Antenna device and radio frequency sensing system

Abstract

An antenna device comprises a first substrate, a second substrate, a signal coupling body, a dielectric resonance element and a radiator. The first substrate has a first top surface and a first bottom surface opposite to the first top surface. The second substrate has a second top surface and a second bottom surface opposite to the second top surface. The signal coupling body is arranged between the first top surface and the second bottom surface and is provided with a cross slot. The dielectric resonance element is arranged on the second top surface. The radiator is arranged on the first bottom surface and comprises a first radiation unit and a second radiation unit, and the first radiation unit and the second radiation unit are used for receiving or outputting different polarization signals. A radio frequency sensing system includes an antenna device and a switching element. The switching element is electrically connected to the radiating body of the antenna device and is used for switching the antenna device to be connected to the radar circuit or the network card.

Description

Technical Field

[0001] This invention relates to an antenna device and a radio frequency sensing system. Background Technology

[0002] With the development of communication technology, the performance requirements for antenna devices are constantly increasing. In chip tags (such as RFID tags), antennas are used to receive and transmit wireless signals. These antennas are typically located inside the tag and can communicate wirelessly with a reader to achieve signal reading and reception. These antennas are usually designed to be small and efficient to fit the compact size of the tag while ensuring reliable signal transmission and reception.

[0003] Generally, tagged chips are detected using circularly polarized antenna sensors to achieve optimal transmission efficiency. However, for disposable, chipless tags, the background scattering field needs to be calibrated to obtain the tag's frequency response. In traditional 5G communication, linear polarization achieves the best transmission efficiency. However, currently, for these different polarization requirements or applications, individual antenna structures or circuits often need to be designed. Summary of the Invention

[0004] In view of the above, the present invention provides an antenna device and a radio frequency sensing system.

[0005] An antenna device according to an embodiment of the present invention includes a first substrate, a second substrate, a signal coupler, a dielectric resonant element, and a radiator. The first substrate has a first top surface and a first bottom surface, wherein the first top surface and the first bottom surface are opposite to each other. The second substrate has a second top surface and a second bottom surface, wherein the second top surface and the second bottom surface are opposite to each other. The signal coupler is disposed between the first top surface and the second bottom surface and has a cross-shaped slot. The dielectric resonant element is disposed on the second top surface. The radiator is disposed on the first bottom surface and includes a first radiating element and a second radiating element, wherein the first radiating element and the second radiating element are used to transmit and receive polarized signals in different directions.

[0006] A radio frequency sensing system according to an embodiment of the present invention includes an antenna device and a switching element. The antenna device includes a first substrate, a second substrate, a signal coupler, a dielectric resonant element, and a radiator. The first substrate has a first top surface and a first bottom surface, wherein the first top surface faces the first bottom surface. The second substrate has a second top surface and a second bottom surface, wherein the second top surface faces the second bottom surface. The signal coupler is disposed between the first top surface and the second bottom surface and has a cross-shaped slot. The dielectric resonant element is disposed on the second top surface. The radiator is disposed on the first bottom surface and includes a first radiating element and a second radiating element, wherein the first radiating element and the second radiating element are used to transmit and receive polarized signals in different directions. The switching element is electrically connected to the radiator of the antenna device and is used to switch the antenna device to a radar circuit or a network interface card (NIC).

[0007] With the above structure, the antenna device and radio frequency sensing system disclosed in this case can improve the bandwidth through the dielectric resonant element, and receive or output different polarization signals through the first radiating unit and the second radiating unit respectively. Furthermore, the radio frequency sensing system disclosed in this case can provide different polarization effects for tag identification or wireless communication applications through the switching element.

[0008] The foregoing description of the contents of this application and the following description of the embodiments are intended to demonstrate and explain the spirit and principles of the present invention, and to provide a further explanation of the claims of the present invention. Attached Figure Description

[0009] Figure 1 This is a perspective view of an antenna device according to an embodiment of the present invention.

[0010] Figure 2 for Figure 1 An exploded view of the antenna device.

[0011] Figure 3 for Figure 1 A plan view of the radiator of the antenna device.

[0012] Figure 4 for Figure 1 A planar schematic diagram of the signal coupler of the antenna device.

[0013] Figure 5 for Figure 1 Line graph of return loss of antenna device.

[0014] Figure 6 This is a functional block diagram of a radio frequency sensing system according to an embodiment of the present invention.

[0015] Figure 7This is a functional block diagram of a radio frequency sensing system according to another embodiment of the present invention.

[0016] Figure 8 This is a functional block diagram of a radio frequency sensing system according to another embodiment of the present invention.

[0017] Symbol explanation:

[0018] 1,1',1": Radio Frequency Sensing System

[0019] 10: Antenna device

[0020] 11: First substrate

[0021] 111: First top surface

[0022] 112: First base

[0023] 12: Second substrate

[0024] 121: Second top surface

[0025] 122: Second base

[0026] 13: Radiation body

[0027] 131: First radiating unit

[0028] 132: Second Radiation Unit

[0029] 133: Unit 3

[0030] 1311, 1321: Signal feed section

[0031] 1312, 1322: Signal transmission segment

[0032] 14: Dielectric Resonance Element

[0033] 15: Signal Coupler

[0034] 151: Cross-groove

[0035] 1511: Center Groove

[0036] 1512a-1512d: Arm Groove

[0037] 20,20',20": Switching element

[0038] 30: Radar circuit

[0039] 40: Network card

[0040] 51: First Phase Shifter

[0041] 52: Second phase shifter

[0042] 60: Power Divider

[0043] 601a, 601b: First side port

[0044] 602a-602c: Second-side port

[0045] 61: First Distributor

[0046] 611: First port

[0047] 612a, 612b: Second port

[0048] 62: Second Distributor

[0049] 621: Third port

[0050] 622a, 622b: Fourth port

[0051] 63: Third Distributor

[0052] 631a, 631b: Port 5

[0053] 632: Port 6

[0054] L1-L9: Length

[0055] T1-T3: Thickness

[0056] W1-W10: Width Detailed Implementation

[0057] The following detailed description of the features and advantages of the present invention in the embodiments is sufficient to enable anyone skilled in the art to understand the technical content of the present invention and implement it accordingly. Based on the disclosure of this specification, the claims, and the accompanying drawings, anyone skilled in the art can easily understand the related objects and advantages of the present invention. The following embodiments further illustrate the points of the present invention in detail, but are not intended to limit the scope of the present invention in any way.

[0058] Please see Figure 1 and Figure 2 , Figure 1 This is a perspective view of an antenna device according to an embodiment of the present invention. Figure 2 for Figure 1 An exploded view of the antenna device.

[0059] The antenna device 10 of this embodiment includes a first substrate 11, a second substrate 12, a radiator 13, a dielectric resonant element 14, and a signal coupler 15. The first substrate 11 has a first top surface 111 and a first bottom surface 112, wherein the first top surface 111 and the first bottom surface 112 are opposite to each other. The second substrate 12 has a second top surface 121 and a second bottom surface 122, wherein the second top surface 121 and the second bottom surface 122 are opposite to each other. The radiator 13 is disposed on the first bottom surface 112 and includes a first radiating element 131, a second radiating element 132, and a third element 133, wherein the first radiating element 131 and the second radiating element 132 are used to transmit and receive polarized signals in different directions, and the third element 133 is a selectively disposed element connected to the first radiating element 131 and the second radiating element 132. For example, the first radiating element 131 can be used to receive or output a vertically polarized signal, and the second radiating element 132 can be used to receive or output a horizontally polarized signal; or, the first radiating element 131 can be used to receive or output a horizontally polarized signal, and the second radiating element 132 can be used to receive or output a vertically polarized signal. The horizontally polarized signal and the vertically polarized signal can be referred to as bilinear polarization. Horizontal polarization can be transmitted through left-right oscillation, and vertical polarization can be transmitted through up-down oscillation. The dielectric resonant element 14 is disposed on the second top surface 121. The signal coupler 15 is disposed between the first top surface 111 and the second bottom surface 122, and has a cross-shaped slot 151.

[0060] In this embodiment, the materials of the first substrate 11 and the second substrate 12 are, for example, RO4003 material. RO4003 material is a glass fiber reinforced polyolefin resin. Through the characteristics of the glass fiber board of RO4003 material, the signal loss radiated by the antenna device 10 can be reduced.

[0061] In this embodiment, the dielectric resonant element 14 can be a dielectric resonator. The dielectric resonant element 14 has a high dielectric constant, which can increase signal bandwidth and gain. The dielectric constant of the dielectric resonant element 14 can range from 35% to 55%, preferably 45%. The material of the dielectric resonant element 14 is, for example, ceramic. The shape of the dielectric resonant element 14 is preferably symmetrical, especially square.

[0062] In this embodiment, the length L1 and width W1 of the first substrate 11, the length L2 and width W2 of the second substrate 12 are all, for example, 55 mm. The thickness T1 of the first substrate 11 is, for example, 0.8 mm. The thickness T2 of the second substrate 12 is, for example, 1.6 mm.

[0063] In this embodiment, the dielectric resonant element 14 disposed on the second top surface 121 may be in a stacked arrangement or bonded with adhesive. The dielectric resonant element 14 may be disposed at the center of the second top surface 121. The length L3 and width W3 of the dielectric resonant element 14 are, for example, 31 mm. The thickness T3 of the dielectric resonant element 14 is, for example, 1.4 mm.

[0064] Please refer to the following: Figure 3 and Figure 4 . Figure 3 for Figure 1 A plan view of the radiator of the antenna device. Figure 4 for Figure 1 A planar schematic diagram of the signal coupler of the antenna device.

[0065] In this embodiment, the radiator 13 is made of, for example, copper foil. The radiator 13 includes a first radiating unit 131, a second radiating unit 132, and a third unit 133. The first radiating unit 131 and the second radiating unit 132 are used to transmit and receive polarized signals in different directions. The third unit 133 is a selectively configured unit connected to the first radiating unit 131 and the second radiating unit 132. The first radiating unit 131 includes a signal feed section 1311 and a signal transmission section 1312, and the second radiating unit 132 includes a signal feed section 1321 and a signal transmission section 1322. The signal feed sections 1311 and 1321 are used to receive the feed signal. Signal transmission segment 1312 is connected to signal feed segment 1311, and signal transmission segment 1322 is connected to signal feed segment 1321. The width W5 of signal transmission segments 1312 and 1322 is greater than the width W6 of signal feed segments 1311 and 1321. This matching of widths can make the impedance more continuous.

[0066] In the radiator 13 of this embodiment, the first radiating unit 131 is perpendicular to the second radiating unit 132, for example. The first radiating unit 131 and the second radiating unit 132 are respectively vertically connected and horizontally connected to the lower right corner of the third unit 133. The length of the first radiating unit 131 and the second radiating unit 132 is, for example, 26.2 mm. The signal feed sections 1311 and 1321 of the first radiating unit 131 and the second radiating unit 132 can extend at least partially relative to the outer periphery of the first substrate 11. The third unit 133 can be a square, and the length L4 and width W4 of the third unit 133 are both, for example, 9.6 mm.

[0067] In detail, the length and width of the signal feed section 1311 of the first radiating unit 131 can be equal to the length and width of the signal feed section 1321 of the second radiating unit 132, and the length and width of the signal transmission section 1312 of the first radiating unit 131 can be equal to the length and width of the signal transmission section 1322 of the second radiating unit 132. The length L5 of the signal transmission section 1322 is, for example, 22.2 mm, the length L6 of the signal feed section 1321 is, for example, 4 mm, the width W5 of the signal transmission section 1322 is, for example, 2.6 mm, and the width W6 of the signal feed section 1321 is, for example, 1.2 mm. The signal feed section 1321 can be connected outward from the center of the short side of the signal transmission section 1322, and the gap W7 at the connection point between the signal feed section 1321 and the signal transmission section 1322 is, for example, 0.7 mm.

[0068] In this embodiment, the horizontal polarization signal and the vertical polarization signal can be determined according to the antenna placement. That is, in one embodiment, the first radiating element 131 can be used to receive or output the vertical polarization signal, and the second radiating element 132 can be used to receive or output the horizontal polarization signal. In another embodiment, the first radiating element 131 can be used to receive or output the horizontal polarization signal, and the second radiating element 132 can be used to receive or output the vertical polarization signal.

[0069] The signal coupler 15 has a cross-shaped slot 151. The cross-shaped slot 151 is used to couple a signal to the radiator 13. The cross-shaped slot 151 includes a central slot 1511 and four arm slots 1512a, 1512b, 1512c and 1512d. The four arm slots 1512a-1512d are respectively connected to the four sides of the central slot 1511, and the lengths L8 and L9 and the widths W8 and W9 of the four arm slots 1512a-1512d are greater than the width W10 of the central slot.

[0070] In this embodiment, the signal coupler 15 is made of, for example, copper foil. In this embodiment, the size of the signal coupler 15 can be equal to that of the first substrate 11 and the second substrate 12, and the length L7 of the signal coupler 15 is, for example, 55 millimeters.

[0071] In this embodiment, the cross-shaped slot 151 can be a cross with four arms of equal length, forming a regular cross. The lengths L8 and L9 and the widths W8 and W9 of the four arm slots 1512a-1512d are, for example, 7 mm each. The width W10 of the center slot 1511 is, for example, 2.5 mm.

[0072] Antenna device 10 is specifically applicable to the n78 band and C band (5GHz to 6GHz) of 5G. Please refer to the following: Figure 5 . Figure 5 for Figure 1The image shows a line graph illustrating the return loss of the antenna device. In this embodiment, the antenna device 10 exhibits low return loss in the C-band (5 GHz to 6 GHz) and the n78 band (5 GHz). Specifically, the return loss of the antenna device 10 in the C-band (5 GHz to 6 GHz) and the n78 band (5 GHz) is mostly below -10 dB, resulting in good impedance matching. Furthermore, generally, the higher the antenna gain, the more concentrated the antenna radiation, allowing the signal to travel a greater distance in a specific direction. The antenna device 10 in this embodiment, for example, has a maximum gain of 8.9 dBi (decibels relative to an isotropic radiator) in the aforementioned frequency bands.

[0073] Please see Figure 6 , Figure 6 This is a functional block diagram of a radio frequency sensing system according to an embodiment of the present invention.

[0074] The radio frequency sensing system 1 of this embodiment includes an antenna device 10 and a switching element 20, wherein the switching element 20 is electrically connected to the radiator of the antenna device 10 (such as...). Figures 1 to 3 The radiator 13 shown is used to switch the antenna device 10 to the radar circuit 30 or the network card 40. Furthermore, the switching element 20 can be switchably connected to, for example... Figure 2 and 3 The antenna device 10 shown includes a first radiating element 131 and a second radiating element 132. One or both of the radar circuit 30 and the network card 40 can be components of the radio frequency sensing system 1 or external components.

[0075] In this embodiment, the radiator of the antenna device 10 can output or receive horizontally polarized signals or vertically polarized signals, respectively. This can be used by the radar circuit 30 for one-time identification of chipless tags in chipless mode, or it can be connected to the network card 40 for wireless communication mode. The switching element 20 is, for example, a double-pole double-throw switch. When operating in chipless mode, one side of the switching element 20 is switched to the radar circuit 30, and the other side is, for example, first connected to the radiator of the antenna device 10 (e.g., a...). Figures 1 to 3 The horizontal polarization port of the radiator 13 shown (e.g.) Figures 2 to 3 The first radiating unit 131 shown transmits signals, and then switches to the vertical polarization port (e.g., Figures 2 to 3The second radiating element 132 shown receives the signal. The switching between the horizontal and vertical polarization ports can be continuous. The radar circuit 30 can be used to perform taggedless identification on the signal acquired by the antenna device 10. When one side of the switching element 20 is switched to the network card 40 for wireless communication, the other side of the switching element 20 can be selected to connect to the horizontal or vertical polarization port depending on the nearby base station. Taggedless information can be transmitted to the cloud for recording and storage via the 5G n78 band, and the data can be analyzed.

[0076] For example, radar circuit 30 may include, but is not limited to, a circulator, a power amplifier (PA), a duplexer, a voltage-controlled oscillator (VCO), a tuned voltmeter (V-tune), a low-noise amplifier (LNA), a mixer, an intermediate frequency amplifier (IFAP), and an analog-to-digital converter (ADC), which can detect and locate the positions of chip-tagged and chipless tags by transmitting and receiving signals.

[0077] Please see Figure 7 , Figure 7 This is a functional block diagram of a radio frequency sensing system according to another embodiment of the present invention.

[0078] In this embodiment, the radio frequency sensing system 1' includes an antenna device 10, a switching element 20', a first phase shifter 51, a second phase shifter 52, and a power divider 60. The switching element 20' is used to switch between connection to the radar circuit 30 and the network card 40. The first phase shifter 51 is connected to the radiator of the antenna device 10 (e.g., [missing information - likely a radiator]). Figures 1 to 3 The first radiating unit (e.g., the radiator 13 shown) Figures 2 to 3 The second phase shifter 52 is connected between the first radiating element 131 (as shown) and the switching element 20', and is connected to the radiator (such as...) of the antenna device 10. Figures 1 to 3 The second radiating unit (e.g., the radiator 13 shown) Figures 2 to 3Between the second radiating unit 132 (shown) and the switching element 20', the power divider 60 has two first-side ports 601a and 601b and three second-side ports 602a-602c. The two first-side ports 601a and 601b are respectively connected to the first phase shifter 51 and the second phase shifter 52. The second-side port 602a is connected to the first-side port 601a, the second-side port 602b is connected to both first-side ports 601a and 601b, and the second-side port 602c is connected to the first-side port 601b. The switching element 20' is switchably connected to the three second-side ports 602a-602c. The switching element 20' is, for example, a double-pole triple-throw switch.

[0079] In this embodiment, when the switching element 20' is connected to the second side port 602a of the power divider 60, it can transmit and receive one of the horizontally polarized signals and the vertically polarized signals through the first radiating unit; when the switching element 20' is connected to the second side port 602c of the power divider 60, it can transmit and receive the other of the horizontally polarized signals and the vertically polarized signals through the second radiating unit; when the switching element 20' is connected to the second side port 602b of the power divider 60, it can transmit and receive both the horizontally polarized signals and the vertically polarized signals simultaneously through both the first and second radiating units. Furthermore, when the switching element 20' is connected to the second side port 602b of the power divider 60, the phase offset setting value of the first phase shifter 51 and the phase offset setting value of the second phase shifter 52 differ by 90 degrees, thereby forming a left-hand circularly polarized or right-hand circularly polarized signal for transmission. The phase difference can refer to the absolute value of the subtraction of the two values.

[0080] In this embodiment, the first phase shifter 51 and the second phase shifter 52 are designed to control the phase of the input port signals, such that the horizontally polarized signal and the vertically polarized signal are 90 degrees out of phase. The horizontally polarized signal and the vertically polarized signal are fed in simultaneously, and the two input signals are 90 degrees out of phase, thus forming either left-hand circularly polarized or right-hand circularly polarized signals. The circularly polarized signal can be the circular rotational oscillation of electromagnetic wave particles; left-hand rotation is left-hand circular polarization, and right-hand rotation is right-hand circular polarization. Therefore, the RF sensing system 1' of this embodiment can provide linear polarization for use in tagless sensing and / or general networking, and can provide circular polarization for use in tag-enabled sensing, tagless sensing, and / or 6G mobile communication.

[0081] Please refer to the following: Figure 8 , Figure 8 This is a functional block diagram of a radio frequency sensing system according to another embodiment of the present invention.

[0082] In this embodiment, the radio frequency sensing system 1 includes an antenna device 10, a switching element 20, a first phase shifter 51, a second phase shifter 52, a first distributor 61, a second distributor 62, and a third distributor 63. The first distributor 61 has a first port 611 on one side and two second ports 612a and 612b on the other side, wherein the first port 611 is connected to the two second ports 612a and 612b. The second distributor 62 has a third port 621 on one side and two fourth ports 622a and 622b on the other side, wherein the third port 621 is connected to the two fourth ports 622a and 622b. The third distributor 63 has two fifth ports 631a and 631b on one side and a sixth port 632 on the other side, wherein the two fifth ports 631a and 631b are connected to the sixth port 632. The first distributor 61, the second distributor 62, and the third distributor 63 can be... Figure 7 The components included in the medium power divider 60, wherein the first port 611 and the third port 621 can respectively serve as Figure 7 The two first-side ports 601a and 601b and the two fifth ports 631a and 631b of the medium power divider 60 can be connected to the second port 612b and the fourth port 622a respectively, and the sixth port 632, the second port 612a and the fourth port 622b can be used as... Figure 7 The medium power divider 60 has three second-side ports 602a-602c. The switching element 20" is, for example, a double-pole triple-throw switch.

[0083] As shown in Table 1, the input port signal phase is controlled by the first phase shifter 51 and the second phase shifter 52, which can transmit four types of polarization signals. In the chipless mode, the four polarization signals can be transmitted simultaneously. In the chip-equipped mode, right-hand circular polarization and left-hand circular polarization signals can be transmitted. In the wireless mode, the switching element 20” is connected to the network card 40, which can transmit horizontal polarization and vertical polarization signals.

[0084] Table 1

[0085]

[0086]

[0087] In another embodiment, at least one of the first distributor 61 and the second distributor 62 may be replaced with a single-pole double-throw switch.

[0088] With the above structure, the antenna device and radio frequency sensing system disclosed in this application can improve bandwidth through a dielectric resonant element, and receive or output different polarization signals through the first radiating element and the second radiating element respectively. Furthermore, the radio frequency sensing system disclosed in this application can provide different polarization effects for tag identification or wireless communication applications through a switching element. In addition, through two phase shifters and a power divider, the radio frequency sensing system disclosed in this application can switch between transmitting circularly polarized signals, expanding the application range of tag identification.

[0089] While the present invention has been disclosed above with reference to the foregoing embodiments, it is not intended to limit the invention. Any modifications and refinements made without departing from the spirit and scope of the invention are within the scope of patent protection of the present invention. For a description of the scope of protection defined in the present invention, please refer to the appended claims.

Claims

1. An antenna device, characterized in that, Include: A first substrate has a first top surface and a first bottom surface, wherein the first top surface and the first bottom surface are opposite to each other. A second substrate has a second top surface and a second bottom surface, wherein the second top surface and the second bottom surface are opposite to each other. A signal coupler is disposed between the first top surface and the second bottom surface, and has a cross-shaped slot; A dielectric resonant element is disposed on the second top surface; and A radiator is disposed on the first bottom surface and includes a first radiating unit and a second radiating unit, wherein the first radiating unit and the second radiating unit are used to transmit and receive polarization signals in different directions.

2. The antenna device as claimed in claim 1, characterized in that, The cross-shaped slot includes: One central slot; and Four arm slots are respectively connected to the four sides of the central slot, wherein the length of each of the four arm slots is greater than the length of the central slot.

3. The antenna device as described in claim 1, characterized in that, The dielectric constant of the dielectric resonant element is in the range of 35% to 55%.

4. The antenna device as claimed in claim 1, characterized in that, At least one of the first radiating element and the second radiating element includes: A signal feed section for receiving an input signal; and A signal transmission segment is connected to the signal feed segment, wherein the width of the signal transmission segment is greater than the width of the signal feed segment.

5. A radio frequency sensing system, characterized in that, Include: An antenna device, comprising: A first substrate has a first top surface and a first bottom surface, wherein the first top surface and the first bottom surface are opposite to each other. A second substrate has a second top surface and a second bottom surface, wherein the second top surface and the second bottom surface are opposite to each other. A signal coupler is disposed between the first top surface and the second bottom surface, and has a cross-shaped slot; A dielectric resonant element is disposed on the second top surface; and A radiator is disposed on the first bottom surface and includes a first radiating unit and a second radiating unit, wherein the first radiating unit and the second radiating unit are used to transmit and receive polarization signals in different directions. as well as A switching element, electrically connected to the radiator of the antenna device, is used to switch the antenna device to a radar circuit or a network card.

6. The radio frequency sensing system as described in claim 5, characterized in that, The switching element is a double-pole double-throw switch.

7. The radio frequency sensing system as described in claim 5, characterized in that, It also includes: A first phase shifter is connected between the first radiation unit and the switching element; A second phase shifter is connected between the second radiation unit and the switching element; and A power divider with two first-side ports and three second-side ports. The two first-side ports are respectively connected to the first phase shifter and the second phase shifter, the first of the three second-side ports is connected to one of the two first-side ports, the second of the three second-side ports is connected to the other of the two first-side ports, the third of the three second-side ports is connected to the two first-side ports, and the switching element is switchably connected to the three second-side ports.

8. The radio frequency sensing system as described in claim 7, characterized in that, When the switching element is connected to the third of the three second-side ports of the power divider, the phase offset setting value of the first phase shifter differs from the phase offset setting value of the second phase shifter by 90 degrees.

9. The radio frequency sensing system as described in claim 7, characterized in that, The power divider described herein includes: A first distributor, having a first port on one side and two second ports on the other side; A second distributor, having a third port on one side and two fourth ports on the other side; and A third distributor, wherein one side of the third distributor has two fifth ports and the other side of the third distributor has a sixth port. The first port and the third port are respectively the two first side ports, the two fifth ports are respectively connected to one of the two second ports and one of the two fourth ports, and the sixth port, the other of the two second ports and the other of the two fourth ports are respectively the three second side ports.

10. The radio frequency sensing system as described in claim 9, characterized in that, At least one of the first distributor and the second distributor is a single-pole double-throw switch.

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