PCB ANTENNA

Description

[0001] The invention relates to an antenna for transmitting or receiving radio signals, which can be implemented on a printed circuit board.

[0002] An electronic device configured to communicate via a wireless communications network typically comprises at least one antenna for receiving and / or transmitting radio signals. The electronic device may be configured to receive and transmit radio signals over a plurality of different frequency bands, in particular over two different frequency bands or frequency ranges. For this purpose, the device may comprise a multi-band antenna, in particular a dual-band antenna. Exemplary dual-band antennas may be provided, for example, for the 2.4-2.5 GHz and 5.1-5.8 GHz frequency bands, i.e., for WLAN (Wireless Local Area Network).

[0003] Antennas typically require a reference ground or reference plane to function. The size and shape of such a reference ground typically have a significant influence on the function and radiation characteristics of an antenna. Often, an antenna is to be inserted into circuit boards of various sizes as a printed circuit board structure or as an attached metal structure (e.g., as a stamped and bent part). Circuit boards of different sizes represent different reference grounds for an antenna. Furthermore, plastic in the vicinity of the antenna (e.g., due to a housing) can also influence the properties of an antenna. As a result, a new antenna tuning is typically required for each circuit board geometry and / or application. This type of antenna tuning can be achieved by modifying the antenna structure and / or using a so-called "matching circuit."

[0004] Printed circuit board antennas known from the prior art are described in WO 99 / 43037 A2, WO 2015 / 148298 A1, EP 3361570 A1, and JP 2015179938 A1.

[0005] This document addresses the technical task of providing a (dual-band) antenna that can be integrated efficiently (in particular without the need for dedicated antenna tuning) on ​​printed circuit boards of different characteristics.

[0006] The problem is solved by the independent claim. Advantageous embodiments are described, among others, in the dependent claims.

[0007] According to one aspect, a printed circuit board antenna is described. The printed circuit board antenna described in this document can be implemented efficiently on differently dimensioned printed circuit boards and / or in different environments or applications. A printed circuit board typically comprises an electrically conductive (first) outer layer (e.g., a front layer) and an electrically conductive further (second) outer layer (e.g., a lower layer). The one or more layers can be electrically insulated from one another by one or more dielectric layers. The layers can comprise an electrically conductive material, in particular copper. The electrically conductive material can be removed from the respective layer at least in part, in particular in order to form a free space between an antenna structure and a reference region.

[0008] The printed circuit board antenna comprises an electrically conductive antenna structure on the (first) outer layer of the printed circuit board. The antenna structure can have an elongated shape (e.g., like a dipole antenna). In particular, the antenna structure can form an inverted-F antenna. Furthermore, the antenna structure can have a first resonant frequency. In particular, the antenna structure can be configured to form a first antenna for a first frequency range around the first resonant frequency. The first frequency range can, in particular, comprise 5.1–5.8 GHz or correspond to this frequency interval.

[0009] Furthermore, the printed circuit board antenna has an electrically conductive reference region on the outer layer. The reference region can be electrically conductively connected to a ground of the printed circuit board. In particular, the reference region can be designed to form a reference ground for the antenna structure, so that the printed circuit board antenna is independent of the size of the reference ground.

[0010] Furthermore, the printed circuit board antenna has an electrically conductive feed line to the antenna structure. The feed line can be arranged substantially perpendicular to the longitudinal orientation of the antenna structure. A radio signal received by the antenna structure can be coupled out via the feed line. On the other hand, a radio signal to be transmitted by the antenna structure can be fed into the antenna structure via the feed line.

[0011] The reference region is designed to partially or completely enclose the antenna structure, except for an insulating feed cutout for the feed line and an insulating web cutout. The web cutout is arranged on a side of the antenna structure facing away from the feed line. The reference region can thus be divided by the two cutouts into (possibly exactly) two parts, i.e., a first partial reference region and a second partial reference region.

[0012] The reference range, in particular the first partial reference range, has a reference range web on the side of the antenna structure facing away from the feed line. The reference range web can be electrically conductively connected to the first partial reference range. Furthermore, the reference range web forms a resonator capacitively coupled to the antenna structure and having a second resonant frequency. The reference range web can have an elongated shape (and thus form, for example, a dipole antenna). In particular, the reference range web can be designed to form a second antenna for a second frequency range around the second resonant frequency. The second frequency range can in particular comprise 2.4 - 2.5 GHz or correspond to this frequency interval.

[0013] Thus, a dual-band antenna is described which, by providing a reference range and an additional reference range ridge, can be used reliably in different installation environments and / or on different circuit board types.

[0014] The antenna structure can be substantially rectangular in shape. In particular, the antenna structure can have an electrically conductive rectangle (to provide the antenna function). The length of the antenna structure running perpendicular to the feed line can be greater than the width of the antenna structure running parallel to the feed line. Furthermore, the longitudinal edge of the reference area web can be arranged parallel to the longitudinal edge of the antenna structure running along the length of the antenna structure. This can achieve a reliable electromagnetic and / or capacitive coupling between the reference area web and the antenna structure. In particular, the reference area web and the antenna structure can be capacitively coupled to one another via an electrically insulating free space arranged between the longitudinal edge of the antenna structure and the longitudinal edge of the reference area web.

[0015] In a preferred example, the free space between the longitudinal edge of the antenna structure and the longitudinal edge of the reference range web may have a width of F*2.2mm ± 10%, where F is any real-valued scaling factor, in particular F=1.

[0016] The antenna structure can have a specific length along the longitudinal edge of the antenna structure, wherein the length of the antenna structure depends on the first resonant frequency. In particular, adjusting the length of the antenna structure can typically be used to adjust the first resonant frequency. In a preferred example, the length of the antenna structure is F*11.4 mm ± 10%. Furthermore, in a preferred example, the width of the antenna structure is F*2.4 mm ± 10%.

[0017] Accordingly, the reference area web has a specific length along a longitudinal edge of the reference area web, wherein the length of the reference area web typically depends on the second resonant frequency. In particular, adjusting the length of the reference area web can be used to adjust the second resonant frequency. In a preferred example, the length of the reference area web is F*11.7 mm ± 10%. Furthermore, the width of the reference area web is F*1.5 mm ± 10% in a preferred example.

[0018] The antenna structure can be electrically connected to the reference area, in particular to the second partial reference area of ​​the reference area, via an electrically conductive antenna structure web (also referred to as a short-circuit web). The antenna structure web can run parallel to the feed line. Furthermore, the antenna structure web can have a significantly greater length (running parallel to the feed line) than its width (running perpendicular to the feed line), in particular by a factor of 10 or more.

[0019] The feed line and / or the antenna structure web typically run perpendicular to a longitudinal direction or longitudinal edge of the antenna structure. Furthermore, the antenna structure web can be arranged at an end and / or at a transverse edge of the antenna structure (in particular at the end or at the transverse edge facing the second partial reference region). In a preferred example, the antenna structure web has a width of F*0.9 mm ± 10%. Furthermore, in a preferred example, the antenna structure web (in particular an edge of the antenna structure web facing the feed line) can have a distance of F*5.7 mm ± 10% from the feed line.

[0020] By using an electrically conductive antenna structure bridge, the impedance of the antenna structure can be adjusted efficiently and precisely. Furthermore, the required size of the antenna structure can be reduced. Furthermore, electrostatic discharges can be reliably kept away from the transmit / receive electronics of the described antenna via the (short-circuit) bridge to the reference area, in particular to the second partial reference area.

[0021] As already explained above, the reference area can be divided by the supply cutout and the web cutout into a first partial reference area and a second partial reference area. The division can be such that the first partial reference area and the second partial reference area are not directly electrically connected to each other on the outer layer (but possibly only indirectly via a via to another layer of the circuit board).

[0022] The second partial reference area can have an L-shape. Furthermore, the first partial reference area can have an L-shape that is arranged (optionally with respect to the feed line) in a mirror image of the second partial reference area, on which the reference area web is additionally arranged parallel to a leg of the L-shape running perpendicular to the feed line. The first partial reference area and the second partial reference area can thus have the same shape and / or the same dimensions (apart from the additional reference area web) and can optionally be arranged in a mirror image with respect to the feed line. This makes it possible to provide an antenna that can be used in a particularly flexible manner in different constellations.

[0023] In a preferred example, a leg of the first partial reference region and / or the second partial reference region extending parallel to the feed line each has a length (running parallel to the feed line) of F*7.4 mm ± 10% (starting from a longitudinal edge of the reference region facing the antenna structure). Furthermore, in a preferred example, the longitudinal edge of the antenna structure (facing the reference region) can have a distance of F*1.3 mm ± 10% from the longitudinal edge of the leg of the first partial reference region and / or the second partial reference region running perpendicular to the feed line.

[0024] The PCB antenna includes an electrically conductive outer layer of the

[0025] Printed circuit board. Furthermore, the printed circuit board antenna comprises an electrically conductive reference region on the further outer layer. The reference region (of the (first) outer layer) is electrically conductively connected to the further reference region (of the further outer layer) via one or more vias.

[0026] The reference area can have a U-shape without the reference area web and without the feed recess (which is composed of the two aforementioned L-shaped partial reference areas). The antenna structure can be enclosed on three sides by the U-shape of the reference area. Furthermore, the reference area web can enclose at least part of the fourth side of the antenna structure (and run parallel to it).

[0027] The additional reference area can also have a U-shape. In a preferred example, the U-shape of the additional reference area and the U-shape of the reference area can be identically dimensioned and / or arranged directly above one another. This allows for the provision of a particularly flexible antenna.

[0028] As already explained above, the (first) outer layer and / or the further (second) outer layer are typically each formed by an electrically conductive layer, in particular a copper layer, of a printed circuit board. Furthermore, the outer layer and the further outer layer are typically insulated from each other by at least one dielectric layer.

[0029] Furthermore, a printed circuit board can have at least one electrically conductive intermediate layer (e.g., a copper layer) arranged between the outer layer and the further outer layer. The intermediate layer preferably has no electrically conductive material (in particular, no copper) in a region of the antenna structure and / or the reference region web (as well as the free space therebetween). Alternatively, the intermediate layer can be electrically conductively connected to the reference region via one or more vias in a region of the reference region. Thus, a printed circuit board antenna can be provided efficiently and precisely even with a printed circuit board having one or more intermediate layers.

[0030] According to a further aspect, a domestic appliance, in particular a household appliance, is described which comprises a communication unit for wireless communication (in particular via WLAN), wherein the communication unit has the printed circuit board antenna described in this document.

[0031] It should be noted that the devices and systems described in this document can be used both alone and in combination with other devices and systems described in this document. Furthermore, any aspects of the devices and systems described in this document can be combined in a variety of ways. In particular, the features of the claims can be combined in a variety of ways.

[0032] The invention will be described in more detail below using exemplary embodiments. Figure 1athe upper or (first) outer layer of a circuit board with an antenna; Figure 1b the bottom layer or the second or further outer layer of a printed circuit board; Figures 1c and1d cross-sections through printed circuit boards, each with an antenna; Figures 2a and 2b exemplary dimensions of an antenna; and Figure 3 Example frequency responses of antennas with different dimensions.

[0033] As stated at the beginning, this document addresses the provision of a (dual-band) antenna that can be efficiently integrated on differently dimensioned and / or designed circuit boards and / or in different environments. The (dual-band) antenna is specifically designed for WLAN radio communication in the 2.4 GHz and 5 GHz frequency bands.

[0034] Figures 1a and 1bshow an exemplary antenna 100 integrated on a circuit board 101. In particular, Fig. 1a the (electrically conductive) upper layer 110 of the circuit board 101 and Fig. 1b the (electrically conductive) lower layer 120 of the circuit board. As shown in the Figures 1c and 1d As shown, one or more dielectric layers 130 and optionally one or more (electrically conductive) intermediate layers 150 are located between the upper layer 110 and the lower layer 120. The electrically conductive layers 110, 120, 150 can comprise a layer of metal, in particular copper. The metal can be removed (e.g., etched away) in partial regions of the layers 110, 120, 150 in order to form different electrically conductive partial regions within a layer 110, 120, 150, wherein the partial regions are electrically insulated from one another.

[0035] The upper layer 110 has an electrically conductive antenna structure 113, which is insulated from an electrically conductive reference region 111, 141 by an (electrically non-conductive) free space 112. The reference region 111, 141 at least partially encloses the antenna structure 113. The reference region 111, 141 enclosing the antenna structure 113 is interrupted at a first location to form a free space or recess 117 through which an electrically conductive feed line 115 can be routed to the antenna structure 113. Furthermore, the reference region 111, 141 has a second recess 142 to form a reference region web 143 running parallel to the antenna structure 113. Due to the two recesses 117, 142, the reference area 111, 141 is thus divided into two partial reference areas, in particular a first partial reference area 111 and a second partial reference area 141.The reference area web 143 is electrically connected to the first partial reference area 111.

[0036] In the Fig. 1a In the example shown, the antenna structure 113 has a rectangular shape. The antenna structure 113 can be used for transmitting or receiving signals in a specific first frequency range (approximately 5.1 - 5.8 GHz). In particular, the antenna structure 113 can form a λ / 4 radiator for a specific first frequency range due to the total length 205 of the antenna structure 113.

[0037] On the other hand, the free space 112 between the antenna structure 113 and the reference range ridge 143 of the reference range 111, 141, and / or the reference range ridge 143 itself can be used as a (slot) antenna for a further (second) frequency range (approximately 2.4 - 2.5 GHz). For this purpose, the free space 112 and in particular the reference range ridge 143 can have a specific length 208, so that the free space 112 and / or the reference range ridge 143 form a λ / 4 radiator for a further (second) frequency range.

[0038] Furthermore, the antenna structure 113 can be electrically connected to the reference region 111, 141, in particular to the second partial reference region 141, via an electrically conductive antenna structure web (in particular via a short-circuit web) 116. The electrically conductive antenna structure web 116 can be arranged at one end of the antenna structure 113, in particular at the narrowest transverse edge of the antenna structure 113. The antenna structure 113 can thus form a (planar) inverted-F antenna.

[0039] The distance 206 between the bridge 116 and the feed point or feed line 115 allows the impedance of the antenna structure 113 to be trimmed to a desired value (e.g., 50 ohms). Furthermore, this short-circuit bridge 116 can largely keep electrostatic discharges away from the transmit / receive electronics of the antenna 100.

[0040] Fig. 1bshows the lower layer 120 of the circuit board 101. The lower layer 120 is at least partially constructed identically to the upper layer 110. In particular, in the illustrated example, the lower layer 120 has a reference region 121 which (apart from the first recess 117 and the web 143) is constructed identically to the reference region 111, 141 of the upper layer 110. The reference region 121 has a U-shape, with a base 124 running parallel to the rectangular antenna structure 113 and two legs 123.

[0041] The reference region 111 of the upper layer 110 can be electrically connected to the reference region 121 of the lower layer 120 via one or more vias or through-contacts 114. The vias or through-contacts 114 are shown in the Figures 1a and 1brepresented as dots. The exact position of the one or more vias or through-holes 114 may vary depending on the via technology.

[0042] The Figures 1c and 1d show exemplary cross sections through exemplary printed circuit boards 101 with an antenna structure 113. A printed circuit board 101 has a dielectric and / or electrically insulating layer 130 between two electrically conductive layers 110, 120. In the Fig. 1d In the example shown, the circuit board 101 has (at least) one electrically conductive intermediate layer 150 between the upper layer 110 and the lower layer 120, which is separated from the upper layer 110 and the lower layer 120 by a dielectric layer 130.

[0043] Fig. 1d illustrates the area 141 in which the Figure 1aThe antenna structure 113 shown, including the free space 112, is arranged therein. This region 151 of an intermediate layer 150 is typically left out, so that the intermediate layer 150 has no electrically conductive material (in particular, no copper) in this region 151. On the other hand, the remaining region 152 of an intermediate layer 150 can be electrically conductively connected to the reference region 111, 121 of the upper layer 110 and the lower layer 120 via the vias or through-holes 114.

[0044] The Figures 2a and 2b show different dimensions of the antenna 100 from the Figures 1a and 1b In particular, the Figures 2a and 2b the distance 201 between the longitudinal edge of the rectangle 118 of the antenna structure 113 facing the (interrupted) base (of the U-shape) of the reference area 111, 141 and the (interrupted) base (of the U-shape) of the reference area 111, 141; the distance 202 between the longitudinal edge of the rectangle 118 of the antenna structure 113 facing away from the (interrupted) base (of the U-shape) of the reference area 111, 141 and the (interrupted) base (of the U-shape) of the reference area 111, 141; the distance 203 between the longitudinal edge of the reference area web 143 facing the (interrupted) base (of the U-shape) of the reference area 111, 141 and the (interrupted) base (of the U-shape) of the reference area 111, 141; the distance 204 between the longitudinal edge of the reference area web 143 facing away from the (interrupted) base (of the U-shape) of the reference area 111, 141 and the (interrupted) base (of the U-shape) of the reference area 111, 141; the length 205 of the rectangle 118 of the antenna structure 113;the distance 206 of the feed line 117 from the antenna structure web 116; the width 207 of the antenna structure web 116; the length 208 of the reference region web 143; the distance 209 of the antenna structure web 116 from the edge of a leg of the second partial reference region 141, which runs parallel to the antenna structure web 116 and faces the free space 112; the distance 210 of the opposite edges of the legs of the first partial reference region 111 and the second partial reference region 141, facing the free space 112; the distance 212 of the opposite edges of the two legs 123 of the reference region 121 of the lower layer 120, facing the free space 122; This distance 212 typically corresponds to the distance 210; the depth 213 of the legs 123 of the reference area 121 of the lower layer 120 (starting from the edge of the base 124 of the reference area 121 facing the free space 122); this depth 213 typically corresponds to the distance 204.

[0045] Preferred values ​​of the above dimensions of the antenna 100 (especially for a dual-band antenna for the frequency bands 2.4 - 2.5 GHz and 5.1 - 5.8 GHz) are: for the distance 201: 1.3mm; and / or for the distance 202: 3.7mm; and / or for the distance 203: 5.9mm; and / or for the distance 204: 7.4mm; and / or for the length 205: 11.4mm; and / or for the distance 206: 5.7mm; and / or for the width 207: 0.9mm; and / or for the length 208: 11.7mm; and / or for the distance 209: 5.7mm; and / or for the distance 210: 21.3mm; and / or for the distance 212: 21.3mm; and / or for the depth 213: 7.4mm.

[0046] The circuit board 101 can, for example, have a thickness of 1.5 mm. A possible copper intermediate layer 150 preferably has a rectangular recess 151 measuring 7.7 mm x 22 mm. Furthermore, the intermediate layer 150 can be connected to the reference regions 111, 141, 121 of the outer layers 110, 120 via external vias 114.

[0047] The above values ​​can vary by up to ±10% (especially to trim the resonance frequencies). Furthermore, the values ​​can be scaled using a common factor F if necessary.

[0048] The printed circuit board antenna 100 can be arranged on a printed circuit board 101 measuring 49 mm x 43 mm. Several of the described printed circuit board antennas 100 can be arranged on the printed circuit board 101, e.g., one antenna 100 on each long edge and one on each short edge of the printed circuit board 101. The individual antennas 100 can be adapted and / or optimized to their position within the printed circuit board 101 (e.g., by adjusting the above-mentioned values ​​of an antenna 100 within a range of ±10%).

[0049] Thus, a planar printed circuit board antenna structure 113 is described, which is surrounded by the reference ground (i.e., by a reference area 111, 121, 141) or integrated into the reference ground. The reference areas 111, 121, 141 can be electrically coupled to ground. By integrating an antenna structure 113 into a reference area 111, 121, 141, the properties of the antenna 100 become independent of the size of the reference ground of a printed circuit board 101. As a result, the antenna 100 can be efficiently installed in printed circuit boards 101 of different sizes and / or in different environments without having to modify the antenna structure 113 and / or a matching circuit. Consequently, a module approval for the described antenna 100 can be used for various overall devices, regardless of the specific installation situation.

[0050] The described antenna 100 can be an extended form of a planar inverted-F antenna (PIFA, for English: Planar Inverted-F-Shaped Antenna) (formed by the antenna structure 113). The antenna 110 has an additional resonator (formed by the reference area ridge 143 of the first partial reference area 111), which creates a second (relatively low) resonant frequency. The additional resonator can be capacitively excited by the inverted-F antenna 113 via the gap (i.e., the free space 112) between the rectangle 118 of the inverted-F antenna 113 and the reference area ridge 143. This capacitive coupling is preferably designed to be relatively weak, whereby the resonances of the inverted-F antenna 113 and the reference range bridge 153 become relatively broadband.

[0051] By using relatively broadband resonators, the radiation pattern of antenna 100 changes relatively little when the resonant frequencies shift (e.g., due to plastic (such as the housing of a device) in the vicinity of antenna 100, or due to manufacturing tolerances). The quality of antenna 100 is therefore relatively insensitive to manufacturing tolerances. Furthermore, antenna 100 can be operated in various installation situations without having to shift the resonances by adapting the structure of antenna 100 or by using a matching circuit. Thus, one approval for antenna 100 can be used for different overall devices, regardless of the installation situation.

[0052] Fig. 3shows example frequency responses 301, 302, and 303 of different antennas. In frequency responses 301, 302, and 303, a resonant frequency in the 2.4–2.5 GHz frequency range can be seen for all antennas. Two of the antennas (frequency responses 301, 302) also have a resonant frequency in the 5.1–5.8 GHz frequency range. It can be seen that the antennas with the two resonant frequencies have a broader bandwidth in the respective frequency ranges than the antenna with only one resonant frequency. This enables flexible use of the dual-band antennas.

[0053] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and figures are intended only to illustrate the principle of the proposed devices and systems.

Claims

1. Printed circuit board antenna (100), which comprises - an electrically conducting antenna structure (113) on an outer layer (110) of a printed circuit board (101); wherein the antenna structure (113) has a first resonance frequency; - an electrically conducting feed line (115) to the antenna structure (113); - an electrically conducting reference region (111, 141) on the outer layer (110); wherein the reference region (111, 141) completely encloses the antenna structure (113) with the exception of an insulating feed recess (117) for the feed line (115) and an insulating web recess (142); wherein the web recess (142) is arranged on a side of the antenna structure (131) facing away from the feed line (115), and wherein the reference region (111, 141) has a reference region web |(143) on the side of the antenna structure (113) facing away from the feed line (115), which forms a resonator with a second resonance frequency which is coupled capacitively to the antenna structure (113), characterised in that - the printed circuit board antenna (100) comprises an electrically conducting further outer layer (120) of the printed circuit board (101); - the printed circuit board antenna (100) comprises an electrically conducting further reference region (121) on the further outer layer (120); and - the reference region (111, 141) is connected in an electrically conducting manner with the further reference region (121) by way of one or more through-connections (114).

2. Printed circuit board antenna (100) according to claim 1, wherein - the antenna structure (113) is substantially rectangular; - a length (205) of the antenna structure (113) running at right angles to the feed line (115) is greater than a width of the antenna structure (113) running parallel to the feed line (115); - a longitudinal edge of the reference region web (143) is arranged parallel to a longitudinal edge of the antenna structure (113) running along the length (205) of the antenna structure (113); - the reference region web (143) and the antenna structure (113) are coupled capacitively to one another by way of an electrically insulating clearance (112) arranged between the longitudinal edge of the antenna structure (113) and the longitudinal edge of the reference region web (143); - the clearance (112) between the longitudinal edge of the antenna structure (113) and the longitudinal edge of the reference region web (143) has in particular a width of F*2.2 mm ± 10%; and - F is any real-value scaling factor, with in particular F=1.

3. Printed circuit board antenna (100) according to one of the preceding claims, wherein - the antenna structure (113) forms a first antenna for a first frequency range about the first resonance frequency; and - the reference region web (143) forms a second antenna for a second frequency range about the second resonance frequency, and - the first frequency range comprises in particular 5.1- 5.8 GHz and the second frequency range in particular 2.4 - 2.5 GHz.

4. Printed circuit board antenna (100) according to one of the preceding claims, wherein - the antenna structure (113) has a length (205) along a longitudinal edge of the antenna structure (113); and - the length (205) of the antenna structure (113) depends on the first resonance frequency.

5. Printed circuit board antenna (100) according to claim 4, wherein - the length (205) of the antenna structure (113) is F*11.4 mm ± 10%; and / or - a width of the antenna structure (113) is F*2.4 mm ± 10%; and - F is any real-value scaling factor, with in particular F=1.

6. Printed circuit board antenna (100) according to one of the preceding claims, wherein - the reference region web (143) has a length (208) along a longitudinal edge of the reference region web (143); and - the length (208) of the reference region web (143) depends on the second resonance frequency.

7. Printed circuit board antenna (100) according to claim 6, wherein - the length (208) of the reference region web (143) is F*11.4 mm ± 10%; and / or - a width of the reference region web (143) is F*2.4 mm ± 10% ; and - F is any real-value scaling factor, with in particular F=1.

8. Printed circuit board antenna (100) according to one of the preceding claims, wherein - the antenna structure (113) is connected in an electrically conducting manner with the reference region (111, 141), in particular with a second sub reference region (141) of the reference region (111), 141) by way of an electrically conducting antenna structure web (116); - the antenna structure web (116) runs parallel to the feed line (115); - the antenna structure web (116) has a substantially greater length which runs parallel to the feed line (115) than width (207), in particular by a factor 10 or more; - the feed line (115) runs at right angles to a longitudinal direction of the antenna structure (113); - the antenna structure web (116) is arranged at one end and / or at a transverse edge of the antenna structure (113); - the antenna structure web (116) has in particular a width (207) of F*0.9 mm ± 10%; - the antenna structure web (116) has in particular a distance (206) of F*5.7 mm ± 10% in relation to the feed line (115); and - F is any real-value scaling factor, with in particular F=1.

9. Printed circuit board antenna (100) according to one of the preceding claims, wherein - the reference region (111, 141) is divided into a first sub reference region (111) and into a second sub reference region (141) by means of the feed recess (117) and by means of the web recess (142); - the first sub reference region (111) and the second sub reference region (141) are not coupled to one another in a directly electrically conducting manner on the outer layer (110); - the second sub reference region (141) has an L shape; - the first sub reference region (111) has an L shape arranged mirror-inverted in relation to the second sub reference region (141), relative to the feed line (115), on which L shape the reference region web (143) is additionally arranged parallel to a limb of the L shape which runs at right angles to the feed line (115); - a limb of the first sub reference region (111) and / or the second sub reference region (141) which extends parallel to the feed line (115) have in particular a length (204) of F*7.4 mm ± 10%; - a longitudinal edge of the antenna structure (113) has in particular a distance (201) of F*1.3 mm ± 10% from a limb of the first sub reference region (111) and / or of the second sub reference region (141) which runs at right angles to the feed line (115); and - F is any real-value scaling factor, with in particular F=1.

10. Printed circuit board antenna (100) according to claim 9, wherein - the reference region (111, 141) without the reference region web (143) and without the feed recess (117) has a U shape; - the antenna structure (113) is enclosed on three sides by the U shape of the reference region (111, 141); - the further reference region (121) has a U shape; and - the U shape of the further reference region (121) and the U shape of the reference region (111, 141) are dimensioned in particular identically and arranged directly one above the other.

11. Printed circuit board antenna (100) according to one of claims 9 to 10, wherein - the outer layer (110) and the further outer layer (120) are formed in each case by an electrically conducting layer, in particular by a copper layer, of the printed circuit board (101); and / or - the outer layer (110) and the further outer layer (120) are insulated from one another by means of at least one dielectric layer (130).

12. Printed circuit board antenna (100) according to claim 11, wherein - the printed circuit board (101) has at least one electrically conducting intermediate layer (150), which is arranged between the outer layer (110) and the further outer layer (120); and - the intermediate layer (150) in a region (151) of the antenna structure (131) and / or the reference region web (143) has no electrically conducting material; and / or - the intermediate layer (150) in a region (152) of the reference region (111, 141) is connected in an electrically conducting manner with the reference region (111, 141) by way of one or more through-connections (114).

13. Printed circuit board antenna (100) according to one of the preceding claims, wherein the reference region (111, 141) forms a reference mass for the antenna structure (113), so that the printed circuit board antenna (100) is independent of a size of the reference mass.

14. Household appliance, which comprises a communication unit with a printed circuit board antenna (100) according to one of the preceding claims.