A radio frequency switch matrix supporting single-transmit multiple-receive detection mode of the reader

Abstract

The present application proposes a radio frequency switch matrix that supports the single-transmit multiple-receive detection mode of the reader, including: a first type of interface, which is used to connect to a single-chip microcomputer to receive digital control instructions, a second type of interface, having a transmitting end and a receiving end, which are respectively used to connect to the ports matched with the RFID reader, and a third type of interface, which is used to match and connect to the independent antenna interface of the end reader antenna. The single-channel transmission and multi-channel reception working mode of the UHF RFID detection system is realized by using a multi-channel radio frequency switch matrix. In this mode, the system can achieve high detection efficiency and reduce overall power consumption at low transmission power. 50 ohm impedance matching is achieved in the UHF RFID frequency band of 840MHz-928MHz; while achieving 50 ohm impedance matching, the module PCB layout area is reduced and the RF signal line width is reduced; a gradient line layout is adopted between the RF signal line and the chip pad to minimize RF signal loss.

Description

Technical Field

[0001] The present application relates to the field of wireless communications, and in particular to a radio frequency switch matrix supporting a single-transmit-multiple-receive detection mode of a reader. Background Art

[0002] Radio frequency identification (RFID) technology is an automatic identification technology based on radio frequency signal detection. The origin of this technology can be traced back to Faraday's discovery of electromagnetic induction in the mid-19th century, and was applied in radio radar technology in the 1940s. It has been widely used in logistics management, asset management, structural health monitoring (SHM), safety verification and other fields. In recent years, with the development of big data, Internet+, and the trend of 5G "Internet of Everything", radio frequency identification technology will have greater application potential in the field of Internet of Things (IoT).

[0003] Traditional radio frequency identification systems use a single-transmit and single-receive working mode, which is limited by the antenna beam angle and has a limited coverage area. In the single-transmit and single-receive mode of a multi-antenna identification system, the transmission and reception time of a single antenna varies from 10 to 200 ms, during which other antennas in the system are in a waiting state, and the antenna utilization rate is low. In response to the problem of low detection efficiency in the single-transmit and single-receive mode: the literature [Chen S, Zhong S, Yang S, et al. A Multi-Antenna RFID Reader with Blind Adaptive Beamforming [J]. IEEE Internet of Things Journal, 2016: 1-1] proposed a multi-antenna ultra-high frequency identification system, studied the reader's identification range, data transmission performance, and the estimation method of the number of tags, and proposed the BABF algorithm to solve the problem of tag collision in a multi-antenna system. However, this article only studied the case of two antennas, and the antennas still worked alone. The author only discussed the recognition efficiency problem under a specific layout, and did not propose a universal solution. For multi-antenna detection systems: References [Zhu F, Xiao B, Liu J, et al. Exploring Tag Distribution in Multi-Reader RFID Systems [J]. IEEE Transactions on Mobile Computing, 2016, 16 (5): 1-1.] and [AS Andrenko and M. Kai, "Novel design of UHF RFID near-field antenna for smart shelf applications," 2013 Asia-Pacific Microwave Conference Proceedings (APMC), Seoul, 2013, pp. 242-244] explored the distribution of tags in multi-reader RFID systems and proposed a protocol that can quickly identify the tag set under each reader, which makes it possible to efficiently manage product inventory. However, when the antenna signal coverage areas of multiple readers overlap, the tags in the overlapping area will be recognized by more than one reader antenna, causing tag collisions and reducing the reliability of the RFID system.The literature [Saadi H, Touhami R, Yagoub MCE. TDMA-SDMA-based RFID algorithm for fast detection and efficient collision avoidance. Int J Commun Syst. 2018; 31: e3392. https: / / doi.org / 10.1002 / dac.3392] and [Xiuwei Xuan, Kun Li. Efficient Anticollision Algorithm for RFID EPC Generation 2 Protocol Based on Continuous Detection [J]. International Journal of Wireless Information Networks (2020) 27: 133–143] proposed new algorithm solutions to improve the detection efficiency of RFID systems and avoid multi-tag collisions, but did not consider hardware issues.On the other hand, many scholars have applied beam scanning array antennas to RFID detection systems, and improved the coverage of the effective detection area by beam switching at the RF front end. The literature [Jeong MG, Kim JH, Bae SH, et al. Miniaturised multi-beam-control led circular eight-port beamforming network for long-range UHF RFID hemispheric coverage [J]. Iet Microwaves Antennas & Propagation, 2018, 12 (2): 154-159] proposed a UHF band multi-beam control eight-port beamforming network, designed 12 orthogonal hybrid couplers and 12 90-degree phase shifters on a 1.2 mm thick FR4 substrate, and achieved a beam coverage of more than 3 dBi of 130° and 180° when phi = 0° and 90° respectively; the literature [H.-T. Chou, Z.-C. Tsai, Near-Field Focus Radiation of Multibeam Phased Array of Antennas Realized by Using Modified Rotman Lens Beamformer[J].IEEE Trans.Antennas Propag,2018,12:6618-6628] uses Rotman lens to realize passive switching of 8×8 antenna array beams, and achieves a recognizable coverage area of ​​75cm×100cm at a test distance of 23cm. However, the use of beamforming technology has high power consumption and complex circuits, which cannot meet the actual application requirements of small channel detection systems. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the purpose of this application is to propose a radio frequency switch matrix that supports the single-transmit multiple-receive detection mode of the reader. The radio frequency switch matrix is ​​suitable for ultra-high frequency (UHF) RFID channel detection and can realize a multi-channel radio frequency switch matrix module with a single antenna transmission and multiple antenna reception detection mode.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] A radio frequency switch matrix supporting a single-transmit multiple-receive detection mode of a reader, characterized in that it comprises: a substrate, on which are arranged:

[0007] The first type of interface is used to connect to the microcontroller to receive digital control instructions.

[0008] The second type of interface has a transmitting end and a receiving end, which are respectively used to connect to the ports matching the RFID reader.

[0009] The third type of interface is used to match and connect with the independent antenna interface of the end reader antenna.

[0010] Preferably, the radio frequency switch matrix comprises: a radio frequency circuit unit,

[0011] The radio frequency circuit unit comprises:

[0012] One SP4T RF switch, four SPDT RF switches and one combiner,

[0013] The combiner has an input end and an output end.

[0014] The single-pole double-throw radio frequency switch has: an input end and two output ends,

[0015] The single-pole four-throw radio frequency switch has: an input end and four output ends,

[0016] The input end of the single-pole four-throw radio frequency switch is connected to the radio frequency signal transmitting end of the reader, and the four output ends are respectively connected to one of the two output ends of the four single-pole double-throw radio frequency switches, and the remaining output ends of the four single-pole double-throw radio frequency switches are respectively connected to the input end of the combiner;

[0017] The input end of the single-pole double-throw radio frequency switch is connected to the radio frequency signal transmitting end of the reader.

[0018] The output end of the combiner is connected to the radio frequency signal receiving end of the reader.

[0019] Preferably, the radio frequency switch matrix supporting the single-transmit-multiple-receive detection mode of the reader is characterized in that:

[0020] The combiner includes a first transmission line chip, a second transmission line chip and a third transmission line chip,

[0021] Among them, the first transmission line chip serves as a first-order combiner and leads out two input pins Comb1 and Comb2, the second transmission line chip and the third transmission line chip constitute a second-order combiner, the output ends of the second transmission line chip and the third transmission line chip are connected to the two input ports of the first transmission line chip, and their respective two input ports serve as signal input ends of the four-in-one combiner.

[0022] Preferably, the radio frequency switch matrix supporting the single-transmit-multiple-receive detection mode of the reader is characterized in that:

[0023] The output floating pins of the single-pole four-throw radio frequency switch and the single-pole double-throw radio frequency switch are set with 50Ω impedance matching, and the single-pole four-throw radio frequency switch and the single-pole double-throw radio frequency switch are both absorptive radio frequency switches.

[0024] Preferably, the single-pole double-throw radio frequency switch is an absorptive radio frequency switch, and its two output ends respectively include a 50Ω impedance matching loop.

[0025] Preferably, the input terminal and two output terminals of the single-pole double-throw radio frequency switch are respectively connected in series with isolation capacitors with a capacitance of 1uF each.

[0026] Preferably, the radio frequency switch matrix supporting the single-transmit multiple-receive detection mode of the reader is characterized by a substrate on which a radio frequency circuit unit and a digital circuit unit are configured, and

[0027] The radio frequency circuit unit and the digital circuit unit are separated by a non-metallic trench.

[0028] Preferably, the radio frequency switch matrix supporting the single-transmit-multiple-receive detection mode of the reader is characterized in that:

[0029] Draw the RF signal line of the RF circuit unit based on the grounded coplanar waveguide structure.

[0030] Preferably, the radio frequency circuit unit achieves 50 ohm impedance matching with the terminal.

[0031] Beneficial Effects

[0032] Compared with the prior art, the RF switch matrix proposed in this application has a single-transmit multiple-receive detection mode. For the application scenario of the intelligent access control detection system, it can realize that a single antenna transmits while all the remaining antennas receive at the same time, thereby improving the antenna utilization rate and the identification signal coverage area. The single-channel transmission and multi-channel reception working modes of the UHF RFID detection system are realized by using a multi-channel RF switch matrix. When working, the system can achieve high detection efficiency at low transmission power and reduce overall power consumption; the second-order four-in-one combiner is designed through the transmission line chip to achieve module miniaturization; the GCPW structure is used to arrange the RF signal line to achieve 50 ohm impedance matching while reducing the module PCB layout area and the RF signal line width; a gradient line layout is adopted between the RF signal line and the chip pad to minimize RF signal loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the functional modules of the detection system according to an embodiment of the present application;

[0034] Figure 2 This is a schematic diagram of the functional modules of the radio frequency switch matrix of an embodiment of the present application;

[0035] Figure 3A topological diagram of a single-pole four-throw device according to an embodiment of the present application.

[0036] Figure 4 This is a topological diagram of a single-pole double-throw circuit according to an embodiment of the present application;

[0037] Figure 5 is a topological diagram of a combiner according to an embodiment of the present application,

[0038] Figure 6 A topological diagram of a digital circuit according to an embodiment of the present application;

[0039] Figure 7 A schematic diagram of the radio frequency circuit layout of an embodiment of the present application;

[0040] Figure 8 A schematic diagram of the radio frequency circuit layout of an embodiment of the present application;

[0041] Fig. 9 A schematic diagram of the structure of a detection system according to an embodiment of the present application;

[0042] Fig.10 This is a test schematic diagram of an embodiment of the present application. DETAILED DESCRIPTION

[0043] The above scheme is further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the present application and are not limited to the scope of the present application. The implementation conditions adopted in the examples can be further adjusted as the conditions of the specific manufacturer, and the unspecified implementation conditions are usually the conditions in conventional experiments.

[0044] The present application provides a radio frequency switch matrix module, which realizes the single-transmit multiple-receive detection mode of a four-antenna channel system. Specifically, a multi-channel radio frequency switch matrix is ​​used to realize the single-channel transmission and multi-channel reception working mode of the UHF RFID detection system (referred to as single-transmit multiple-receive). In this mode, the system can achieve high detection efficiency and reduce overall power consumption at low transmission power. The transmission line chip in the radio frequency switch matrix module is designed as a second-order four-in-one combiner to achieve module miniaturization; the radio frequency signal line is arranged using a GCPW structure to achieve 50 ohm impedance matching in the UHF RFID frequency band of 840MHz-928MHz; while achieving 50 ohm impedance matching, the module PCB layout area is reduced and the width of the radio frequency signal line is reduced; a gradient line layout is adopted between the radio frequency signal line and the chip pad to minimize radio frequency signal loss.

[0045] Next, the radio frequency switch matrix (hereinafter referred to as the radio frequency switch matrix) supporting the single-transmit-multiple-receive detection mode of the reader proposed in the present application is described in conjunction with the accompanying drawings.

[0046] like Figure 1The figure shows a typical connection diagram of the radio frequency switch matrix of the embodiment of the present application;

[0047] The RF switch matrix includes:

[0048] The first type of interface is connected to the microcontroller to receive digital control instructions.

[0049] The second type of interface has a transmitting end and a receiving end, which are respectively connected to the ports matching the RFID reader.

[0050] The third type of interface (antenna port) is used to connect to the system front-end reader antenna. Specifically, the antenna port is used to connect to the four independent antenna interfaces of the system front-end reader antenna. This RF switch matrix is ​​used in the RFID system. When running, a single antenna can transmit while all the remaining antennas receive at the same time, thus improving the antenna utilization rate and the identification signal coverage area. The system can achieve a detection accuracy of 99% in single-transmit multiple-receive mode, meeting the actual application requirements.

[0051] The radio frequency switch matrix module includes: radio frequency circuit and digital circuit, wherein:

[0052] The RF circuit (such as Figure 2 shown) include:

[0053] One single-pole four-throw (SP4T) RF switch, four single-pole double-throw (SP2T) RF switches, and a combiner.

[0054] The combiner has an input end and an output end.

[0055] Single-pole double-throw (SP2T) RF switch with 2 output terminals (Port 1 / Port 2) and an input terminal.

[0056] The single-pole four-throw (SP4T) RF switch has an input end and four output ends (ports 1-4), the input end is connected to the RF signal transmitting end of the reader, and the four output ends (ports 1-4) are respectively connected to one of the two output ends of the four SP2T switches; the input end of the single-pole double-throw (SP2T) RF switch is connected to the RF signal transmitting end of the reader, and the remaining output end (port 2) of each single-pole double-throw (SP2T) RF switch is respectively connected to the input port of the combiner;

[0057] The output end of the combiner is connected to the radio frequency signal receiving end of the reader.

[0058] In this embodiment, the combiner is a four-in-one combiner, which has four input terminals. The four-in-one combiner is composed of three transmission line chips, the transmission line chip model is ETC1-1-13, and the chip is a directional coupler composed of coupled lines adjacent at both ends. When the pin 1 of the chip is grounded, a combiner with pin 2 as the output (here refers to the pin of the chip, the box in the schematic diagram represents the chip, and the number in the box is the pin number, for example, the chip pin 3 corresponds to the first input port Comb1, and pin 5 corresponds to the second input port Comb2) and pins 3 and 5 as the input is formed. At this time, the transmission loss meets S 23 =S 25 =0.5dB (corrected to S 23 , the numbers should be subscripts, the same below). The schematic diagram of the four-in-one combiner is as follows Figure 5 As shown, the three transmission line chips are named T1, T2, and T3 respectively, with T1 serving as the first-order combiner (two-in-one combiner) and leading out two input pins Comb1 and Comb2; the second-order combiner is composed of T2 and T3, and the specific connection is that the output ends of T2 and T3 are connected to the two input ports of T1, and the two input ports of each serve as the signal input ends of the four-in-one combiner.

[0059] The single-pole four-throw RF switch (SP4T) uses the model HSWA4-63DR+, which is an absorptive RF switch that supports two-way digital signal control. The switch sets a 50Ω impedance matching at the output floating pin (the switch input end and one of its output ends are turned on, and the remaining output pins are in a floating state). This design avoids the problem of the RF input signal from the reader leaking to the floating pin. Improve recognition accuracy. The SP4T switch requires a 5V voltage supply when in use. In a preferred embodiment, the power supply circuit part uses a series-connected 220Ω magnetic bead L1 of model BLM18PG221 and two parallel-connected capacitors C1 and C2 packaged in 0603 with capacitances of 100pF and 1uF respectively, which are used to filter out low-frequency signals and noise interference mixed in the power supply. The power supply schematic diagram is shown as follows Figure 3 As shown. 1-1 With V 1-2 Represents the two-bit logic control level of the SP4T switch; R14 and R16 are two grounding resistors with a package size of 0603 and a resistance of 1MΩ; R11, R12, R13, and R15 are reserved test points with a package size of 0603 to facilitate the measurement of the wire voltage during the debugging process. In other implementations, SP4T is not limited to this model as long as it can achieve this function.

[0060] The single-pole double-throw RF switch (SP2T) uses an absorptive RF switch model SKY13348. The two output ends of this switch contain a 50Ω impedance matching loop, which can prevent RF signal leakage from the floating end of the combiner. The SP2T switch does not require additional power supply, and only requires two digital control signals of opposite levels to select the output pins. In order to filter out the low-frequency noise of the RF signal, isolation capacitors are connected in series at the input end and the two output ends of the switch, such as Figure 4 As shown, the packages of C3, C4 and C5 are all 0603, and the capacitance is all 1uF. In other implementations, SP2T is not limited to this model as long as it can realize this function.

[0061] The digital circuit part includes: a control signal distribution circuit. In the implementation of the present application, since each RF switch chip requires two sets of digital level control, which occupies too many single-chip microcomputer port resources, and the control signal of the SP2T switch is two-way always opposite level, the design Figure 6 The NOT gate driver circuit shown provides eight digital control levels for four SP2T switches. Figure 6 The inverter chip is MM74HC14M from ON Semiconductor. Under the working voltage of 3.3V, there are 6 groups of NOT gates to negate the input signal (for example, if the input is high level, the output is low level). In this embodiment, 4 groups of NOT gates are used. Digital signal V X-1 、V X-2 Represents the two control signals of a SP2T switch (x = 2, 3, 4, 5; 1 / 2 represents a set of logically opposite signals). The control instruction truth table of the entire module is shown in Table 1. A1 and V 1-1 Connected, A2 and V 1-2 Connected, B1 and V 2-1 Connected, B2 and V 3-1 Connected, B3 and V 4-1 Connected, B4 and V 5-1 Connected, high level is 3.3V, low level is 0V.

[0062] The PCB (Printed Circuit Board) substrate of the RF switch matrix module is made of FR4 material, whose relative dielectric constant ε r= 4.4, the loss tangent is 0.001, and the thickness is h = 1.6 mm. The PCB layout is divided into two parts: the RF circuit and the digital circuit. To avoid interference between analog and digital signals, the two parts of the PCB circuit are separated by a non-metal groove, and several magnetic beads with a package of 0603 and a model of BLM18PG221, 220 Ω are connected across the analog ground and the digital ground. The RF circuit needs to achieve a 50-ohm impedance match with the terminal to minimize the RF signal loss caused by the trace. Therefore, the GCPW (ground coplanar waveguide) structure is used to draw the RF signal line. The layout of part of the RF circuit is as Figure 7 shown, and the specific requirements are as follows: The coplanar waveguide with ground structure is adopted. The width of the RF signal line is w = 0.84 mm (33.071 mil), the distance from the ground copper pour is g1 = 0.1524 mm (6 mil), and the edge of the ground copper pour adjacent to the RF signal line uses a copper-plated via with an inner diameter d1 = 0.254 mm (10 mil) and an outer diameter d1 = 0.508 mm (20 mil) to strengthen the grounding. The vias are evenly distributed along the RF signal line, and the distance between the vias is 1 mm < d < 2 mm; at the corner of the RF signal line, to reduce the transmission path loss, a right angle is prohibited, and a 45° trace transition must be used, and the line length l0 of the transition part shall not be less than 1.2 mm; since the width of the 50-ohm RF line far exceeds the pad size of the RF switch chip, to ensure low loss of the line, the RF trace and the chip are connected by a transition line structure as Figure 8 shown. The pad size of the SP4T switch chip is length x1 = 1.4 mm and width y1 = 0.25 mm. The length of the first trace extending from the chip pad is l1 = 1.37 mm and the width is w1 = 0.3 mm. The angle of the second arc trace is α = 90 deg, the radius is r = 0.81 mm, and the line width is w2 = 0.35 mm. The digital circuit is mainly a NOT gate drive circuit and a reserved pin socket. Its PCB layout is as Figure 8 shown: The distance between the traces and the ground copper pour in the digital circuit part is g2 = 0.254 mm (10 mil), the width of the signal line is w3 = 0.254 mm (10 mil), and the width of the power line is w4 = 0.508 mm (20 mil); to achieve good grounding, several copper-plated vias with an inner diameter d1 = 0.254 mm (10 mil) and an outer diameter d2 = 0.508 mm (20 mil) can be placed in the copper pour area. The digital circuit does not require strict impedance matching, so there are no special requirements for the via positions; the reserved pin socket is 10 copper-plated via pads with an inner diameter d3 = 0.9 mm, an outer diameter d4 = 1.5 mm, and a pitch d5 = 2.54 mm.

[0063] The working principle of this RF switch matrix module is as follows:

[0064] The microcontroller accesses six digital control signals through the reserved pin header port to select the transmitting channel and receiving channel of the reader's RFID signal. In the actual intelligent access control detection system, the transmitting and receiving ends of the UHF RFID reader with separate transmitting and receiving are connected to the corresponding interfaces of the module respectively, and four pairs of UHF (840MHz-928MHz) frequency band and 50 ohm impedance reader antennas are connected to the four antenna ports of the module through RF feeders.

[0065] The RF switch matrix module is configured in the detection system, such as the detection system for smart access control, and is suitable for the multi-way switch matrix of the ultra-high frequency radio frequency identification system. The RFID system equipped with this module can achieve a single antenna transmitting while all the remaining antennas receive at the same time, improving the antenna utilization rate and the identification signal coverage area. Fig. 9 To describe a schematic diagram of a detection system for access control.

[0066] The installation location diagram of the four antennas is as follows: Fig. 9 As shown, four antennas are installed on both sides of the access control channel in a "left-right symmetrical, top-bottom separated" manner. The digital control signal is reasonably sent by the single-chip microcomputer. The system can ensure that when the four antennas are polling, a single antenna transmits while the other three antennas receive at the same time, thereby greatly improving the antenna utilization rate and effective coverage area.

[0067] Fig.10 This is a test scenario diagram. This module is used to test the smart access control of police equipment. The test samples include ordinary printed labels ( Fig.10 As shown in the middle right half, (police hat, law enforcement instrument, shoulder light) and anti-metal special tags (flashlight, handcuffs, baton)), the tester carries these equipment and walks through the detection level at a normal speed ( Fig.10 The test results show that under the 26dBm transmission power of the reader, the system can identify all tags within 3ms without missing or misreading tags. Repeated measurement results show that the detection accuracy of the system in single-send and multiple-receive mode can reach 99%, meeting the actual application requirements.

[0068] Test steps: Use a transceiver RFID reader working in the UHF band and four reader microstrip antennas with the same frequency band and a gain of more than 8dBi. Fig. 9 As shown, the antenna is installed and fixed, and the test personnel or automatic test equipment passes through the detection channel at a normal walking speed. The starting and ending points of a single test are more than 3 meters away from the test system to ensure the independence and integrity of the test process. The working time and measurement results of each measurement system are recorded, and the test is repeated and the detection accuracy is counted. The channel detection RFID system is supported to correctly detect tags in the coverage area.

[0069] In circuit design, the antenna impedance, chip impedance and module RF circuit impedance need to be conjugate matched, so the module RF circuit part adopts GCPW structure wiring, and has strict requirements on line width, copper spacing and bending method. The module uses a double-layer PCB board with small size, modularization and simple logic control instructions.

[0070] The above embodiments are only for illustrating the technical concept and features of the present application, and their purpose is to enable people familiar with the technology to understand the content of the present application and implement it accordingly, and they cannot be used to limit the protection scope of the present application. Any equivalent transformation or modification made according to the spirit of the present application shall be included in the protection scope of the present application.

Claims

1. A radio frequency switch matrix supporting a single-transmit multiple-receive detection mode of a reader, characterized in that: The radio frequency switch matrix comprises: a radio frequency circuit unit, The radio frequency circuit unit comprises: One SP4T RF switch, four SPDT RF switches and one combiner, The combiner has an input end and an output end. The single-pole double-throw radio frequency switch has: an input end and two output ends, The single-pole four-throw radio frequency switch has: an input end and four output ends, The input end of the single-pole four-throw radio frequency switch is connected to the radio frequency signal transmitting end of the reader, and the four output ends are respectively connected to one of the two output ends of the four single-pole double-throw radio frequency switches, and the remaining output ends of the four single-pole double-throw radio frequency switches are respectively connected to the input end of the combiner; The input end of the single-pole double-throw radio frequency switch is connected to the antenna. The output end of the combiner is connected to the RF signal receiving end of the reader. The combiner comprises: a first transmission line chip, a second transmission line chip and a third transmission line chip, Among them, the first transmission line chip serves as a first-order combiner and leads out two input pins Comb1 and Comb2, the second transmission line chip and the third transmission line chip constitute a second-order combiner, the output end of the second transmission line chip is connected to the input pin Comb1 of the first transmission line chip, the output end of the third transmission line chip is connected to the input pin Comb2 of the first transmission line chip, and the input pins Comb1 and Comb2 of the first transmission line chip, the second transmission line chip and the third transmission line chip serve as signal input ends of the four-in-one combiner, The output floating pins of the single-pole four-throw radio frequency switch and the single-pole double-throw radio frequency switch are set to 50Ω impedance matching.

2. The radio frequency switch matrix supporting the single-transmit multiple-receive detection mode of the reader as claimed in claim 1, characterized in that: The single-pole four-throw radio frequency switch and the single-pole double-throw radio frequency switch are both absorptive radio frequency switches.

3. The radio frequency switch matrix supporting the single-transmit multiple-receive detection mode of the reader as claimed in claim 1, characterized in that: The single-pole double-throw radio frequency switch is an absorptive radio frequency switch, and its two output ends respectively include a 50Ω impedance matching loop.

4. The radio frequency switch matrix supporting the single-transmit multiple-receive detection mode of the reader as claimed in claim 3, characterized in that: The input end and two output ends of the single-pole double-throw radio frequency switch are respectively connected in series with isolation capacitors with a capacitance of 1uF each.

5. The radio frequency switch matrix supporting the single-transmit multiple-receive detection mode of the reader as claimed in claim 1, characterized in that: A substrate, on which a radio frequency circuit unit and a digital circuit unit are arranged, and The radio frequency circuit unit and the digital circuit unit are separated by a non-metallic trench.

6. The radio frequency switch matrix supporting the single-transmit multiple-receive detection mode of the reader as claimed in claim 5, characterized in that: Draw the RF signal line of the RF circuit unit based on the grounded coplanar waveguide structure.

7. The radio frequency switch matrix supporting the single-transmit multiple-receive detection mode of the reader as claimed in claim 6, characterized in that: The RF circuit unit and the terminal achieve 50 ohm impedance matching.

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