FI119304B - Detection of component mismatch in RFID reader - Google Patents

Description

119304

Detecting component mismatch in RFID reader Ala

The invention relates to radio frequency identification tags and in particular to the detection of mismatches of the components of a radio frequency identification reader.

5 Background

Radio Frequency Identification (RFID) is a technology that uses radio frequency spectrum electromagnetic or electrostatic matching to identify objects to which RFID tags have been attached. In general, RFID systems offer the advantage of not requiring direct contact or line-of-sight scanning. A typical RFID system includes an RFID reader and a plurality of RFID tags affixed to the objects of interest. The RFID reader includes an antenna and a transceiver. An RFID reader uses an antenna and a transceiver to transmit radio frequency signals to an RFID tag. In response to radio frequency signals received from the RFID reader, the identifier sends the data back to the reader by modulating the signal received at the RFID reader antenna. As an example, some tags use variable impedance applied to the antenna, which can be used to change the amount of energy reflected from the tag. These tags can send data to the reader by varying the impedance to selectively modulate the impedance. 20 broken signals. RFID tags can be used as such to identify and track multiple items. In addition, since RFID tags are * · * · relatively inexpensive components, they can track a large number of • ♦ objects at a relatively low cost.

Fig. 1 shows an example of an RFID reader 100. The RFID reader 100 comprised *: 25 a transmission circuit 102 to enable radio signals to be transmitted to an RFID tag ***. The RFID reader 100 further comprises a reception circuit 106 »· To receive radio signals transmitted from RFID tag 122. The RFID reader preferably comprises a single antenna 110 for use in both transmission and reception to reduce the physical size of the reader. The transmitted sig - “* 30 signals are routed from the reader transmit circuit 102 to the antenna 110 via the rotation member 104.

· · Φ

On the other hand, the same rotating member 104 forwards the sig - *: ** signals received through the antenna 110 to the receiver circuitry 106 of the RFID reader 100. This results in the worst misalignment of the components at the antenna port and the echo reflection of almost the entire transmitted signal. The high power near-reflection signal reflected to the reader's receiver circuit usually breaks the receiver circuit. In such cases, it would be advantageous to find a solution to prevent breakage of the receiver circuit.

Short description

It is an object of the invention to provide a solution for detecting a component failure in a radio frequency identification reader.

According to one aspect of the invention, a method performed in a radio frequency identification (RFID) reader comprising one or more antenna ports. The method comprises: transmitting, during the test phase, a test signal to one or more antenna ports 10 of the RFID reader and receiving leaking components of the transmitted test signal to the receiver side of the RFID reader. The method further comprises: determining, based on the received components of the test signal, whether a properly functioning antenna is connected to one or more antenna ports.

The invention is shown in accordance with another aspect of a radio frequency 15 identification (RFID) reader, comprising a transmission circuit, a reception circuit, one or more antenna ports operationally coupled with the transmission and a receiving circuits, and a processing unit which is configured to control The transmitter-medium circuit to transmit a test signal to at least one RFID reader antenna ports and receive components of the tes-20 signal to the receiving circuit through the receiving circuit. The processing unit is further configured to be configured. . ·. Based on the received components of the test signal, determine whether a properly functioning antenna is connected to one or more antenna ports.

. *. * To the invention is provided a computer • · in accordance with another aspect of the "V program product encoding a computer program of instructions for executing a computer • ♦ ·. · Γ 25 process for component mismatch identification in a radio frequency identification (RFID) reader process comprises: controlling the RFID a · · · transmitting circuit to transmit a test signal to at least one of the antenna ports of the RFID reader, receiving components of the transmitted test signal leaking through the RFID reader receiving circuit, the process further comprising: determining based on the received components of the test signal, one or more antenna ports way antenna.

The invention prevents breakage of the RFID reader receiver circuit if the RFID reader antenna is broken or disconnected from the reader antenna port. The invention ··· also allows the antenna to be changed in-flight without the need to connect a reader * ···. ···. 35 off. This greatly improves the usability of the reader.

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List of figures

The invention will now be described in more detail in connection with the preferred embodiments, with reference to the accompanying drawings, in which Figure 1 is a block diagram of an RFID reader and an RFID identifier; Figure 2 shows the structure of an RFID reader according to an embodiment of the invention; Fig. 3 is a detailed block diagram of an RFID reader comprising a compensation circuit according to an embodiment of the invention; Figure 4 is a block diagram of an RFID reader 10 according to another embodiment of the invention, and Figure 5 is a flow chart illustrating a process for compensating for component mismatch in an RFID reader according to another embodiment of the invention.

DESCRIPTION OF EMBODIMENTS Referring to Figure 2, the general structure of a Radio Frequency Identification Reader (RFID) reader 200, in which embodiments of the invention may be implemented, is considered. Furthermore, the general structure of the RFID tag 220 communicating with the RFID reader 200 is described.

The RFID reader 200 comprises a transmit / receive circuit 208 which enables the transmission and reception of radio signals. The transmitting / receiving circuit 208 may be functionally divided into a transmitting circuit and a receiving circuit. Transmit circuit: performs the functions necessary to convert the transmitted signals. **! sex for transmission. The transmission circuit may perform upmix, amplification, and filtering procedures for the · · ·! V signal to be transmitted. The receiving circuit: * V 25, in turn, performs the functions necessary to convert the received signals into a form suitable for detecting data. The receiving circuit may perform downmix, gain, and filtering procedures on the received signal and then supply it to the analog-to-digital converter for further processing. The transmit / receive circuit 208 may use a single antenna for both transmitting and receiving radio signals 30.

The RFID reader 200 further comprises a processing unit 204 which controls the operations performed in the RFID reader. The processing unit 204 may control the transmission and reception of signals transmitted or received through the transmit / receive circuit 208. The processing unit 204 may also control the operation of the other components of the RFID reader -: "] · 354 The processing unit may be implemented by digital signal processor and suitable software stored on a computer readable storage medium or by separate logic circuits, such as ASIC Circuit).

The RFID reader 200 further comprises a memory unit 206 for storing parameters and information necessary for the operation of the RFID reader 200 5. The memory unit 206 may store the commands and parameters of the processing unit 204 for transmitting and / or receiving signals to be transmitted from the RFID reader / reader.

The RFID reader 200 may further comprise a user interface 202 for communicating between the user of the RFID reader 10 200 and the RFID reader 200. The user interface 202 may comprise, for example, a display unit and an input device.

The RFID reader 200 communicates with the RFID tag 220 over a wireless radio connection. The RFID tag comprises a transmit / receive circuit 222 and a memory unit 224. The transmit / receive circuit is configured to receive the radio signal transmitted from the RFID reader 200, modulate the received radio signal with information stored in the memory unit 224, and transmit the modulated signal back to RFID reader 200. The RFID tag 220 can only respond to a specific type of activation signal received from an RFID reader. If the RFID tag 220 receives other types of signals, it may be configured not to respond to them. The RFID tag typically does not comprise an energy source, and thus the energy required to operate RFID tag 220: is taken from the received signal. The RFID reader • t1; *. J 200 may also transmit additional energy bursts to provide the RFID tag: *. *] With sufficient power.

FIG. 3 shows a detailed block diagram of an RFID reader 200 according to an embodiment of the invention: * Y. The processing unit 204 is the same as described above with reference to FIG. The processing unit 204 transmits * ···: signals through the transmission circuit 302 to the antenna port 330. A digital-to-analog converter (D / A- * ··· 30 converter) 322 may be mapped between the processing unit 204 and the transmission circuit 302. The transmitting circuit 302 processes the information signal to be transmitted. The transmission circuit 302 may perform the same functions as the transmission circuit described above. The transmission circuit then supplies a radio frequency signal to the antenna port 330 via the rotary member 306.

The rotary member 306 transmits the received signals from the transmitting circuit 302 to the antenna connected to the antenna port 330 and the signals received from the antenna port 330 to the receiving circuit 310. The receiving circuit 310 may perform the same operations as the receiving circuit described above. The receiving circuit 310 then supplies the signals to the processing unit 204 via an analog-to-digital converter (A / D converter) 320.

As mentioned above, the rotary member 306 may not be an ideal component, and components of the transmitted signals may leak into the receiving circuit 310, impairing the data detection performance. The RFID reader 200 may first transmit a data signal to the RFID tag 220 and then energy bursts to provide energy to the RFID tag 220 so that the RFID tag 220 may generate a response signal to the data signal received from the reader 200. Thus, the RFID-10 reader 200 receives a response signal from the RFID tag 220 when transmitting energy bursts, and components of the transmitted signal (energy bursts) leak to the receiver side of the reader 200 when receiving a response signal from the tag 220. This may be a problem. Reported by RFID readers using the same antenna for simultaneous transmission. If signal 15 is transmitted while receiving another signal, the components of the transmitted signals will leak into the receiving circuit 310, impairing the detection performance of the received signal. In addition, there may be antenna mismatches between the antenna port and the antenna, resulting in a partial reflection of the transmitted signal from the antenna port. These signal components are also transmitted to the receiving circuit 20 310 via the rotation member 306.

The components of the transmitted signal leaking to the receiving circuit 310. for attenuation, an RFID reader 200 according to an embodiment of the invention.]] *: includes a compensation circuit 340. The signal produced from the transmission circuit 302 may be transmitted to the rotary member 306 via the switching unit 304. The switching unit 304 may be a directional switch configured to transmit a received signal from the transmitting circuit 302 to the compensation circuit 340 in addition to the rotating member 306.

• · ·

The compensation circuit 340 comprises an amplitude control unit 312 and a phase control unit 314 which modulate the amplitude and phase of the input signal (signal received from the transmission circuit 302 through the switching unit 304). The amplitude control unit 312 and the phase control unit 314 may be implemented, for example, with a vector modulator. The operation of the compensation circuit 340 is controlled by the processing unit 204, which provides the amplitude control unit 312 with an amplitude parameter - ** '\ metric value and the phase control unit 314 with a phase parameter value. The parameters determine the amplitude and phase magnitude of the input signal. Processor unit 35 204 may supply parameter values to control units 312 and 314 via D / A converters 316 and 318. The purpose of the compensation circuit 340 is to provide a compensation signal which suppresses the transmitted signal leaking to the receiving circuit when these signals are combined. Compensation terminal 340 also comprises a compound 308 which combines a signal received from the antenna port 330 with a compensation signal from the rotary member 306 and supplies the resulting signal 5 to a receiving circuit 310. Thus, the combiner 308 may be disposed between the rotating member 306 and the receiving circuit 310.

The amplitude of the signal received through the switching unit 304 may be modified before phase adjustment or vice versa. Alternatively, the signal received through the switching unit 304 may be divided into two signals. One of these two signals may be supplied to the amplitude control unit 312 and the other to the phase control unit 314. The responses of the amplitude control unit 312 and the phase control unit 314 may then be combined, for example, to sum them together.

The processing unit 204 provides the amplitude control unit 312 and the phase control unit 15 with parameter values based on information on the signal components of the transmitted signals leaking to the receiving circuit 310. Based on this information, processing unit 204 may select an optimal set of parameter values to attenuate leaking components of the transmitted signal.

Information on the signal components of the transmitted signals leaking to the receiving circuit 310 may be obtained by transmitting the test signal to the antenna port 330 during the testing phase, whereby neither data transmission nor reception is performed. The processing unit 204 transmits a test signal to the antenna port 330 via a transmission circuit 302, a switching unit 304, and a rotation member 306. Switching:. the unit 304 also directs the test signal to the compensation circuit 340. The components of the test signal • * V 25 leak through the rotation member 306 and are reflected from the antenna port 'V to the compensation circuit 340 combiner 308.

*;!; * During the testing phase, the processing unit 204 provides the amplitude * · * ·· '' control unit 312 and the phase control unit with different combinations of amplitude and phase shift parameter values and monitors the received circuit 310 and the A / D converter. signal level. The idea is to generate a compensating signal that completely attenuates the leaking signal components, that is, ···, the signal from the combiner 308 output is minimized.

The amplitude and phase adjustment parameter combinations may be predetermined and stored in the RFID reader memory unit 206. Modification of the test signal in the compensation circuit 340 with different amplitude and phase shift parameter combinations results in different test signal modifications and variations in the test signal. the modified test signal is combined with the signal received from the rotary member. The combination is performed in the combination 308, which may be, for example, a summation unit. The residual signal received in response to the combination is supplied to the processing unit 204 via the receiving circuit 310 and the A / D converter 320.

The processing unit 204 measures the level of the residual signal, supplies to the compensation circuit 340 a different combination of amplitude and phase shift parameter values, and measures the level of the residual signal (or composite signal) thus obtained. Alternatively, the processing unit 204 may measure another property of the residual signal, such as power. Thus, the processing unit 204 measures the levels of the residual signals obtained by modifying the test signal by 10 different amplitude and phase shift parameter combinations, and selects a parameter combination to obtain the lowest residual signal level. The lowest level indicates that the lowest level compensating signal is optimal for attenuating signal components leaking through the rotation member and / or reflected from the antenna port 330. In an ideal case, the compensation signal has the same amplitude and opposite phase as the test signal leaking from the transmission side to the receiving side. The processing unit 204 then selects an amplitude and phase shift parameter combination that provides the most optimal compensation signal for use in transmitting and receiving information signals in the RFID reader 200.

If the RFID reader 200 comprises multiple antenna ports, the testing step may be performed on each of the antenna ports. Thus, a test signal may be transmitted to each antenna port, and a compensation signal may be generated for each antenna port according to the procedure described above. The parameters of the compensation signal associated with each antenna port can be stored in the memory unit 206 and downloaded from the memory unit at the start of data transmission. The downloaded · · ·] * V parameters then determine the compensation signal used for data transmission. Although antenna ports may have the same design and similar ** ·· 'components, antenna port mismatches may vary. Thus, it may be advantageous to provide a unique compensation signal for each antenna port.

: * "30 During data transmission, the RFID reader 200 may further optimize the parameters of the compensation signal (amplitude and / or phase). The processing unit · · · 204 may initiate a parameter optimization procedure according to a predetermined criterion. The processing unit 204 can input parameters 340 different than those specified during the testing phase in the parameter optimization procedure and monitor the effect of the new parameters on the data reception. If the number of successful read events is higher with the new parameters than those determined during the test step 5, the processing unit 204 may keep If, on the other hand, the number of successful read transactions is smaller with the new parameters, the processing unit 204 may discard the new parameters and return to the old parameters. The advantage of optimizing the parameters of the compensation signal during data transmission is, for example, compensation for changes in component properties caused by temperature changes.

The use of a compensation circuit 340 according to an embodiment of the invention is particularly advantageous in situations where the signal is transmitted and received simultaneously. However, the benefits of the compensation circuit 340 are not limited to this. If there is an external interference signal that is stronger than the transmitted signal leaking to the receiving side, the above procedure may be used to attenuate this external interference signal component. The procedure described above for generating a compensation signal can thus be used to attenuate the strongest signal interfering with the reception of the desired data signal. If there are multiple interference signals, multiple pairs of amplitude and phase control units can be chained, each pair attenuating one interference signal.

: The test signal can be transmitted to the antenna port at a lower power: * ·, · sols than the power level used to transmit the data signal. Thus, the testing phase:. It can also be used to determine whether the antenna port is properly connected to the antenna port. When no antenna is connected to the antenna port or when the • · · "V antenna is broken, the antenna port has a bad mismatch and the test signal is reflected almost completely back to rh '. On the other hand, if a properly operating antenna is connected, a small portion of the transmitted test signal is reflected at the rear antenna port.

Figure 4 illustrates a structure for determining whether an RFID reader according to an embodiment of the invention is provided on a plurality of antenna ports 330,. 332 and 334 connected properly working antenna. The same reference numerals refer to “* · having the same components as in Figure 3. Figure 4 is simplified. block diagram showing only those components that are relevant to the description .. '. V 35 relevant. The switching mechanism 400 controlled by the processing unit 204 is rigidly arranged between the rotation member 306 and the antenna ports 330-334. The switching mechanism 400 is controlled by the processing unit 9 119304 204 to select the antenna port 330, 332 or 334 to which the signal is to be transmitted. Thus, the processing unit 204 controls the switching mechanism to connect the transmitting circuit 302 (via the rotation member 306) to the selected antenna port 330, 332 or 334.

The processing unit 204 may transmit a test signal to each antenna port 330, 332, and 334, and monitor the level of the reflected signal from the antenna ports 330, 332, and 334 through the rotating member 306 and the receiving circuit 310 to determine which antenna ports 330, 332, and 334 are properly connected. The processing unit 204 can control the switch mechanism 400 to switch 10 to transmit transmit circuit 302 to each of the antenna ports 330, 332 and 334 in turn, so that each antenna port is tested separately. The processing unit 204 may first control the switch mechanism 400 to connect the transmit circuit 302 to the first antenna port 330, transmit the test signal to the first antenna port 330 via the transmit circuit 302, receive the reflected signal component through the receive circuit 310, and measure the received signal level. The test signal may be the same test signal as described above with reference to Figure 3. If the measured level of the received signal exceeds a predetermined threshold, the processing unit 204 determines that a properly functioning antenna is not connected to the first antenna port 330. On the other hand, if the measured level 20 of the received signal is less than a threshold, the processing unit 204 determines that a properly functioning antenna is connected to the first antenna port 330. For others: antenna ports 332 and 334 may be subjected to the same procedure. Now that the processing unit 204 has determined which antenna ports 330, 332 and 334 have a · ·:. \ Properly connected antenna, it can select the antenna port (or ports) • * V 25 for data transmission. Thus, the processing unit 204 may transmit the data signal to the antenna port (s) to which a properly functioning antenna is connected via the transmitter circuit 302, and prevent the data signal from being transmitted to the antenna ports that are not connected. If none of the antenna ports is configured to have a properly functioning antenna connected: * ·· 30 processing unit 204 may prevent the data signal from being transmitted to all antenna ports.

. · * ·. If a high power data signal were sent to an antenna port without a · properly functioning antenna, the signal would be reflected to the antenna port. almost completely back to the receiving circuit, and would likely break the receiving circuit. The above-described embodiment of the invention transmits to low-power antenna ports during the test phase to detect antenna ports to which a properly functioning antenna is not connected and to prevent high power data signal from being transmitted to these antenna ports. The testing step can be performed periodically between data signal transmissions. This solution prevents the receiving circuit from breaking if the antenna is accidentally removed from the antenna port 5 or if it is broken. The RFID reader may further notify the reader user of a malfunction at the antenna port through the RFID reader interface. Alternatively, the RFID reader may report a malfunction to another entity, such as a central system that communicates with the RFID reader.

The present solution further enables the antenna to be replaced with a Len-10 lift. For example, if the antenna connected to the antenna port of the RFID reader is replaced with another antenna, the exchange may be performed while the RFID reader is on or even transmitting. Together with the compensation circuit 340 described above, this automated antenna port circuit check further enables one type of antenna to be switched to another type of antenna without impairing the detection performance of the received signals. If the antenna is replaced by another type of antenna, there may be mismatch between the antenna port and the new type of antenna, resulting in stronger reflection components of the signal transmitted to the antenna port. Compensation circuit 340 is now used to suppress these reflective components in the receiving circuit, thereby eliminating data reception degradation effects. Thus, the RFID reader according to an embodiment of the invention automatically adapts to a new type of antenna, and no separate testing and antenna tuning arrangements are required.

It should be noted at this point that the embodiment described above with reference to Fig. 4 may be implemented without the limitations of the compensation circuit of Fig. 3. However, it will be apparent to one skilled in the art that the embodiments of Figs. 3 and 4 · · py may be implemented in the same RFID reader as shown above and in the following description.

FIG. 5 is a flowchart illustrating a process component for offset mismatch in an RFID reader according to an embodiment of the invention. An RFID reader can use a single antenna for simultaneous transmission and reception. Thus, the transmitted and received signals are transmitted. * ··. through the circulatory system. The process begins in block 500.

• · pp. In block 502, a test signal is transmitted to one or more of the antenna ports of the RFID reader during the testing phase. Because the components of the RFID reader are not ideal and because one or more antenna ports may have mismatches, the components of the transmitted signal are leaking into the receiving circuit of the RFID reader. These leaking components of the transmitted test signal are received in block 504.

Block 506 determines whether a properly functioning antenna is connected to each of the one or more antenna ports. This can be determined by measuring the level of the signal components received from one or more antenna ports. The antenna port connected to a properly functioning antenna can then be selected for use in data transmission.

In block 508, a compensation signal is generated based on the signal components received from the selected antenna port. The compensation signal 10 may be generated by directing the test signal transmitted to the selected antenna port to a compensation circuit which modifies the test signal to form a compensation signal to attenuate the components of the test signal leaking to the receiver side. The compensation signal may be generated by modifying the amplitude and phase of the test signal in the compensation circuit, combining the modified test signal with the components of the test signal leaking to the receiver side, and measuring the level of the combined residual signal. This can be accomplished by various amplitude and phase shift modifications, and the amplitude and phase shift parameters of the compensation signal that best attenuate the components of the test signal leaking to the receiver side can be selected.

During the data transmission and reception step, a first data signal and:,: \ * energy bursts at step 510 can be transmitted to the selected antenna port and also to the compensation circuit. receives another data signal. Signal leaking to receiver side:. The components can be attenuated by a compensation signal formed by "V modifying the signal controlled by the compensation circuit with selected amplitude and phase shift parameters in block 512. The compensation signal and the received ***** second data signal can then be combined in block 514 to remove leaking components from the signal. The received second data signal may then be detected in block 516.

• • e

In block 518, the compensation signal (s) .1. parameters. The optimization can be accomplished by changing the parameters and observing the effect on the quality of data reception. The new parameters may be within the • • • proximity of the parameters specified in the test step. If the use of new parameters leads to better reception quality, the new parameters will be retained. Otherwise, the new parameters are discarded and the parameters defined in test step 12 119304 are restored. The optimization can be performed during the specified optimization intervals for each antenna port of the RFID reader.

In block 520, it is determined whether a second testing step is performed to modify the parameters used to generate the compensation signal 5 and to re-check the antenna ports. If it is determined that a test step is performed, the process returns to block 502 for the second test step. Otherwise, the process returns to block 510 for transmitting a second data signal.

Embodiments of the invention may be implemented in an RFID reader 10 comprising a transmit circuit, a receive circuit, and a processing unit operatively coupled to the transmit and receive circuits. The processing unit may be configured to perform at least some of the steps described in connection with the flow chart of Figure 5 and Figure 4. Embodiments may be implemented as computer software comprising commands for compensating for component mismatching to perform a computer process for use in an RFID reader.

The computer software may be stored on a computer software distribution medium readable by a computer or a processor. The computer software distribution medium may include, but is not limited to, an electrical, magnetic, optical, infrared or semiconductor system, device, or transmission medium. The computer software distribution medium may include at least one of the following: a computer readable medium, a software storage medium, a '', line, storage medium, computer readable memory, operating memory, erasable programmable read only memory, computer readable memory software:. * * file distribution package, computer readable signal, telecommunication signal, V · 25, computer readable printed matter and computer readable • · · * “Y package.

• · ·

Although the invention has been described above with reference to the example of the accompanying drawings, it is clear that the invention is not limited thereto, but can be modified in many ways within the scope of the appended claims.

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Claims (13)

A method of performing in a radio frequency identification (RFID) reader comprising one or more antenna ports, the method comprising: during a test phase (502), a test signal is transmitted to one or more of the antenna ports of the RFID reader; components of the transmitted test signal that lacquer to the receiver side of the RFID reader are received (504), characterized in that the method further comprises: on the basis of the received components of the test signal, it is determined (506) whether or not there is a properly functioning antenna coupled to said or multiple antenna ports. Method according to claim 1, characterized in that the method further comprises: a data signal is transmitted (510) to an antenna port which is determined to be connected to a properly functioning antenna and the transmission of the data signal is prevented to the antenna port or ports which are determined to not connected to a properly functioning antenna. Method according to claim 1, characterized in that on the basis of the power level of the received components of the test signal it is determined whether or not a properly functioning antenna is connected to said one. . ·. or multiple antenna ports. Method according to any of the preceding claims, characterized in that the determination comprises:; * y level of the received components of the transmitted test signal which is measured from a particular antenna port; : .i .: the measured level is compared to a predetermined threshold level and it is determined that the data signal can be transmitted to the antenna port if the measured signal falls below the threshold and that the data signal cannot be sent to the antenna port if the measured level exceeds the threshold. · '* · 30 5. A method according to any of the preceding claims, characterized by the test phase being performed periodically between the data transmission intervals. 6. Method according to any of the preceding claims, characterized in that the same antenna port is used for transmitting and receiving ·: radio signals. • •• s • · ♦ • * • · • M 17 1 1 9304 A radio frequency identification (RFID) reader (200), comprising: a transmission circuit (302); a receiving circuit (310); one or more antenna ports (330, 332, 334) which are functionally coupled / coupled to the transmit and receive circuit and a processing unit (204) configured to control the transmit circuit to transmit a test signal to at least one of the RFID reader's antenna ports and via receiving circuit receiving components In the transmitted test signal leaking to the receiving circuit, characterized in that the processing unit is further configured to determine on the basis of the received components of the test signal whether or not a properly functioning antenna is connected to one or several antenna ports. RFID reader according to claim 7, characterized in that the processing unit is configured to determine, based on the power level of the received components of the test signal, whether or not a properly functioning antenna is connected to one or more antenna ports. RFID reader according to claim 7 or 8, characterized in that the processing unit is configured to perform the determination by measuring the level of the received one or more components of the transmitted test signal received from a particular antenna port, comparing the measured level with: predetermined threshold level and determine that the antenna port is connected to a ·· «properly functioning antenna, if the measured signal is below the threshold, and that the antenna port is not connected to a properly functioning antenna if the measured level exceeds the threshold. RFID reader according to claim 9, characterized in that the processing unit is further configured to determine that the transmit circuit should not be connected to the antenna port, if the measured level exceeds the threshold value, and that the transmit circuit shall be connected to the antenna port. , if the measured level is below the threshold. RFID reader according to any of claims 7-10, characterized by ···. further, the RFID reader further comprises a switching mechanism controlled by the processing unit (400) and the processing unit is further configured to control the switching mechanism to connect the transmission circuit to an antenna port which is determined to be connected to a properly functioning antenna and switch off the antenna switching port. or the ports determined / determined that 18 1 1 9304 is not connected to a properly functioning antenna. RFID reader according to any of claims 7-11, characterized in that the RFID reader is configured to use the same antenna port for transmitting and receiving radio signals. A computer program product which encodes a computer program of instructions for executing a computer process for identifying component mismatch in a radio frequency identification (RFID) reader, which process comprises: a transmission circuit in the RFID reader is controlled to send a test signal to At least one of the RFID reader antenna ports, via a receiving circuit in the RFID reader, receives components in the transmitted test signal leaking to the receiving circuit, characterized in that the process further comprises determining, on the basis of the received components of the test signal, whether there is not a properly functioning antenna connected to said one or more antenna ports. * 1 2 3 · • · · • 1 1 • · • · · · · · · · · · · 1 ** · · •% • t · • · # ··· I * 1 1 • · · • · · ··· * · • · ♦ ·· • · • · • · # «· * ·« ·· M * · 2 • «3« · • »·» • M ·· «• i • · ···