A Multiple-Input Multiple-Output High-Isolation Continuous Wave Radar Antenna System

Abstract

Frequency-modulated continuous wave (FM-CW) radar boasts advantages such as small blind zone, high range resolution, and strong signal carrying capacity, making it promising for applications in industrial and medical precision measurement, and automotive autonomous driving collision avoidance monitoring. This invention proposes a multiple-input multiple-output (MIMO) high-isolation CW radar antenna system, comprising six parts: a transceiver antenna board, a front-end assembly, a digital transceiver module, a power supply module, a metal shielding housing, and an array adapter board. Based on the dual-antenna spatial isolation method, and through the rational utilization of array layout, the transceiver antennas are integrated on the same antenna array, achieving an isolation of 80 dB between them. This significantly improves the detection range of the MIMO FM-CW radar and has strong engineering application value.

Description

Technical Field

[0001] This invention belongs to the field of radar technology, and particularly relates to a multiple-input multiple-output high-isolation continuous wave radar antenna system. Background Technology

[0002] The commercial drone technology is developing rapidly, and low-cost, small multi-rotor drones have been widely used. However, this has also brought many safety hazards, attracting the attention of relevant departments. Drone systems are characterized by low altitude, slow speed, and small size, placing higher demands on radar detection. Frequency-modulated continuous wave (FM-CW) radar has advantages such as small blind zone, high range resolution, and strong signal carrying capacity, and has broad application prospects in fields such as industrial and medical precision measurement and automotive autonomous driving collision avoidance monitoring. For low-altitude, small, and slow targets like drones within the measurement range, FM-CW radar typically requires multiple transmitting and receiving antennas to achieve accurate measurement and positioning. Such radar systems are usually called MIMO (Multiple-Input Multiple-Output) radar systems. In particular, MIMO radar systems play a greater role when it is necessary not only to determine the target's distance and speed but also to calculate the target's azimuth angle. Generally, FM-CW radar typically has a detection range of a few meters to 300 meters, so the antenna array's transmission power is low. However, the single-channel transmission power of the array in this design reaches 20W. At this level, the absolute value of the transmitted leakage signal is very large, which can easily block the receiving link and affect the receiver's dynamic range. It can be seen that transmit / receive isolation is the most important indicator in frequency modulated continuous wave radar.

[0003] Several methods can improve isolation, including dual-antenna spatial isolation, single-antenna isolators, and signal cancellation techniques. The single-antenna isolator method uses a single antenna for both transmit and receive channels, employing a circulator or coupler as the isolation device. In higher frequency bands such as microwaves and millimeter waves, circulators can only provide 25-30 dB of isolation, and this requires perfect matching at all ports. For frequency-modulated continuous wave radars with high transmit power and long operating ranges, this isolation level is far from sufficient. Signal cancellation techniques generate a coupled signal with the same amplitude, consistent delay, and opposite phase as the actual leaky branch signal. Through signal synthesis, they cancel each other out. Because signal cancellation techniques are highly sensitive to changes in the system's electromagnetic environment, they are generally suitable for suppressing leaky signals within narrow-bandwidth RF front-end modules. In complex and variable electromagnetic environments, leaky signals exhibit multipath effects, and their amplitude and phase information are time-varying, posing a significant challenge to the design of cancellation circuits. The dual-antenna spatial isolation method involves placing the transmitting and receiving antennas on two separate arrays. By increasing the distance between the antennas and adding absorbing materials, the isolation between the transmitting and receiving antennas can be significantly increased. However, this method generally leads to drawbacks such as increased array size, which is not conducive to the miniaturization and integration of the system. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention proposes a Multiple-Input Multiple-Output (MIMO) high-isolation continuous wave radar antenna system. This system addresses the high-precision angle measurement requirements and low isolation between transmit and receive antennas in current frequency-modulated continuous wave radars. It meets the needs of diverse application scenarios and deployment methods, and is compatible with portable, mobile, and fixed operating modes. The continuous wave radar antenna system comprises six parts: a transmit and receive antenna board, a front-end assembly, a digital transceiver module, a power supply module, a metal shielding housing, and an array adapter board. Based on the dual-antenna spatial isolation method, and through the rational utilization of the array layout, the transmit and receive antennas are integrated on the same antenna array, achieving an isolation of 80dB between them. This significantly improves the detection range of the MIMO frequency-modulated continuous wave radar and has strong engineering application value.

[0005] In this invention, the transceiver antenna board includes one transmitting antenna and six receiving antennas. However, depending on the application scenario and the required coverage area, one or more transceiver antenna boards can be used in the system to form a multiple-input multiple-output configuration. The implementation only requires improvements to the external housing structure, but the principle is the same as that of a single transceiver antenna board.

[0006] The present invention provides a multiple-input multiple-output (MIMO) high-isolation continuous wave radar antenna system, comprising a transceiver antenna board (1), a front-end assembly (2), a digital transceiver module (3), a power supply module (4), a metal shielding housing (5), and an array adapter board (6);

[0007] The transceiver antenna board (1) includes a carrier reflector (11), multiple receiving antennas (12), a transmitting antenna (13), and a metal isolation baffle (14). The transmitting antenna (13) completes the spatial radiation of the radar linear frequency modulated signal, and the receiving antenna (12) completes the sampling of the radar echo signal.

[0008] The front-end component (2) includes a receiving front-end component and a transmitting front-end component. The receiving front-end component provides low-noise amplification and gain control for each receiving antenna (12), and the transmitting front-end component provides power signal output for the transmitting antenna (13).

[0009] The digital transceiver module (3) includes a frequency conversion module (31), a frequency source (32), and a digital processing module (33). The frequency conversion module (31) receives the signal from the front-end component, performs frequency conversion, amplification, and filtering, and then sends it to the digital processing module (33). The digital processing module (33) generates a broadband intermediate frequency signal and sends it to the frequency conversion module (31). After amplification, mixing, and filtering, a broadband excitation signal is finally generated and sent to the front-end component (2). The digital processing module (33) has six sampling channels and receives multiple signals simultaneously. It performs data sampling, deskewing, and packet transmission functions in the digital processing module. The frequency source (32) generates a clock reference signal through a crystal oscillator and sends it to the digital processing module (33). It generates a local oscillator and a second local oscillator signal through phase-locked loop and sends them to the frequency conversion module (31).

[0010] The power module (4) converts the 220V AC input voltage into the voltage required by each module inside the radar antenna system;

[0011] The metal shielding shell (5) is composed of multiple metal plates, which provide waterproof protection and electromagnetic shielding for the internal circuits;

[0012] The array adapter board (6) is an array-to-external interface integration board, including a power interface, a network control interface, and an optical fiber interface, for data transmission with external processing equipment.

[0013] Furthermore, the radar antenna system adopts an integrated design, integrating the transceiver antenna board (1), front-end component (2), digital transceiver module (3), power supply module (4) and array adapter board (6) into the same structure, with the outside being a metal shielding shell (5).

[0014] Furthermore, the transmitting antenna (31) and the receiving antenna (12) are arranged on the same plane. The receiving antenna (12) is arranged in an L-shape and occupies three corners of the rectangular array. The transmitting antenna (13) is located at the fourth corner of the rectangular array. A metal isolation baffle (14) is installed between the transmitting antenna (31) and the receiving antenna (12).

[0015] Furthermore, the receiving antenna (12) and the transmitting antenna (13) are of the same type of antenna, and the antenna unit adopts a microstrip patch form and a stripline feed layout, which is integrally formed by PCB printed circuit board.

[0016] Furthermore, the antenna unit is composed of three dielectric substrates and four metal layers, namely the first dielectric layer, the second dielectric layer and the third dielectric layer; the four metal layers include the first metal layer, the second metal layer, the third metal layer and the fourth metal layer; their arrangement order from top to bottom is the first metal layer, the first dielectric layer, the second metal layer, the second dielectric layer, the third metal layer, the third dielectric layer and the fourth metal layer, wherein the first metal layer is the patch radiating unit (15), the first dielectric layer adopts a thicker low dielectric constant dielectric substrate, the second dielectric layer and the third dielectric layer adopt a thinner high dielectric constant dielectric substrate, the second metal layer and the fourth metal layer are the transmission stripline and the ground plane of the patch radiating unit (15), the third metal layer is the feed stripline (17), the electromagnetic signal is transmitted along the stripline and radiated from the H-shaped slot (16) of the second metal layer to the first metal layer.

[0017] Furthermore, the receiving front-end component includes six limiters (23) and six low-noise amplifiers (24), which are connected one-to-one. The six limiters (23) at the input end are connected to the six receiving antennas (12) on the transceiver antenna board (1), and the low-noise amplifiers (24) at the output end are connected to the six digital receiving channels of the digital transceiver module (3). The transmitting front-end component includes a driver amplifier (26), a power amplifier (25), and an isolator (27). The excitation signal is initially amplified by the driver amplifier (26), then output to the isolator (27) after passing through the power amplifier (25), and then output to the transmitting antenna (13) after passing through the isolator (27).

[0018] Furthermore, the frequency conversion module (31) includes six digital receiving channels, which respectively receive signals from the front-end component (2). The received signals are then sent to the digital processing module (33) for signal processing after passing through a power amplifier, mixer and filter in each channel. The digital processing module (33) generates a broadband intermediate frequency signal and sends it to the frequency conversion module (31). After the reverse processing of the received signal processing flow, a broadband excitation signal is finally generated and sent to the front-end component (2). The digital processing module (33) has six sampling channels, which simultaneously receive six downlink signal data and complete data sampling, deskewing, and packet transmission in the digital processing module (33).

[0019] Furthermore, the digital transceiver module (3) adopts a two-stage frequency conversion superheterodyne architecture to realize digital angle measurement. It digitally processes and samples the signals received by the six receiving channels, and calculates the incident angle of the target by measuring the phase difference of the echo signals obtained by the three receiving antennas in each of the two dimensions, thereby realizing the coordinate positioning of the target.

[0020] The beneficial effects of this invention are as follows:

[0021] It can solve the current shortcomings of frequency-modulated continuous wave radar, such as the high-precision angle measurement requirements and low transmit / receive antenna isolation. It is highly adaptable to various platforms and can address technical issues related to transmit / receive isolation and miniaturization in frequency-modulated continuous wave radar. Specifically:

[0022] 1. By making reasonable use of the array space layout, the transceiver antenna board achieves an integrated design of multiple transceiver antennas on the same array surface and achieves an isolation of 80dB between the transceiver antennas, greatly improving the detection range of the frequency modulated continuous wave radar. This transceiver antenna board can provide reliable transmission and reception isolation and meet the requirements of ultra-high power transmission, which helps to improve the overall performance of the radar.

[0023] 2. The antenna elements employ a slot-coupled feeding method, introducing a resonant point through slot coupling to extend the antenna's radiation bandwidth. A stripline feed is used to achieve higher inter-antenna isolation.

[0024] 3. The digital transceiver module realizes the functions of phased array signal generation, signal amplification, signal frequency conversion and signal acquisition. It has a wide range of applications and can be used independently in other types of radar antenna systems.

[0025] 4. The modular system front-end components completely isolate the front-end transceiver channel circuits through structural separation, further reducing the signal coupling effect of the transmitting channel on the receiving channel and avoiding saturation of the receiving channel during transmission.

[0026] 5. Compact structure and high reliability. The radar antenna system of this invention has only a power interface and an optical signal interface as external interfaces. All electronic control signals are generated and distributed by the internal digital transceiver module. The external interface is simple and efficient, which greatly improves the versatility and platform adaptability of the radar antenna system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a radar antenna system.

[0028] Figure 2 This is a schematic diagram of the layout of the transceiver antenna board of a radar antenna system.

[0029] Figure 3 This is a stacked diagram of a radar broadband low-profile antenna element model.

[0030] Figure 4 This is a schematic diagram of the front-end components of a radar antenna system.

[0031] Figure 5 This is a schematic diagram of the digital transceiver module of a radar antenna system.

[0032] In the diagram: 1-Transceiver antenna board, 2-Front-end component, 3-Digital transceiver module, 4-Power supply module, 5-Metal shielding housing, 6-Array adapter board, 11-Bearing reflector, 12-Receiving antenna, 13-Transmitting antenna, 14-Metal isolation baffle, 15-Patch radiating element, 16-H-type coupling slot, 17-Stripline transmission line, 23-Limiter, 24-Low noise amplifier, 25-Power amplifier, 26-Drive amplifier, 27-Isolator, 31-Frequency conversion module, 32-Frequency source, 33-Digital processing module, 34-Filter, 35-Mixer, 36-Amplifier. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] like Figure 1 As shown, Figure 1 This is a schematic diagram of the system principle of a specific implementation of the multiple-input multiple-output (MIMO) high-isolation frequency-modulated continuous wave radar antenna system of the present invention, which includes six parts: transceiver antenna board 1, front-end component 2, digital transceiver module 3, power supply module 4, metal shielding housing 5, and array adapter board 6.

[0035] The transceiver antenna board 1 consists of a carrier reflector 11, six receiving antennas 12, one transmitting antenna 13, and a metal isolation baffle 14. The transmitting antenna 13 realizes spatial radiation of the radar linear frequency modulated signal, and the receiving antenna 12 realizes sampling of the radar echo signal. Both the receiving antenna 12 and the transmitting antenna 13 are composed of antenna arrays consisting of 2×4 antenna elements. Through the design of the antenna positions on the transceiver antenna board 1 and the isolation baffle 14, the isolation between the transmitting and receiving antennas is improved. The front-end component 2 consists of a transmitting front-end component and a receiving front-end component. The receiving front-end component includes six limiters 23 and six low-noise amplifiers 24, which provide low-noise amplification and gain control for the six receiving antennas 12. The transmitting front-end component 21 includes a power amplifier 25, which provides a 20W power signal output for the transmitting antenna 13. The digital transceiver module 3 consists of a frequency conversion module 31, a frequency source 32, and a digital processing module 33, which realizes the functions of phased array signal generation, signal amplification, signal frequency conversion, and signal acquisition. The power module 4 includes multiple power conversion modules and input / output capacitor banks, converting the 220V AC input voltage into the voltage values ​​required by each module within the radar antenna system. The metal shielding housing 5 serves as the external protective housing for all modules, composed of multiple metal plates, providing waterproof protection and electromagnetic shielding for the internal circuitry. The array adapter board 6 is an integrated board for external interfaces, including power interfaces, network control interfaces, and fiber optic interfaces, enabling data transmission with external processing equipment.

[0036] In a specific embodiment, the transmitting antenna 13 and the receiving antenna 12 are located on the transceiver antenna board 1 at the following positions: Figure 2 As shown. Due to the requirement of integrated transmit and receive array, the transmitting antenna 13 needs to be arranged on the same plane as the receiving antenna 12. The receiving antenna 12 has an L-shaped layout, occupying three corners of the rectangular array, and the transmitting antenna 13 is located at the fourth corner of the rectangular array. At this time, the distance between the transmitting antenna 13 and the receiving antenna 12 is small. Adding a metal baffle between the transmitting and receiving antennas can improve the isolation between the transmitting antenna 13 and the six receiving antennas 12. The receiving antenna 12 and the transmitting antenna 13 both use the same type of antenna. The antenna element adopts the form of a microstrip patch antenna, fed by an H-shaped slot 16. In this invention, following the principle of low cost, a PCB printed circuit board is used for integrated processing, eliminating the need for foam, metal patches, and other stacked structures that require secondary assembly. To obtain higher isolation, a stripline feed layout is adopted, with the port feed of the antenna element placed between the upper and lower ground layers. The final designed antenna stacked structure is as follows. Figure 3The antenna consists of three dielectric substrates and four metal layers: a first dielectric layer, a second dielectric layer, and a third dielectric layer; and four metal layers: a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer. The topmost first dielectric layer uses a thicker low-dielectric-constant dielectric substrate, while the second and third dielectric layers use thinner high-dielectric-constant dielectric substrates. This enhances the confinement of the field by the dielectric to reduce back radiation and reduces the width of the back-feed microstrip line, thereby reducing interference from feed line stray radiation. The first metal layer is a patch radiating element 15, the second and fourth metal layers are the transmission stripline and the ground plane of the patch radiating element 15, and the third metal layer is the feed stripline 17. Electromagnetic signals are transmitted along the stripline, achieving unbalanced to balanced conversion within the cavity formed by the vias, and radiating from the H-shaped slot 16 of the second metal layer to the first metal layer. The frequency-modulated continuous wave radar antenna system can also be composed of multiple transceiver antenna boards 1, which, when combined, cover a larger airspace range.

[0037] Combination Figure 4 As shown, the front-end component 2 includes a receiving front-end component and a transmitting front-end component. The receiving front-end component includes six limiters and six low-noise amplifiers 24, connected one-to-one. The input limiters are connected to the six receiving antennas 12 on the transceiver antenna board, and the output low-noise amplifiers are connected to the six digital receiving channels of the digital transceiver module 3. A centralized design is adopted, with each receiving channel in the receiving component corresponding to a low-noise amplifier 24, which can effectively improve the link noise figure and avoid introducing insertion loss into the link. The transmitting front-end component includes a driver amplifier 26, a power amplifier 25, and an isolator 27. During operation, the excitation signal is initially amplified by the driver amplifier 26, then output to the isolator 27 after passing through the power amplifier 25, and finally output to the transmitting antenna 13, providing a high-power signal output for the transmitting antenna 13. The isolator 27 can isolate reverse high-power signals, preventing internal components from burning out.

[0038] Combination Figure 5As shown, the digital transceiver module 3 consists of a frequency conversion module 31, a frequency source 32, and a digital processing module 33. In this embodiment, the digital transceiver module 3 adopts a two-stage frequency conversion superheterodyne architecture to implement a digital angle measurement scheme, and performs digital processing sampling on the signals received by the six receiving channels. The incident angle of the target is calculated by measuring the phase difference of the echo signals obtained by the three receiving antennas in each of the two dimensions, thereby realizing the coordinate positioning of the target. The digital transceiver module (3) includes a frequency conversion module (31), a frequency source (32), and a digital processing module (33). The frequency conversion module (31) contains six digital receiving channels, which respectively receive the signals sent from the front-end component (2). The received signals are then sent to the digital processing module (33) for signal processing after passing through a power amplifier, a mixer, and a filter in each channel. The digital processing module 33 generates a broadband intermediate frequency signal and sends it to the frequency conversion module 31. The frequency conversion module 31 receives the broadband intermediate frequency signal and amplifies, mixes, and filters it, and finally generates a broadband excitation signal which is sent to the front-end component 2. The frequency source 32 contains a crystal oscillator, which generates a clock reference signal and sends it to the digital processing module 33. It also generates high local oscillator and low local oscillator signals through phase locking and sends them to the frequency conversion module 31.

[0039] This invention is not limited to the specific embodiments described above, and various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made to the above embodiments based on the technical essence of this invention should be included within the scope of protection of this invention.

Claims

1. A multiple-input multiple-output high-isolation continuous wave radar antenna system, characterized in that: It includes a transceiver antenna board (1), a front-end assembly (2), a digital transceiver module (3), a power supply module (4), a metal shielding housing (5), and an array adapter board (6). The transceiver antenna board (1) includes a carrier reflector (11), multiple receiving antennas (12), a transmitting antenna (13), and a metal isolation baffle (14). The transmitting antenna (13) completes the spatial radiation of the radar linear frequency modulated signal, and the receiving antenna (12) completes the sampling of the radar echo signal. The front-end component (2) includes a receiving front-end component and a transmitting front-end component. The receiving front-end component provides low-noise amplification and gain control for each receiving antenna (12), and the transmitting front-end component provides power signal output for the transmitting antenna (13). The digital transceiver module (3) includes a frequency conversion module (31), a frequency source (32), and a digital processing module (33). The frequency conversion module (31) receives the signal from the front-end component, performs frequency conversion, amplification, and filtering, and then sends it to the digital processing module (33). The digital processing module (33) generates a broadband intermediate frequency signal and sends it to the frequency conversion module (31). After amplification, mixing, and filtering, a broadband excitation signal is finally generated and sent to the front-end component (2). The digital processing module (33) has six sampling channels and receives multiple signals simultaneously. It performs data sampling, deskewing, and packet transmission functions in the digital processing module. The frequency source (32) generates a clock reference signal through a crystal oscillator and sends it to the digital processing module (33). It generates a local oscillator and a second local oscillator signal through phase-locked loop and sends them to the frequency conversion module (31). The power module (4) converts the 220V AC input voltage into the voltage required by each module inside the radar antenna system; The metal shielding shell (5) is composed of multiple metal plates, which provide waterproof protection and electromagnetic shielding for the internal circuits; The array adapter board (6) is an array-to-external interface integration board, including a power interface, a network control interface, and an optical fiber interface, for data transmission with external processing equipment; The transmitting antenna (13) and the receiving antenna (12) are arranged on the same plane. The receiving antenna (12) is arranged in an L-shape and occupies three corners of the rectangular array. The transmitting antenna (13) is located at the fourth corner of the rectangular array. A metal isolation baffle (14) is installed between the transmitting antenna (13) and the receiving antenna (12). The antenna unit consists of three dielectric substrates and four metal layers, namely a first dielectric layer, a second dielectric layer, and a third dielectric layer; the four metal layers include a first metal layer, a second metal layer, a third metal layer, and a fourth metal layer. The arrangement order from top to bottom is: first metal layer, first dielectric layer, second metal layer, second dielectric layer, third metal layer, third dielectric layer, and fourth metal layer. The first metal layer is a patch radiating unit (15). The first dielectric layer uses a thicker low dielectric constant dielectric substrate. The second and third dielectric layers use thinner high dielectric constant dielectric substrates. The second and fourth metal layers are the transmission stripline and the grounding plane of the patch radiating unit (15). The third metal layer is the feed stripline (17). The electromagnetic signal is transmitted along the stripline and radiated from the H-shaped gap (16) of the second metal layer to the first metal layer.

2. The multiple-input multiple-output high-isolation continuous wave radar antenna system according to claim 1, characterized in that: The radar antenna system adopts an integrated design, integrating the transceiver antenna board (1), front-end component (2), digital transceiver module (3), power supply module (4) and array adapter board (6) into the same structure, with the outside being a metal shielding shell (5).

3. The multiple-input multiple-output high-isolation continuous wave radar antenna system according to claim 1, characterized in that: The receiving antenna (12) and the transmitting antenna (13) are of the same type. The antenna unit adopts a microstrip patch form and a stripline feed layout, and is integrally formed by PCB printed circuit board.

4. The multiple-input multiple-output high-isolation continuous wave radar antenna system according to claim 1, characterized in that: The receiving front-end component includes 6 limiters (23) and 6 low-noise amplifiers (24), which are connected one-to-one. The 6 limiters (23) at the input end are connected to the 6 receiving antennas (12) on the transceiver antenna board (1), and the low-noise amplifiers (24) at the output end are connected to the 6 digital receiving channels of the digital transceiver module (3). The transmitting front-end component includes a driver amplifier (26), a power amplifier (25) and an isolator (27). The excitation signal is initially amplified by the driver amplifier (26), and then output to the isolator (27) after passing through the power amplifier (25). After passing through the isolator (27), it is output to the transmitting antenna (13).

5. A multiple-input multiple-output high-isolation continuous wave radar antenna system according to claim 1, characterized in that: The frequency conversion module (31) includes six digital receiving channels, which respectively receive signals from the front-end component (2). The received signals are then sent to the digital processing module (33) for signal processing after passing through a power amplifier, mixer and filter in each channel. The digital processing module (33) generates a broadband intermediate frequency signal and sends it to the frequency conversion module (31). After the reverse processing of the received signal processing flow, a broadband excitation signal is finally generated and sent to the front-end component (2). The digital processing module (33) has six sampling channels, which simultaneously receive six downlink signal data and complete data sampling, deskewing, and packet transmission in the digital processing module (33).

6. A multiple-input multiple-output high-isolation continuous wave radar antenna system according to claim 5, characterized in that: The digital transceiver module (3) adopts a superheterodyne architecture with two-stage frequency conversion to realize digital angle measurement. It digitally processes and samples the signals received by the six receiving channels, and calculates the incident angle of the target by measuring the phase difference of the echo signals obtained by the three receiving antennas in each of the two dimensions, thereby realizing the coordinate positioning of the target.

7. A multiple-input multiple-output high-isolation continuous wave radar antenna system according to claim 1, characterized in that: Depending on the application scenario and the area to be covered, multiple transceiver antenna boards can be selected to form a multiple-input multiple-output configuration.

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