CN210665995U

CN210665995U - Radio frequency switch-based on-site detection circuit for RFID reader-writer antenna

Info

Publication number: CN210665995U
Application number: CN201921134411.4U
Authority: CN
Inventors: 谈熙
Original assignee: Wuxi Qilian Electronic Technology Co ltd
Current assignee: Wuxi Qilian Electronic Technology Co ltd
Priority date: 2019-07-18
Filing date: 2019-07-18
Publication date: 2020-06-02
Anticipated expiration: 2029-07-18

Abstract

The utility model relates to a RFID read write line antenna is at position detection circuitry based on radio frequency switch, the circuit includes controller, transmitter and antenna, controller and transmitter are connected, the circuit still includes the transmission line of connecting between transmitter and radio frequency switch's input, and antenna and standard load are connected respectively to two outputs of radio frequency switch, be provided with two power check points on the transmission line, two check points are connected to the controller through detection circuitry. The utility model relates to a RFID read write line antenna detection circuitry on throne based on radio frequency switch, circuit structure is simple and it is high to detect the precision.

Description

Radio frequency switch-based on-site detection circuit for RFID reader-writer antenna

Technical Field

The utility model relates to a RFID read write line's antenna detection circuitry on throne especially relates to one kind and can detects the read write line antenna and connect good circuit to can be convenient for the controller under the antenna condition of not connecting or bad connection, the transmission of restriction read write line, the protection transmitter does not receive the damage, prolongs the life of read write line.

Background

At present, the circuit for detecting the in-place of the antenna of the conventional RFID reader has two design schemes:

firstly, a direct-current line short circuit antenna is used, a controller judges whether the antenna is in place or not by detecting direct-current impedance of an antenna port, detects high impedance (open circuit) and judges that the antenna is not in place, and detects low impedance (short circuit) and judges that the antenna is in place; the detection circuit has the advantages that the detection means is simple, and the defect that whether the radio frequency impedance is good or not cannot be judged; when the antenna is connected but the contact is poor, although the direct current impedance can be detected to be low, the radio frequency impedance can be very poor, and the damage of a reader-writer transmitter can still be caused by normal operation;

secondly, the controller directly detects the reflected power of the antenna to judge the in-place condition of the antenna; the specific method is that the transmitter sends out signals during detection, and signals returned by the antenna are detected to judge. The signal transmitted at this time is set to be not demodulated by the tag, so the received signal is only the reflection signal of the antenna (at this time, the received signal also contains the reflection generated by other components on the signal path such as transmission line, cable, connector, active/passive device, etc. besides the reflection of the antenna, but the reflection signal of the antenna port is dominant when the antenna is not in place). The antenna is judged not to be in place when the reflection signal is large, and the antenna is judged to be in place when the reflection signal is small. A disadvantage of this approach is that when the transmitted signal and the reflected signal are superimposed, standing waves are formed. The amplitude of the standing wave is smallest at the node and largest at the antinode. The appearance of nodes and antinodes is location dependent. The distance between two adjacent nodes/antinodes is one half wavelength (the wavelength is the wavelength of the electron wave in the transmission medium). Therefore, if the detection position is at a node, a smaller signal is likely to be detected, resulting in erroneous judgment;

in summary, a detection circuit with simple circuit structure and high detection precision is needed

Disclosure of Invention

An object of the utility model is to overcome above-mentioned not enough, provide a circuit structure and detect the high RFID read write line antenna detection circuitry on throne based on radio frequency switch of precision.

The purpose of the utility model is realized like this:

an RFID reader-writer antenna on-position detection circuit based on a radio frequency switch comprises a controller, a transmitter and an antenna, wherein the controller is connected with the transmitter; the length of the transmission line between two adjacent detection points is one eighth of the wavelength of the detection signal transmitted by the transmitter; the detection circuit is a power detection circuit, an RMS detector or a peak-to-peak detection circuit.

An RFID reader-writer antenna in-place detection circuit based on a radio frequency switch comprises a controller, a transmitter and an antenna, wherein the controller is connected with the transmitter, the circuit further comprises a phase shifter connected between the transmitter and the input end of the radio frequency switch, two output ends of the radio frequency switch are respectively connected with the antenna and a standard load, a first detection point is arranged between the phase shifter and the transmitter, a second detection point is arranged between the phase shifter and the radio frequency switch, and the first detection point and the second detection point are respectively connected to the controller after passing through the detection circuit.

Compared with the prior art, the beneficial effects of the utility model are that:

the utility model has simple circuit structure and small volume; the detection signal that will acquire that only need to construct transmission line (or move looks ware) and supporting detection circuitry can be convenient compares to the state of accurate knowing antenna compares in conventional detection circuitry, and the detection signal that acquires through the circuit of this patent structure is more favorable to accurate detection.

Drawings

Fig. 1 is the utility model relates to a circuit diagram of the in-place detection circuit of the RFID reader antenna based on the radio frequency switch.

Fig. 2 is a circuit diagram of another embodiment of the present invention, which is based on the RFID reader antenna of the rf switch.

Detailed Description

The first embodiment is as follows: referring to fig. 1, the utility model relates to an in-place detection circuitry of RFID read write line antenna based on radio frequency switch, the circuit includes controller, transmitter and antenna, controller and transmitter are connected, its characterized in that:

the circuit also comprises a transmission line connected between the transmitter and the input end of the radio frequency switch, two output ends of the radio frequency switch are respectively connected with the antenna and the standard load, two power detection points are arranged on the transmission line, the two detection points are connected to the controller through the detection circuit, the length of the transmission line between every two adjacent detection points is one eighth of wavelength, and the wavelength is the wavelength of a detection signal transmitted by the transmitter;

further, the detection circuit is a power detection circuit, an RMS detector or a peak-to-peak detection circuit;

the advantage of this embodiment lies in that circuit structure is simple, the detection precision is high, and the required overall layout area of circuit is little, and its theory of operation is:

firstly, the radio frequency switch is switched to the antenna, and the power of D1 and D3 points is detected to obtain P1 and P3 respectively. And then switching the radio frequency switch to a standard load, and carrying out detection in the same step to obtain corresponding power detection results P1_ s and P3_ s. The variable PD2 is set to max (abs (P1-P3), abs (P1-P1_ s), abs (P3-P3 _ s)). And judging whether the antenna is in place according to the size of the PD 2. The judgment method is similar to the scheme I: presetting a threshold value, and judging that the antenna is not in place when the PD2 exceeds the threshold value; when the PD2 is less than the threshold, the antenna is determined to be in position. The threshold may be set by testing the size of the PD2 for the antenna in and out of bit, taking an appropriate intermediate value between them.

Example two: referring to fig. 2, the utility model relates to an in-place detection circuitry of RFID read write line antenna based on radio frequency switch, the circuit includes controller, transmitter and antenna, controller and transmitter are connected, its characterized in that:

the circuit also comprises a phase shifter connected between the transmitter and the input end of the radio frequency switch, two output ends of the radio frequency switch are respectively connected with the antenna and the standard load, a first detection point is arranged between the phase shifter and the transmitter, a second detection point is arranged between the phase shifter and the radio frequency switch, and the first detection point and the second detection point are respectively connected to the controller after passing through the detection circuit; the circuit size is further reduced through the phase shifter;

the comparison method in each embodiment of the patent is the same as the second scheme in the background art, and is different in that a transmission line and a power detection point are arranged to obtain different comparison parameters, so that the precision is improved; therefore, the present patent is characterized by the configuration of the detection circuit, not in the comparison method (program) after acquiring the parameters, and thus belongs to the protection object of the utility model.

In addition: it should be noted that the above-mentioned embodiment is only a preferred embodiment of the present patent, and any modification or improvement made by those skilled in the art based on the above-mentioned conception is within the protection scope of the present patent.

Claims

1. The utility model provides a RFID read write line antenna is at position detection circuitry based on radio frequency switch, the circuit contains controller, transmitter and antenna, the controller is connected with the transmitter, its characterized in that:

the circuit further comprises a transmission line connected between the transmitter and the input end of the radio frequency switch, two output ends of the radio frequency switch are respectively connected with the antenna and the standard load, two power detection points are arranged on the transmission line, and the two detection points are connected to the controller through the detection circuit.

2. The in-place detection circuit of the RFID reader antenna based on the radio frequency switch as claimed in claim 1, characterized in that: the length of the transmission line between two adjacent detection points is one eighth of the wavelength of the detection signal transmitted by the transmitter.

3. The in-place detection circuit of the RFID reader antenna based on the radio frequency switch as claimed in claim 1, characterized in that: the detection circuit is a power detection circuit, an RMS detector or a peak-to-peak detection circuit.

4. The utility model provides a RFID read write line antenna is at position detection circuitry based on radio frequency switch, the circuit contains controller, transmitter and antenna, the controller is connected with the transmitter, its characterized in that:

the circuit further comprises a phase shifter connected between the transmitter and the input end of the radio frequency switch, two output ends of the radio frequency switch are respectively connected with the antenna and the standard load, a first detection point is arranged between the phase shifter and the transmitter, a second detection point is arranged between the phase shifter and the radio frequency switch, and the first detection point and the second detection point are respectively connected to the controller after passing through the detection circuit.

5. The RFID reader antenna in-situ detection circuit based on the radio frequency switch as claimed in claim 4, characterized in that: the detection circuit is a power detection circuit, an RMS detector or a peak-to-peak detection circuit.