Sparse array large plane wave generator for OTA test

Abstract

According to the sparse array large plane wave generator for the OTA test, the amplitude and the phase of each antenna unit in an array are reasonably regulated and controlled, and large plane waves are synthesized in a short distance. The generator comprises a vector network analyzer, a signal generator, a channel simulator, a power amplifier, N paths of amplitude-phase adjustable feed networks, an antenna unit and a sparse array antenna. The signal generator generates an analog communication test signal, the analog communication test signal enters the power amplifier through a target channel created by the channel simulator, the signal is transmitted to the sparse array antenna through the N paths of amplitude-phase adjustable feed networks, and a large plane wave is formed on a radiation aperture of the sparse array antenna. Excitation amplitude and phase distribution of the sparse array antenna are calculated through a constraint optimization algorithm, and a saddle-shaped beam can be formed in a far-field area, which is equivalent to forming a plane wave at a radiation aperture of the sparse array antenna. Amplitude and phase distribution of the sparse array antenna is realized by adopting an amplitude and phase adjustable feed network.

Description

Technical Field

[0001] The invention belongs to the field of communication testing, and in particular relates to a sparse array large plane wave generator for OTA testing. Background Art

[0002] In Over the Air (OTA) testing, plane wave generators are used to simulate the far-field test environment of wireless communication to help test and verify the communication performance of wireless communication equipment. OTA testing usually involves the performance evaluation of mobile devices or wireless terminals under different wireless channel conditions, especially key performance indicators such as signal strength, coverage and frequency response. In this process, the plane wave generator simulates the ideal electromagnetic wave propagation environment to provide the device with test conditions that are close to the actual electromagnetic environment. Traditional wireless communication testing usually relies on free space propagation models or uses actual wireless signal sources, but this approach is limited by factors such as environmental complexity, signal interference and device positioning. Therefore, plane wave generators came into being as a controllable and standardized wireless communication test tool. Plane waves refer to electromagnetic waves propagating in a uniform medium, with a plane and equal phase plane in the wavefront, which is generally considered to be an idealized electromagnetic wave propagation mode. By precisely controlling the electromagnetic wave propagation characteristics in the simulated environment, the plane wave generator can generate plane electromagnetic waves with specific wavelengths, frequencies and directions, thereby effectively simulating the wireless communication environment. Compared with traditional test methods, the main advantage of the plane wave generator is its precise control and repeatability of the test environment, which can eliminate the interference of the external environment on the test results. Summary of the invention

[0003] Purpose of the invention: The technical problem to be solved by the present invention is to provide a sparse array large plane wave generator for OTA testing in view of the shortcomings of the prior art. The plane wave generator emits electromagnetic waves with plane wave characteristics, so that the device under test is in an ideal electromagnetic environment with a uniform wave front.

[0004] The present invention specifically provides a sparse array large plane wave generator for OTA testing, including a vector network analyzer, a signal generator, a channel emulator, a power amplifier, an N-channel amplitude and phase adjustable feeding network, an antenna unit and a sparse array antenna; Each amplitude and phase adjustable feeding network channel includes a digitally adjustable attenuator and phase shifter; The sparse array antenna is composed of N antenna units arranged in a sparse manner.

[0005] The vector network analyzer generates a test carrier signal, modulates the test signal with the communication signal generated by the signal generator, and then enters the channel simulator to simulate the transmission channel. The channel simulation signal passes through the power amplifier and then enters the N-channel amplitude and phase adjustable feeding network to excite the sparse array antenna composed of N antenna units, and finally forms a plane wave in the test area of ​​the device under test; after the device under test receives the test signal, it transmits the received signal back to the vector network analyzer to verify the communication performance of the device under test.

[0006] The antenna unit is a microstrip patch antenna unit, comprising a rectangular metal patch, a dielectric substrate, a rectangular metal floor and a coaxial feeding port; The rectangular metal patch is arranged on the surface of the dielectric substrate, and the rectangular metal floor is arranged on the bottom surface of the dielectric substrate.

[0007] A circular hole with a radius of 1.5 mm is dug on the rectangular metal floor, and a metal probe with a radius of 0.6 mm is passed through the entire dielectric substrate and welded to the rectangular metal patch on the surface of the dielectric substrate to form a coaxial feeding port.

[0008] The antenna unit is fed by a 50Ω coaxial feeding port.

[0009] The dielectric substrate material is FR4 board, the relative dielectric constant is 4.4, and the loss tangent value is 0.02.

[0010] Electric field observation points are set on the radiation aperture of the sparse array antenna, and the electric field intensity and phase angle at the observation points are optimized using an optimization algorithm so that the electric field intensity and phase angle meet the plane wave requirements, thereby obtaining the excitation distribution of the sparse array antenna.

[0011] According to the relationship between the electric field on the observation point plane and the far-field gain pattern, when the electric field strength and phase angle at the observation point on the finite far plane of the sparse array antenna are equal, the applied far-field gain pattern is a cosecant square pattern, and the formula of the optimization algorithm is: , in, For observation point Radiation direction The gain on M is the number of observation points. is the cosecant function; the physical meaning of the main function Max indicates that the sparse array antenna radiates the maximum power on the radiation aperture and satisfies the gain constraint condition ST; the genetic optimization algorithm is used to solve the above maximum value problem; The excitation distribution digital control host computer outputs the amplitude and phase control code corresponding to the excitation distribution, so that the attenuators and phase shifters on the N channels of the N-channel amplitude-phase adjustable feeding network are regulated according to the excitation distribution, and finally the corresponding amplitude and phase are output, and the N antenna units of the sparse array antenna are excited at the same time, so as to form a corresponding plane wave on the radiation aperture of the sparse array antenna.

[0012] The signal generator generates a communication analog modulation signal, which is loaded onto the baseband signal emitted by the vector network analyzer, and then transmitted to the N-channel amplitude-phase adjustable feeding network through the channel simulator and the power amplifier. The N-channel amplitude-phase adjustable feeding network feeds the N antenna units of the sparse array antenna simultaneously, and finally forms a plane wave on the radiation aperture of the sparse array antenna, simulating the far field of the plane wave to illuminate the device under test.

[0013] The number of antenna units (56 antenna units for a sparse array) is much less than that of a conventional antenna array (128 antenna units for a full array); when the antenna unit operating frequency is in the 0.5~1.5GHz frequency band, the typical size of the designed 56-element sparse array antenna is 1.2m×2.1m.

[0014] The minimum spacing between two adjacent antenna units in the sparse array antenna is 150 mm (1 / 2 the wavelength of the center operating frequency), and the spacing between other antenna units (it can be understood that all antenna units other than the two adjacent antenna units are called other antenna units) other than the two adjacent antenna units is an integer multiple of the minimum spacing (the spacing between adjacent antenna units is either the minimum spacing, or greater than and an integer multiple of the minimum spacing, such as 2 times, 3 times, etc.); The sparse array antenna excitation distribution calculated by the optimization algorithm can achieve a large plane wave quiet zone of 5×12 meters at a close distance of 12.5 meters. The amplitude ripple in the quiet zone is less than 0.8dB and the phase ripple is ±1°, which meets the requirements of engineering applications.

[0015] The beneficial effects of the present invention are as follows: the present invention proposes a sparse array large plane wave generator for OTA testing, wherein the sparse array antenna is composed of 56 antenna units arranged in a sparse manner, and a saddle-shaped beam can be formed in the far field region by optimizing the excitation distribution of the sparse array antenna, which is equivalent to forming a plane wave in the radiation aperture of the sparse array antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The invention discloses a sparse array large plane wave generator for OTA testing according to an embodiment of the present invention.

[0017] Figure 2 is a top view of an antenna unit according to an embodiment of the present invention.

[0018] Figure 3 is a side view of an antenna unit according to an embodiment of the present invention.

[0019] Figure 4 is a structural diagram of a sparse array antenna according to an embodiment of the present invention.

[0020] Figure 5 This is the principle diagram of plane wave formation of sparse array antenna.

[0021] Figure 6 It is the gain pattern on the X-axis at the center of the radiation aperture of the sparse array antenna according to an embodiment of the present invention.

[0022] Figure 7 It is the gain pattern on the Y-axis at the center of the radiation aperture of the sparse array antenna according to an embodiment of the present invention.

[0023] Figure 8 This is the optimization result (top view) of the electric field amplitude distribution on the radiation aperture of the sparse array antenna according to an embodiment of the present invention.

[0024] Fig. 9 This is the optimization result of the electric field phase distribution on the radiation aperture of the sparse array antenna according to an embodiment of the present invention (top view).

[0025] Fig.10 It is the electric field amplitude ripple on the X-axis at the center of the radiation aperture of the sparse array antenna according to an embodiment of the present invention.

[0026] Fig.11 It is the electric field phase ripple on the X-axis at the center of the radiation aperture of the sparse array antenna according to an embodiment of the present invention.

[0027] Fig.12 It is the electric field amplitude ripple on the Y-axis at the center of the radiation aperture of the sparse array antenna according to an embodiment of the present invention.

[0028] Fig.13 It is the electric field phase ripple on the Y-axis at the center of the radiation aperture of the sparse array antenna according to an embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1. Vector network analyzer; 2. Signal generator; 3. Channel simulator; 4. Power amplifier; 5. Excitation distribution digital control host computer; 6. N-channel amplitude and phase adjustable feeding network; 7. Sparse array antenna; 8. Sparse array antenna radiation aperture; 9. Device under test; 10. Dielectric substrate; 11. Rectangular metal patch; 12. Coaxial feeding port; 13. Rectangular metal floor. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0032] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] In the description of the present invention, unless otherwise specified, “N” means 56; therefore, it should not be understood as a limitation to the present invention.

[0034] In the description of the present invention, it should be noted that the term "sparse arrangement" is defined as an arrangement distribution having the same size as the sparse array antenna units, to distinguish it from a conventional array antenna in which antenna units are periodically arranged at half-wavelength intervals.

[0035] The specific implementation of the present invention is further described in detail below in conjunction with the drawings and examples.

[0036] The embodiment of the present invention provides a sparse array large plane wave generator for OTA testing, comprising a vector network analyzer 1, a signal generator 2, a channel emulator 3, a power amplifier 4, an N-channel amplitude and phase adjustable feeding network 6, an antenna unit and a sparse array antenna 7; The sparse array antenna 7 is composed of 56 antenna units arranged in a sparse manner; For example, the number of antenna units of the sparse array antenna 7 can be set to 56, and after being arranged in a sparse manner in the X and Y axis directions, as shown in FIG. Figure 4 shown.

[0037] In this embodiment, the antenna unit includes a rectangular metal patch 11, a dielectric substrate 10, a rectangular metal floor 13 and a coaxial feeding port 12. Figure 3As shown. The amplitude and phase distribution of the sparse array antenna is calculated by the constrained optimization algorithm, and a large plane wave is formed on the sparse array antenna radiation aperture 8. Specifically, a number of electric field observation points are set on the sparse array antenna radiation aperture 8, and the electric field strength and phase angle at the observation points are calculated to be equal by the constrained optimization algorithm, thereby obtaining the excitation distribution of the sparse array antenna. The excitation distribution is used to digitally control the host computer 5 to output the corresponding amplitude and phase control code, so that the N communication attenuators and phase shifters of the N-channel amplitude and phase adjustable feeding network 6 are regulated according to the excitation distribution, and finally the corresponding amplitude and phase are output to simultaneously excite the N antenna units of the sparse array antenna, thereby forming a corresponding plane wave on the sparse array antenna radiation aperture 8.

[0038] Exemplarily, 56 antenna elements are arranged in a specific sparse manner to form a sparse array antenna 7, such as Figure 4 As shown. The signal generator 2 generates a communication analog modulation signal, which is loaded onto the baseband signal emitted by the vector network analyzer 1, and then transmitted to the N-channel amplitude-phase adjustable feeding network 6 through the channel simulator 3 and the power amplifier 4. The N-channel amplitude-phase adjustable feeding network 6 simultaneously feeds the N antenna units of the sparse array antenna 7, and finally forms a plane wave on the sparse array antenna radiation aperture 8, simulating the plane wave far field to illuminate the device under test 9.

[0039] In this embodiment, the sparse array large plane wave generator is as follows: Figure 1 As shown, a sparse array antenna 7 composed of 56 antenna elements arranged in a specific sparse manner and an N-channel amplitude-phase adjustable feeding network 6 is formed. In addition, the excitation distribution of the sparse array antenna to form a large plane wave on the radiation aperture can be achieved through the N-channel amplitude-phase adjustable feeding network 6.

[0040] In this embodiment, an antenna unit is designed to work at 0.5~1.5GHz, such as Figure 2 As shown, the size of the rectangular metal patch 11 on the surface of the dielectric substrate 10 in the antenna unit is 70mm×70mm, the size of the dielectric substrate 10 and the rectangular metal floor 13 on the bottom of the dielectric substrate 10 are both 150mm×150mm, and the size of the sparse array antenna 7 is 1.2m×2.1m. The commercial electromagnetic simulation software is used for structural modeling, and a number of electric field observation points are set on the sparse array antenna radiation aperture 8. The constrained optimization algorithm is used to calculate the excitation distribution of the sparse array antenna, so that the electric field amplitude and phase angle at the electric field observation point are uniformly distributed. According to the calculated excitation distribution of the sparse array antenna, an N-channel amplitude-phase adjustable feeding network 6 is designed to excite the sparse array antenna, so as to form a uniform plane wave on its radiation aperture.

[0041] Figure 6It is the gain pattern in the X-axis direction of the radiation aperture center of the sparse array antenna, which satisfies the cosecant square relationship within the range of ±26.5°.

[0042] Figure 7 It is the gain pattern in the Y-axis direction of the radiation aperture center of the sparse array antenna, which satisfies the cosecant square relationship within the range of ±11.5°.

[0043] Figure 8 It is the electric field amplitude distribution diagram of the sparse array antenna at the radiation aperture. The radiation aperture is 12.5m away from the sparse array antenna, and the size of the plane wave formed is 12m×5m.

[0044] Fig. 9 It is the electric field phase distribution diagram of the sparse array antenna on the radiation aperture plane. The radiation aperture is 12m away from the sparse array antenna, and the size of the plane wave formed is 12m×5m.

[0045] Fig.10 It is the electric field amplitude ripple of the sparse array antenna on the X-axis at the center of the radiation aperture. The amplitude ripple in the 12m observation area is less than 1.0dB.

[0046] Fig.11 It is the electric field phase ripple of the sparse array antenna on the X-axis at the center of the radiation aperture. The phase ripple in the 12m observation area is less than ±1°.

[0047] Fig.12 It is the electric field amplitude ripple of the sparse array antenna on the Y-axis at the center of the radiation aperture. The amplitude ripple in the 5m observation area is less than 1.0dB.

[0048] Fig.13 It is the electric field phase ripple of the sparse array antenna on the Y-axis at the center of the radiation aperture. The phase ripple in the 5m observation area is less than ±1°.

[0049] In summary, the sparse array antenna achieves a large-scale plane wave test quiet zone of the order of 10 meters at a distance of 12.5 meters.

[0050] The present invention provides a sparse array large plane wave generator for OTA testing. There are many methods and ways to implement the technical solution. The above is only a preferred implementation of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A sparse array large plane wave generator for OTA testing, characterized in that: It includes a vector network analyzer, a signal generator, a channel emulator, a power amplifier, an N-channel amplitude and phase adjustable feeding network, an antenna unit and a sparse array antenna; Each amplitude and phase adjustable feeding network channel includes a digitally adjustable attenuator and phase shifter; The sparse array antenna is composed of N antenna units arranged in a sparse manner; The vector network analyzer generates a test carrier signal, modulates the communication signal generated by the signal generator, and then enters the channel simulator to simulate the transmission channel. The channel simulation signal passes through the power amplifier and then enters the N-channel amplitude and phase adjustable feeding network to excite the sparse array antenna composed of N antenna units, and finally forms a plane wave in the test area of ​​the device under test; After receiving the test signal, the device under test transmits the received signal back to the vector network analyzer to verify the communication performance of the device under test.

2. A sparse array large plane wave generator for OTA testing according to claim 1, characterized in that: The antenna unit is a microstrip patch antenna unit, comprising a rectangular metal patch, a dielectric substrate, a rectangular metal floor and a coaxial feeding port; The rectangular metal patch is arranged on the surface of the dielectric substrate, and the rectangular metal floor is arranged on the bottom surface of the dielectric substrate.

3. A sparse array large plane wave generator for OTA testing according to claim 2, characterized in that: A circular hole with a radius of 1.5 mm is dug on the rectangular metal floor, and a metal probe with a radius of 0.6 mm is passed through the entire dielectric substrate and welded to the rectangular metal patch on the surface of the dielectric substrate to form a coaxial feeding port.

4. A sparse array large plane wave generator for OTA testing according to claim 3, characterized in that: The antenna unit is fed by a 50Ω coaxial feeding port.

5. A sparse array large plane wave generator for OTA testing according to claim 4, characterized in that: The dielectric substrate material is FR4 board, the relative dielectric constant is 4.4, and the loss tangent value is 0.

02.

6. A sparse array large plane wave generator for OTA testing according to claim 5, characterized in that: Electric field observation points are set on the radiation aperture of the sparse array antenna, and the electric field intensity and phase angle at the observation points are optimized using an optimization algorithm so that the electric field intensity and phase angle meet the plane wave requirements, thereby obtaining the excitation distribution of the sparse array antenna.

7. A sparse array large plane wave generator for OTA testing according to claim 6, characterized in that: The formula of the optimization algorithm is: ， in, For observation point Radiation direction The gain on M is the number of observation points. is the cosecant function; the physical meaning of the main function Max indicates that the sparse array antenna radiates the maximum power on the radiation aperture and satisfies the gain constraint condition ST; The excitation distribution digital control host computer outputs the amplitude and phase control code corresponding to the excitation distribution, so that the attenuators and phase shifters on the N channels of the N-channel amplitude-phase adjustable feeding network are regulated according to the excitation distribution, and finally the corresponding amplitude and phase are output, and the N antenna units of the sparse array antenna are excited at the same time, so as to form a corresponding plane wave on the radiation aperture of the sparse array antenna.

8. The sparse array large plane wave generator for OTA testing according to claim 7, characterized in that: The signal generator generates a communication analog modulation signal, which is loaded onto the baseband signal emitted by the vector network analyzer, and then transmitted to the N-channel amplitude-phase adjustable feeding network through the channel simulator and the power amplifier. The N-channel amplitude-phase adjustable feeding network feeds the N antenna units of the sparse array antenna simultaneously, and finally forms a plane wave on the radiation aperture of the sparse array antenna, simulating the far field of the plane wave to illuminate the device under test.

9. A sparse array large plane wave generator for OTA testing according to claim 8, characterized in that: When the antenna unit operates in the 0.5~1.5GHz frequency band, the size of the designed 56-element sparse array antenna is 1.2m×2.1m.

10. A sparse array large plane wave generator for OTA testing according to claim 9, characterized in that: The minimum spacing between two adjacent antenna units in the sparse array antenna is 150 mm, and the spacing between other antenna units except the two adjacent antenna units is an integer multiple of the minimum spacing.

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