Device for mode turbulence

Abstract

Device (10) with an antenna array (11) with at least four antennas (121, 122, 123, 124) arranged offset from one another, wherein each antenna has its own feed line connection (131, 132, 133, 134), wherein the feed line connections of antennas arranged immediately adjacent to each other have a geometric offset of 90° from each other, a control device (14) designed to feed the individual antennas (121, 122, 123, 124) via their respective feed line connections (131, 132, 133, 134), so that the antenna array (11) has different radiation characteristics at different times, wherein a first radiation characteristic has a polarized field distribution, and a second radiation characteristic has an unpolarized field distribution.

Description

[0001] The invention relates to a device for disrupting modes that can occur in the case of electromagnetic waves propagating within a shielded environment. In particular, the invention relates to a device for preventing the formation of standing waves, or a device for displacing standing waves, within a closed metallic environment, such as a housing.

[0002] In systems that can communicate wirelessly using electromagnetic waves, the receiving and transmitting antennas should be matched to each other to ensure good communication quality. RFID (Radio Frequency Identification) systems are one example of such systems.

[0003] For example, to increase range, save transmission power, and reduce radiation emissions, transmitting antennas with a linearly polarized field distribution can be used. This could be, for instance, vertical or horizontal polarization. However, the receiving antennas should also be tuned to the same linear polarization. This means that, for example, in RFID systems, the transponders should assume a specific orientation in space to properly receive the polarized waves. However, in such RFID systems, the transponders are typically distributed chaotically or haphazardly. An example would be goods equipped with transponders in a supermarket, where customers usually place the items in their shopping carts regardless of their orientation.

[0004] To address this issue, modern systems that communicate using electromagnetic waves employ circular polarization instead of linear polarization. This means the transmitting antenna emits circularly polarized waves. As the name suggests, these waves propagate in a circular or helical pattern in space. The advantage is that the receiving antenna (e.g., an RFID transponder) can receive the emitted circularly polarized wave regardless of its orientation in space.

[0005] Linear and circular polarizations are idealized extreme examples of possible wave polarizations. In reality, a mixture of these two polarizations usually occurs, which is generally referred to as elliptical polarization. Therefore, the term elliptical polarization used here encompasses both linear and circular polarization.

[0006] Such wireless communication systems are used, for example, in clinical settings like hospitals for identification and counting, or for cleaning and disinfecting surgical instruments. In this process, surgical instruments equipped with transponders are sterilized in an autoclave. These autoclaves are usually made of stainless steel and therefore provide shielding against electromagnetic waves.

[0007] Within such a shielded, especially metallic, environment, such as in a sterilization chamber (autoclave) for surgical instruments, or even in an oven, tunnel gates, or similar environments, standing waves, so-called modes, form when electromagnetically coupled systems, such as RFID systems, are used. The shape of the modes is determined by the boundary conditions under which the wave propagates. That is, the shape of the modes depends on the frequency or wavelength and also on the shape and dimensions of the space within which the wave propagates.

[0008] In light of this, the modes exhibit local maxima and minima within the space in which they originate. Within the minima, the field strength of the emitted electromagnetic wave is zero, or nearly zero. Therefore, for example, in RFID systems, transponders located in areas of minimum field strength cannot be powered or read.

[0009] Several solutions have already been proposed to address this problem, all aimed at changing the spatial position of the maxima and minima. This is also known as mode shifting or mode sweeping. In the prior art, for example, several spatially separated antennas are switched sequentially, or the transmitting antenna is pivoted or rotated relative to the receiving antenna. Other prior art solutions involve arranging reflectors in different orientations within the space where the electromagnetic waves propagate. While these known solutions do result in suitable mode sweeping, these systems have many individual components that must be aligned with each other, leading to a complex design and thus high production costs.

[0010] For example, EP 2 117 078 B1 describes a network antenna in the form of an array with a first, second, and third patch antenna. The first patch antenna transmits and receives electromagnetic radiation polarized in a first direction. The second patch antenna transmits and receives electromagnetic radiation polarized in a second direction. The third patch antenna transmits and receives electromagnetic radiation polarized in a third direction.

[0011] EP 1 622 221 A1 describes an antenna array with several patch antennas, each arranged at a 90° angle to the others. The feed lines of the respective patch antennas are also at a 90° angle to each other, and this antenna array has circular polarization.

[0012] DE 10 2014 014 628 A1 describes a mode-stirring chamber and two transmitting antennas arranged therein, which are supplied with a corresponding high-frequency signal by a high-frequency signal generator. The phase of the high-frequency signal for one of the two antennas is shifted relative to the phase of the high-frequency signal for the other antenna.

[0013] It is an object of the present invention to improve devices for mode turbulence in such a way that they can be manufactured using simple means and thus cost-effectively, while at the same time allowing good turbulence of modes that may occur during the use of the device, and which in particular can prevent the formation of standing waves in a closed environment or displace standing waves.

[0014] To solve this problem, a device with the features of claim 1 is proposed. Embodiments and further advantageous aspects of the device according to the invention are specified in dependent claims 2 to 13. Furthermore, an RFID reader according to claim 14 and with such a device is proposed. Finally, a system according to claim 15 and with such a device, as well as with a three-dimensional body (e.g., a housing) having a recess in which the electromagnetic waves can propagate, is proposed. Embodiments and further advantageous aspects of the system according to the invention are specified in dependent claims 16 and 17.

[0015] The device according to the invention includes, among other things, an antenna array. The antenna array comprises at least four individual antennas arranged spatially offset from one another. Each antenna has its own feed line connection, also referred to as a port or feed port. The individual feed line connections of the individual antennas are arranged such that the feed line connections of antennas arranged directly adjacent to each other are geometrically offset by 90°. For example, the feed line connection of a first antenna is geometrically offset by 90° from the feed line connection of an immediately adjacent second antenna. In other words, the feed line connections of all antennas are geometrically offset from each other by 90°. Furthermore, a feed signal can be applied to the individual antennas, which serves to feed the individual antennas.The same feed signals can be applied to each antenna, whereby the individual feed signals at the respective feed line terminals can each have a phase shift Δφ, for example, of Δφ = 90°, relative to immediately adjacent feed line terminals. That is, a first antenna can be fed with a first feed signal, and an immediately adjacent second antenna can be fed with a second feed signal, whereby the second feed signal can have a phase shift Δφ relative to the first feed signal, for example, of Δφ = 90°. In other words, the feed signals of immediately adjacent antennas can each have a relative phase shift Δφ, for example, of Δφ = 90°, from each other. The phase shift Δφ can be achieved, for example, by varying the length of the feed line to the respective antenna, which leads to different signal propagation times.It would also be conceivable to directly integrate the phase shift Δφ into the feed network. The antenna array could thus, for example, have a fixed radiation pattern. In the case described above, the antenna array would, for example, have a fixed circularly polarized radiation pattern. The device according to the invention further comprises a control device. The control device is configured to feed the individual antennas via their respective feed line connections in such a way that the antenna array exhibits different radiation patterns at different times. In other words, the control device can feed the individual antennas at a first time in a first configuration in which the antennas radiate such that the antenna array exhibits a first predetermined radiation pattern.At a second point in time, the control device can feed the individual antennas in a second configuration, in which the antennas radiate in such a way that the antenna array exhibits a second predetermined radiation pattern. The first configuration, and thus the first radiation pattern, differs from the second configuration and the second radiation pattern. It should also be noted that the antennas are actively fed in both configurations. This means that the antennas are active in both configurations. Therefore, a configuration and a radiation pattern do not imply that the antennas are not fed and the antenna array is thus inactive, meaning it does not emit any radiation. The radiation pattern described herein refers to the prevailing active radiation pattern of an antenna array with actively fed antennas at the respective point in time.This means that the antenna array with the fed antennas actively emits electromagnetic radiation with its respective prevailing radiation characteristic at any given time. According to this definition, the first radiation characteristic of the antenna array exhibits a polarized field distribution. According to the invention, a second radiation characteristic of the antenna array exhibits an unpolarized field distribution. This unpolarized field distribution is also occasionally referred to herein as a depolarized field distribution. The unpolarized or depolarized field distribution differs from the polarized field distributions described above in that its electromagnetic waves do not exhibit a discernible or preferred polarization.The control device can therefore switch the feed configuration of the individual antennas back and forth between two points in time, so that the antenna array exhibits a different field distribution at the first time than at the second. This shifts the modes occurring in a space, thus also shifting their minima and maxima spatially. This mode mixing ensures that, after the shift, higher field strengths prevail in locations where field strength minima were previously present. Consequently, a receiving antenna can receive the electromagnetic wave in precisely those locations where reception was previously impossible. Switching between two different radiation characteristics of the antenna array offers a simple way to achieve mode mixing. Simultaneously, conventional antenna arrays with a standard feed port arrangement can be used.The invention is based, among other things, on the use of feed configurations for these antenna arrays that are otherwise explicitly avoided in the prior art. While the prior art teaches that this type of antenna array is driven in such a way that the antenna array emits elliptically polarized waves, according to the invention these same antenna arrays are driven in such a way that the antenna array can deliberately emit a depolarized or unpolarized wave.

[0016] Some exemplary embodiments are shown in the drawing and are explained below. They show: Fig. 1 a schematic view of a device according to the invention in an exemplary embodiment, Fig. 2A-2E a schematic view of various possible arrangements of antennas on an antenna array for use in a device according to the invention in an exemplary embodiment, Fig. 3A a schematic view of an antenna array for use in a device according to the invention in an exemplary embodiment, Fig. 3B a schematic view of an antenna array with a fixed feed network for use in a device according to the invention in an exemplary embodiment, Fig. 4A, Fig. 4B a schematic view of an analogous implementation of a control device for controlling an antenna array for use in a device according to an embodiment of the invention, Fig. 5A a 3D plot of a far-field antenna characteristic resulting from a first feed configuration, Fig. 5B a 3D plot of a far-field antenna characteristic resulting from a second feed configuration, Fig. 6A a 2D section of the far-field antenna characteristic from Fig. 5A, Fig. 6B a 2D section of the far-field antenna characteristic from Fig. 5B, Fig. 7 a schematic view of a digital implementation of a control device for controlling an antenna array for use in a device according to an embodiment of the invention, Fig. 8A a flowchart illustrating the switching back and forth between a first and a second power supply configuration according to an exemplary embodiment, Fig. 8B a flowchart illustrating the switching back and forth between a first and a second power supply configuration according to a further embodiment, Fig. 9A a schematic view of a system according to the invention with a device according to the invention, which is operated in a first feeding configuration, Fig. 9B a schematic view of a system according to the invention with a device according to the invention which is operated in a second feeding configuration, and Fig. 10A, Fig. 10B a schematic view of an implementation of a control device for controlling an antenna array for use in a device according to the invention in an exemplary embodiment.

[0017] The following are examples of embodiments described in more detail with reference to the figures, whereby elements with the same or similar function are provided with the same reference numerals.

[0018] Furthermore, radio waves are described herein as an exemplary, non-limiting example of electromagnetic waves. The device according to the invention can preferably be operated in frequency ranges between 30 and 500 kHz, and in particular at about 125 kHz, or between 3 and 30 MHz, and in particular at about 13.56 MHz, or between 400 MHz and 1000 MHz, and in particular at about 433 MHz, or about 868 MHz, or about 915 MHz, or about 950 MHz, or between 2 GHz and 30 GHz, and in particular at about 2.4 to 2.5 GHz, or at about 5.8 GHz.

[0019] Furthermore, individual antennas of an antenna array are described using the non-limiting example of patch antennas. However, it is also conceivable that other antenna designs can be used as an alternative or in addition to patch antennas.

[0020] Furthermore, a three-dimensional body with a recess is described using the non-limiting example of a housing with closed wall structures. However, it is also conceivable that the three-dimensional body has other configurations, such as perforated wall structures, as in shopping baskets and shopping carts. In addition, the three-dimensional body can be closed or at least partially open.

[0021] Furthermore, a metallic coating is described as a non-limiting example of shielding for blocking electromagnetic radiation. However, other materials suitable for shielding electromagnetic radiation can also be used. Moreover, shielding should not necessarily be understood as the complete containment of electromagnetic radiation, but at least as a reduction of it.

[0022] Whenever this document refers to a maximum value, this includes a tolerance range whose values ​​lie within ±10% of the specified maximum value. Similarly, whenever this document refers to a minimum value, this includes a tolerance range whose values ​​lie within ±10% of the specified minimum value.

[0023] Where this document refers to a phase, phase position or phase offset with a specific numerical value, this includes a tolerance range whose values ​​are within ±10% of this numerical value.

[0024] Fig. Figure 1 shows a schematic representation of a device 10 according to the invention in an exemplary embodiment.

[0025] The device 10 comprises an antenna array 11. The antenna array 11 has at least four individual antennas 121, 122, 123, 124, which are spatially offset from one another. The four individual antennas 121, 122, 123, 124 are also spatially spaced apart from one another. The spatial distance between the individual antennas can be an integer or rational multiple of the wavelength λ, i.e., n times λ, with n ∈ ℕ.

[0026] The individual antennas 121, 122, 123, 124 are shown here as example patch antennas. However, other common antenna configurations are also conceivable. The antennas 121, 122, 123, 124 can be arranged on a common substrate 15 and form an antenna array 11.

[0027] In the present example, a first antenna 121 is arranged at the top right of the antenna array 11. Starting from this first antenna 121, a second antenna 122, a third antenna 123 and a fourth antenna 124 are arranged counterclockwise.

[0028] Each antenna 121, 122, 123, 124 has its own feed line connection 131, 132, 133, 134. The feed line connections 131, 132, 133, 134 of antennas 121, 122, 123, 124 that are arranged directly adjacent to each other are geometrically offset from each other by 90°. In other words, the feed line connections 131, 132, 133, 134 have a geometric angular difference of 90° from each other.

[0029] A feed line 161, 162, 163, 164 is arranged at each of the feed terminals 131, 132, 133, 134. A feed signal for feeding the antennas 121, 122, 123, 124 can be applied to the feed lines 161, 162, 163, 164, where the feed signal is hereinafter referred to simply as the signal. The signals applied to the respective feed lines 161, 162, 163, 164 can have a fixed, preset relative phase offset Δφ from each other. This fixed, preset phase shift Δφ can be achieved, for example, by varying the length of the feed lines 161, 162, 163, 164 (also referred to as feed lines) of the respective antennas 121, 122, 123, 124, resulting in different signal propagation times. Alternatively, the phase shift Δφ could be directly integrated into the feed network.

[0030] For example, the feed line 161 of the first antenna 121 can be defined as a reference line, which defines a reference phase of φ = 0°.

[0031] The second antenna 122 and the fourth antenna 124 are each arranged directly adjacent to the first antenna 121. In the present example, the feed terminal 132 of the second antenna 122 is geometrically offset by 90° relative to the feed terminal 131 of the first antenna 121. That is, the feed terminal 132 of the second antenna 122 has a geometric angular difference of 90° with respect to the feed terminal 131 of the first antenna 121. In addition to the geometric angular difference of 90°, in this embodiment the signal fed into the feed terminal 132 of the second antenna 122 has a phase shift of Δφ. 21 = 90° relative to the signal fed into the feed point 131 of the first antenna 121, which represents the reference signal with a phase angle φ = 0°.

[0032] The third antenna 123 is arranged directly adjacent to the second antenna 122. In the present example, the feed terminal 133 of the third antenna 123 is geometrically offset by 90° relative to the feed terminal 132 of the second antenna 122. That is, the feed terminal 133 of the third antenna 123 has a geometric angular difference of 90° with respect to the feed terminal 132 of the second antenna 122. In addition to the geometric angular difference of 90°, in this embodiment the signal fed into the feed terminal 133 of the third antenna 123 has a phase shift of Δφ. 32= 90° relative to the signal fed into the feed terminal 132 of the second antenna 122. Therefore, the feed terminal 133 of the third antenna 123 has a geometric angle difference of 180° relative to the feed terminal 131 of the first antenna 121, and the signal fed into the feed terminal 133 of the third antenna 123 has a phase shift of Δφ relative to the reference signal fed into the feed terminal 131 of the first antenna 121 with a reference phase angle φ = 0°. 31 = 180° up.

[0033] The fourth antenna 124 is arranged directly adjacent to the third antenna 123. In the present example, the feed terminal 134 of the fourth antenna 124 is geometrically offset by 90° relative to the feed terminal 133 of the third antenna 123. That is, the feed terminal 134 of the fourth antenna 124 has a geometric angular difference of 90° with respect to the feed terminal 133 of the third antenna 123. In addition to the geometric angular difference of 90°, in this embodiment the signal fed into the feed terminal 134 of the fourth antenna 124 has a phase shift of Δφ. 43= 90° relative to the signal fed into the feed terminal 133 of the third antenna 123. Therefore, the feed terminal 134 of the fourth antenna 124 has a geometric angle difference of 270° relative to the feed terminal 131 of the first antenna 121, and the signal fed into the feed terminal 134 of the fourth antenna 124 has a phase shift of Δφ relative to the reference signal fed into the feed terminal 131 of the first antenna 121 with a reference phase angle φ = 0°. 41 = 270° up.

[0034] Since the fourth antenna 124 is arranged directly adjacent to the first antenna 121, in the present example the feed terminal 134 of the fourth antenna 124 is geometrically offset by + 270° to the feed terminal 131 of the first antenna 121, which in turn is equivalent to a geometric angular difference of - 90° and a phase shift of Δφ 14= - 90° relative to the reference signal fed into the feed point 131 of the first antenna 121 with reference phase φ = 0°.

[0035] The feed line connections 131, 132, 133, 134 of antennas 121, 122, 123, 124 arranged directly adjacent to each other are therefore all geometrically offset from each other by 90° in magnitude.

[0036] In summary, the signals fed into antennas 121, 122, 123, 124, which are arranged directly adjacent to each other, can have a fixed, preset phase shift of Δφ = 90°, i.e., Δφ = ±90°. This corresponds to a feed configuration that results in a polarized radiation pattern.

[0037] An antenna that is immediately adjacent is defined as the antenna that has the smallest spatial distance to the antenna under consideration. For example, the second and fourth antennas 122 and 123 would each be immediately adjacent to the first antenna 121, whereas the diagonally opposite third antenna 123 has a greater spatial distance to the first antenna 121 than the second and fourth antennas 122 and 124, and therefore is not an immediately adjacent antenna.

[0038] The device 10 according to the invention further comprises a control device 14. As explained below with reference to the Fig. 4A and Fig. As explained in more detail in section 4B, the control device 14 can be implemented as an analog component with phase actuators 41 and / or amplitude actuators 44 and corresponding switches 42, 43, or the control device 14 can be implemented digitally ( Fig. 7), for example by means of a digital signal processing 72 on an FPGA, ASIC, DSP or microcontroller and an optional analog front end 71 arranged between the digital domain and the antenna array 11.

[0039] In any case, the control device 14 is designed according to the invention to feed the individual antennas 121, 122, 123, 124 via their respective feed line connections 131, 132, 133, 134 in different feed configurations, so that the antenna array 11 has different radiation characteristics at different times.

[0040] This means that the control device 14 provides a first feed configuration at a first time, in which the antennas 121, 122, 123, 124 are controlled or fed such that the antenna array 11 exhibits a first radiation characteristic at this first time. The control device 14 provides a second feed configuration at a second time, in which the antennas 121, 122, 123, 124 are controlled or fed such that the antenna array 11 exhibits a second radiation characteristic at this second time, which differs from the first.

[0041] The first radiation characteristic exhibits a polarized field distribution. This means that in the first feed configuration, antennas 121, 122, 123, and 124 are driven or fed in such a way that the antenna array 11 emits polarized waves. These can be elliptically polarized, i.e., linearly and / or circularly polarized waves, with the specific type of polarization depending on the type of first feed configuration, as will be discussed later with reference to the Fig. 4A and Fig. 4B will be explained in more detail.

[0042] According to the invention, the second radiation characteristic exhibits an unpolarized or depolarized field distribution. That is, in the second feed configuration, the antennas 121, 122, 123, 124 are driven or fed in such a way that the antenna array 11 emits unpolarized or depolarized waves. This will also be discussed later with reference to the Fig. 4A and Fig. 4B is explained in more detail.

[0043] First, however, with reference to the Fig. 2A to 2E, as well as 3A and 3B, are possible configurations of antenna arrays 11 that can be used in the device 10 according to the invention.

[0044] Fig. 2A shows a single antenna 121, which can also be called a single radiator.

[0045] Fig. Figure 2B shows an antenna array 11, comparable to the one previously mentioned with reference to Fig. 1. Antenna array 11 was discussed. This is a 2x2 array on which two times two individual antennas 121, 122, 123, 124 are arranged.

[0046] Fig. Figure 2C shows another embodiment of an antenna array 11. This is a 2x4 array on which a total of eight individual antennas are arranged, with four individual antennas arranged in each of two parallel rows.

[0047] Fig. Figure 2D shows another embodiment of an antenna array 11. This is a 4x2 array on which a total of eight individual antennas are arranged, with four individual antennas arranged in each of two parallel columns.

[0048] Fig. Figure 2E shows another embodiment of an antenna array 11. This is a 4x4 array on which a total of sixteen individual antennas are arranged, with four individual antennas arranged in each of four parallel rows or columns.

[0049] For further description, the 2×2 arrangement will be used, as referred to in Fig. 1 discussed, considered, since all other embodiments can be traced back to a parallelization of this 2×2 arrangement.

[0050] Fig. Figure 3A shows such a 2×2 array 11 with four individual antennas 121, 122, 123, 124 with feed connections 131, 132, 133, 134 each geometrically offset by 90° from each other. Fig. Figure 3B shows a possible implementation of a feed network with a fixed phase / amplitude setting, resulting in a fixed preset phase offset Δφ. This feed network features a 2x2 antenna array 11 with four individual patch antennas 121, 122, 123, 124 on a common substrate 15.

[0051] The Fig. 4A and Fig. Figure 4B shows a schematic block diagram of a control device 14, which can be used to provide the above-mentioned different feed configurations for the antenna array 11.

[0052] Fig. Figure 4A shows an example of a feed network in which the individual antennas 121, 122, 123, 124 are fed such that the signals fed to immediately adjacent antennas 121, 122, 123, 124 have a fixed, preset phase shift (e.g., due to the line length) of Δφ = ±90° relative to each other. In the depicted 2x2 antenna array 11, the feed line 161 of the first antenna 121 defines the reference phase with a phase angle φ = 0°. This means that the signal applied to the first antenna 121 has a reference phase of φ = 0°. The signal applied to the second antenna 122 has a fixed, preset phase shift of Δφ. 21= 90° relative to the signal applied to the first antenna 121. In general terms, the individual signals fed into antennas arranged directly adjacent to each other have a fixed, preset phase offset of Δφ = ±90°.

[0053] As previously mentioned with reference to Fig. As already described in Figure 1, the feed terminal 132 of the second antenna 122 is geometrically offset by 90° relative to the feed terminal 131 of the first antenna 121, the feed terminal 133 of the third antenna 123 is geometrically offset by 180° relative to the feed terminal 131 of the first antenna 121, and the feed terminal 134 of the fourth antenna 124 is geometrically offset by 270° relative to the feed terminal 131 of the first antenna 121. Antennas arranged directly adjacent to each other are geometrically offset by 90° relative to each other, as discussed previously with reference to Figure 1.

[0054] Fig. Figure 4B shows an exemplary analog embodiment of the control device 14 by means of which different feed configurations can be provided. The control device 14 can have a number of ports corresponding to the number of feed connections 131, 132, 133, 134, wherein each port can be connected via a feed line or supply line 161, 162, 163, 164 to a feed connection 131, 132, 133, 134 of an antenna 121, 122, 123, 124. In the present example, port 1 is connected to the feed terminal 131 of the first antenna 121, port 2 is connected to the feed terminal 132 of the second antenna 122, port 3 is connected to the feed terminal 133 of the third antenna 123, and port 4 is connected to the feed terminal 134 of the fourth antenna 124.

[0055] In each branch or path belonging to a port 1 to port 4, the control device 14 can have at least one phase actuator 41 and / or at least one amplitude actuator 44. The phase actuators 41 are used to adjust the phase of the respective signal. Depending on the selected feed configuration, the phases of the individual signals can be reversed using the phase actuators 41. The amplitude actuators 44 are used to adjust the amplitudes of the individual signals to approximately the same signal level. This is advantageous because, for example, fixed preset feed networks can have feed lines 161, 162, 163, 164 of different lengths, which can attenuate the signals to varying degrees. Using the amplitude actuators 44, the different attenuations can be compensated for and the amplitudes of the individual signals adjusted to approximately the same level.

[0056] In the non-limiting example shown here, the control device 14 (from top to bottom) has four phase actuators (φ=0°, φ=90°, φ=180°, φ=270°) and one associated amplitude actuator 44 in the branch belonging to port 2. In the branch belonging to port 1, the control device 14 has two phase actuators (φ=0°, φ=180°) and one associated amplitude actuator 44. In the branch belonging to port 4, the control device 14 has four phase actuators (φ=0°, φ=90°, φ=180°, φ=270°) and one associated amplitude actuator 44. In the branch belonging to Port 3, the control device 14 has two phase actuators (φ=0°, φ=180°) and an associated amplitude actuator 44.

[0057] A switch 42, 43 can be arranged in each branch before and after the phase actuators 41. Amplitude or power actuators 44 can also be provided for adjusting the amplitude or antenna power, respectively. Optionally, the control device 14 can include a reading device 45. This could, for example, be an RFID reading unit that is integrated into the control device 14 or at least connectable to it.

[0058] In Fig. Figure 4B shows different examples of feed configurations in the upper right corner, represented by circled Arabic numerals ①, ②, ③, and ④. As mentioned earlier, in a first feed configuration, antennas 121, 122, 123, and 124 are fed such that the antenna array 11 exhibits a first radiation pattern with a field distribution of elliptical polarization. Paths ① and ③ show examples of such a first feed configuration.

[0059] According to the invention, the antennas 121, 122, 123, 124 are fed in a second feed configuration such that the antenna array 11 exhibits a second radiation characteristic with a field distribution without polarization or with a positively or negatively depolarized field distribution. Paths ③ and ④ show examples of such a second feed configuration.

[0060] In the first path ③, antennas 121, 122, 123, and 124 are fed such that the antenna array 11 exhibits a field distribution with left-circular polarization. As mentioned earlier, the individual antennas 121, 122, 123, and 124 are fed such that the signals fed to immediately adjacent antennas 121, 122, 123, and 124 have a fixed, preset phase shift (e.g., due to the line length) of Δφ = ±90° relative to each other. In the first path ③, an initial feed configuration is provided in which the control device 14 does not perform any phase inversion of the signals. This results, purely by way of example, in a fixed left-circular polarization of the antenna array 11.Due to the fixed preset relative phase shift of Δφ = ±90° and no further phase rotation performed by the control device 14, the individual signals fed into the respective antennas 121, 122, 123, 124 thus have the fixed preset phase shift of φ = +90° to each other.

[0061] In the second path ③, an alternative first feed configuration is provided. Here, antennas 121, 122, 123, and 124 are fed such that the antenna array 11 exhibits a field distribution with right-hand circular polarization. While a left-hand circular polarization of the antenna array 11 is also preset here (purely as an example), in the second path ②, compared to the left-hand circular polarization mentioned above, the phase angles of the signals applied to the second and fourth antennas 122 and 124 are rotated by the control device 14 by φ = 180° each. The individual signals fed to the respective antennas 121, 122, 123, and 124 thus exhibit a relative phase shift of Δφ = -90° to each other.

[0062] This means that in the first feed configuration (first path ④ or second path ®) the individual signals fed into immediately adjacent antennas 121, 122, 123, 124 have a phase offset of Δφ = 90° to each other.

[0063] Instead of the circular polarizations mentioned as examples, linear polarizations can also be used in the first feed configuration. Generally, circular and linear polarizations are combined here under the term elliptical polarization. That is, in both the first path ④ and the second path ®, the antennas 121, 122, 123, 124 are fed in such a way that the antenna array 11 exhibits a field distribution with elliptical polarization.

[0064] In the example shown here, the antenna array 11 has a fixed preset radiation characteristic with left circular polarization, or more generally, with elliptical polarization.

[0065] The third path ④ and the fourth path ④ represent two exemplary possibilities for a second feed configuration and thus a part of the concept according to the invention. Here, the individual antennas 121, 122, 123, 124 are fed in such a way that the previously described fixed elliptical polarization with a fixed preset phase shift of Δφ = 90° is compensated. In other words, the individual antennas 121, 122, 123, 124 are fed in such a way that the antenna array 11 is deliberately depolarized despite the fixed radiation characteristic with elliptical polarization. As described below using a non-limiting example, phase shifts can be performed on one or more signals for this purpose.

[0066] In an example of a second feed configuration, according to the third path @, antennas 121, 122, 123, and 124 are fed such that the antenna array 11 exhibits a positively depolarized or unpolarized field distribution. The fixed, preset phase shift of Δφ = 90° between immediately adjacent antennas 121, 122, 123, and 124 is compensated. In this example, the phases of those signals that have a fixed, preset phase shift Δφ relative to the reference phase φ = 0° are rotated such that all signals ultimately exhibit no phase shift Δφ = 0 relative to the reference phase.

[0067] This means that the reference phase of φ = 0° of the signal fed into the first antenna 121 remains constant in the third path ③. The phase of the signal fed into the second antenna 122 has a fixed, preset phase shift of Δφ relative to the first antenna 121. 21 = 90° and is therefore rotated by φ = 270°. As a result, the signal fed into the second antenna 122 no longer exhibits a phase shift (Δφ = 0°) compared to the signal fed into the first antenna 121 with the reference phase φ = 0°. The phase of the signal fed into the third antenna 123 has a fixed, preset phase shift of Δφ relative to the first antenna 121. 31= 180° and is therefore rotated by φ = 180°. As a result, the signal fed into the third antenna 123 no longer exhibits a phase shift (Δφ = 0°) compared to the signal fed into the first antenna 121 with the reference phase φ = 0°. The phase of the signal fed into the fourth antenna 124 has a fixed, preset phase shift of Δφ relative to the first antenna 121. 41 = 270° and is therefore rotated by φ = 90°. As a result, the signal fed into the fourth antenna 124 no longer exhibits a phase shift (Δφ = 0°) compared to the signal fed into the first antenna 121 with the reference phase φ = 0°.

[0068] In another example of a second feed configuration, according to the fourth path ④, antennas 121, 122, 123, and 124 are fed such that the antenna array 11 has an opposite, i.e., negatively depolarized or unpolarized, field distribution. Here, too, the fixed preset phase shift of Δφ = 90° between immediately adjacent antennas 121, 122, 123, and 124 is compensated. However, in this example, the reference phase is rotated by φ = 180°, meaning the reference phase at port 1 is no longer φ = 0° but φ = 180°. Furthermore, the phases of those signals that have a fixed preset phase offset Δφ relative to the reference phase φ = 180° are rotated in such a way that all signals as a result no longer have a phase offset Δφ = 0 relative to the reference phase.

[0069] This means that the phase of φ = 0° of the signal fed into the first antenna 121 is first rotated by 180°, so that the new reference phase is φ = 180°. The phase of the signal fed into the second antenna 122 has a fixed, preset phase shift of Δφ relative to the first antenna 121. 21 = 90° and is therefore rotated by φ = 90°. As a result, the signal fed into the second antenna 122 no longer exhibits a phase shift (Δφ = 0) compared to the signal fed into the first antenna 121 with the reference phase φ = 180°. The phase of the signal fed into the third antenna 123 has a fixed, preset phase shift of Δφ relative to the first antenna 121. 31= 180° and is therefore not rotated further. As a result, the signal fed into the third antenna 123 no longer exhibits a phase shift (Δφ = 0) compared to the signal fed into the first antenna 121 with the reference phase φ = 180°. The phase of the signal fed into the fourth antenna 124 has a fixed, preset phase shift of Δφ relative to the first antenna 121. 41 = 270° and is therefore rotated by φ = 270°. As a result, the signal fed into the fourth antenna 124 no longer exhibits a phase shift (Δφ = 0°) compared to the signal fed into the first antenna 121 with the reference phase φ = 180°.

[0070] The first radiation characteristic is therefore an elliptical radiation characteristic, and the second radiation characteristic is a positively depolarized or a negatively depolarized radiation characteristic.

[0071] According to the invention, the first radiation characteristic (elliptical polarization) of the antenna array 11 can be fixedly preset, and the second radiation characteristic (depolarized) of the antenna array 11 can be switched on by means of the control device 14 despite the fixed preset of the first radiation characteristic.

[0072] In Fig. In Figure 4B, the Arabic numerals ①, ②, ③, and ④ of the respective feed configurations are found on the respective phase adjusters 41. For each example described above, the respective configuration of the phase adjusters 41 for the first and second radiation characteristics is shown. The following table lists, for each path, the phase shift of the respective feed signal at each port relative to the reference signal φ=0° that can be set by means of a phase adjuster 41: Table 1 Port 1 Port 2 Port 3 Port 4 ① Linkszirkular φ=0° φ=0° φ=0° φ=0° ② Rechtszirkular φ=0° φ=180° φ=0° φ=180° ③ Depolarisiert + φ=0° φ=270° φ=180° φ=90° ④ Depolarisiert - φ=180° φ=90° φ=0° φ=270°

[0073] As mentioned at the outset, the first path ① provides a variant of a first feed configuration that generates a left-circular field distribution at the antenna array 11. The feed signals applied to the respective feed terminals 131, 132, 133, 134 each have a fixed phase offset of Δφ = ±90° relative to each other. This results in a left-circular field, and the individual phase adjusters 41 in the first path ① do not need to perform any further phase rotation; that is, the phase angle of all phase adjusters 41 in the first path ① is φ = 0°.

[0074] According to such an embodiment, the control device 14 according to the invention can be configured to feed the individual antennas 121, 122, 123, 124 in a first feed configuration such that the antenna array 11 has the first radiation characteristic, wherein the control device 14 can be configured to feed each individual antenna 121, 122, 123, 124 with a feed signal, wherein the feed signals to be fed to the respective antenna 121, 122, 123, 124 each have a fixed preset phase offset of Δφ = 90° in magnitude, i.e. Δφ = ±90°.

[0075] In the second path ②, another variant of a first feed configuration is provided, which generates a right-circular field distribution at the antenna array 11. In the second path ②, the phases at ports 2 and 4 are now each rotated by φ = 180° relative to the reference signal with φ = 0°, and port 3 is driven with a phase rotation of φ = 0°, so that the third antenna 123 operates with the fixed preset phase difference of Δφ. 31The phase shift is 180° relative to the reference signal φ = 0°. This results in a right-hand circular field. The individual phase shifters 41 in the second path ② therefore perform a phase shift of φ = 180° (compared to the reference phase of φ = 0° of the reference signal fed into the first antenna 121) on the feed signal at port 2 and port 4, respectively. This feed signal is then fed into the feed terminals 132 and 134 of the second and fourth individual antennas 122 and 124.In other words, the feed signals provided by the control device 14, which are fed into the second and fourth individual antennas 122, 124, have a phase shift of Δφ = 180° each compared to the reference phase of φ = 0° of the reference signal fed into the first antenna 121, and the feed signals provided by the control device 14, which are fed into the first and third individual antennas 121, 123, have a phase shift of Δφ = 0° each compared to the reference phase of φ = 0° of the reference signal fed into the first antenna 121.

[0076] In this feed configuration according to the second path ②, the feed signals at the respective feed terminals 131, 132, 133, 134 each exhibit a relative phase shift of Δφ = -90°. However, due to the phase shift of φ = 180° of the signals fed into the second and fourth antennas 122, 124, a right-circular field is not generated.

[0077] According to such an embodiment, the control device 14 according to the invention can also be configured to feed the individual antennas 121, 122, 123, 124 in a first feed configuration such that the antenna array 11 has the first radiation characteristic, wherein the control device 14 can be configured to feed each individual antenna 121, 122, 123, 124 with a feed signal such that the feed signals fed to the respective antenna 121, 122, 123, 124 each have a phase offset of Δφ = 90° in magnitude, i.e. Δφ = ±90°.

[0078] In the third path ③, a variant of a second feed configuration according to the invention is provided, which generates a positively depolarized field distribution at the antenna array 11. In the third path ③, the individual phase adjusters 41 perform a phase shift on the feed signals that are fed to the feed terminals 132, 133, 134 of the second, third, and fourth individual antennas 122, 123, 124, in order to compensate for the fixed preset phase offset of Δφ = 90° to the respective adjacent antenna.

[0079] This means that the control device 14 is designed to rotate the phases of the respective signals so that the signals fed into the respective antennas 121, 122, 123, 124 no longer exhibit any phase shift with each other. The fixed preset phase shift Δφ is thus compensated.

[0080] According to such an embodiment, the control device 14 according to the invention can therefore be configured to feed the individual antennas 121, 122, 123, 124 in a second feed configuration such that the antenna array 11 has the second radiation characteristic, wherein the control device 14 can be configured to feed each individual antenna 121, 122, 123, 124 with a feed signal such that the feed signals fed to the respective antenna 121, 122, 123, 124 no longer have a phase offset Δφ with each other.

[0081] In the third path ③, the first line 161 defines the reference phase φ = 0°. The phase of the signal at port 2 is rotated by φ = 270° using the control device 14, for example, to achieve the fixed preset phase offset of Δφ. 21The phase shift of Δφ is compensated for by 90° on the second line 162, so that there is no longer any phase shift Δφ to the reference phase φ = 0°. The phase of the signal at port 3 is rotated by φ = 180° to compensate for the fixed, preset phase shift of Δφ. 31 = 180° at the third line 163 to compensate, so that there is no longer any phase shift Δφ to the reference phase φ = 0°. The phase of the signal at port 4 is rotated by φ = 90° to compensate for the fixed preset phase shift of Δφ. 41 The phase shift of 270° at the fourth line 164 is compensated for, so that there is no longer any phase shift Δφ relative to the reference phase φ = 0°. In total, the signals fed into the respective antennas no longer exhibit any phase shift Δφ relative to each other due to the phase shifts mentioned above. The fixed, preset phase shift Δφ is thus compensated.

[0082] In the fourth path ④, a further variant of a second feed configuration according to the invention is provided, which generates a negatively depolarized field distribution at the antenna array 11. Here, the reference phase of the feed signal fed to the first antenna 121 is rotated by φ = 180° compared to the previously described second feed configuration, which generates a positively depolarized field distribution; that is, the reference phase in this case is not φ = 0° but φ = 180°. The phases of the other feed signals, which serve to feed the second, third, and fourth antennas 122, 123, 124 respectively, are also rotated by φ = 180° compared to the previously described positive depolarization.

[0083] Here too in the fourth path ④, the individual phase adjusters 41 perform a phase shift on the feed signals, which are fed into the feed terminals 132, 133, 134 of the second, third and fourth individual antennas 122, 123, 124, in order to compensate for the fixed phase offset of Δφ = 90° to the respective adjacent antenna.

[0084] This means that the control device 14 is designed to rotate the phases of the respective signals so that the signals fed into the respective antennas 121, 122, 123, 124 no longer exhibit a phase shift Δφ with each other. In other words, the fixed, preset phase shift Δφ is compensated.

[0085] In the fourth path ④, the phase of the signal at port 1 is rotated by φ = 180° using the control device 14, which represents the new reference phase. The phase of the signal at port 2 is rotated by φ = 90°, so that there is no longer any phase shift Δφ relative to the reference phase φ = 180°. The phase of the signal at port 3 is not rotated, so that there is no longer any phase shift Δφ relative to the reference phase φ = 180°. The phase of the signal at port 4 is rotated by φ = 270°, so that there is no longer any phase shift Δφ relative to the reference phase φ = 180°. In summary, due to the phase rotations mentioned above, the signals fed into the respective antennas no longer exhibit any phase shift Δφ relative to each other.

[0086] According to such an embodiment, the control device 14 according to the invention can therefore be configured to feed the individual antennas 121, 122, 123, 124 in a second feed configuration such that the antenna array 11 has the second radiation characteristic, wherein the control device 14 can be configured to feed each individual antenna 121, 122, 123, 124 with a feed signal such that the feed signals fed to the respective antenna 121, 122, 123, 124 do not have a phase shift Δφ with each other. The fixed preset phase shift Δφ is thus compensated.

[0087] In summary, it can be stated that the control device 14 according to the invention can be designed to rotate the phases of the individual feed signals with which the individual antennas 121, 122, 163, 164 are fed, despite a fixed preset relative phase shift Δφ (e.g., due to the length of the respective supply lines 161, 162, 163, 164), such that the feed signals no longer exhibit any phase shift with each other. The fixed phase shift Δφ is thus compensated.

[0088] On the in the Fig. 4A and Fig. As illustrated in the specific example shown in Figure 4B, in such an embodiment the control device 14 according to the invention can be configured to feed the individual antennas 121, 122, 123, 124 in the second feed configuration in such a way that relative to a reference phase of φ = 0° • the phase of the feed signal fed into the first antenna 121 is not reversed, • the phase angle of the feed signal fed into the second antenna 122 is rotated by a phase angle of φ = 270°, • the phase of the feed signal fed into the third antenna 123 is rotated by a phase angle of φ = 180°, and • the phase of the feed signal fed into the fourth antenna 124 is rotated by a phase angle of φ = 90°.

[0089] This second feed configuration results in a second radiation characteristic with a positively depolarized field. A radiation characteristic with a negatively depolarized field, on the other hand, can be achieved with an alternative second feed configuration in which the control device 14 according to the invention is configured to feed the individual antennas 121, 122, 123, 124 in such a way that, relative to a reference phase of φ = 180° • the phase of the feed signal fed into the first antenna 121 is rotated by a phase angle of φ = 180°, • the phase angle of the feed signal fed into the second antenna 122 is rotated by a phase angle of φ = 90°, • the phase of the feed signal fed into the third antenna 123 is not reversed, and • the phase of the feed signal fed into the fourth antenna 124 is rotated by a phase angle of φ = 270°.

[0090] According to the invention, the fixed preset phase difference Δφ of the power supply network at the respective feed connections 131, 132, 133, 134 is compensated. This fixed preset phase shift Δφ is described here using the non-limiting example of Δφ = 90°. The fixed preset phase shift Δφ, also referred to as phase difference Δφ, can generally have other values.

[0091] The Fig. 10A and Fig. 10B are similar to those discussed above. Fig. 4A and Fig. 4B and show a general example of setting phase positions of the individual feed signals using the control device 14 to generate a second radiation characteristic with a depolarized field.

[0092] Here again, the first line 161 defines the reference phase with a phase angle φ = 0°. The control device 14 applies a phase shift of φ1 = 0° plus an offset of φ = x° to the signal fed into the first antenna 121 at port 1, i.e., φ1 = 0° + x°. The control device 14 applies a phase shift of φ2 = 270° plus the same offset of φ = x° to the signal fed into the second antenna 122 at port 2, i.e., φ2 = 270° + x°. The control device 14 applies a phase shift of φ2 = 270° plus the same offset of φ = x° to the signal fed into the third antenna 123 at port 3. CP3 = 180° plus the same offset of φ = x°, i.e., φ3 = 180° + x°. The control device 14 applies a phase shift of φ4 = 90° plus the same offset of φ = x° to the signal to be fed into the fourth antenna 124 at port 4, i.e., φ4 = 90° + x°.

[0093] To obtain the second radiation characteristic with the depolarized field distribution, the offset φ = x° should have the same value at all antenna ports. The following applies to the offset value x: 0° ≤ x ≤ 360°.

[0094] On the in the Fig. 10A and Fig. As illustrated in the specific example shown in Figure 10B, in such an embodiment the control device 14 according to the invention can be configured to feed the individual antennas 121, 122, 123, 124 in the second feed configuration in such a way that relative to a reference phase of φ = 0° • the phase of the feed signal fed into the first antenna 121 is rotated by an offset angle φ = x°, • the phase of the feed signal fed into the second antenna 122 is rotated by a phase angle of φ = 270° plus the same offset angle φ = x°, • the phase of the feed signal fed into the third antenna 123 is rotated by a phase angle of φ = 180° plus the same offset angle φ = x°, and • the phase of the feed signal fed into the fourth antenna 124 is rotated by a phase angle of φ = 90° plus the same offset angle φ = x°, where for the offset angle x: 0° ≤ x ≤ 360°.

[0095] This therefore describes a generally valid possibility for a second feed configuration to generate a second radiation characteristic with a depolarized field.

[0096] As mentioned at the outset, in contrast, there is a first feed configuration for generating a first radiation characteristic with a polarized field. Apart from the circular polarizations mentioned above as examples, the control device 14 makes it possible to provide further alternative first feed configurations in which the antennas 121, 122, 123, 124 generate linearly polarized waves instead of the circularly polarized waves mentioned as examples. This possibility is described in the Fig. 4A and Fig. 4B is not explicitly shown for the sake of clarity. Linear polarization can involve horizontally or vertically polarized waves.

[0097] As mentioned at the outset, all polarization types are summarized here under the common term elliptical polarization. All such initial feed configurations that lead to elliptical polarization share the common characteristic of exhibiting a field strength maximum at the center of the antenna array 11.

[0098] This is in Fig. 5A clearly shows. Here, an example of a 3D plot of a far-field antenna diagram 51 of a 2x2 antenna array 11 is shown, which was fed in a first feed configuration in which the individual antennas 121, 122, 123, 124 of the array 11 generate linearly polarized waves.

[0099] Each individual antenna 121, 122, 123, 124 generates a respective field strength maximum 521, 522, 523, 524 at the center of the respective individual antenna 121, 122, 123, 124. In the feed configuration shown, however, a field strength maximum 52 occurs at the center of the array 11. Maxa result of a superposition of the field distribution of the individual antennas 121, 122, 123, 124 in the first feed configuration.

[0100] In Fig. Figure 5B shows a second feed configuration according to the invention, in which positively or negatively depolarized waves are established. Here again, each individual antenna 121, 122, 123, 124 generates a respective field strength maximum 521, 522, 523, 524 at the center of the respective individual antenna 121, 122, 123, 124. In contrast to the one shown in Fig. However, the first feed configuration shown in 5A results in the following: Fig. 5B shown in the second feed configuration according to the invention, a field strength minimum 52 Min in the center of the antenna array 11.

[0101] According to such an embodiment, the first radiation characteristic can therefore have a first field distribution which has a maximum field strength 52 in the center of the antenna array 11. Maxexhibits, and the second radiation characteristic can exhibit a second field distribution which has a minimum field strength of 52 in the center of the antenna array 11 Min exhibits.

[0102] The case of minima and maxima described above represents an extreme example. In general, for the concept according to the invention, it is sufficient if the first field distribution in the center of the antenna array 11 has a different field strength than the second field distribution.

[0103] According to such an embodiment, the first radiation characteristic can have a first field distribution, and the second radiation characteristic can have a second field distribution, wherein the first field distribution has a greater field strength, or alternatively a smaller field strength, in the center of the antenna array 11 than the second field distribution.

[0104] The Fig. 6A and Fig. Figure 6B shows, for clarification, 2D sections of the radiation characteristics resulting from the respective feed configurations. Fig. Figure 6A shows a 2D section of the 3D plot from Fig. 5A. Here it can be seen that in the first feed configuration, which leads to polarized waves, a field strength maximum occurs. 52 Max can be located in the center of antenna array 11.

[0105] Fig. 6B, on the other hand, shows a 2D section of the 3D plot from Fig. 5B. Here it can be seen that in the second feed configuration according to the invention, which leads to positively or negatively depolarized waves, a field strength minimum 52 Min can be located in the center of antenna array 11.

[0106] Fig. Figure 7 shows a further embodiment of a device 10 according to the invention, but in a possible exemplary digital implementation. Functionally, the device essentially corresponds to the one described in the Fig. 4A and Fig. The analogous design described in section 4B explains why elements with the same or similar function are provided with the same reference symbols. For its functional description, please refer to the explanations above.

[0107] Antenna array 11 is again implemented as an example of a 2x2 array with four individual antennas 121, 122, 123, 124, wherein the feed terminals 131, 132, 133, 134 of the individual antennas 121, 122, 123, 124 are geometrically offset from each other by 90°. The feed terminal 131 of the first antenna 121 defines the reference phase of 0°.

[0108] The difference to the analog design according to the Fig. 4A and Fig. 4B consists, among other things, in the provision of a digital processing unit 72, such as a microcontroller, an ASIC, an FPGA or a DSP, which takes over the setting of the phases and amplitudes of the respective supply signals in order to provide the different supply configurations.

[0109] Furthermore, an analog frontend 71 for controlling the antenna array 11 can be provided between the antenna array 11 and the digital processing unit 72. The analog frontend 71 and the digital processing unit 72 can be arranged together in a reader 73, for example, in an RFID reader.

[0110] Regardless of whether the control device 14 is now, as in Fig. 7 shown, digitally or, as in the Fig. 4A and Fig. As shown in 4B, the control device 14 can be designed according to the invention to switch back and forth at least once between the two supply configurations described above.

[0111] That is, the control device 14 provides the first feed configuration described above at a first time point, wherein the individual antennas 121, 122, 123, 124 are controlled or fed in a first time interval such that the antenna array 11 emits polarized waves and a field strength maximum 52 Max can be generated in the center of the antenna array 11 (see Fig. 5A).

[0112] At a second time point, the control device 14 provides the second feed configuration described above, wherein the individual antennas 121, 122, 123, 124 are controlled or fed in a second time interval such that the antenna array 11 emits positively or negatively depolarized waves and a field strength minimum 52 Min can be generated in the center of the antenna array 11 (see Fig. 5B).

[0113] The first feed configuration of the control device 14 therefore leads to a first radiation characteristic of the antenna array 11 and the second feed configuration of the control device 14 leads to a second radiation characteristic of the antenna array 11.

[0114] The control device 14 can further be configured to switch back and forth between the first and second feeding configurations multiple times.

[0115] The Fig. 8A and Fig. Figure 8B shows two flowcharts as examples, illustrating the switching back and forth between different states, i.e., feed configurations.

[0116] In Fig. In block 801A, a first feed configuration is provided during a first time interval t1, resulting in elliptical polarization. This means that in block 801A, a feed configuration is provided during a first time interval t1 in which the individual antennas 121, 122, 123, 124 are driven or fed in such a way that the antenna array 11 radiates polarized waves. Therefore, during this first time interval t1, the antenna array 11 exhibits its first radiation characteristic (polarized).

[0117] In block 802A, a second feeding configuration according to the invention is provided in a second time interval t2. While retaining the nomenclature from the Fig. 4A and Fig. 4B can provide a second food configuration according to the third path ③ or alternatively according to the fourth path ④. This is in the Fig. 8A and Fig. 8B is designated as state 3 or state 4. Accordingly, a second feed configuration is provided in block 802A, in which the individual antennas 121, 122, 123, 124 are controlled or fed in such a way that the antenna array 11 emits positively depolarized (state 3) or negatively depolarized (state 4) waves according to the invention. That is, the antenna array 11 exhibits the second radiation characteristic (positively or negatively depolarized) in this second time interval t2.

[0118] In block 803A, a first feed configuration is provided again in a third time interval t3, in which the individual antennas 121, 122, 123, 124 are controlled or fed in such a way that the antenna array 11 radiates polarized waves. That is, the antenna array 11 again exhibits the first radiation characteristic (polarized) in this third time interval t3.

[0119] In block 804A, a second feed configuration according to the invention is provided in a fourth time interval t4, in which the individual antennas 121, 122, 123, 124 are controlled or fed such that the antenna array 11 emits positively or negatively depolarized waves according to the invention. The difference to block 802A, however, is that the opposite depolarized second feed configuration is provided in block 804A. That is, if a second feed configuration leading to positively depolarized waves (state 3) is provided in block 802A, then a second feed configuration leading to negatively depolarized waves (state 4) is provided in block 804A, and vice versa.This means that in this fourth time interval t4, the antenna array 11 again exhibits the second radiation characteristic (positively or negatively depolarized), but with the opposite sign as in the second time interval t2.

[0120] In Fig. In block 801B, a first feed configuration is provided during a first time interval t1, resulting in elliptical polarization. This means that in block 801B, a feed configuration is provided during a first time interval t1 in which the individual antennas 121, 122, 123, 124 are driven or fed in such a way that the antenna array 11 radiates polarized waves. Therefore, during this first time interval t1, the antenna array 11 exhibits its first radiation characteristic (polarized).

[0121] In block 802B, a second feeding configuration according to the invention is provided in a second time interval t2. While retaining the nomenclature from the Fig. 4A and Fig. 4B can provide a second food configuration according to the third path ③ or alternatively according to the fourth path ④. This is in the Fig. 8A and Fig. 8B is designated as state 3 or state 4. Accordingly, a second feed configuration is provided in block 802B, in which the individual antennas 121, 122, 123, 124 are controlled or fed in such a way that the antenna array 11 emits positively depolarized (state 3) or negatively depolarized (state 4) waves according to the invention. That is, the antenna array 11 exhibits the second radiation characteristic (positively or negatively depolarized) in this second time interval t2.

[0122] In block 803B, a first feed configuration is provided again in a third time interval t3, in which the individual antennas 121, 122, 123, 124 are controlled or fed in such a way that the antenna array 11 radiates polarized waves. That is, the antenna array 11 again exhibits the first radiation characteristic (polarized) in this third time interval t3.

[0123] In block 804B, a second feed configuration according to the invention is then provided again in a fourth time interval t4, in which the individual antennas 121, 122, 123, 124 are controlled or fed in such a way that the antenna array 11 emits positively or negatively depolarized waves according to the invention. The difference to Fig. However, 8A is that the same signed depolarized second feed configuration is provided in both blocks 802B and 804B. That is, if a feed configuration leading to positively depolarized waves (state 3) is provided in block 802B, then a feed configuration leading to positively depolarized waves (state 3) is also provided in block 804B. The same applies to negatively depolarized waves (state 4). This means that in this fourth time interval t4, the antenna array 11 again exhibits the second radiation characteristic (positively or negatively depolarized), but with the same sign as in the second time interval t2.

[0124] The control device 14 is therefore designed according to the invention to feed the individual antennas 121, 122, 123, 124 in a first time interval t1 such that the antenna array 11 has the first radiation characteristic (positively or negatively depolarized), and to feed the individual antennas 121, 122, 123, 124 in a second time interval t2 such that the antenna array 11 has the second radiation characteristic (polarized), wherein the control device 14 is designed to switch back and forth at least once between the first and the second feed configuration or between the first and the second radiation characteristic.

[0125] This switching back and forth between the first and second radiation characteristics (polarized vs. depolarized) or between the first and second feed configurations causes the minima and maxima of an emerging mode to shift. Thus, in a shielded space where the waves propagate, modal turbulence can be created.

[0126] This switching back and forth can occur at different time intervals. Regarding the temporal behavior, there are several possibilities: A) switching between states so quickly that no modes form, B) switching so slowly that modes form and shift with the new radiation characteristic during the switchover, i.e., mode mixing occurs. The modes occurring in the first feed configuration (positively or negatively depolarized) differ from the modes occurring in the second feed configuration (polarized).

[0127] According to a first conceivable embodiment, the control device can therefore be designed to switch back and forth between the first and the second radiation characteristic (or between the first and the second feed configuration) so quickly that no modes form in a space surrounding the radiation of the antenna array 11.

[0128] According to a second conceivable embodiment, the control device 14 can be designed to switch back and forth so slowly between the first and the second radiation characteristic (or between the first and the second feed configuration) that modes form in a space surrounding the radiation of the antenna array 11, wherein the modes that form in the first radiation characteristic differ from the modes that form in the second radiation characteristic, so that a mode vortex results in the space surrounding the radiation of the antenna array 11 due to the switching back and forth.

[0129] Alternatively or additionally, such mode turbulence can be generated by designing the control device 14 to vary the frequency of a feed signal coupled via the respective feed line 131, 132, 133, 134 of a respective antenna 121, 122, 123, 124 within the bandwidth of the respective antenna 121, 122, 123, 124.

[0130] Furthermore, alternatively or additionally, the control device 14 can be configured to selectively deactivate one or more antennas 121, 122, 123, 124 of the antenna array 11 in a first time interval t1, and to reactivate one or more of the deactivated antennas 121, 122, 123, 124 in a second time interval t2.

[0131] The Fig. 9A and Fig. Figure 9B shows exemplary embodiments of a system 90 according to the invention, which includes, among other things, the antenna array 11 described above and the associated control device 14. Furthermore, the system 90 has a three-dimensional body 91 which has at least one recess 92 within which the electromagnetic waves 94A, 94B emitted by the antenna array 11 propagate.

[0132] The three-dimensional body 91 can, for example, be a housing. The interior 92 of the three-dimensional body 91 can, at least partially, have a shield to reduce outward-emanating radiation. This shield can, for example, be made of metal and be provided, for example, in the form of a metallic coating that is arranged, at least partially, on at least one inner wall of the three-dimensional body 91. Alternatively or additionally, the three-dimensional body 91 can have metal or consist of metal.

[0133] The antenna array 11 is fixedly arranged on the three-dimensional body 91. That is, in contrast to the prior art, the antenna array 11, or rather the individual antennas 121, 122, 123, 124 of the antenna array 11, are fixed relative to the three-dimensional body 91.

[0134] The antenna array 11 can, as described in the Fig. 9A and Fig. The antenna array 11, as shown in Figure 9B, can be arranged inside the three-dimensional body 91 or in the recess 92 of the three-dimensional body 91. Alternatively, the antenna array 11 can be arranged on the outside of the three-dimensional body 91, in which case the antenna array 11 should be arranged on the three-dimensional body 91 such that the electromagnetic waves propagate into the recess 92 of the three-dimensional body 91.

[0135] Fig. Figure 9A shows the system 90 described above, wherein the control device 14 provides a first feed configuration such that the antenna array 11 has a first radiation characteristic. In this first feed configuration, the individual antennas 121, 122, 123, 124 are controlled or fed in such a way that the antenna array 11 emits polarized waves. The Fig. The standing wave 94A shown in 9A, or mode, forms in the recess 92 of the three-dimensional body 91.

[0136] Fig. Figure 9B shows the same system 90, wherein the control device 14 provides a second feed configuration according to the invention, such that the antenna array 11 has a second radiation characteristic. In this second feed configuration, the individual antennas 121, 122, 123, 124 are controlled or fed in such a way that the antenna array 11 emits positively or negatively depolarized waves according to the invention. The Fig. The standing wave 94B shown in 9B, or mode, forms in the recess 92 of the three-dimensional body 91.

[0137] How now in comparison the Fig. 9A and Fig. As can be seen in 9B, the local maxima shift 95A Max , 95B Max and Minima 95A Min , 95B Minthe respective modes 94A and 94B that develop. In the extreme case shown here only as an example, the modes 94A and 94B shift in such a way that at the locations where in the first feeding configuration ( Fig. 9A) a maximum of 95A Max predominates in the second food configuration ( Fig. 9B) a minimum of 95B Min occurs, and vice versa.

[0138] The concept according to the invention will now be summarized again in other words: Within a closed or nearly closed environment where standing waves can occur, an antenna array 11 (e.g., array 11 with patch antennas 121, 122, 123, 124) with the arrangement 2x2 ( Fig. 2B), Fig. 2x4 ( Fig. 2C), 4x2 ( Fig. 2D), 4x4 ( Fig. 2E) or further corresponding multiples are mounted. For the remainder of the discussion, the 2x2 arrangement is considered, since everything else represents a parallelization of this arrangement. Antenna arrays 11 are well known from antenna technology. Feed networks are dimensioned to define specific polarities or antenna lobes. The invention is based on the use of a feed network configuration that is avoided in the prior art.

[0139] State of the art: To generate, for example, a left- or right-circularly polarized field with a 2x2 antenna array and feed network, it is necessary to position the feed ports of the individual antennas 121, 122, 123, 124 of the antenna array 11 with a geometric angular difference of 90° to each other. Furthermore, it is necessary that the individual antennas 121, 122, 123, 124 are electrically driven with the same power and additionally with a phase difference of either +90° or -90° to each other, so that the summation of the radiated field components results in a left- or right-circularly polarized field. An exemplary fixed-setting feed network is shown in Fig. 3B shown.

[0140] The different food configurations are in the Fig. 4A and Fig. 4B shown. A previously mentioned feed configuration (polarized) results, for example, in an arrangement via path ①, where a left-circularly polarized field is created, as well as in an arrangement via path ②, where a right-circularly polarized field is created.

[0141] Furthermore, by using phase actuators 41 and amplitude actuators 44, it is possible in such an arrangement to polarize the antennas 121, 122, 123, 124 elliptically, circularly, horizontally / vertically, and linearly, depending on the set phase / amplitude control. These arrangements have in common that, ideally, they achieve their maximum field 52 Max at the center of antenna array 11, see Fig. 5A and Fig. 6A. Elliptical polarization is the normal state with the extremes of circular polarization on one side and linear polarization on the other.

[0142] The inventive idea lies in constructing the antenna array 11 geometrically as described above and driving the individual antennas 121, 122, 123, 124 of the array 11 with a 0° phase difference to each other (and optionally the same power). This inventive feed configuration is described in the Fig. 4A and Fig. 4B is represented by the paths ③ (positively depolarized) and ④ (negatively depolarized).

[0143] In this control configuration, unlike the state of the art, a minimum of 52 is located in the center of the antenna array 11. Min before, see Fig. 5B and Fig. 6B.

[0144] If switching is now performed between the depolarized state according to the invention (positively or negatively) and at least one of the different elliptical polarizations, a shift in the center of the antenna array 11 occurs between minimum 52 Min and maximum 52 Max cf. Fig. 5A and Fig. 5B, as well as Fig. 6A and Fig. 6B. This results in a turbulence / displacement of the developing modes 94A, 94B in the closed or nearly closed (metallic) environment, see Fig. 9A and Fig. 9B.

[0145] Regarding the temporal behavior, there are several possibilities: A) switching between states so quickly that no modes form, B) switching so slowly that modes form and shift with the new polarization during the switchover.

[0146] Further possibilities for turbulence of the modes arise from appropriate combinations of phases and power driving of the individual antennas 121, 122, 123, 124 in the antenna array 11. Fig. 4A and Fig. Figure 4B shows an example of an analog implementation (antenna integration possible). This is also possible directly via digital signal generation / processing, e.g. in an RFID reader 73, see [reference]. Fig. 7.

[0147] The phase and amplitude actuators 41 and 44 can be used to further enhance mode distortion (e.g., in metallic environments) with beamforming. Furthermore, modes 94A and 94B can be directed and shaped via non-synchronous phase and amplitude control of the individual radiators 121, 122, 123, and 124. Individual radiators 121, 122, 123, and 124 can be switched off and on again for mode distortion.

[0148] The phase / amplitude setting can be fixed ( Fig. 4A, Fig. 4B) or variable ( Fig. 3B) or digital ( Fig. 7) be realized.

[0149] In parallel, the frequency can be shifted across the bandwidth of antennas 121, 122, 123, 124 to influence the formation of modes 94A, 94B.

[0150] The inventive method or arrangement enables, for example, the simple reading of transponders in a metallic environment. Non-limiting examples of this would be surgical instruments in an autoclave, logistics transponders in a tunnel gate, etc.

[0151] The individual emitters 121, 122, 123, 124 can have a distance of λ or fractional lambda multiples.

[0152] Generating electrical mode turbulence within the power supply network / digital signal processing results in several advantages: - Reading chaotically arranged transponders within a closed metallic environment, - Faster handling and process acceleration, for example in the area of ​​disinfection / sterilization of surgical instruments / packing of the sieve. - Check for completeness - less complex than the state of the art Fewer antennas -> lower costs and less cabling effort - No mechanical parts / rotating parts, therefore no maintenance costs - cheaper than state of the art - adaptable to applications other than surgical instruments, e.g. tools - Targeted shifting of the minima & maxima of standing waves -> significant increase in bulk readability for RFID systems in metallic environments.

[0153] Applications can include: • RFID Bulk Reading • Surgical instrument identification during sterilization / disinfection (autoclave). • Tool identification • Sensor transponders in ovens / convection ovens • Transponder reading device for metallic environments where standing waves form, e.g. tunnel gates

[0154] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, so that a block or component of a device is also to be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device.

Claims

[1] Device (10) with an antenna array (11) with at least four antennas (121, 122, 123, 124) arranged offset from one another, wherein each antenna has its own feed line connection (131, 132, 133, 134), wherein the feed line connections of antennas arranged immediately adjacent to each other have a geometric offset of 90° from each other, a control device (14) designed to feed the individual antennas (121, 122, 123, 124) via their respective feed line connections (131, 132, 133, 134), so that the antenna array (11) has different radiation characteristics at different times, wherein a first radiation characteristic has a polarized field distribution, and a second radiation characteristic has an unpolarized field distribution. [2] Device (10) according to claim 1, wherein the control device (14) is configured to feed the individual antennas (121, 122, 123, 124) in a first time interval (t1) such that the antenna array (11) has the first radiation characteristic, and to feed the individual antennas (121, 122, 123, 124) in a second time interval (t2) such that the antenna array (11) has the second radiation characteristic, and wherein the control device (14) is configured to switch back and forth between the first and the second radiation characteristic at least once. [3] Device (10) according to claim 2, wherein the control device (14) is configured to switch back and forth between the first and the second radiation characteristic so slowly that modes (94A, 94B) are formed in a space (92) surrounding the radiation of the antenna array (11), wherein the modes (94A) that are formed during the first radiation characteristic differ from the modes (94B) that are formed during the second radiation characteristic, so that a mode vortex is created in the space (92) surrounding the radiation of the antenna array (11) as a result of the switching back and forth. [4] Device (10) according to claim 2, wherein the control device (14) is configured to switch back and forth between the first and the second radiation characteristics so quickly that no modes are formed in a space (92) surrounding the radiation of the antenna array (11). [5] Device (10) according to any one of claims 1 to 4, wherein the first radiation characteristic has a first field distribution, and the second radiation characteristic has a second field distribution, wherein the first field distribution has a greater field strength in the center of the antenna array (11) than the second field distribution. [6] Device (10) according to one of claims 1 to 5, wherein the first radiation characteristic has a first field distribution which has a maximum field strength (52) in the center of the antenna array (11). Max ) exhibits, and wherein the second radiation characteristic exhibits a second field distribution which has a minimum field strength (52) in the center of the antenna array (11). Min ) exhibits. [7] Device (10) according to one of claims 1 to 6, wherein the control device (14) is configured to feed the individual antennas (121, 122, 123, 124) arranged in a feed network in a first feed configuration such that the antenna array (11) has the first radiation characteristic, wherein the control device (14) is configured to feed each individual antenna (121, 122, 123, 124) with a feed signal, wherein the feed network has a fixed preset phase difference Δφ according to which the feed signals to be fed into the respective antenna (121, 122, 123, 124) each have a phase offset of Δφ = ±90°. [8] Device (10) according to one of claims 1 to 7, wherein the control device (14) is configured to feed the individual antennas (121, 122, 123, 124) arranged in a feed network in a second feed configuration such that the antenna array (11) has the second radiation characteristic, wherein the control device (14) is configured to feed each individual antenna (121, 122, 123, 124) with a feed signal and to adjust the phase of the respective feed signals in such a way that a fixed preset phase difference Δφ of the feed network is compensated. [9] Device (10) according to claim 8, wherein the control device (14) is configured to feed the individual antennas (121, 122, 123, 124) in the second feed configuration such that relative to a reference phase of φ = 0° • the phase of the feed signal fed into the first antenna 121 is not reversed, • the phase angle of the feed signal fed into the second antenna 122 is rotated by a phase angle of φ = 270°, • the phase of the feed signal fed into the third antenna 123 is rotated by a phase angle of φ = 180°, and • the phase of the feed signal fed into the fourth antenna 124 is rotated by a phase angle of φ = 90°, or wherein the control device (14) is configured to feed the individual antennas (121, 122, 123, 124) in the second feed configuration such that relative to a reference phase of φ = 180° • the phase of the feed signal fed into the first antenna 121 is rotated by a phase angle of φ = 180°, • the phase angle of the feed signal fed into the second antenna 122 is rotated by a phase angle of φ = 90°, • the phase of the feed signal fed into the third antenna 123 is not reversed, and • the phase of the feed signal fed into the fourth antenna 124 is rotated by a phase angle of φ = 270°. [10] Device (10) according to claim 8, wherein the control device (14) is configured to feed the individual antennas (121, 122, 123, 124) in the second feed configuration such that relative to a reference phase of φ = 0° • the phase of the feed signal fed into the first antenna 121 is rotated by an offset angle φ = x°, • the phase angle of the feed signal fed into the second antenna 122 is rotated by a phase angle of φ = 270° plus the same offset angle φ = x°, • the phase of the feed signal fed into the third antenna 123 is rotated by a phase angle of φ = 180° plus the same offset angle φ = x°, and • the phase of the feed signal fed into the fourth antenna 124 is rotated by a phase angle of φ = 90° plus the same offset angle φ = x°, where for the offset angle x: 0° ≤ x ≤ 360°. [11] Device (10) according to any one of claims 1 to 10, wherein the control device (14) is configured to feed each of the individual antennas (121, 122, 123, 124) of the antenna array (11) with the same power. [12] Device (10) according to one of claims 1 to 11, wherein the control device (14) is configured to vary the frequency of a feed signal coupled via the respective feed line of a respective antenna (121, 122, 123, 124) within the bandwidth of the respective antenna (121, 122, 123, 124). [13] Device (10) according to one of claims 1 to 12, wherein the control device (14) is configured to deactivate one or more antennas (121, 122, 123, 124) of the antenna array (11) in a first time interval (t1) and to activate one or more of the deactivated antennas (121, 122, 123, 124) in a second time interval (t2). [14] RFID reader (73) with a device (10) according to one of the preceding claims. [15] System (90) comprising a device (10) according to any one of claims 1 to 13, and comprising a three-dimensional body (91) comprising at least one recess (92) which defines a space within which the electromagnetic waves emitted by the antenna array (11) propagate. [16] System (90) according to claim 15, wherein the recess (92) has a shield designed to reduce the emission of electromagnetic waves from the recess (92). [17] System (90) according to claim 15 or 16, wherein the antenna array (11) is arranged immovably within the recess (92), or wherein the antenna array (11) is arranged immovably on the three-dimensional body (91) such that the electromagnetic waves propagate into the recess (92).

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