阅读说明：本技术 一种基于准光理论的相位修正面型功率合成器设计方法 (phase correction surface type power combiner design method based on quasi-optical theory ) 是由 付浩 李孚嘉 罗勇 于 2019-11-20 设计创作，主要内容包括：本发明公开了一种基于准光理论的相位修正面型功率合成器设计方法,涉及微波功率合成领域。本方法则是根据传播至中继面或辐射场的正、逆向衍射场的幅值和相位分布进行相位修正,其物理机理为根据镜面变换,促使两个场在幅值与相位分布方面同时趋向一致。通过改进经典KS算法,增加波束正逆向传播循环体系,在多个相位修正面间形成效应联系,进而能够实现多镜面系统的良好设计,达到高效功率合成的目的。相比于仅适用于单镜面系统设计的经典KS算法,本方法可以对多镜面系统进行良好设计,有利于复杂波形变换的高效实现；相比于经典KS算法,本方法对相位修正面的赋形优化效果持续稳定,最终的波形变换效率可以得到大幅提高。(The invention discloses a phase correction surface type power synthesizer design method based on quasi-optical theory, which relates to the field of microwave power synthesis, the method carries out phase correction according to the amplitude and phase distribution of a positive diffraction field and a negative diffraction field which are transmitted to a relay surface or a radiation field, the physical mechanism of the method is that according to mirror transformation, two fields tend to in the aspects of amplitude and phase distribution simultaneously, through improving a classical KS algorithm, a beam positive and negative propagation circulation system is increased, effect connection is formed among a plurality of phase correction surfaces, and further the good design of a multi-mirror system can be realized, and the purpose of high-efficiency power synthesis is achieved.)

1, A design method of phase correction surface type power synthesizer based on quasi-optical theory, the method includes:

step 1: determining parameters of an input field and an output field of the phase correction surface type power synthesizer and a power synthesis efficiency target value;

step 2: calculating the number of the mirrors according to the parameters of the input field and the output field, and initializing the shape of each mirror;

and step 3: generating a virtual relay surface between adjacent metal reflecting surfaces according to the spatial position of the mirror surface;

step 4, respectively calculating the reverse diffraction field distribution of the reverse propagation output field at each relay surface from the Nth relay surface to the th relay surface after the reverse propagation output field passes through each mirror surface;

step 5, forward propagation of the input field is carried out, and the forward diffraction field distribution of the input field which passes through the th mirror surface and is propagated to the th relay surface is calculated;

step 6, according to the positive and reverse diffraction field distribution at the th relay surface, using a KS algorithm to shape and optimize the th mirror surface;

step 7, forward propagating the input field, calculating the th mirror surface and the second mirror surface in the initial state after times of shaping, and propagating the forward diffraction field distribution to the second relay surface;

and 8: according to the positive and reverse diffraction field distribution at the second relay surface, a KS algorithm is used for shaping and optimizing the second mirror surface;

step 9, adopting the same method from the step 5 to the step 8, positively propagating the input field, and optimizing the next unoptimized mirrors according to the optimized mirrors until the last mirrors are optimized in a shaping manner;

and 10, calculating each shaped mirror surface of the input field, transmitting the shaped mirror surface to an observation field at the plane of the output field, calculating degrees of the observation field and the output field, finishing the design of the power synthesizer if the degree is greater than the target power synthesis efficiency value, and otherwise, circulating the steps 4 to 9 to perform rounds of mirror surface shaping optimization until the target power synthesis efficiency value or the preset maximum circulation times are reached.

2. The design method of phase correction surface type power combiners based on quasi-optical theory as claimed in claim 1, wherein said step 4 is performed by calculating the inverse diffraction distribution of the field by using the integration formula of kirchhoff's inverse diffraction:

wherein u is_Inver(r_m) Denotes the inverse diffraction field, r_mRepresenting the observed point position vector, r representing the known field position vector, s representing the plane of the known field, z representing the inverse diffraction direction coordinate perpendicular to the s-plane, (x, y) representing the coordinate on the s-plane, u (r) representing the known field distribution, and G 'representing the green's function when the beam propagates in the reverse direction:

wherein k represents a wave number of the electromagnetic wave in free space;

step 5, calculating the forward diffraction distribution of the field by kirchhoff diffraction integral formula:

wherein G represents the green's function when the beam is propagating forward:

3. the method of designing quasichotonic based phase correction planar power combiners according to claim 1, wherein the KS algorithm in step 6 first defines u on the observation plane S₁,u₂Difference E between the two field distributions:

wherein r is_SPosition vector, u, representing observation plane S₁(r_S) Represents the distribution of the forward diffraction field on the observation plane S, u₂(r_S) Representing the distribution of the inverse diffraction field on the observation surface S; then, by solving the zero gradient equation, the mirror deformation amount Δ z is obtained:

in the process, the mirror surface is deformed and the phase is corrected

where k is the wave number of the electromagnetic wave in free space, and θ is the incident angle of the incident field at a certain point on the metal mirror surface.

4. The method for designing a phase-corrected planar power combiner based on quasi-optical theory as claimed in claim 1, wherein the step 10 measures the observed field u by the following equation_OAnd the output field u_T degree ε:

ε＝|∫_Tu_O·u_Tds|²/[(∫_T|u_O|²ds)(∫_T|u_T|²ds)](8)

where T represents the output field plane.

Technical Field

The invention relates to microwave power synthesis, in particular to a design method of power synthesizers based on quasi-optical theory.

Background

The traditional waveguide power synthesizer uses the electromagnetic propagation mode of guided waves, so that the electromagnetic waves have more ohmic loss on the metal waveguide wall, and meanwhile, the device is difficult to give consideration to both power capacity and mode purity. The quasi-optical power synthesizer changes the phase distribution of waves in the transmission process according to the diffraction theory under the condition that the electromagnetic wave diffraction effect is obvious, and further changes the diffraction field distribution of the waves, so that the convergent synthesis from multi-path beams to single-path beams is realized. The power combiner is different from the traditional power combiner, adopts an electromagnetic propagation mode of free space waves, and has the characteristics of low loss, high combining efficiency, capability of working in high-power and high-frequency environments and the like.

Currently, quasi-optical power combiners include the following types: 1. regular mirror type. It is characterized in that the mirror surface is a part of regular paraboloid or ellipsoid; 2. and (5) phase correction surface type. The method is characterized in that the mirror surface is an irregular curved surface obtained by numerical calculation based on a phase correction principle; 3. a diffractive phase element type. The device is characterized in that the device is composed of a diffraction phase element or a diffraction phase element, a regular mirror surface, a phase correction surface and the like. The diffraction phase element has a grating structure, a two-dimensional periodic pore structure and the like. The design method of the phase correction surface type quasi-optical power combiner mainly comprises a KS algorithm [1], a GS algorithm [2], a radiation moment algorithm [3] and the like. The KS algorithm can be applied to the shaping optimization of a single mirror system, but the KS algorithm is difficult to be applied to a multi-mirror system because the input field and the output field before and after the target optimization mirror are required to be determined due to the application of the KS algorithm. The GS algorithm can be applied to the forming optimization of a multi-mirror system, but the optimization principle based on phase difference between fields causes the physical mechanism to be not obvious, and the problem of low iterative convergence speed exists. Complex quasi-optical waveform transformations, such as multi-beam power combining and distribution, often require multi-mirror systems to perform well. Therefore, in current practical applications, the GS algorithm suitable for the design of the multi-mirror system is used.

The following are references cited in this patent:

[1]Jin J,Piosczyk B,Thumm M,et al.Quasi-optical mode converter/mirrorsystem for a high-power coaxial-cavity gyrotron[J].IEEE transactions onplasma science,2006,34(4):1508-1515.

[2]Bogdashov A A,Denisov G G.Synthesis of the sequence of phasecorrectors forming the desired field[J].Radiophysics and quantum electronics,2004,47(12):966-973.

[3]Wang H,Lu Z,Liu X,et al.Investigations on shaped mirror systems inquasi-optical mode converters based on irradiance moments method[J].International Journal of Antennas and Propagation,2016,2016.

disclosure of Invention

Aiming at the defects of the prior art, the invention improves the classical KS algorithm, increases a beam forward and backward propagation circulation system, and forms effect relation among a plurality of phase correction surfaces, thereby realizing the good design of a multi-mirror system and achieving the purpose of high-efficiency power synthesis.

The technical scheme of the invention is phase correction surface type power synthesizer design methods based on quasi-optical theory, the method includes:

step 1: determining parameters of an input field and an output field of the phase correction surface type power synthesizer and a power synthesis efficiency target value;

step 2: calculating the number of the mirrors according to the parameters of the input field and the output field, and initializing the shape of each mirror;

and step 3: generating a virtual relay surface between adjacent metal reflecting surfaces according to the spatial position of the mirror surface; the results of the above steps are shown in FIG. 1;

step 4, respectively calculating the reverse diffraction field distribution of the reverse propagation output field at each relay surface from the Nth relay surface to the th relay surface after the reverse propagation output field passes through each mirror surface;

step 5, forward propagation of the input field is carried out, and the forward diffraction field distribution of the input field which passes through the th mirror surface and is propagated to the th relay surface is calculated;

step 6, according to the positive and reverse diffraction field distribution at the th relay surface, using a KS algorithm to shape and optimize the th mirror surface;

step 7, forward propagating the input field, calculating the th mirror surface and the second mirror surface in the initial state after times of shaping, and propagating the forward diffraction field distribution to the second relay surface;

and 8: according to the positive and reverse diffraction field distribution at the second relay surface, a KS algorithm is used for shaping and optimizing the second mirror surface;

step 9, adopting the same method from the step 5 to the step 8, positively propagating the input field, and optimizing the next unoptimized mirrors according to the optimized mirrors until the last mirrors are optimized in a shaping manner;

and 10, calculating each shaped mirror surface of the input field, transmitting the shaped mirror surface to an observation field at the plane of the output field, calculating degrees of the observation field and the output field, finishing the design of the power synthesizer if the degree is greater than the target power synthesis efficiency value, and otherwise, circulating the steps 4 to 9 to perform rounds of mirror surface shaping optimization until the target power synthesis efficiency value or the preset maximum circulation times are reached.

, step 4 calculating the inverse diffraction profile of the field by using kirchhoff's inverse diffraction integral formula:

wherein u is_Inver(r_m) Denotes the inverse diffraction field, r_mRepresenting the observed point position vector, r representing the known field position vector, s representing the plane of the known field, z representing the inverse diffraction direction coordinate perpendicular to the s-plane, (x, y) representing the coordinate on the s-plane, u (r) representing the known field distribution, and G 'representing the green's function when the beam propagates in the reverse direction:

wherein k represents a wave number of the electromagnetic wave in free space;

step 5, calculating the forward diffraction distribution of the field by kirchhoff diffraction integral formula:

wherein G represents the green's function when the beam is propagating forward:

in step , the KS algorithm first defines u on the observation plane S in step 6₁,u₂Difference E between the two field distributions:

wherein r is_SPosition vector, u, representing observation plane S₁(r_S) Represents the distribution of the forward diffraction field on the observation plane S, u₂(r_S) Representing the distribution of the inverse diffraction field on the observation surface S; then, by solving the zero gradient equation, the mirror deformation amount Δ z is obtained:

in the process, the mirror surface is deformed and the phase is corrected

Are linked by:

where k is the wave number of the electromagnetic wave in free space, and θ is the incident angle of the incident field at a certain point on the metal mirror surface.

Further to step , step 10 measures the observation field u by_OAnd the output field u_T degree ε:

ε＝|∫_Tu_O·u_Tds|²/[(∫_T|u_O|²ds)(∫_T|u_T|²ds)](8)

where T represents the output field plane.

Compared with the existing design method, the design method of the power synthesizer based on the quasi-optical theory provided by the invention has the remarkable advantages that:

1. compared with the classical KS algorithm only suitable for single-mirror system design, the method can well design a multi-mirror system, and is beneficial to efficient realization of complex wave form transformation;

2. compared with the classical KS algorithm, the method has the advantages that the shaping optimization effect on the phase correction surface is continuous and stable, and the final waveform transformation (such as power synthesis) efficiency can be greatly improved;

3. compared with the classic GS algorithm, the physical mechanism of the method is clear and intuitive, and the method is convenient to understand and apply.

It is worth pointing out that the GS algorithm also has the process of forward and backward diffraction propagation of the beam, and it is this process that makes it applicable to the design of multi-mirror system, however, the GS algorithm is different from the physical mechanism of this patent method, the former changes the phase correction mirror, only according to the phase distribution difference of the forward and backward diffraction field propagated to the mirror or radiation field, the phase compensation and the mirror shaping are carried out, the amplitude distribution difference is not the basis of shaping optimization, so the physical mechanism of the mirror shaping is not significant, the method carries out the phase correction according to the amplitude and phase distribution of the forward and backward diffraction field propagated to the relay surface or radiation field, the physical mechanism is to make the two fields tend to simultaneously in terms of amplitude and phase distribution according to the mirror transformation, but the concept of the GS algorithm also provides reference and help for the proposal of this patent method.

Drawings

FIG. 1 is a schematic diagram of the relative positions of the input field, output field, mirror and relay surfaces of a multi-mirror system.

FIG. 2 is a diagram of the magnitude distribution of the input field of four Gaussian beams in the example.

FIG. 3 is a distribution diagram of field amplitude of single Gaussian beam output in the embodiment.

FIG. 4 is a schematic diagram of a design structure of a dual mirror system in an embodiment.

FIG. 5 is a diagram showing the amplitude distribution of the power combining field in the embodiment.

Fig. 6 is a phase distribution diagram of the power combining field in the embodiment.

FIG. 7 is a diagram of a mirror structure of a dual mirror system according to an embodiment.

Detailed Description

To explain the technical solution disclosed in the present invention in detail, the following is made an explanation of step with reference to the embodiments and the accompanying drawings.

In this embodiment, under the condition of 30GHz frequency, the convergent synthesis of four gaussian beams with a beam waist radius of 10.4mm to gaussian beams with a beam waist radius of 10.4mm is realized.

According to the design method provided by the invention, the following steps are carried out:

(1) parameters of the input field and the output field are determined and power synthesis efficiency target values are determined. The input field takes the beam waist section field distribution of four Gaussian beams with the beam waist radius of 10.4mm, and the beam waist centers of the four Gaussian beams are respectively positioned at coordinates (19,19, -25), (19, -19, -25), (19,19, -25) and (19, -19, -25) and the amplitude distribution in unit millimeter in consideration of the wall thickness and the interval of devices of a radiation port is shown in FIG. 2. The normal vector of the input field plane is (0,0, 1). The output field takes the beam waist section field distribution of a single-path Gaussian beam with the beam waist radius of 10.4mm, and the amplitude distribution is shown in FIG. 3. The normal vector of the plane of the output field is (0,0, 1). Since the input field and the output field are both fields at the waist section of the gaussian beam, the phase distribution is zero everywhere.

The target value of the power synthesis efficiency is set to 94%.

(2) The present embodiment takes the form of a two mirror system, the th mirror is set to 180 x 180mm, depending on the radiation characteristics of the input field²The structure is rectangular, the center of the mirror surface is located at coordinates (0,0,90), the unit millimeter is millimeter, and the normal vector is (1.41,0, -1.41); setting the second mirror surface to 160 × 160mm²Rectangular structure, mirror center located at coordinates (180,0,90), unit millimeter, normal vector of (-1.41,0, 1.41). Based on the above information, output field center coordinates (180,0,175) are set in millimeters.

(3) Because this embodiment uses a dual mirror system, only relay planes need to be set, with central coordinates of (90,0,90), unit millimeters, and sizes of 72 × 72mm²The normal vector is (1,0, 0). The results of the above steps are shown in fig. 4.

(4) And calculating the reverse diffraction field distribution of the output field which is transmitted to the relay surface through the second mirror surface.

(5) The input field is propagated in the forward direction, and the distribution of the forward diffraction field which is propagated to the relay surface through the th mirror surface is calculated.

(6) And (3) optimally shaping the th mirror by using a KS algorithm according to the distribution of the forward and backward diffraction fields at the relay surface, wherein the shaping can enable the th mirror to carry out phase correction on the radiation field of the input field, so that the forward diffraction field propagated to the relay surface is more similar to the backward diffraction field obtained in the step (4).

(7) The input field is propagated in the forward direction, the th mirror surface and the second mirror surface in the initial state after times of shaping are calculated, and the input field is propagated to the observation field at the surface of the output field;

(8) and according to the known output field and the observation field, the KS algorithm is used for shaping and optimizing the second mirror surface, the shaping can enable the second mirror surface to carry out -step adjustment on the field transmitted by the front-stage system, and the input field is transmitted to the observation field obtained at the surface of the output field through shaping optimized mirror surfaces and the second mirror surfaces and is closer to the field distribution of the output field.

(9) And calculating an th mirror and a second mirror after the input field is subjected to shaping optimization, an observation field propagated to the output field, and calculating degree of the observation field and the output field, wherein the degree of the observation field and the output field is 86.92% and is smaller than a power synthesis efficiency target value 94% through round of mirror optimization, and therefore, the method enters a lower round of circulation.

After 4 rounds of optimized shaping, the degree of the observation field and the output field reaches 94.41%, which is larger than the target value of the power synthesis efficiency, and the cycle is ended, at this time, the amplitude distribution and the phase distribution of the observation field are respectively shown in fig. 5 and fig. 6, the amplitude distribution is similar to the gaussian distribution of the amplitude of the output field, the phase distribution is flat and close to zero distribution, and the characteristics of the zero phase distribution of the output field are .

The optimized double-mirror system is shown in fig. 7, in addition, smoothing treatment needs to be carried out on the mirror surface during device processing, processing is convenient, and the breakdown voltage threshold of the device is improved.

Table 1 shows degrees of 7 iterations of this example, and compared with the results of 7 iterations of the single-mirror classical KS algorithm under the same parameters (excluding the second mirror and the output field position).

TABLE 1 comparison of the optimization results of this patent method with classical KS algorithm