S 1 ) Set in level 1 TE 101 Signal input side of a mode-substrate integrated waveguide resonator, the TE n01 Mode substrate integrated waveguide resonant cavity passnThe coupling windows respectively transfer energy fromnAn output port (L i ) Output, the output ports: (L i ) Is equal to the ratio of the inverse powers of the output ports.
2. The millimeter wave filtering power divider with an arbitrary power dividing ratio according to claim 1, wherein: the TE n01 The 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.
3. According to claim1 the millimeter wave filtering power divider with any power dividing ratio is characterized in that: the input port (S 1 ) By grounding coplanar waveguide to first stage TE 101 The mode-substrate integrated waveguide resonant cavity connection feeds energy into the first stage TE 101 A mode substrate is integrated with a waveguide resonant cavity.
4. The design method of the millimeter wave filtering power divider with any power dividing ratio is characterized by comprising the following steps of:
step 1, calculating low-pass prototype lumped parameters according to performance indexes required by the pass band of the filtering power divider, calculating external quality factors of input ports according to the low-pass prototype lumped parameters, and determining the order of the filterNCoupling coefficient of adjacent resonators and number of output portsnInitially assume the filter power divider asnA filtering power divider with equal power division;
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 TE 101 The 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, any output port of the power divider model of the power division filtering in the step 2 is extracted through simulation (L i ) Obtaining 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 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 output window size-external quality factor curve chart in the step 4 n01 Output port of mode substrate integrated waveguide resonant cavity (L i ) The coupling window size of (a) so that it meets the output port of the design requirementL i ) The external figure of merit of (1).
5. The design method of the millimeter wave filtering power divider with any power dividing ratio as claimed in claim 4, wherein: the TE n01 The 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.
6. The design method of the millimeter wave filtering power divider with any power dividing ratio as claimed in claim 4, wherein: the power division ratio of the output port is equal to the ratio of the inverse of the quality factor external to the output port.
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