CN110866361B - Waveguide port excitation method for electromagnetic finite element solution - Google Patents
Waveguide port excitation method for electromagnetic finite element solution Download PDFInfo
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- CN110866361B CN110866361B CN201911174059.1A CN201911174059A CN110866361B CN 110866361 B CN110866361 B CN 110866361B CN 201911174059 A CN201911174059 A CN 201911174059A CN 110866361 B CN110866361 B CN 110866361B
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Abstract
The invention provides a waveguide port excitation method for solving electromagnetic finite elements, which is characterized in that a current source and a magnetic current source are applied to a waveguide port simultaneously to generate electromagnetic waves exciting a waveguide antenna in one direction, so that the waves in the other direction are mutually offset without generating electromagnetic waves, and disturbance to a calculation area is avoided. The port can be placed at any position of the calculation region to perform electromagnetic finite element solution without being limited by the placement position; the co-workers solve the problem of excitation of the waveguide port in the appointed direction during finite element electromagnetic calculation, and the convenience of the solving process is improved; in the formula of finite element solution, the invention has small variation of the original calculation program, small increased calculation amount and strong portability.
Description
Technical Field
The invention belongs to the technical field of computational electromagnetics, and particularly relates to a waveguide port excitation method for solving electromagnetic finite elements.
Background
In electromagnetic computing software there are many radiators, such as horns, whose port excitation is applied in the form of waveguide ports; the algorithm is based on calculating the magnetic field distribution of the eigenmodes and then adding the magnetic field to the algorithm in the form of an equivalent current source to produce the excitation. The result of this is the generation of electromagnetic fields in two directions perpendicular to the surface of the current source: the field in one direction is the useful field to excite the antenna; the other direction field is a useless field that would interfere with the calculation region. In the current mainstream commercial software based on finite element electromagnetic calculation, the waveguide port can only be applied to the end face of the outer side of the enclosure body, so that the calculation is inconvenient; if the port needs to be placed at a certain location inside the enclosure, the business software cannot be implemented. The existing commercial software adopts a method of applying a waveguide port at the outermost side to absorb the field intensity which is not needed in the other direction, so as to avoid interference with the calculated area field. The problem with this approach is that the waveguide excitation ports can only be placed outermost; when the computational scenario is complex, resulting in the need to set the excitation antenna inside the computational area, then this solution fails to work. The above scenario is a frequent scenario, such as an environmental problem of providing an antenna or exciting the cabin in the center of the cabin of the ship.
Disclosure of Invention
The invention aims to solve the technical problems that: the waveguide port excitation method for solving the electromagnetic finite element is provided, so that the electromagnetic finite element can be solved when the port is placed at any position of a calculation area.
The technical scheme adopted by the invention for solving the technical problems is as follows: a waveguide port excitation method for electromagnetic finite element solution comprises the following steps:
s1: introducing a Huygens source on the excitation end face as an excitation source of the waveguide port;
s2: solving a Huygens source on an excitation end face of the waveguide port;
s3: substituting the Huygens source obtained in the step S2 into a three-dimensional finite element solving formula, and solving the electromagnetic field distribution of an electromagnetic finite element calculation region and the far-field radiation excited by a waveguide port.
According to the above scheme, in the step S1, the waveguide port includes a fed waveguide and an opened horn antenna; the excitation source is arranged in the middle of the waveguide, the excitation end face is perpendicular to the length direction of the waveguide, and the normal vector of the section of the waveguide port to which the excitation source is applied is n.
Further, in the step S2, the specific steps are as follows:
s21: solving the distribution of the intrinsic electric field E on the excitation end face by a two-dimensional vector finite element method;
s22: solving the distribution of the intrinsic magnetic field H on the excitation end face according to the relation between the magnetic field and the electric field;
s23: the electric and magnetic fields obtained in steps S21 and S22, respectively, are converted into equivalent huyghen sources.
Further, in the step S23, the specific steps are as follows: converting magnetic field H into current source J imp The electric field E is converted into a magnetic current source M imp Current source J imp And a magnetic current source M imp The relation of (2) is:
J imp ＝n×H，
M imp ＝E×n；
current source J imp And a magnetic current source M imp Together forming a huyghen source for exciting the horn antenna.
Further, in the step S3, the specific steps are as follows:
s31: mu is set r Is relative permeability epsilon r For the relative dielectric constant of the material,
for vector rotation, k 0 、Z 0 The free space wave vector impedance and the wave impedance are respectively, and j is an imaginary unit; the electric field vector wave equation of the calculation area is deduced according to Maxwell equation set of the electromagnetic field:
s32: let T be the test function, the cross-sectional surface be S,
for the outside direction of the port cross-sectional surface, dV is the differential volume of the calculation region, derived from the formula obtained in step S31 according to the vector formula:
s33: and (3) converting the formula obtained in the step (S32) into a linear equation set according to a finite element numerical value solving theory, and solving the electromagnetic field distribution of a calculation area and the far-field radiation of the horn antenna.
The beneficial effects of the invention are as follows:
1. according to the waveguide port excitation method for solving the electromagnetic finite element, an electric field and a magnetic field are applied to the port position at the same time, the electric field and the magnetic field of the port are obtained through two-dimensional vector finite element electromagnetic solving, so that the electromagnetic finite element solving can be carried out when the port is placed at any position of a calculation area, and the limitation of the placement position is avoided.
2. The method solves the problem of excitation of the waveguide port in the appointed direction in finite element electromagnetic calculation, and improves the convenience of the solving process.
3. In waveguide port excitation of electromagnetic finite element calculation, only one excitation field is generated by introducing a Huygens source, and no electromagnetic field in other directions is generated, so that disturbance to a calculation area is avoided.
4. In the formula of finite element solution, the invention has small variation of the original calculation program, small increased calculation amount and strong portability.
Drawings
FIG. 1 is a flow chart of an embodiment of the present invention.
Fig. 2 is a horn antenna diagram for waveguide excitation in accordance with an embodiment of the present invention.
Fig. 3 is a cross-sectional view of a mid-waveguide excited feedhorn in accordance with an embodiment of the present invention.
Fig. 4 is an electric field distribution diagram of the eigenmodes of a waveguide according to an embodiment of the present invention.
Fig. 5 is a magnetic field profile of the eigenmodes of a waveguide according to an embodiment of the invention.
Fig. 6 is an electric field distribution diagram of the eigenmodes of a waveguide excitation port according to an embodiment of the invention.
FIG. 7 is a graph of a computational region of a three-dimensional finite element solution according to an embodiment of the present invention.
Fig. 8 is an electric field distribution diagram of a cross section of a waveguide port excitation near a flare in an embodiment of the present invention.
Fig. 9 is an electric field distribution diagram of a cross section of waveguide port excitation away from a flare in an embodiment of the present invention.
Fig. 10 is a directional diagram of a waveguide port excited feedhorn according to an embodiment of the present invention.
Detailed Description
The invention will be described in further detail with reference to the drawings and the detailed description.
Huyghen sources, including current sources and magnetic current sources; because the current sources can simultaneously generate electromagnetic waves at two sides of the excitation surface, the electromagnetic waves are symmetrically distributed along the excitation surface; the magnetic current source also generates electromagnetic waves at the two sides of the excitation surface at the same time and is symmetrically distributed along the excitation surface. When the current source and the magnetic current source are present at the same time, the electromagnetic waves generated by them are mutually enhanced in one direction and mutually offset in the other direction. I.e. the huyghen source only generates electromagnetic waves in one direction, which are also electromagnetic waves exciting the antenna.
The invention is illustrated by calculating the radiation field of a waveguide excited feedhorn, see fig. 2, with the waveguide port comprising a fed waveguide and an open feedhorn.
Referring to fig. 1, the waveguide port excitation method for solving the electromagnetic finite element according to the invention comprises the following steps:
s1: introducing a Huygens source on the excitation end face as an excitation source of the waveguide port; referring to fig. 3, an excitation source is disposed in the middle of the waveguide, the excitation end face is perpendicular to the length direction of the waveguide, the normal vector of the section of the waveguide port to which the excitation source is applied is n, and the n perpendicular section points in the horn mouth direction.
S2: solving the huyghen source on the excitation end face of the waveguide port:
s21: solving the distribution of the intrinsic electric field E on the excitation end face by a two-dimensional vector finite element method, see fig. 4 and 6;
s22: solving the distribution of the intrinsic magnetic field H on the excitation end face according to the relation between the magnetic field and the electric field, see FIG. 5;
s23: converting magnetic field H into current source J imp The electric field E is converted into a magnetic current source M imp Current source J imp And a magnetic current source M imp The relation of (2) is:
J imp ＝n×H，
M imp ＝E×n；
current source J imp And a magnetic current source M imp Together forming a huyghen source for exciting the horn antenna.
S3: substituting the huyghen source obtained in the step S2 into a three-dimensional finite element solving formula to solve the electromagnetic field distribution of the electromagnetic finite element calculation region and the far-field radiation excited by the waveguide port, see fig. 7:
s31: mu is set r Is relative permeability epsilon r For the relative dielectric constant of the material,
for vector rotation, k 0 、Z 0 The free space wave vector impedance and the wave impedance are respectively, and j is an imaginary unit; the electric field vector wave equation of the calculation area is deduced according to Maxwell equation set of the electromagnetic field:
s32: referring to FIG. 7, let T be the test function, the cross-sectional surface be S, and the calculated area be the truncated surface S of the periphery of the feedhorn 0 An enclosed region, an absorption boundary being provided on the cut-off surface,
for the outside direction of the port cross-sectional surface, dV is the differential volume of the calculation region, derived from the formula obtained in step S31 according to the vector formula:
s33: and (3) converting the formula obtained in the step (S32) into a linear equation set according to a finite element numerical value solving theory, and solving the electromagnetic field distribution of a calculation area and the far-field radiation of the horn antenna.
Referring to fig. 8, the electric field distribution on the waveguide section on the side close to the flare (the left side of the excitation end face) and fig. 9 on the side far from the flare (the right side of the excitation end face) when the waveguide port is excited; the right cross section can be seen without field distribution, indicating that the set huyghen source propagates only to the left, and no propagating field exists on the right.
Referring to fig. 10, a directional diagram of a feedhorn when excited by a waveguide port; the small back lobe of the horn can be seen, indicating that the horn radiates very little in the back and no radiation at the right port of the waveguide, indicating that the set huyghen source only excites the antenna and no other electromagnetic field is generated.
The above embodiments are merely for illustrating the design concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, the scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications according to the principles and design ideas of the present invention are within the scope of the present invention.
Claims (1)
1. A waveguide port excitation method for solving electromagnetic finite elements is characterized in that: the method comprises the following steps:
s1: introducing a Huygens source on the excitation end face as an excitation source of the waveguide port;
the waveguide port comprises a fed waveguide and an open horn antenna; arranging an excitation source in the middle of a waveguide, wherein the excitation end face is perpendicular to the length direction of the waveguide, and the normal vector of the section of a waveguide port to which the excitation source is applied is n;
s2: solving a Huygens source on an excitation end face of the waveguide port;
the method comprises the following specific steps:
s21: solving the distribution of the intrinsic electric field E on the excitation end face by a two-dimensional vector finite element method;
s22: solving the distribution of the intrinsic magnetic field H on the excitation end face according to the relation between the magnetic field and the electric field;
s23: converting the electric field and the magnetic field obtained in the steps S21 and S22 into equivalent Huygens sources;
the method comprises the following specific steps: converting magnetic field H into current source J imp The electric field E is converted into a magnetic current source M imp Current source J imp And a magnetic current source M imp The relation of (2) is:
J imp ＝n×H，
M imp ＝E×n；
current source J imp And a magnetic current source M imp Together forming a huyghen source for exciting the horn antenna;
s3: substituting the Huygens source obtained in the step S2 into a three-dimensional finite element solving formula, and solving the electromagnetic field distribution of an electromagnetic finite element calculation region and the far-field radiation excited by a waveguide port;
the method comprises the following specific steps:
s31: mu is set r Is relative permeability epsilon r For the relative dielectric constant of the material,
for vector rotation, k 0 、Z 0 The free space wave vector impedance and the wave impedance are respectively, and j is an imaginary unit; the electric field vector wave equation of the calculation area is deduced according to Maxwell equation set of the electromagnetic field:
s32: let T be the test function, the cross-sectional surface be S,
for the outside direction of the port cross-sectional surface, dV is the differential volume of the calculation region, derived from the formula obtained in step S31 according to the vector formula:
s33: and (3) converting the formula obtained in the step (S32) into a linear equation set according to a finite element numerical value solving theory, and solving the electromagnetic field distribution of a calculation area and the far-field radiation of the horn antenna.
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| CN102411676A (en) * | 2011-10-31 | 2012-04-11 | 中国舰船研究设计中心 | Surface exciting method applicable to calculation of direction diagrams of waveguides in different shapes |
| CN106252860A (en) * | 2016-08-31 | 2016-12-21 | 重庆大学 | The multi-layer PCB little Huygens's source antenna of electricity |
| CN106649197A (en) * | 2016-10-13 | 2017-05-10 | 上海无线电设备研究所 | Calculation method of internal scattering characteristic of complicated cavity |
| CN108767409A (en) * | 2018-09-06 | 2018-11-06 | 成都邑电信息技术服务有限公司 | A kind of novel chip integrated wave guide power rate distribution/synthesizer |
| US10423738B1 (en) * | 2015-02-06 | 2019-09-24 | Ansys, Inc. | Systems and methods for electromagnetic field analysis |
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| EP2784798B1 (en) * | 2013-03-27 | 2016-03-23 | Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. | Determining an electromagnetic response of a sample |
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| CN102411676A (en) * | 2011-10-31 | 2012-04-11 | 中国舰船研究设计中心 | Surface exciting method applicable to calculation of direction diagrams of waveguides in different shapes |
| US10423738B1 (en) * | 2015-02-06 | 2019-09-24 | Ansys, Inc. | Systems and methods for electromagnetic field analysis |
| CN106252860A (en) * | 2016-08-31 | 2016-12-21 | 重庆大学 | The multi-layer PCB little Huygens's source antenna of electricity |
| CN106649197A (en) * | 2016-10-13 | 2017-05-10 | 上海无线电设备研究所 | Calculation method of internal scattering characteristic of complicated cavity |
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