A method for calculating an average angle of incidence of a radome beam

Abstract

The application discloses a method for calculating an average incidence angle of a radome beam, which uses an electromagnetic integral algorithm with high precision to replace a geometric optical method with low precision, and combines threshold screening and weighted average to obtain more accurate parameters of the average incidence angle of the radome beam, so as to provide more accurate design parameters for electric performance design and optimization of the radome.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radar antenna radome design, in particular to a method for designing the electrical performance of a radome. BACKGROUND

[0002] The radar antenna radome is an important component of the seeker radar system, which can protect the seeker radar system from the influence of complex external environment. In addition to the physical protection function, in the electrical performance level, the radome also needs to have good electromagnetic wave transmission characteristics. For the common single-layer dielectric radome, the electrical performance is mainly affected by the design effect of the radome wall thickness parameter. When designing the electrical performance of the radome, the radome wall thickness parameter design mainly depends on the calculation result of the average incidence angle of the radome beam. The average incidence angle of the radome beam refers to the equivalent angle formed by the beam propagation direction and the normal direction of the radome wall when the electromagnetic beam emitted by the antenna propagates to the inner wall surface of the radome. The traditional method for calculating the average incidence angle of the radome beam is the ray solving method based on geometric optics theory. This method ignores the diffraction effect of the electromagnetic beam, and the calculation error is large, which has obvious adverse effects on the electrical performance design of the radome. SUMMARY

[0003] The purpose of the present application is to provide a method for calculating the average incidence angle of the radome beam, to obtain more accurate parameters of the average incidence angle of the radome beam, and to provide more accurate design parameters for the electrical performance design and optimization of the radome.

[0004] In order to achieve the above purpose, the present application provides a method for calculating the average incidence angle of the radome beam, which comprises the following steps:

[0005] Step S1, a geometric model of the radome outer surface is established, and the triangular surface elements are divided;

[0006] Step S2, the rotation angle of the antenna is set, and the aperture plane radiation electromagnetic field distribution and position information of the antenna are extracted;

[0007] Step S3, based on the physical optics theory formula, the electromagnetic integration of the antenna aperture plane field is performed, and the electromagnetic field distribution of the antenna beam propagating to each triangular surface element of the radome outer surface is calculated;

[0008] Step 4, the beam incidence angle of the antenna emitted electromagnetic wave on each triangular surface element is obtained by calculating the electromagnetic wave Poynting vector on each triangular surface element and combining the normal vector of the triangular surface element to calculate the included angle;

[0009]

[0010]

[0011] wherein, is a unit vector of the unit Poynting vector, is an electric field vector of the triangular facet element of the radome profile, is a magnetic field vector of the triangular facet element of the radome profile, and is obtained by a physical optical integral algorithm; θ represents a beam incidence angle of the antenna electromagnetic wave on each triangular facet element of the inner wall of the radome, is a unit vector corresponding to the outer normal vector of each triangular facet element;

[0012] Step S5, processing the beam incidence angle data set of all triangular facet elements to obtain an average beam incidence angle of the antenna transmitted electromagnetic wave on the inner wall of the radome.

[0013] The beam incidence angle data set processing method comprises:

[0014] Screening: taking a modulus value of the Poynting vector of all triangular facet elements and obtaining a modulus maximum value; setting a screening threshold, which is the modulus maximum value of the Poynting vector multiplied by a proportional coefficient; deleting the triangular facet element incidence angle data whose Poynting vector modulus value is lower than the screening threshold, and only retaining the triangular facet element incidence angle data whose Poynting vector modulus value is higher than the screening threshold;

[0015] Weighted average: taking the Poynting vector modulus value as a weight, performing a weighted average on the triangular facet element incidence angle data whose Poynting vector modulus value is higher than the screening threshold, and finally obtaining an equivalent beam incidence angle value θ of the antenna beam on the inner wall of the radome. equivalent ;

[0016]

[0017] Wherein, S1, S2,..., S n is a Poynting vector modulus value of the triangular facet element after threshold screening, θ1, θ2,..., θ n is a triangular facet element incidence angle corresponding to S1, S2,..., S n .

[0018] The proportional coefficient is between 0 and 1.

[0019] The present application uses an electromagnetic integral algorithm with higher precision to replace a geometric optical method with lower precision, combines threshold screening and weighted average, and obtains more accurate radome beam average incidence angle parameters, so as to provide more accurate design parameters for radome electrical performance design and optimization. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flow chart for calculating the radome beam average incidence angle in the present application;

[0021] Figure 2 is a triangular facet element profile dissection schematic diagram of the radome in the present application;

[0022] Figure 3 Fig. 1 is a schematic diagram of electromagnetic energy distribution on the inner wall of the antenna cover in the present application, including comparison of distribution before and after screening according to energy density;

[0023] Figure 4 Fig. 2 is a calculation result diagram of the average incidence angle of the antenna cover beam varying with the antenna scanning angle in the present application. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present application are specifically described below according to Figures 1-4 .

[0025] The present application provides a method for calculating the average incidence angle of the antenna cover beam based on physical optics algorithm. In the case of known antenna cover shape, antenna aperture electromagnetic field distribution, antenna-antenna cover relative position relationship and antenna frequency, the average incidence angle of the antenna cover beam is calculated. As shown in Fig. 1, the specific calculation steps are as follows: Figure 1

[0026] Step S1, a geometric model of the antenna cover shape surface is established, and triangular surface elements are used for division. After the modeling of the antenna cover shape surface, the effect after the triangular surface element division is as shown in Fig. 2 (the division can be performed by self-division or with the aid of special software such as HyperMesh, Ansys, CATIA, FEKO, etc.). The antenna cover shape surface after the division can be equivalent to a collection of a series of triangular surface elements. Figure 2

[0027] Step S2, the antenna rotation angle is set, which can be equivalent to rotating the antenna aperture electromagnetic field distribution by the same angle, and the aperture radiation electromagnetic field distribution and position information of the antenna are extracted.

[0028] Step S3, based on the physical optics theory formula, the electromagnetic integration of the antenna aperture field is performed, and the electromagnetic field distribution of the antenna beam propagating to each triangular surface element of the antenna cover shape surface is calculated and

[0029] Step S4, the beam incidence angle of the antenna transmitted electromagnetic wave on each triangular surface element of the antenna cover is calculated.

[0030] The beam incidence angle of the antenna transmitted electromagnetic wave on each triangular surface element is obtained by calculating the electromagnetic beam Poynting vector on each triangular surface element and then combining the normal vector of the triangular surface element to obtain the included angle.

[0031]

[0032]

[0033] Among them, ​​is the unit vector of the unit Poynting vector, is the electric field vector of the divided triangular facet of the radome, is the magnetic field vector of the triangular facet, and is obtained by a physical optics integral algorithm; θ represents the beam incidence angle of the antenna electromagnetic wave beam on each triangular facet of the inner wall of the radome, and n→ is the unit vector corresponding to the outer normal vector of each triangular facet;

[0034] Step S5, processing the beam incidence angle data set of all triangular facets to obtain the average beam incidence angle of the antenna transmitted electromagnetic wave on the inner wall of the radome;

[0035] In the triangular facet beam incidence angle data set processing flow, the screening step and the weighted average step are included;

[0036] The screening step includes: first, taking the modulus value of the Poynting vector of all triangular facets (corresponding to the high and low electromagnetic energy density), and obtaining the maximum modulus value; then, setting a screening threshold according to the specific scene, the screening threshold is the maximum modulus value of the Poynting vector multiplied by a specific proportion coefficient (between 0 and 1); deleting the triangular facet incidence angle data whose Poynting vector modulus value is lower than the screening threshold, and only keeping the triangular facet incidence angle data whose Poynting vector modulus value is higher than the screening threshold;

[0037] The weighted average step includes: taking the Poynting vector modulus value as the weight, and performing weighted average on the triangular facet incidence angle data whose Poynting vector modulus value is higher than the screening threshold, to finally obtain the equivalent beam incidence angle value θ equivalent of the antenna beam on the inner wall of the radome;

[0038]

[0039] Wherein, S1, S2,..., S n is the Poynting vector modulus value of the triangular facet after threshold screening, θ1, θ2,..., θ n is the triangular facet incidence angle corresponding to S1, S2,..., S n .

[0040] Figure 3 is the electromagnetic field energy distribution diagram of the antenna beam propagating to the inner wall of the radome in the present application, wherein the left graph is the electromagnetic energy distribution without energy density screening processing, and the right graph is the electromagnetic energy distribution after energy screening processing, only the electromagnetic distribution area with higher energy density is retained.

[0041] Figure 4 is the calculation result diagram of the change of the average beam incidence angle of the radome with the increase of the antenna scanning angle in the present application, wherein the abscissa is the antenna scanning angle, and the ordinate is the corresponding average beam incidence angle of the radome. From the diagram, it can be seen that the average beam incidence angle of the radome increases with the increase of the antenna scanning angle.Figure 4 It can be seen that when the antenna is directly opposite the radome (the scanning angle is zero), the average beam incidence angle reaches the maximum value, and as the antenna scanning angle increases, the average beam incidence angle gradually decreases.

[0042] The application uses the electromagnetic integral algorithm with higher precision to replace the geometric optics method with lower precision, and combines threshold screening and weighted average to obtain more accurate radome average beam incidence angle parameters, thereby providing more accurate design parameters for radome electrical performance design and optimization.

[0043] It should be noted that in the embodiments of the present application, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0044] Although the content of the present application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation on the present application. After reading the above content, various modifications and alternatives of the present application will be apparent to those skilled in the art. Therefore, the protection scope of the present application should be defined by the appended claims.

Claims

1. A method for calculating the average incident angle of an antenna radome beam, characterized in that, Includes the following steps: Step S1: Establish the geometric model of the radome's outer surface and use triangular elements for subdivision; Step S2: Set the antenna rotation angle and extract the distribution and location information of the electromagnetic field radiated from the antenna aperture; Step S3: Based on the physical optics theory formula, perform electromagnetic integration of the antenna aperture field to calculate the electromagnetic field distribution of each triangular surface element of the antenna beam propagating to the outer surface of the antenna radome. Step S4: By calculating the Poynting vector of the electromagnetic beam on each triangular element and then combining it with the normal vector of the triangular element to find the included angle, the incident angle of the electromagnetic wave transmitted by the antenna on each triangular element is obtained. in, The unit Poynting vector is the unit vector. The electric field vectors of the triangular facet elements of the radome are obtained by partitioning the radome. The magnetic field vector of the triangular surface element. and The angle θ is obtained through a physical optics integration algorithm; θ represents the incident angle of the antenna electromagnetic beam on each triangular element on the inner wall of the radome. The unit vector corresponding to the outward normal vector of each triangular facet element; Step S5: Process the beam incidence angle dataset of all triangular elements to obtain the average beam incidence angle of the electromagnetic wave transmitted by the antenna on the inner wall of the radome. The method for processing the beam incidence angle dataset includes: Filtering: Take the modulus of the Poynting vector for all triangular elements and find the maximum modulus value; set a filtering threshold, which is the maximum modulus value of the Poynting vector multiplied by a scaling factor; delete the incident angle data of triangular elements whose Poynting vector modulus value is lower than the filtering threshold, and only keep the incident angle data of triangular elements whose Poynting vector modulus value is higher than the filtering threshold. Weighted average: Using the Poynting vector magnitude as the weight, the incident angle data of triangular facets with Poynting vector magnitudes higher than the screening threshold are weighted and averaged to obtain the equivalent beam incident angle θ of the antenna beam on the inner wall of the radome. equivalent ; Among them, S1, S2, ... S n The Poynting vector magnitudes of the triangular facets after threshold filtering are θ1, θ2, ... θ. n To be related to S1, S2, ...S n The incident angle of the corresponding triangular element.

2. The method for calculating the average incident angle of the radome beam as described in claim 1, characterized in that, The scaling factor is between 0 and 1.

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