CN108710035B - Method and device for improving uniformity of reverberation chamber - Google Patents
Method and device for improving uniformity of reverberation chamber Download PDFInfo
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- CN108710035B CN108710035B CN201810167800.0A CN201810167800A CN108710035B CN 108710035 B CN108710035 B CN 108710035B CN 201810167800 A CN201810167800 A CN 201810167800A CN 108710035 B CN108710035 B CN 108710035B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
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Abstract
The invention discloses a method and a device for improving the uniformity of a reverberation chamber, which solve the problems of single improvement factor and poor improvement effect of the existing method. The method comprises the following steps: modeling and analyzing two factors influencing the uniform characteristic of the reverberation chamber field, namely the length-width ratio of the stirring blades and the included angle of the stirring blades by a two-factor variance analysis method, and determining that the factor with large influence is a first factor and the factor with small influence is a second factor; optimizing the first factor to obtain a first factor optimized value; optimizing the second factor on the basis of the first factor optimization value to obtain a second factor optimization value; and determining the combination of the first factor optimization value and the second factor optimization value as the optimal design value of the reverberation chamber. The method can be popularized to the design of reverberation chambers with other sizes, and provides basis for the optimization design of a stirrer of the reverberation chamber, so that the aim of improving the field uniformity of the reverberation chamber is fulfilled.
Description
Technical Field
The invention relates to the field of electromagnetic compatibility, in particular to a method and a device for improving the uniformity of a reverberation chamber.
Background
The field uniformity is one of the most main performance parameters of the reverberation chamber, the consistency of the test result is influenced by the quality of the field uniformity of the reverberation chamber, and the field uniformity parameters of the reverberation chamber are definitely required in the IEC 61000-4-21 standard. The influence factors of the field uniformity of the reverberation chamber are more, and include the size of the cavity of the reverberation chamber, the structure of the stirrer, the layout of the cavity of the reverberation chamber, the selection of a working area in the cavity of the reverberation chamber, the use of an antenna, the characteristics of manufacturing materials of the reverberation chamber and the like. Among these factors, when the size and material of the chamber are determined, the selection and development of the shape and size of the blades and the included angle between the blades are the most important key factors for improving the field uniformity of the reverberation chamber in the design stage. The existing reverberation room field uniformity improvement scheme only considers a single factor, ignores multiple factors influencing field uniformity and the mutual relation between the multiple factors, and has poor improvement effect.
Disclosure of Invention
The invention provides a method and a device for improving the uniformity of a reverberation chamber, which solve the problems of single improvement factor and poor improvement effect of the existing method.
A method of improving the uniformity of a reverberant chamber comprising the steps of: modeling and analyzing two factors influencing the uniform characteristic of the reverberation chamber field, namely the length-width ratio of the stirring blades and the included angle of the stirring blades by a two-factor variance analysis method, and determining that the factor with large influence is a first factor and the factor with small influence is a second factor; optimizing the first factor to obtain a first factor optimized value; optimizing the second factor on the basis of the first factor optimization value to obtain a second factor optimization value; and determining the combination of the first factor optimization value and the second factor optimization value as the optimal design value of the reverberation chamber.
Further, the method further comprises: setting a plurality of monitoring frequency points according to the uniformity monitoring frequency band of the reverberation chamber; respectively calculating the optimal design value for each monitoring frequency point; and carrying out statistical averaging on the optimal design value of each monitoring frequency point to obtain the optimal design value of the reverberation chamber of the monitoring frequency band.
Preferably, the step of performing modeling analysis on two factors affecting the uniform characteristic of the field of the reverberation chamber, the length-width ratio of the stirring blade and the included angle of the stirring blade by a two-factor variance analysis method, and determining that the factor with a large influence is a first factor and the factor with a small influence is a second factor further includes: respectively carrying out level decomposition on two factors of the length-width ratio of the stirring blades and the included angle of the stirring blades, combining the level of the length-width ratio of the stirring blades and the level of the included angle of the stirring blades, and establishing a test orthogonal table; recording the field uniformity observed value of each combination of the test orthogonal table to obtain test data; calculating to obtain the mean square sum of the length-width ratio of the stirring blades and the included angle of the stirring blades according to the test data; according to the mean square sum data, determining a first factor and a second factor as follows: when the mean square sum of the length-width ratios of the stirring blades is larger than or equal to the mean square sum of the included angles of the stirring blades, determining that the length-width ratios of the stirring blades are a first factor, and the included angles of the stirring blades are a second factor, and when the mean square sum of the length-width ratios of the stirring blades is smaller than the mean square sum of the included angles of the stirring blades, determining that the included angles of the stirring blades are the first factor, and the length-width ratios of the stirring blades are the second factor.
Preferably, the step of calculating a mean square sum of the length-width ratio of the stirring blade and the included angle of the stirring blade according to the test data further includes: establishing a model according to the test data as follows:
Xij＝μ+αi+βj+ij,i＝1,...,k；j＝1,...,m
α1+...+αk＝0
β1+...+βm＝0
wherein, XijIs the experimental observation value of the combination of the ith position level of the stirring blade included angle factor and the jth position level of the length-width ratio of the stirring blade, and mu is XijMean value of (a)iIs the effect of the ith level of the mixing blade angle factor, betajIs the effect of the jth bit stage of the aspect ratio of the mixing blades,ijare experimental errors, are independent of each other and obey the distribution N (0, σ)2) (ii) a And calculating to obtain the mean square sum and the degree of freedom of the length-width ratio of the stirring blades and the included angle of the stirring blades.
Preferably, the included angle of the stirring blade comprises 3 bit levels, namely a first bit level 90 °, a second bit level 120 ° and a third bit level 150 °, and the aspect ratio of the stirring blade comprises 4 bit levels, namely a first bit level 1:1, a second bit level 1.2:1, a third bit level 1.5:1 and a fourth bit level 2: 1.
Preferably, the monitoring frequency points are 1GHz, 1.1GHz, 1.2GHz, 1.3GHz, 1.4GHz and 1.5 GHz.
Further, the size of the cavity of the reverberation chamber is 1.05m multiplied by 0.64m multiplied by 0.46m, and the fixed length of the long side of the stirrer blade of the reverberation chamber is 16 cm.
An apparatus for improving the uniformity of a reverberation chamber using the method of the embodiments of the present application, the apparatus comprising a stirrer, a transmitting antenna; the stirrer is horizontally arranged, the included angle of blades of the stirrer is 120 degrees, and the side length ratio of the blades of the stirrer is 1: 1.5; the transmitting antenna is placed inside the cavity of the reverberation chamber, and the cavity size of the reverberation chamber is 1.05m × 0.64m × 0.46 m.
The beneficial effects of the invention include: the invention provides a method for improving the field uniformity of a reverberation chamber, and provides a concept that a two-factor variance analysis method is used for improving the field uniformity pair of the reverberation chamber.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of an embodiment of a method for improving the uniformity of a reverberation chamber;
FIG. 2 is a flowchart of an embodiment of a method for improving the uniformity of a reverberation chamber including multiple frequency point measurements;
FIG. 3 is a flowchart of an embodiment of a method for improving the uniformity of a reverberation chamber including two-factor analysis of variance;
FIG. 4 is an example of the results of a test of a reverberation room improvement method;
fig. 5 is an embodiment of an apparatus for improving the uniformity of a reverberation chamber.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The reverberation chamber is one of the fields for carrying out the electromagnetic compatibility test, and can be regarded as a high-quality-factor Q-value resonant cavity. When the indoor transmitting antenna generates radio-frequency signals, electromagnetic energy is reflected back and forth by the wall of the reverberation room and the metal mechanical stirrer, the electromagnetic energy rotates slowly along with the stirrer, the electric field distribution in the reverberation room changes continuously, the field intensity and direction of each point in the indoor space also change continuously, the rotation of the stirrer can effectively change the electromagnetic boundary generated by the indoor transmitting antenna, so that the indoor electric field distribution is changed, and finally, the mode electric field distribution meeting the electromagnetic boundary condition is stabilized and formed. Statistically, the electric field is uniform and isotropic over a range of operating regions in the center of the reverberation chamber. Since the reverberation room is different from the conventional electromagnetic compatibility test sites such as an open field and a microwave dark room, it has no special measures for ensuring the wave to propagate under ideal conditions, and can not avoid the phenomena of wave reflection, wave refraction and the like, so that the field distribution at a certain moment is not possible to be uniform. But the uniform field required by the reverberation chamber is statistical. That is, although the field distribution at a certain time is not uniform, the electric field of each observation point changes as the disturbance progresses, and if the maximum distribution of the electric field of each point is observed within one disturbance period, the uniform distribution of the field is completely possible.
The technical solutions provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Fig. 1 is a flowchart of an embodiment of a method for improving the uniformity of a reverberation chamber, and an embodiment of the present invention provides a method for improving the field uniformity of a reverberation chamber, including the following steps:
101, performing modeling analysis on two factors influencing the uniform characteristic of the reverberation chamber field, namely the length-width ratio of the stirring blades and the included angle of the stirring blades by using a two-factor variance analysis method, and determining that the factor with large influence is a first factor and the factor with small influence is a second factor.
In step 101, it should be noted that two factors considered to be important for the uniform characteristics of the field of the reverberation chamber by the embodiment of the present invention are the length-width ratio of the stirring blade and the included angle of the stirring blade, and other factors may also be subjected to modeling analysis.
And 102, optimizing the first factor to obtain a first factor optimized value.
In step 102, the method for optimizing the first factor is obtained according to the test data, and the method is selected according to the field characteristic data values corresponding to different first factor data values.
And 103, optimizing the second factor on the basis of the first factor optimized value to obtain a second factor optimized value.
In step 103, after the first factor optimization value is fixed, the second factor is optimized to obtain the second factor optimization value.
And 104, determining the combination of the first factor optimization value and the second factor optimization value as the optimal design value of the reverberation chamber.
Further, the size of the cavity of the reverberation chamber is 1.05m multiplied by 0.64m multiplied by 0.46m, and the fixed length of the long side of the stirrer blade of the reverberation chamber is 16 cm. It should be noted that the size of the cavity of the reverberation chamber and the length of the side of the stirrer blade of the reverberation chamber may be the values in the embodiments of the present invention, or may be other values, and are not particularly limited herein.
Further, when the size of the cavity of the reverberation chamber is 1.05m × 0.64m × 0.46m, the included angle of the blades of the stirrer is 120 degrees, the side length ratio of the blades of the stirrer is 1:1.5, and the field uniformity of the reverberation chamber is best. It should be noted that the optimized values of the included angle and the side length ratio of the stirrer blade of the reverberation chamber are obtained under the size of the cavity of the reverberation chamber in the embodiment of the present invention.
After the size and the material of the cavity of the reverberation chamber are determined, the invention provides a method for optimizing the shape and the size of blades of a stirrer and the included angle between the blades in order to improve the field uniformity of the reverberation chamber. The method comprises the steps of firstly designing a simulation experiment of influences of different included angles and different blade length-width ratios of a plurality of groups of stirrer blades on the field uniformity of a reverberation chamber on the basis of the reverberation chamber with a specific size, analyzing results of influences on the field uniformity of the reverberation chamber, and further performing two-factor variance analysis on the field uniformity results to obtain a weight relation of two geometric quantities of a stirrer in the influences on the field uniformity of the reverberation chamber.
Fig. 2 is a flowchart of an embodiment of a method for improving the uniformity of a reverberation chamber, which includes multiple frequency point measurements, where the method for improving the uniformity of a reverberation chamber provided in the embodiment of the present invention includes measuring multiple frequency points in a frequency band of the reverberation chamber, and specifically includes the following steps:
101, performing modeling analysis on two factors influencing the uniform characteristic of the reverberation chamber field, namely the length-width ratio of the stirring blades and the included angle of the stirring blades by using a two-factor variance analysis method, and determining that the factor with large influence is a first factor and the factor with small influence is a second factor.
And 102, optimizing the first factor to obtain a first factor optimized value.
And 103, optimizing the second factor on the basis of the first factor optimized value to obtain a second factor optimized value.
And 104, determining the combination of the first factor optimization value and the second factor optimization value as the optimal design value of the reverberation chamber.
And 105, setting a plurality of monitoring frequency points according to the uniformity monitoring frequency band of the reverberation room.
Preferably, the monitoring frequency points are 1GHz, 1.1GHz, 1.2GHz, 1.3GHz, 1.4GHz and 1.5 GHz.
It should be noted that, in the embodiment of the present invention, the monitoring frequency band of the reverberation chamber is 1GHz-1.5GHz, and the setting of the monitoring frequency point is step-by-step 0.1GHz, so that the monitoring frequency point is 1GHz, 1.1GHz, 1.2GHz, 1.3GHz, 1.4GHz, and 1.5GHz, and the monitoring frequency point of the reverberation chamber may be other values, which is not particularly limited herein.
And 106, calculating the optimal design value for each monitoring frequency point respectively.
In step 106, modeling analysis needs to be performed on two factors, namely the length-width ratio of the stirrer and the included angle of the stirrer, of each monitored frequency point to obtain the first factor and the second factor, and further obtain an optimal design value of the corresponding frequency point.
In step 106, the optimal design values calculated for each monitored frequency point are shown in table 1 below.
Table 1 simulation data analysis of variance results
In table 1, the factor a is the included angle of the stirrer, the factor B is the aspect ratio of the stirrer, and in the simulation data, when the frequency point is 1GHz, the mean square sum of the factor a is 0.1116, the mean square sum of the factor B is 0.1813, and the mean square sum of errors is 0.7681; when the frequency point is 1.1GHz, the mean square sum of the factor A is 0.0213, the mean square sum of the factor B is 0.8996, and the mean square sum of the errors is 0.0241; when the frequency point is 1.2GHz, the mean square sum of the factor A is 0.6223, the mean square sum of the factor B is 0.9685, and the mean square sum of the errors is 0.2687; when the frequency point is 1.3GHz, the mean square sum of the factor A is 0.0607, the mean square sum of the factor B is 0.261, and the mean square sum of the errors is 0.1073; when the frequency point is 1.4GHz, the mean square sum of the factor A is 0.6294, the mean square sum of the factor B is 0.0615, and the mean square sum of the errors is 0.1101; at the frequency point of 1.5GHz, the mean square sum of the factors A is 1.382, the mean square sum of the factors B is 1.1912, and the mean square sum of errors is 0.2241.
In the six frequency points, the mean square sum of the B factors of each point is larger than the mean square sum of the A factors in four points of 1GHz-1.3 GHz. At two points of 1.4GHz and 1.5GHz, the mean square sum of the A factors is larger than that of the B factors. However, from six points, the B factor is not only larger than the sum of the mean square of the majority points, but is also larger than the sum of the mean square of the a factor at some points, and the difference is not large at points smaller than the sum of the mean square of the a factor. And comprehensively obtaining that the influence of the change of the included angle of the blade on the field uniformity of the reverberation chamber is larger than the influence of the change of the side length ratio on the field uniformity.
It should be noted that the sum of squares of errors of some frequency points is relatively large, because the influence of interaction between the two factors is included in the sum of squares of errors in order to extract the independent influence of the two factors on the field uniformity during analysis, and the interaction of the side length ratio and the included angle on the influence of the field uniformity exists.
And 107, carrying out statistical averaging on the optimal design value of each monitoring frequency point to obtain the optimal design value of the reverberation chamber of the monitoring frequency band.
In step 107, it should be noted that the optimal design value of each frequency point may be the same or different, and if different, the optimal design value of each frequency point needs to be statistically averaged to obtain the optimal design value of the reverberation chamber of the monitored frequency band.
The embodiment of the invention provides a method for improving the field uniformity of a reverberation chamber, which is suitable for the whole monitoring frequency band, carries out statistical averaging on the basis of single frequency point optimization, and is beneficial to improving the field uniformity characteristic of the reverberation chamber of the whole monitoring frequency band.
Fig. 3 is a flowchart of an embodiment of a method for improving the uniformity of a reverberation chamber including a two-factor analysis of variance method, which specifically includes the following steps:
step 201, performing level decomposition on two factors, namely the length-width ratio of the stirring blades and the included angle of the stirring blades, and combining the level of the length-width ratio of the stirring blades and the level of the included angle of the stirring blades to establish a test orthogonal table.
In step 201, the included angle of the stirring blade includes 3 bit levels, i.e., a first bit level of 90 °, a second bit level of 120 °, and a third bit level of 150 °, the aspect ratio of the stirring blade includes 4 bit levels, i.e., a first bit level of 1:1, a second bit level of 1.2:1, a third bit level of 1.5:1, and a fourth bit level of 2:1, and the test orthogonal table is shown in table 2.
TABLE 2 test orthogonalization table
Wherein the factor A is the included angle of the stirring blade, the included angle of the stirring blade comprises 3 stages, namely 90 degrees of the first stage of A1, 120 degrees of the second stage of A2 and 150 degrees of the third stage of A3, the factor B is the length-width ratio of the stirring blade, the length-width ratio of the stirring blade comprises 4 stages, namely 1:1 of the first stage of B1, 1.2:1 of the second stage of B2, 1.5:1 of the third stage of B3 and 2:1 of the fourth stage of B4. The first column of test numbers in the orthogonal table are test numbers, 12 numbers are required to be completed in the embodiment of the invention, 2 factors exist for problems to be analyzed, namely the included angle of the stirring blades, the column number 1 is the included angle factor of the stirring blades, the column number 2 is the side length ratio factor of the stirring blades, the column number 1 is repeatedly arranged for 4 times according to the sequence of 90 degrees of the first level of A1, 120 degrees of the second level of A2 and 150 degrees of the third level of A3, and the column number 2 is arranged for 3 times according to the sequence of 1:1 of the first level of B1, 1.2:1 of the second level of B2, 3 times of 1:1 of the third level of B3 and 3 times of 2:1 of the fourth level of B4. Therefore, the 12 tests to be completed in the embodiment of the present invention are respectively: test No. 1A 1B1, namely the included angle of the stirrer blade is 90 degrees, and the side length ratio of the stirrer blade is 1: 1; test No. 2A 2B1, namely the included angle of the stirrer blade is 120 degrees, and the side length ratio of the stirrer blade is 1: 1; test No. 3A 3B1, namely the included angle of the stirrer blade is 150 degrees, and the side length ratio of the stirrer blade is 1: 1; test No. 4A 1B2, namely the included angle of the stirrer blade is 90 degrees, and the side length ratio of the stirrer blade is 1.2: 1; test No. 5A 2B2, namely, the included angle of the stirrer blade is 120 degrees, and the side length ratio of the stirrer blade is 1.2: 1; test No. 6A 3B2, namely the included angle of the stirrer blade is 150 degrees, and the side length ratio of the stirrer blade is 1.2: 1; test No. 7A 1B3, namely the included angle of the stirrer blade is 90 degrees, and the side length ratio of the stirrer blade is 1.5: 1; test No. 8A 2B3, namely the included angle of the stirrer blade is 120 degrees, and the side length ratio of the stirrer blade is 1.5: 1; test No. 9, test A3B3, namely, the included angle of the stirrer blade is 150 degrees, and the side length ratio of the stirrer blade is 1.5: 1; test No. 10, test A1B4, i.e., the included angle of the stirrer blade is 90 degrees, and the side length ratio of the stirrer blade is 2: 1; test No. 11, test A2B4, i.e., the included angle of the stirrer blade is 120 degrees, and the side length ratio of the stirrer blade is 2: 1; run No. 12, test A3B4, i.e. the stirrer blade included angle was 150 °, the stirrer blade side length ratio was 2: 1.
The method for performing the bit-level decomposition on the two factors, i.e., the length-width ratio of the stirring blade and the included angle of the stirring blade, may be the bit-level decomposition method in the embodiment of the present invention, or may be other bit-level decomposition methods, and is not particularly limited herein.
And 203, calculating to obtain the mean square sum of the length-width ratio of the stirring blades and the included angle of the stirring blades according to the test data.
Preferably, the step of calculating a mean square sum of the length-width ratio of the stirring blade and the included angle of the stirring blade according to the test data further includes: establishing a model according to the test data as follows:
Xij＝μ+αi+βj+ij,i＝1,...,k；j＝1,...,m (1)
α1+...+αk＝0 (2)
β1+…+βm＝0 (3)
wherein, XijIs the experimental observation value of the combination of the ith position level of the stirring blade included angle factor and the jth position level of the length-width ratio of the stirring blade, and mu is XijMean value of (a)iIs the effect of the ith level of the mixing blade angle factor, betajIs the effect of the jth bit stage of the aspect ratio of the mixing blades,ijare experimental errors, are independent of each other and obey the distribution N (0, σ)2) (ii) a Calculating to obtain the mean square sum and the degree of freedom of the length-width ratio of the stirring blades and the included angle of the stirring blades as follows:
fT＝k*m-1 (5)
fA＝k-1 (7)
fB＝m-1 (9)
fE＝(m-1)*(k-1) (11)
wherein S isTK is the number of the level of the included angle of the stirring blades, i is the number of the level of the included angle of the stirring blades, m is the number of the level of the length-width ratio of the stirring blades, j is the number of the level of the length-width ratio of the stirring blades, and X isijIs a test observation value of the combination of the ith bit level of the stirring blade included angle factor and the jth bit level of the length-width ratio of the stirring blade,
is the mean value of the observed values, A is the included angle of the stirring blades, B is the length-width ratio of the stirring blades, SAIs the sum of squares of the effects of the included angles of the mixing blades, fTAs a result of the total degree of freedom,
is the mean value of the ith level of the included angle of the stirring blades, fAIs the degree of freedom of the included angle of the stirring blades, SBIs the sum of the squares of the effects of the length to width ratio of the mixing blades, fBIs a stand forThe degree of freedom of the aspect ratio of the stirring blade,
is the average value of the jth level of the length-width ratio of the stirring blades, SEFor the sum of mean square errors, MSAIs the mean square sum of the included angles of the stirring blades, MSBIs the mean square sum of the length to width ratio of the mixing blades.
In step 204, according to the value of the mean square sum, the significance of each factor in the effect of the result, i.e. the weight relationship: if MSA≥MSBFactor A has significant effect if MS is usedA＜MSBFactor B plays a significant role, with MSAIs the mean square sum of the included angles of the stirring blades, MSBThe mean square sum of the length-width ratio of the stirring blades is taken as a factor A, and the length-width ratio of the stirring blades is taken as a factor B.
The embodiment of the invention provides a concept that a two-factor variance analysis method is used for improving the field uniformity pair of a reverberation chamber, the weight of two factors influencing the field uniformity is obtained through variance analysis, and the two factors have interaction.
Fig. 4 shows an example of test results of a reverberation room improvement method, and test conditions of the embodiment of the present invention are as follows: the monitoring frequency points are respectively 1GHz, 1.1GHz, 1.2GHz, 1.3GHz, 1.4GHz and 1.5GHz, and the test results of 12 tests which need to be recorded in the embodiment of the invention are as follows: the side length ratio of the stirrer blades is 1:1, and the included angles of the stirrer blades are respectively 90 degrees, 120 degrees and 150 degrees; the side length ratio of the stirrer blades is 1.2:1, and the included angles of the stirrer blades are respectively 90 degrees, 120 degrees and 150 degrees; the side length ratio of the stirrer blades is 1.5:1, and the included angles of the stirrer blades are respectively 90 degrees, 120 degrees and 150 degrees; the side length ratio of the stirrer blades is 2:1, and the included angles of the stirrer blades are respectively 90 degrees, 120 degrees and 150 degrees.
Fig. 5 is an embodiment of an apparatus for improving the uniformity of a reverberation chamber, and the embodiment of the invention provides an apparatus for improving the uniformity of a reverberation chamber, and a method for improving the uniformity of a reverberation chamber using the apparatus. The device includes: stirrer 1, transmitting antenna 2.
The stirrer is horizontally arranged, the included angle of blades of the stirrer is 120 degrees, and the side length ratio of the blades of the stirrer is 1: 1.5; the transmitting antenna is placed inside the cavity of the reverberation chamber, and the cavity size of the reverberation chamber is 1.05m × 0.64m × 0.46 m.
In order to simply examine the influence of the ratio of the included angle of the blades of the stirrer and the side length of the blades on the field uniformity of the reverberation chamber, the Z-shaped stirrer with five blades is adopted in the embodiment of the invention, the reverberation chamber with the stirrer horizontally arranged is used as an analysis model, and in addition, a transmitting antenna is arranged in the cavity of the reverberation chamber. The size of the cavity is 1.05m multiplied by 0.64m multiplied by 0.46m, and the fixed length of the long side of the stirrer blade is 16 cm. The field intensity monitoring points are arranged at eight vertexes of the working area rectangle, and the area size is 0.55m multiplied by 0.26m multiplied by 0.2 m. The field uniformity monitoring frequency band of the reverberation room is 1GHz-1.5GHz, the step is 0.1GHz, and the frequency points are six in total.
It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The above description is only an example of the present invention, and is not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (6)
1. A method of improving the uniformity of a reverberant chamber comprising the steps of:
modeling and analyzing two factors influencing the uniform characteristic of the reverberation chamber field, namely the length-width ratio of the stirring blades and the included angle of the stirring blades by a two-factor variance analysis method, and determining that the factor with large influence is a first factor and the factor with small influence is a second factor;
optimizing the first factor to obtain a first factor optimized value;
optimizing the second factor on the basis of the first factor optimization value to obtain a second factor optimization value;
determining the combination of the first factor optimization value and the second factor optimization value as the optimal design value of the reverberation chamber;
setting a plurality of monitoring frequency points according to the uniformity monitoring frequency band of the reverberation chamber;
respectively calculating the optimal design value for each monitoring frequency point;
and carrying out statistical averaging on the optimal design value of each monitoring frequency point to obtain the optimal design value of the reverberation chamber of the monitoring frequency band.
2. The method of improving the uniformity of a reverberation chamber of claim 1, wherein the step of performing a modeling analysis on two factors, the mixing blade length-width ratio and the mixing blade included angle, which affect the field uniformity of the reverberation chamber by a two-factor analysis of variance method, and determining the factor with a large influence as a first factor and the factor with a small influence as a second factor further comprises:
respectively carrying out level decomposition on two factors of the length-width ratio of the stirring blades and the included angle of the stirring blades, combining the level of the length-width ratio of the stirring blades and the level of the included angle of the stirring blades, and establishing a test orthogonal table;
recording the field uniformity observed value of each combination of the test orthogonal table to obtain test data;
calculating to obtain the mean square sum of the length-width ratio of the stirring blades and the included angle of the stirring blades according to the test data;
according to the mean square sum data, determining a first factor and a second factor as follows: when the mean square sum of the length-width ratios of the stirring blades is larger than or equal to the mean square sum of the included angles of the stirring blades, determining that the length-width ratios of the stirring blades are a first factor, and the included angles of the stirring blades are a second factor, and when the mean square sum of the length-width ratios of the stirring blades is smaller than the mean square sum of the included angles of the stirring blades, determining that the included angles of the stirring blades are the first factor, and the length-width ratios of the stirring blades are the second factor.
3. The method of improving the uniformity of a reverberation chamber of claim 2, wherein the step of calculating the mean square sum of the mixing blade length to width ratio and the mixing blade angle from experimental data further comprises:
establishing a model according to the test data as follows:
Xij＝μ+αi+βj+ij,i＝1,...,k；j＝1,...,m
α1+...+αk＝0
β1+...+βm＝0
wherein, XijIs the experimental observation value of the combination of the ith position level of the stirring blade included angle factor and the jth position level of the length-width ratio of the stirring blade, and mu is XijMean value of (a)iIs the effect of the ith level of the mixing blade angle factor, betajIs the effect of the jth bit stage of the aspect ratio of the mixing blades,ijare experimental errors, are independent of each other and obey the distribution N (0, σ)2)；
Calculating to obtain the mean square sum and the degree of freedom of the length-width ratio of the stirring blades and the included angle of the stirring blades as follows:
fT＝k*m-1
fA＝k-1
fB＝m-1
fE＝(m-1)*(k-1)
wherein S isTK is the number of the level of the included angle of the stirring blades, i is the number of the level of the included angle of the stirring blades, m is the number of the level of the length-width ratio of the stirring blades, j is the number of the level of the length-width ratio of the stirring blades, and X is the sum of the total squaresijIs a test observation value of the combination of the ith bit level of the stirring blade included angle factor and the jth bit level of the length-width ratio of the stirring blade,
is the observed values are allThe value is that A is the included angle of the stirring blades, B is the length-width ratio of the stirring blades, SAIs the sum of squares of the effects of the included angles of the mixing blades, fTAs a result of the total degree of freedom,
is the mean value of the ith level of the included angle of the stirring blades, fAIs the degree of freedom of the included angle of the stirring blades, SBIs the sum of the squares of the effects of the length to width ratio of the mixing blades, fBIs the degree of freedom of the aspect ratio of the stirring blade,
is the average value of the jth level of the length-width ratio of the stirring blades, SEIs the sum of mean square errors, MSAIs the mean square sum of the included angles of the stirring blades, MSBIs the mean square sum of the length to width ratio of the mixing blades.
4. The method of improving the uniformity of a reverberation chamber of any of the claims 1 to 3, wherein the mixing blade angle comprises 3 bit levels, respectively, a first bit level 90 °, a second bit level 120 °, and a third bit level 150 °, and wherein the mixing blade aspect ratio comprises 4 bit levels, respectively, a first bit level 1:1, a second bit level 1.2:1, a third bit level 1.5:1, and a fourth bit level 2: 1.
5. The method for improving the uniformity of the reverberation room of any of the claims 1 to 3, wherein the monitoring frequency points are 1GHz, 1.1GHz, 1.2GHz, 1.3GHz, 1.4GHz and 1.5 GHz.
6. The method for improving the uniformity of the reverberation chamber of any of the claims 1 to 3, wherein the size of the cavity of the reverberation chamber is 1.05m x 0.64m x 0.46m, and the fixed length of the long side of the stirrer blade of the reverberation chamber is 16 cm.
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