Methods for measuring the reflection coefficient of the internal field of an electromagnetic structure

Abstract

This invention discloses a method for measuring the reflection coefficient of an internal electromagnetic field. Based on field values ​​measured at three equally spaced points, this method extracts the field values ​​of the forward and backward waves from the total electromagnetic wave, including both forward and backward waves, using the field values ​​of these three points within a one-dimensional uniform or periodic structure. The reflection coefficient within the structure is then obtained accordingly. This method is simple, fast, and accurate, and can be used in the design of transmission lines and antennas. It can be applied to both uniform and periodic structures; both closed transmission line structures such as waveguides and open transmission lines such as microstrip lines; both waveguide structures of transmission lines and radiating structures of antennas; and both lossless and lossy structures.

Description

Technical Field

[0001] This invention relates to a method for measuring the reflection coefficient of the internal field of an electromagnetic structure, belonging to the technical field of measuring electromagnetic wave reflection parameters inside an electromagnetic structure. Background Technology

[0002] Uniform transmission line structures and one-dimensional periodic structures are commonly used one-dimensional electromagnetic structures in the microwave and antenna fields, frequently applied in the design of microwave components and antennas such as power dividers, phase shifters, filters, and amplifiers. In a uniform transmission line, the propagation direction is called the longitudinal direction. In a one-dimensional periodic structure, the periodic direction is also longitudinal, representing the propagation direction of the electromagnetic wave. These structures often consist of two waves with opposite propagation directions superimposed. These two waves are typically called forward and backward waves. At the structure's ports, the forward wave is also called the incident wave, and the backward wave is called the reflected wave. In a uniform structure, the forward and backward waves may be generated by two separate wave sources at opposite ends of the structure. In a periodic structure, the forward and backward waves can be generated by discontinuities in the periodic structure. The ratio of the reflected wave field value to the incident wave field value is called the reflection coefficient, used to characterize the reflection properties of the electromagnetic structure. In the design of microwave components and antennas, it is often necessary to understand not only the reflection characteristics at the external ports but also the reflection characteristics within the electromagnetic structure. To understand reflection characteristics and obtain the reflection coefficient, it is often necessary to separate and extract the forward and backward waves from the total electromagnetic wave. At the external ports of a structure, the incident and reflected waves can be obtained separately, and the reflection coefficient can then be calculated, whether through measurement or electromagnetic field simulation software. However, there is no good method for measuring the reflection coefficient inside an electromagnetic structure. Especially inside a one-dimensional periodic structure, the reflection coefficient differs for different components of the electric field, and also for different components of the magnetic field. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for measuring the reflection coefficient of the internal field of an electromagnetic structure, which can obtain the field values ​​of the forward and backward waves inside the structure, and thereby obtain the reflection coefficient inside the structure. This method is applicable to various types of periodic structures, including lossy or open radiating structures.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A method for measuring the reflection coefficient of an internal field of an electromagnetic structure, the method comprising the following steps:

[0006] Step 1: In the electromagnetic structure, take three points along the longitudinal direction of the electromagnetic structure and mark them as the left point, the middle point and the right point respectively. The interval between any two adjacent points is equal.

[0007] Let p be the interval between two adjacent points. When the electromagnetic structure is a uniform structure, p is any length not greater than half the length of the entire electromagnetic structure. When the electromagnetic structure is a periodic structure, p is an integer multiple of the period length of the electromagnetic structure, and p is less than or equal to half the length of the entire electromagnetic structure.

[0008] Step 2: Measure the electric field i-component at the three points: left, middle, and right; and measure the electric field j-component at the three points: left, middle, and right.

[0009] Step 3: Based on the field values ​​of the electric field i component at the three points (left, middle, and right) measured in Step 2, calculate the complex numbers a and b, as follows:

[0010]

[0011]

[0012] Among them, F i-1 F i0 and F i+1 These represent the field values ​​of the i-component of the electric field at the three points: the left point, the middle point, and the right point, respectively.

[0013] Step 4: Extract the normalized field values ​​of the forward and backward waves of the electric field i-component, as shown in the following formula:

[0014]

[0015]

[0016] in, These represent the normalized field values ​​of the forward and backward waves of the electric field i-component, respectively.

[0017] Step 5: Extract the normalized field values ​​of the forward and backward waves of the electric field j component, as shown in the following formula:

[0018]

[0019]

[0020] in, F represents the normalized field values ​​of the forward and backward electric field components j, respectively. j0 F j+1 These represent the field values ​​of the j-component of the electric field at the midpoint and the rightpoint, respectively.

[0021] Step 6, when the phase angle of the complex number b is greater than zero, the electric field reflection coefficient from the i-component of the electric field to the j-component at the midpoint is: The electric field reflection coefficient at the midpoint between the j-component and the i-component of the electric field is: When the phase angle of the complex number b is less than zero, the electric field reflection coefficient from the i-component of the electric field to the j-component at the midpoint is: The electric field reflection coefficient at the midpoint between the j-component and the i-component of the electric field is:

[0022] In a preferred embodiment of the present invention, in step 2, the electric field i component and the electric field j component are any two of the three components of the electric field, or the electric field i component and the electric field j component are the same component of the three components of the electric field.

[0023] As a preferred embodiment of the present invention, when measuring the reflection coefficient of a lossless electromagnetic structure, the imaginary part of the complex number a is set to zero.

[0024] As a preferred embodiment of the present invention, when measuring the field value of any one of the three components of the electric field at any one of the three points (left, middle, and right), the lateral distribution of the excitation mode at the excitation port is the same as the lateral distribution of the electromagnetic mode of the electromagnetic structure.

[0025] The field value can be the field value of any component of the electric field or the field value of any component of the magnetic field. When it is the field value of any component of the magnetic field, the calculated value is the magnetic field reflection coefficient.

[0026] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0027] 1. The method for measuring the reflection coefficient of the internal field of an electromagnetic structure proposed in this invention utilizes the field values ​​of the electric or magnetic fields at three points inside the structure. By extracting the forward and backward waves inside the one-dimensional structure, the reflection coefficient inside the structure is obtained. This method is simple, fast, and accurate.

[0028] 2. The method proposed in this invention can be used for both uniform and periodic structures; it can be used for both closed transmission line structures such as waveguides and open transmission lines such as microstrip lines; it can be used for both waveguide structures of transmission lines and radiating structures of antennas; and it can be used for both lossless and lossy structures. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the method for measuring the reflection coefficient of the internal field of the electromagnetic structure according to the present invention. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] This invention proposes a method for measuring the reflection coefficient of the internal field of an electromagnetic structure, the specific steps of which are as follows:

[0032] The first step is to take three points along the longitudinal direction of the electromagnetic structure, and label them as the left point, the middle point, and the right point, with an interval of p between adjacent points, as follows: Figure 1 As shown.

[0033] When the structure is a uniform structure, p is any length not greater than half the length of the entire structure, but it must be ensured that the left point, the middle point, and the right point are all inside the structure.

[0034] When the structure is a periodic structure, p is an integer multiple of the period length of the structure and no more than half of the total length of the structure, but it must be ensured that the left point, the middle point, and the right point are all within the structure.

[0035] The second step is to measure the electric field values ​​of the i-component at three points: left point 1, middle point 2, and right point 3. These values ​​are labeled as Fi. i-1 F i0 and F i+1 The electric field values ​​of the j-component at points 1 (left), 2 (middle), and 3 (right) are labeled as F. j-1 F j0 and F j+1 .

[0036] The electric field i-component and the electric field j-component can be any two of the three components of the electric field, or they can be the same component of the three components.

[0037] The field value can be the field value of any component of the electric field or any component of the magnetic field. When it is the field value of any component of the electric field, the calculated value is the electric field reflection coefficient; when it is the field value of any component of the magnetic field, the calculated value is the magnetic field reflection coefficient. The third step is to calculate the complex number a:

[0038]

[0039] Step 4: Calculate the complex number b:

[0040]

[0041] Fifth step: Extract the normalized field value of the forward wave of the electric field i component.

[0042]

[0043] Step 6: Extract the normalized field value of the backwave of the electric field i-component.

[0044]

[0045] Step 7: Extract the normalized field value of the forward wave of the j-component of the electric field.

[0046]

[0047] Step 8: Extract the normalized field value of the backwave of the j-component of the electric field.

[0048]

[0049] Step 9: If the phase angle of the complex number b is greater than zero, the reflection coefficient from the i-component of the electric field to the j-component at the midpoint 2 is... The reflection coefficient from the j-component of the electric field to the i-component at the midpoint 2 is: If the phase angle of the complex number b is less than zero, the reflection coefficient from the i-component of the electric field to the j-component at the midpoint 2 is: The reflection coefficient from the j-component of the electric field to the i-component at the midpoint 2 is:

[0050] When measuring the reflection coefficient of a lossless electromagnetic structure, the imaginary part of the complex number a is set to zero to improve accuracy.

[0051] When measuring the field value of any component of the electric or magnetic field at three points—left point 1, middle point 2, and right point 3—the lateral distribution of the excitation mode at the excitation port is the same as the lateral distribution of the mode of the calculated electromagnetic structure.

[0052] To measure the electric or magnetic field value of any component at three points—left, middle, and right—you can use direct measurement methods, such as near-field probes, indirect measurement methods, or calculation methods using electromagnetic field simulation software.

[0053] Another solution to b is b -1 The propagation direction of the electromagnetic wave corresponding to is opposite to that of the electromagnetic wave corresponding to b. There is no substantial difference in the calculation of the reflection coefficient between the two. As long as the relationship between the direction of the incident wave and the direction of the reflected wave and the direction of the forward wave and the backward wave is determined according to the propagation direction of the electromagnetic wave, the reflection coefficient can be calculated.

[0054] In a one-dimensional uniform structure, the electric field reflection coefficient and the magnetic field reflection coefficient inside the one-dimensional uniform structure are the same, and the i-component direction and the j-component direction can be the same, because the reflection coefficient values ​​measured for different components of the one-dimensional uniform structure are the same.

[0055] When used for one-dimensional periodic structures, since the electric field reflection coefficient and magnetic field reflection coefficient inside the one-dimensional periodic structure need to be represented by tensors, when measuring the electric field reflection coefficient, the three components of the electric field need to be traversed twice in sequence, and when measuring the magnetic field reflection coefficient, the three components of the magnetic field need to be traversed twice in sequence.

[0056] A uniform structure can be viewed as a periodic structure with an arbitrary period.

[0057] When used in a uniform structure, the three points on the left (point 1), the middle (point 2), and the right (point 3) in the first step are adjacent to each other with the same interval. This interval can be of any size, but it cannot be too small. If the field values ​​of the three points on the left (point 1), the middle (point 2), and the right (point 3) are too close, it will cause a large measurement error.

[0058] When used for periodic structures, the three points—left point 1, middle point 2, and right point 3—are spaced at the same interval in the first step. This interval cannot be too small to avoid the field values ​​of left point 1, middle point 2, and right point 3 being too close, resulting in a large measurement error. Therefore, if the period length is relatively small, the interval can be the length of several periods.

[0059] When the field value of any component of the electric or magnetic field is obtained through calculation, electromagnetic field simulation software can be used. For example, software such as CST, HFSS, or Comsol can be used.

[0060] The success of this invention depends on the periodicity of the structure. Therefore, this invention can also be applied to periodic structures in other technical fields. The embodiments of this invention in the electromagnetic field are not intended to limit its application in other fields; all such applications should be included within the scope of protection of this invention. For example, this invention can also be used to extract the forward and backward waves of sound waves from one-dimensional acoustic structures, and to measure or calculate the sound wave reflection coefficient; it can also be used to extract the forward and backward waves of electron waves from one-dimensional crystal structures, and to measure or calculate the electron wave reflection coefficient, etc.

[0061] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for measuring the reflection coefficient of an internal field of an electromagnetic structure, characterized in that, The method includes the following steps: Step 1: In the electromagnetic structure, take three points along the longitudinal direction of the electromagnetic structure and mark them as the left point, the middle point and the right point respectively. The interval between any two adjacent points is equal. Let p be the interval between two adjacent points. When the electromagnetic structure is a uniform structure, p is any length not greater than half the length of the entire electromagnetic structure. When the electromagnetic structure is a periodic structure, p is an integer multiple of the period length of the electromagnetic structure, and p is less than or equal to half the length of the entire electromagnetic structure. Step 2: Measure the electric field i-component at the three points: left, middle, and right; and measure the electric field j-component at the three points: left, middle, and right. Step 3: Based on the field values ​​of the electric field i component at the three points (left, middle, and right) measured in Step 2, calculate the complex numbers a and b, as follows: where F i-1 , F i0 , and F i+1 represent the field values of the electric field i component at the left, middle, and right points, respectively; Step 4: Extract the normalized field values ​​of the forward and backward waves of the electric field i-component, as shown in the following formula: in, These represent the normalized field values ​​of the forward and backward waves of the electric field i-component, respectively. Step 5: Extract the normalized field values ​​of the forward and backward waves of the electric field j component, as shown in the following formula: in, F represents the normalized field values ​​of the forward and backward electric field components j, respectively. j0 F j+1 These represent the field values ​​of the j-component of the electric field at the midpoint and the rightpoint, respectively. Step 6, when the phase angle of the complex number b is greater than zero, the electric field reflection coefficient from the i-component of the electric field to the j-component at the midpoint is: The electric field reflection coefficient at the midpoint between the j-component and the i-component of the electric field is: When the phase angle of the complex number b is less than zero, the electric field reflection coefficient from the i-component of the electric field to the j-component at the midpoint is: The electric field reflection coefficient at the midpoint between the j-component and the i-component of the electric field is:

2. The method for measuring the reflection coefficient of the internal field of an electromagnetic structure according to claim 1, characterized in that, In step 2, the electric field i component and the electric field j component are any two of the three components of the electric field, or the electric field i component and the electric field j component are the same component of the three components of the electric field.

3. The method for measuring the reflection coefficient of the internal field of an electromagnetic structure according to claim 1, characterized in that, When measuring the reflection coefficient of a lossless electromagnetic structure, let the imaginary part of the complex number a be equal to zero.

4. The method for measuring the reflection coefficient of the internal field of an electromagnetic structure according to claim 1, characterized in that, When measuring the field value of any one of the three components of the electric field at any one of the three points (left, middle, and right), the lateral distribution of the excitation mode at the excitation port is the same as the lateral distribution of the electromagnetic mode of the electromagnetic structure.

5. A method for measuring the reflection coefficient of an internal field of an electromagnetic structure, characterized in that, The method includes the following steps: Step 1: In the electromagnetic structure, take three points along the longitudinal direction of the electromagnetic structure and mark them as the left point, the middle point and the right point respectively. The interval between any two adjacent points is equal. Let p be the interval between two adjacent points. When the electromagnetic structure is a uniform structure, p is any length not greater than half the length of the entire electromagnetic structure. When the electromagnetic structure is a periodic structure, p is an integer multiple of the period length of the electromagnetic structure, and p is less than or equal to half the length of the entire electromagnetic structure. Step 2: Measure the field value of the i-component of the magnetic field at the three points: the left point, the middle point, and the right point; and measure the field value of the j-component of the magnetic field at the three points: the left point, the middle point, and the right point. Step 3: Based on the field values ​​of the magnetic field i component at the three points (left, middle, and right) measured in Step 2, calculate the complex numbers a and b, as follows: Among them, F i-1 F i0 and F i+1 These represent the field values ​​of the i-component of the magnetic field at the three points: the left point, the middle point, and the right point, respectively. Step 4: Extract the normalized field values ​​of the forward and backward waves of the magnetic field i-component, as shown in the following formula: in, These represent the normalized field values ​​of the forward and backward waves of the i-component of the magnetic field, respectively. Step 5: Extract the normalized field values ​​of the forward and backward waves of the magnetic field j-component, as shown in the following formula: in, F represents the normalized field values ​​of the forward and backward waves of the j-component of the magnetic field, respectively. j0 F j+1 These represent the field values ​​of the j-component of the magnetic field at the midpoint and the rightpoint, respectively. Step 6, when the phase angle of the complex number b is greater than zero, the magnetic field reflection coefficient at the midpoint between the i-component and the j-component of the magnetic field is: The magnetic field reflection coefficient at the midpoint between the j-component and the i-component of the magnetic field is: When the phase angle of the complex number b is less than zero, the magnetic field reflection coefficient at the midpoint between the i-component and the j-component of the magnetic field is: The magnetic field reflection coefficient at the midpoint between the j-component and the i-component of the magnetic field is:

6. The method for measuring the reflection coefficient of the internal field of an electromagnetic structure according to claim 5, characterized in that, In step 2, the i-component and j-component of the magnetic field are any two of the three components of the magnetic field, or the i-component and j-component of the magnetic field are the same component of the three components of the magnetic field.

7. The method for measuring the reflection coefficient of the internal field of an electromagnetic structure according to claim 5, characterized in that, When measuring the reflection coefficient of a lossless electromagnetic structure, let the imaginary part of the complex number a be equal to zero.

8. The method for measuring the reflection coefficient of the internal field of an electromagnetic structure according to claim 5, characterized in that, When measuring the field value of any one of the three components of the magnetic field at any one of the three points (left, middle, and right), the lateral distribution of the excitation mode at the excitation port is the same as the lateral distribution of the electromagnetic mode of the electromagnetic structure.

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