TWI698649B - Antenna measurment system for mimo ota - Google Patents

Abstract

An antenna measurement system for MIMO OTA includes an anechoic chamber, a rotating base and a plurality of CATR units. The rotating base is used to place a DUT. The DUT includes a plurality of antennas to be tested. A signal source in each of the CATR units is configured to emit a first RF signal toward the corresponding concave mirror, the concave mirror reflecting the first RF signal into a second RF signal, wherein each of the second RF signals is a uniform plane wave and each second RF signal is transmitted toward a platform of the rotating base, and the concave mirrors of any two CATR units are not disposed face to face.

Description

Antenna measurement system for multi-input multi-output air transmission

The invention relates to a measurement system, in particular to a multi-input multi-output air transmission measurement system applied in a multi-path environment.

1 is a partial schematic diagram of an antenna testing system disclosed in US Patent Application No. US 2012/0282863 A1 (hereinafter referred to as known technology 1). This known technology is to place a device under test 17 in an anechoic chamber 1 , And use 6 test antennas to surround the device under test 17 at equal intervals to measure the antenna characteristics of the device under test 17.

The disadvantages of this known technology 1 are: (1) The test antenna 11 and the test antenna 12 are opposite to each other, so when measuring the receiving characteristics of the device under test 17, the electromagnetic waves emitted by the two opposite test antennas 11, 12 are It will collide and interfere with each other and cause measurement errors. Similarly, the two opposite test antennas 13, 14 and the opposite two test antennas 15, 16 will have the same problem. (2). Convention 1 If far-field measurement technology is used, the distance r between any one of the test antennas 11, 12, 13, 14, 15, 16 and the device under test 17 must be much greater than 2D ² /λ, so that the electromagnetic waves arriving at the device under test 17 from each test antenna 11, 12, 13, 14, 15, 16 are approximately uniform plane waves. In a purely theoretical calculation, the parameter D is the maximum geometric diameter of the antenna 171 under test, and λ is the working wavelength of the antenna 171 under test during measurement. However, in practical applications, if the device under test 17 is a mobile phone, a tablet, or For notebook computers, the antenna under test 171 is connected to a circuit board (not shown in the figure) inside the device under test 17 to use this circuit board as a reference ground plane, which will make the entire device under test 17 participate in radiation, not just It is only the antenna 171 under test. Therefore, in order to correct the deviation between theory and practice, the parameter D should be corrected to the maximum geometric diameter of the device under test 17. In the era of 5G millimeter wave communication, the size of the smartphone corresponds to the parameter D is almost unchanged, but the wavelength λ of millimeter waves is as small as millimeters, and 2D ² /λ will become very large after calculation. Therefore, the space of the anechoic chamber 1 used for 5G communication measurement is much larger than the 4G communication volume. Time measurement requirements, which will seriously increase the site requirements for construction and increase construction costs. (3). If the problem in item (2) above is to be solved, the known technology similar to Figure 1 has to use near-field measurement technology to replace far-field measurement technology, but near-field measurement technology has been passive in the past For antenna measurement, the phase of the non-uniform plane wave arriving at the device under test 17 must undergo complex calculations to convert to approximate far-field measurement results. Not only does it unavoidably introduce conversion calculation errors, but also reduces the calculation time. Measurement efficiency, but the more difficult problem to overcome is that the near field measurement is only suitable for passive measurement (the device under test 17 is turned off and the antenna 171 under test is measured with a conductive wire connected to an external instrument), and the device under test 17 cannot be measured. Active measurement (that is, the device under test 17 is turned on to enter the actual communication mode for measurement). The reason is that the near-field measurement must know the phase of the electromagnetic wave during the measurement, and then use numerical calculation to convert the near-field data into the far-field However, the electromagnetic waves of the device under test 17 during active measurement are all signals after communication modulation, so it is difficult to calculate the phase of the electromagnetic waves before the unmodulation, and the more complicated the calculation process introduces errors and calculation time The demand is also greater, and therefore, the known technology cannot solve the problem of the space requirement of the anechoic chamber 1 during the 5G millimeter wave active measurement.

In order to solve the aforementioned problems of the known technology, the present invention proposes a method that saves the space of the anechoic chamber compared to the far-field measurement, and does not require the complexities of converting the near field to the far field. Calculation, applicable to both active and passive measurement, as well as a test system that can avoid electromagnetic interference between multiple test antennas.

The antenna measurement system used for multi-input multi-output air transmission of the present invention includes an electric wave anechoic chamber, a rotating base and a plurality of short-distance field antenna units.

The rotating base is arranged in the anechoic chamber, and the rotating base includes a platform surface for placing a device to be tested, and the device to be tested includes a plurality of antennas to be tested.

Each narrow field antenna unit includes a signal feed, a concave mirror, and a connecting arm for fixing the signal feed and the concave mirror. The signal feed in each narrow field antenna unit is used to face the corresponding The concave mirror emits a first radio frequency signal, and the concave mirror is arranged facing the platform surface of the rotating base to reflect the first radio frequency signal into a second radio frequency signal facing the platform surface of the rotating base, wherein each The two radio frequency signals are uniform plane waves, and the concave mirrors of any two narrow-field antenna units are not arranged face to face.

Preferably, the anechoic chamber is in the shape of a cube and includes a first top corner, a second top corner, a third top corner, a fourth top corner, a first bottom corner, a second bottom corner, and a The third bottom corner, a fourth bottom corner. The first top angle, the platform surface of the rotating base, and the third bottom angle are sequentially arranged along a straight line; the second top angle, the platform surface of the rotating base, and the fourth bottom angle are arranged according to The sequence is arranged along a straight line; the third vertex, the platform surface of the rotating base, and the first bottom angle are sequentially arranged along a straight line; the fourth vertex angle, the platform surface of the rotating base, and the The three bottom corners are arranged in sequence along a straight line. Among them, the contraction The number of distance field antenna elements is two, which are located at the first top corner and the second bottom corner respectively.

Preferably, the anechoic chamber is in the shape of a cube and includes a first top corner, a second top corner, a third top corner, a fourth top corner, a first bottom corner, a second bottom corner, and a The third bottom corner, a fourth bottom corner. The first top angle, the platform surface of the rotating base, and the third bottom angle are sequentially arranged along a straight line; the second top angle, the platform surface of the rotating base, and the fourth bottom angle are arranged according to The sequence is arranged along a straight line; the third vertex, the platform surface of the rotating base, and the first bottom angle are sequentially arranged along a straight line; the fourth vertex angle, the platform surface of the rotating base, and the The three bottom corners are arranged in sequence along a straight line. Wherein, the number of the reduced-distance field antenna units is three, which are respectively located at the first top corner, the second bottom corner, and the middle of the line connecting the third bottom corner and the fourth top corner.

Preferably, the anechoic chamber is in the shape of a cube and includes a first top corner, a second top corner, a third top corner, a fourth top corner, a first bottom corner, a second bottom corner, and a The third bottom corner, a fourth bottom corner. The first top angle, the platform surface of the rotating base, and the third bottom angle are sequentially arranged along a straight line; the second top angle, the platform surface of the rotating base, and the fourth bottom angle are arranged according to The sequence is arranged along a straight line; the third vertex, the platform surface of the rotating base, and the first bottom angle are sequentially arranged along a straight line; the fourth vertex angle, the platform surface of the rotating base, and the The three of the two bottom corners are arranged in sequence along a straight line, wherein the number of the reduced-distance field antenna units is four, which are respectively located at the first top corner, the second bottom corner, the third top corner, and the fourth bottom corner.

Preferably, the anechoic chamber is a cube and includes a first Top corner, a second top corner, a third top corner, a fourth top corner, a first bottom corner, a second bottom corner, a third bottom corner, and a fourth bottom corner. The first top angle, the platform surface of the rotating base, and the third bottom angle are sequentially arranged along a straight line; the second top angle, the platform surface of the rotating base, and the fourth bottom angle are arranged according to The sequence is arranged along a straight line; the third vertex, the platform surface of the rotating base, and the first bottom angle are sequentially arranged along a straight line; the fourth vertex angle, the platform surface of the rotating base, and the The three bottom corners are arranged in sequence along a straight line. Among them, the number of the reduced-distance field antenna units is six, which are located in the middle of the line connecting the first top corner, the second bottom corner, the third top corner, the fourth bottom corner, the second top corner, and the second bottom corner. , And the middle of the line between the third top corner and the third bottom corner.

Preferably, the anechoic chamber further includes a plurality of screw holes, and the connecting arm of each shortened field antenna unit includes a first arm portion and a second arm portion, and each first arm portion is fixed to the anechoic chamber, each The second arm part of a connecting arm is connected with the concave mirror.

Preferably, the concave mirror can rotate relative to the second arm portion of the connecting arm.

Preferably, the antenna measurement system for multi-input multi-output air transmission further includes a first support plate, the first support plate is non-conductor, low permittivity (permittivity), low dielectric loss (dielectric loss) Material, the first supporting plate is fixed to a wall plate of the anechoic chamber to support the weight of a corresponding one of the short-distance field antenna units, and the short-distance field antenna unit supported by the first supporting plate is located in the first The position in the middle of the line between the three top corners and the third bottom corner Set.

Preferably, the antenna measurement system for multi-input multi-output air transmission further includes a second support plate that is also non-conductor, low dielectric constant, and low dielectric loss, and the second support plate is fixed to the anechoic chamber. The wall plate is used to support the weight of another corresponding narrow-range field antenna unit, and the narrow-range field antenna unit supported by the second support plate is located in the middle of the line connecting the second top corner and the second bottom corner s position.

Preferably, the antenna measurement system for multi-input multi-output air transmission further includes a first support column and a second support column in a T shape or an inverted L shape, and the first support plate is a non-conductor, low dielectric The first support column is fixed on a bottom plate of the electric wave anechoic chamber to support the weight of a corresponding one of the narrow-distance field antenna units, and is supported by the first support column. The distance field antenna unit is located in the middle of the line connecting the third top angle and the third bottom angle. The second support column is also a non-conductor, low dielectric constant, and low dielectric loss material. The second support column is fixed on the On the bottom plate of the anechoic chamber, it is used to support the weight of another corresponding narrowing field antenna unit, and the narrowing field antenna unit supported by the second supporting column is located at the second top corner and the second bottom corner The position in the middle of the connection.

The effect of the present invention is to use the concave mirror of the telescopic field antenna unit to reflect the non-uniform plane wave (the first radio frequency signal) from the signal feed into a uniform plane wave (the second radio frequency signal). The parameter r must be much larger than 2D ² /λ to reach the device under test to reach the limit of the uniform plane wave. Therefore, the problem of large space requirement of the anechoic chamber for far-field measurement or complex calculation of near-field measurement and not suitable for active measurement is improved; In addition, the present invention also considers the spatial configuration of the plurality of short-distance field antenna units in the anechoic chamber, so as to avoid the collision and interference of the second radio frequency signals reflected by any two short-distance field antenna units during the multiple input multiple output (MIMO) test. problem.

1: anechoic chamber

11~16: Test antenna

17: Device under test

171: Antenna to be tested

2: anechoic chamber

200: siding

201: Floor

21: The first vertex

22: second top corner

23: third vertex

24: fourth vertex

25: first bottom corner

26: second bottom corner

27: Third bottom corner

28: Fourth bottom corner

3: Rotating base

31: platform surface

4: Short-distance field antenna unit

41: signal feed

42: Concave mirror

43: connecting arm

431: first arm

4311: screw

4312: fixed metal sheet

432: second arm

5: Device to be tested

51: Antenna to be tested

111: The first RF signal

112: Second RF signal

291, 293: Location

20: Screw hole

61: The first support plate

61: second support plate

71: The first support column

72: second support column

Figure 1 is a partial schematic diagram of the conventional technology.

Figure 2 is a schematic diagram of the first preferred embodiment of the present invention.

Figure 3 is a schematic diagram illustrating the reduced-range field antenna unit of the first preferred embodiment.

Figure 4 is a schematic diagram of the second preferred embodiment of the present invention.

Figure 5 is a schematic diagram of the third preferred embodiment of the present invention.

Figure 6 is a schematic diagram of a fourth preferred embodiment of the present invention.

Fig. 7 is a schematic diagram illustrating a method of fixing the distance field antenna unit and the anechoic chamber of any preferred embodiment.

Fig. 8 is a schematic diagram illustrating another method of fixing the distance field antenna unit and the anechoic chamber of any preferred embodiment.

Figure 9 is a schematic diagram illustrating that the first preferred embodiment further includes a first support plate.

Figure 10 is a schematic diagram illustrating that the first preferred embodiment further includes a second supporting plate.

Fig. 11 is a schematic diagram illustrating an embodiment in which a T-shaped first support column replaces the first support plate.

Figure 12 is a schematic diagram illustrating an embodiment in which a T-shaped second support column is used instead of the second support plate.

Figure 13 is a schematic diagram illustrating an embodiment in which an L-shaped first support column is used instead of the first support plate.

Fig. 14 is a schematic diagram illustrating an embodiment in which the second support plate is replaced by an L-shaped second support column.

2 and 3, the antenna measurement system for multi-input multi-output air transmission of the present invention includes an anechoic chamber 2, a rotating base 3, and a plurality of narrow field antenna units 4.

The rotating base 3 is disposed in the anechoic chamber 2. The rotating base 3 includes a platform surface 31 for placing a device under test 5, and the device under test 5 includes a plurality of antennas 51 under test.

In the first preferred embodiment, the anechoic chamber 2 is in the shape of a cube, and includes a first apex 21, a second apex 22, a third apex 23, a fourth apex 24, and a first bottom. Corner 25, a second bottom corner 26, a third bottom corner 27, and a fourth bottom corner 28. The first vertex 21, the platform surface 31 of the rotating base 3, and the third bottom corner 27 are arranged in a straight line; the second vertex 22, the platform surface 31 of the rotating base 3, and the The three fourth bottom corners 28 are arranged in sequence along a straight line; the third top corner 23, the platform surface 31 of the rotating base 3, and the first bottom corner 25 are arranged in sequence along a straight line; The angle 24, the platform surface 31 of the rotating base 3, and the second bottom angle 26 are sequentially arranged along a straight line.

Each narrow field antenna unit 4 includes a signal feed 41, a concave mirror 42, and a connecting arm 43 for fixing the signal feed 41 and the concave mirror 42. The signal feed 41 in each narrow field antenna unit 4 is used to transmit a first radio frequency signal 111 toward the corresponding concave mirror 42. The concave mirror 42 is arranged facing the platform surface 31 of the rotating base 3 for the The first radio frequency signal 111 is reflected as a second radio frequency signal 112 toward the platform surface 31 of the rotating base 3, wherein each second radio frequency signal 112 is a uniform plane wave, and the concave mirrors of any two narrow field antenna units 4 42 is not set face to face.

Among them, the number of the shortened field antenna units 4 is six, which are located at the first apex angle 21, the second apex angle 26, the third apex angle 23, the fourth apex angle 28, the second apex angle 22, and the second apex angle. The middle of the line of the bottom corner 26 (position 293), and the middle of the line of the third top corner 23 and the third bottom corner 27 (position 291).

For example, in FIG. 2, a short-range field antenna unit 4 is provided at the first apex 21, then the third bottom corner 27 cannot be provided with a short-distance field antenna unit 4; the third apex 23 is provided with a short-distance field antenna unit 4, Therefore, the short-distance field antenna unit 4 cannot be installed at the second bottom corner 25; in the same way, if a short-distance field antenna unit 4 is installed at the position 291, the short-distance field antenna unit 4 cannot be installed at the position 292. In this way, it is possible to avoid the problem of destructive interference of the two second radio frequency signals 112 when the concave mirrors 42 of any two narrow field antenna units 4 are arranged face to face.

Refer to FIG. 4, which is a schematic diagram of the second preferred embodiment of the present invention. The second preferred embodiment is similar to the first preferred embodiment, but the difference is that the number of the reduced field antenna units 4 is four, respectively Located at the first top corner 21, the second bottom corner 26, the third top corner 23 and the fourth bottom corner 28.

Referring to FIG. 5, it is a schematic diagram of the third preferred embodiment of the present invention. The third preferred embodiment is similar to the second preferred embodiment, except that the number of the antenna units 4 of the shortened field is Three are located at the first top corner 21, the second bottom corner 26, and the middle 291 between the third bottom corner 27 and the fourth top corner 24, respectively.

Refer to FIG. 6, which is a schematic diagram of the fourth preferred embodiment of the present invention. The fourth preferred embodiment is similar to the third preferred embodiment, but the difference lies in that the number of the narrow field antenna units 4 is two, respectively Located at the first top corner 21 and the second bottom corner 26.

Referring to FIG. 7, the anechoic chamber 2 of any of the foregoing preferred embodiments further includes a plurality of screw holes 20, and the connecting arm 43 of each shortened field antenna unit 4 includes a first arm 431 and a second arm. 432. Each first arm portion 431 is fastened to the wall plate 200 of the anechoic chamber 2 with a screw 4311. The second arm portion 432 of each connecting arm 43 is connected to the concave mirror 42, and the concave mirror 42 can be opposite to each other. The second arm 432 of the connecting arm 43 rotates to adjust the direction of the second radio frequency signal 112, and the second arm 432 can also rotate about the Z-direction axis relative to the first arm 431.

Referring to FIG. 8, the reduced-range field antenna unit 4 further includes a fixed metal sheet 4312 compared to that of FIG. 7. The fixed metal sheet 4312 and the first arm portion 431 are respectively located on both sides of the wall plate 200 of the anechoic chamber 2. Two screws 4311 lock and fix the first arm 431, the wall plate 200, and the fixing metal sheet 4312. In addition, the actual application is not limited to the use of screws 4311 for locking, but can also be fixed by direct welding.

2 and 9, FIG. 9 shows that the first preferred embodiment further includes a first support plate 61, the first support plate 61 is a non-conductor, low dielectric constant, low dielectric loss material to reduce the electromagnetic wave The first support plate 61 is fixed to the wall plate 200 of the anechoic chamber 2 to support the weight of the corresponding one of the retracted field antenna units 4, and the retracted field supported by the first support plate 61 The antenna unit 4 is located at a position 291 in the middle of the line connecting the third top corner 23 and the third bottom corner 27.

2 and 10, FIG. 10 shows that the first preferred embodiment further includes a It is the second support plate 62 with non-metallic conductor, low dielectric constant and low dielectric loss. The second supporting plate 62 is fixed to the wall plate 200 of the anechoic chamber 2 to support the weight of the corresponding other short-range field antenna unit 4, and the short-range field antenna supported by the second support plate 62 The unit 4 is located at a position 293 in the middle of the line connecting the second top corner 22 and the second bottom corner 26.

Referring to Figures 2, 11, and 12, it is explained that the first support plate 61 and the second support plate 62 (see Figures 9 and 10) can also be replaced by a first support column 71 and a second support column 72, respectively. A supporting column 71 and the second supporting column 72 each have a T-shape, and are arranged and fixed on a bottom plate 201 of the anechoic chamber 2, and the retracted field antenna unit 4 supported by the first supporting column 71 is located At the position 291 in the middle of the line connecting the third top corner 23 and the third bottom corner 27, the reduced-distance field antenna unit 4 supported by the second supporting column 72 is located at the connection between the second top corner 22 and the second bottom corner 26 Position 293 in the middle of the line.

Referring to Figs. 2, 13, and 14, the first support column 71 and the second support column 72 can also be replaced with an inverted L shape.

The effect of the present invention is that the concave mirror 42 of the narrow field antenna unit 4 is used to reflect the non-uniform plane wave (the first radio frequency signal 111) from the signal feed 41 into a uniform plane wave (the second radio frequency signal 112). Figure 1 The conventional technical parameter r must be much larger than 2D ² /λ to reach the device under test 5 to reach the limit of the uniform plane wave, so the far-field measurement anechoic chamber 2 has a large space requirement or the near-field measurement calculation is complicated and unsuitable The problem of active measurement; in addition, the present invention also considers the spatial configuration of the plurality of short-range field antenna units 4 in the anechoic chamber 2 to avoid reflections of any two short-range field antenna units 4 during multiple input multiple output (MIMO) testing. The second radio frequency signals 112 collide and interfere with each other.

2: anechoic chamber

21: The first vertex

22: second top corner

23: third vertex

24: fourth vertex

25: first bottom corner

26: second bottom corner

27: Third bottom corner

28: Fourth bottom corner

3: Rotating base

31: platform surface

4: Short-distance field antenna unit

5: Device to be tested

51: Antenna to be tested

111: The first RF signal

112: Second RF signal

291, 292, 293, 294: location

Claims (5)

An antenna measurement system for multi-input and multi-output air transmission includes: an anechoic chamber, which is in the form of a cube and includes a first apex angle, a second apex angle, a third apex angle, and a second apex angle. Four top corners, a first bottom corner, a second bottom corner, a third bottom corner, a fourth bottom corner, the first top corner, the platform surface of the rotating base, and the third bottom corner The order is arranged along a straight line, the second apex angle, the platform surface of the rotating base and the fourth bottom angle are arranged in sequence along a straight line, the third apex angle, the platform surface of the rotating base and the first A bottom corner is arranged in sequence along a straight line, the fourth top corner, the platform surface of the rotating base, and the second bottom corner are arranged in sequence along a straight line; a rotating base is arranged in the anechoic chamber Wherein, the rotating base includes a platform surface for placing a device to be tested, the device to be tested includes a plurality of antennas to be tested; The bottom corner, the third top corner, the fourth bottom corner, the middle of the line between the second top corner and the second bottom corner, and the middle of the line between the third top corner and the third bottom corner, each of the reduced-distance field antenna units includes A signal feed, a concave mirror, a connecting arm for fixing the signal feed and the concave mirror, the signal feed in each narrow field antenna unit is used to transmit a first radio frequency signal toward the corresponding concave mirror, The concave mirror faces the rotating base The platform surface is configured to reflect the first radio frequency signal into a second radio frequency signal toward the platform surface of the rotating base, wherein each second radio frequency signal is a uniform plane wave, and any two narrow field antennas The concave mirrors of the unit are not arranged face to face; and a first support plate, the first support plate is a non-conductor, low permittivity (permittivity), low dielectric loss (dielectric loss) material, the first support plate is fixed to the A wall plate of the anechoic chamber is used to support the weight of a corresponding one of the distance field antenna units, and the distance field antenna unit supported by the first support plate is located at the third top corner and the third bottom corner. The position in the middle of the line. According to the first item of the scope of patent application, the antenna measurement system for multi-input multi-output air transmission, wherein the anechoic chamber also includes a plurality of screw holes, and the connecting arm of each shortened field antenna unit includes a first arm and A second arm part, each first arm part is fixed to the anechoic chamber, and the second arm part of each connecting arm is connected with the concave mirror. According to the second item of the scope of patent application, the antenna measurement system for multiple input multiple output air transmission, wherein the concave mirror can rotate relative to the second arm of the connecting arm. According to item 3 of the scope of patent application, the antenna measurement system for multi-input multi-output air transmission further includes a second support plate that is also non-conductor, low dielectric constant, and low dielectric loss. The second support plate is fixed on The wall plate of the anechoic chamber is used to support the corresponding weight of another antenna unit of the reduced distance field. The distance field antenna unit supported by the second support plate is located in the middle of the line connecting the second top corner and the second bottom corner. According to item 1 of the scope of patent application, the antenna measurement system for multi-input multi-output air transmission further includes a first support column and a second support column in a T shape or an inverted L shape. The first support plate is Non-conductor, low-dielectric constant, low-dielectric loss material, the first support column is fixed on a bottom plate of the anechoic chamber, used to support the weight of a corresponding short-distance field antenna unit, and is supported by the first The narrow-distance field antenna unit supported by the column is located in the middle of the line connecting the third top corner and the third bottom corner. The second support column is also a non-conductor, low dielectric constant, and low dielectric loss material. The supporting column is fixed on the bottom plate of the anechoic chamber to support the weight of another corresponding narrow-range field antenna unit, and the narrow-range field antenna unit supported by the second supporting column is located at the second vertex angle and The position in the middle of the line at the second bottom corner.

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