Patent Application
20190305429
The present invention relates to antennas, antenna devices with one or more antennas and communication devices equipped with such antenna device.
In wireless communication technologies, various frequency bands are utilized for conveying communication signals. In order to meet increasing bandwidth demands, also frequency bands in the millimeter wavelength range, corresponding to frequencies in the range of about 10 GHz to about 100 GHz, are considered. For example, frequency bands in the millimeter wavelength range are considered as candidates for 5G (5th Generation) cellular radio technologies. However, an issue which arises with the utilization of such high frequencies is that antenna sizes need to be sufficiently small to match the wavelength. Further, in order to achieve sufficient performance, multiple antennas (e.g., in the form of an antenna array) may be needed in small sized communication devices, such as mobile phones, smartphones, or similar communication devices.
Further, since losses on cables or other wired connections within the communication device typically increase towards higher frequencies, it may also be desirable to have an antenna design in which the antenna can be placed very close to radio front end circuitry.
Further, it is desirable to have a compact antenna design which supports multiple polarizations.
Accordingly, there is a need for compact size antennas which can be efficiently integrated in a communication device.
According to an embodiment, an antenna is provided. The antenna comprises an antenna patch and an extension patch. The extension patch is conductively coupled to the antenna patch and is arranged in plane offset from the antenna patch. The antenna patch is formed of multiple conductive strips extending in a horizontal direction along an edge of a multi-layer circuit board having multiple layers stacked along a vertical direction. Each of the conductive strips of the antenna patch is arranged on a different layer of the multi-layer circuit board. The conductive strips of the antenna patch are electrically connected to each other by conductive vias extending between two or more of the conductive strips of the antenna patch, which are arranged on different layers of the multi-layer circuit board. The extension patch is formed of multiple conductive strips extending in the horizontal direction. Each of the conductive strips of the extension patch is arranged on a different layer of the multi-layer circuit board. The conductive strips of the extension patch are electrically connected to each other by conductive vias extending between two or more of the conductive strips of the extension patch, which are arranged on different layers of the multi-layer circuit board.
The multi-layer circuit board may be a multi-layer printed circuit board (multilayer PCB). Further, the multi-layer circuit board may be a multi-layer circuit board formed in a LTCC (low-temperature co-fired ceramic).
According to an embodiment, the conductive strips and the conductive vias of the antenna patch are arranged to form a mesh pattern. For example, the conductive strips and the conductive vias of the antenna patch may form a regular grid extending in a plane defined by the horizontal direction and the vertical direction.
Similarly, the conductive strips and the conductive vias of the extension patch may be arranged to form a mesh pattern. For example, the conductive strips and the conductive vias of the extension patch may form a regular grid extending in a plane defined by the horizontal direction and the vertical direction and offset from the plane of the antenna patch.
According to an embodiment, the extension patch is conductively coupled to the antenna patch by a common conductive strip which is part of the antenna patch and of the extension patch. This common conductive strip may be located on an edge of the antenna strip and the extension strip. Accordingly, the extension patch may have the form of a folded arm extending from one edge of the antenna patch.
According to an embodiment, the antenna further comprises an electrically floating parasitic patch, i.e., a patch which is merely capacitively coupled to the antenna patch and not conductively coupled to ground or some other fixed potential. The electrically floating parasitic patch is arranged in a further plane offset from the antenna patch, on a side opposite to the extension patch. The electrically floating parasitic patch is formed of multiple conductive strips extending in the horizontal direction. Each of the conductive strips of the electrically floating parasitic patch are arranged on a different layer of the multi-layer circuit board. The conductive strips of the electrically floating parasitic patch are electrically connected to each other by conductive vias extending between two or more of the conductive strips of the electrically floating parasitic patch, which are arranged on different layers of the multilayer circuit board. Accordingly, the antenna patch, the extension patch, and the parasitic patch may form a sandwich structure, with the antenna patch being sandwiched between the extension patch and the parasitic patch.
The conductive strips and the conductive vias of the electrically floating parasitic patch may be arranged to form a mesh pattern. For example, the conductive strips and the conductive vias of the electrically floating parasitic patch may form a regular grid extending in a plane defined by the horizontal direction and the vertical direction.
According to an embodiment, the electrically floating parasitic patch has a size which substantially corresponds to a size of the antenna patch. By choosing the size of the electrically floating parasitic patch (i.e., its dimension in the vertical and/or horizontal direction) and/or the distance between the antenna patch and the electrically floating parasitic patch, characteristics of the antenna can be tuned. By introducing the electrically floating parasitic patch, a bandwidth of the antenna can be increased as compared to a configuration without the electrically floating parasitic patch. By choosing the size of the electrically floating parasitic patch and/or the distance between the antenna patch and the electrically floating parasitic patch, the bandwidth can be tuned to a desired range.
According to an embodiment, the extension patch has a width in the horizontal direction which is smaller than a width of the antenna patch in the horizontal direction. If the antenna has a dual-polarization configuration, e.g., is configured for transmission of first radio signals polarized in the vertical direction and for transmission of second radio signals polarized in the horizontal direction, cross-polarization effects can be reduced.
According to an embodiment, a length of the extension patch in the vertical direction is selected depending on a wavelength of radio signal to by transmitted by the antenna. By choosing the vertical length of the extension patch and/or the distance between the antenna patch and the electrically floating parasitic patch, characteristics of the antenna can be tuned. Specifically, by introducing the extension patch, a resonant frequency of the antenna can be reduced as compared to a configuration without the extension patch. Accordingly, the antenna can be optimized for lower wavelengths without increasing the overall vertical dimension of the antenna, which is limited by a thickness of the multi-layer circuit board. By choosing the length of the extension patch and/or the distance between the antenna patch and the extension patch, the wavelengths supported by the antenna can be tuned to a desired range.
According to an embodiment, the antenna comprises two feeding points on the antenna patch, which are offset from each other in the horizontal direction and the vertical direction. In this way, the antenna can be provided with a dual-polarization configuration which supports transmission of first radio signals polarized in the vertical direction and for transmission of second radio signals polarized in the horizontal direction. The feeding points may be provided on conductive strips on different layers of the multi-layer circuit board.
According to an embodiment, the antenna is configured for transmission of radio signals having a wavelength of more than 1 mm and less than 3 cm, corresponding to frequencies of the radio signals in the range of 10 GHz to 300 GHz.
According to a further embodiment, a device is provided. The device comprises at least one antenna according to any one of the above embodiments and the multi-layer circuit board. Further, the device may comprise radio front end circuitry arranged on the multi-layer circuit board. The radio front end circuitry may for example include one or more amplifiers and/or one or more modulators for processing radio signals transmitted via the antennas. The device may for example correspond to an antenna module including multiple antennas. Further, the device may correspond to an antenna circuit package including one or more antennas and radio front end circuitry for feeding radio frequency signals to the antenna(s). According to an embodiment, the device may include an array of multiple antennas according to any one of the above embodiments.
If the device includes radio front end circuitry arranged on the multi-layer circuit board, the multi-layer circuit board may comprise a cavity in which the radio front end circuitry is received.
According to a further embodiment, a communication device is provided, e.g., in the form of a mobile phone, smartphone or similar user device. The communication device comprises a device according to any one of the above embodiments, i.e., a device including at least one antenna according to any one of the above embodiments and the multi-layer circuit board. Further, the communication device comprises at least one processor configured to process communication signals transmitted via the at least one antenna of the device.
The above and further embodiments of the invention will now be described in more detail with reference to the accompanying drawings.
In the following, exemplary embodiments of the invention will be described in more detail. It has to be understood that the following description is given only for the purpose of illustrating the principles of the invention and is not to be taken in a limiting sense, Rather, the scope of the invention is defined only by the appended claims and is not intended to be limited by the exemplary embodiments described hereinafter.
The illustrated embodiments relate to antennas for transmission of radio signals, in particular of short wavelength radio signals in the cm/mm wavelength range. The illustrated antennas and antenna devices may for example be utilized in communication devices, such as a mobile phone, smartphone, tablet computer, or the like.
In the illustrated concepts, a multi-layer circuit board is utilized for forming a patch antenna. The multi-layer circuit board has multiple layers stacked in a vertical direction. The layers of the multi-layer circuit board may be individually structured with patterns of conductive strips. In particular, conductive strips formed on different layers of the multi-layer circuit board may be connected to each other by conductive vias extending between the conductive strips of different layers to form an antenna patch and an extension patch which is conductively coupled to the antenna patch. Accordingly, the antenna patch and the extension patch may be formed to extend in the vertical direction, perpendicular to the planes of the layers of the multi-layer circuit board, thereby allowing a compact vertical antenna design. In this way, an antenna allowing for transmission of radio signals polarized in the vertical direction may be formed in an efficient manner. Further, one or more layers of the multi-layer circuit board may be utilized in an efficient manner for connecting the patch antenna to radio front end circuitry. Specifically, a small size of the patch antenna and short lengths of connections to the patch antenna may be achieved. Further, it is possible to integrate a plurality of such patch antennas on the multi-layer circuit board. Moreover, the patch antenna(s) can be efficiently provided with a dual-polarization configuration, supporting not only the transmission of radio signals polarized in the vertical direction, but also transmission of radio signals polarized in a horizontal direction, extending in the plane of the multi-layer circuit board. Accordingly, different polarization directions may be supported in a compact structure. In the embodiments as further detailed below, it will be assumed that the multilayer circuit board is a printed circuit board (PCB), based on structured metal layers printed on resin and fiber based substrate layers. However, it is noted that other multi-layer circuit packaging technologies could be used as well for forming the multi-layer circuit board, such as LTCC. The technology and materials used to form the multi-layer circuit board may also be chosen according to achieve desirable dielectric properties for supporting transmission of radio signals of a certain wavelength, e.g., based on the relation
where L denotes an effective dimension of the patch antenna, λ denotes the wavelength of the radio signals to be transmitted, and εr denotes the relative permittivity of the substrate material of the multi-layer circuit board.
Further, the antenna device 100 includes a radio front end circuitry chip 180 which is arranged in a cavity 170 formed in the multi-layer PCB 110. Accordingly, electric connections from the radio front end circuitry chip 180 to the antenna 120 can be efficiently formed by conductive strips on one or more of the PCB layers. In particular, the electric connections may be formed with short lengths, so that signal losses at high frequencies can be limited. Further, one or more of the PCB layers may also be utilized for connecting the radio front end circuitry chip 180 to other circuitry, e.g., to power supply circuitry or digital signal processing circuitry.
As can be seen, the patch antenna 120 includes an antenna patch 121 which extends in a plane which is perpendicular to the PCB layers and extends along the edge of the multi-layer PCB 110. The antenna patch 121 is formed of multiple conductive strips 122 on different PCB layers. The conductive strips 122 are stacked above each other in the vertical direction, thereby forming a three-dimensional superstructure. The conductive strips 122 of the different PCB layers are connected by conductive vias 123, e.g., metalized via holes. As illustrated, the conductive strips 122 and the conductive vias of the antenna patch 121 are arranged in a mesh pattern and form a substantially rectangular conductive structure extending the plane perpendicular to the PCB layers and in parallel to the edge of the multi-layer PCB 110. The grid spacing of the mesh pattern is selected to be sufficiently small so that, at the intended wavelength of the radio signals to be transmitted by the patch antenna 120, differences as compared to a uniform conductive structure are negligible. Typically, this can be achieved by a grid spacing of less than a quarter of the vertical and/or horizontal size of the antenna patch 121. It is noted that various kinds of grid structures may be utilized, e.g., based on an irregular spacing of the conductive strips 122 and regular spacing of the vias 123, based on regular spacings both in the horizontal direction and vertical direction, or based on irregular spacings both in the horizontal direction and vertical direction. It is noted that also vias 123 which are not-aligned in the vertical direction could be utilized in the grid structure. Further, it is noted that various numbers of the conductive strips 122 and/or vias 123 may be used.
In the illustrated example, the patch antenna 120 is configured for transmission of radio signals with a vertical polarization direction (illustrated by a solid arrow), i.e., a direction perpendicular to the PCB layers, and for transmission of radio signals with a horizontal polarization direction (illustrated by an open arrow), i.e., a direction parallel to the PCB layers and parallel to the edge of the multi-layer PCB 110. Accordingly, the patch antenna 120 is provided with a dual-polarization configuration. In the case of the horizontal polarization direction, the wavelength of the radio signals which can be transmitted by the antenna 120 is determined by an effective horizontal dimension of the antenna patch 121. For example, the horizontal width of the antenna patch 121 (measured along the edge of one of the PCB layers) may be used as the effective dimension L to determine the wavelength A of radio signals for which the antenna 120 is resonant. In the case of the vertical polarization direction, the wavelength of the radio signals which can be transmitted by the antenna 120 is determined by an effective vertical dimension of the antenna patch 121. For example, the vertical width of the antenna patch 121 (measured perpendicular to the PCB layers) may be used as the effective dimension L to determine the wavelength A of radio signals for which the antenna 120 is resonant. However, since the vertical width of the antenna patch 121 is limited by the thickness of the multi-layer PCB 110, the illustrated antenna 120 further includes an extension patch which has the purpose of extending the effective vertical dimension of the antenna patch 121 beyond its vertical width. An exemplary configuration of the antenna patch 121 and the extension patch is illustrated in
As can be seen from
As further shown in
As further illustrated, the extension patch 125 is spaced by a distance G from the antenna patch 121. The antenna patch 121 has a dimension W along the vertical direction, and the extension patch 125 has a length L. As can be seen, the extension patch 125 increases the effective vertical dimension of antenna patch 121, namely to a length substantially corresponding to the vertical width W of the antenna patch 121 plus the vertical length of the extension patch 125 and the size G of the gap between the antenna patch 121 and the extension patch 125.
The distance G and the length L of the extension patch 125 may be set with the aim of optimizing the antenna for a certain wavelength range. In particular, by introducing the extension patch 125, the resonant frequency of the antenna 120 can be reduced as compared to a configuration without the extension patch 125, and the antenna 120 thus be optimized for radio signals of lower wavelength.
Further, simulations using the above-mentioned configuration of the antenna 120 have shown that a good bandwidth, an almost uniform omnidirectional transmission characteristic, and a low cross-polarization level between horizontal direction and vertical direction can be achieved.
Accordingly, the vertical width W, the distance G, and the length L may be set according to the nominal wavelength of radio signals to be transmitted or received via the patch antenna 120, e.g., using relation (1) and assuming that the effective dimension L of the antenna patch 121 corresponds to the sum of the vertical width W, the length L, and the distance G. By using the extension patch 125, an optimization for longer wavelengths can be achieved by increasing the length L, without requiring an increase of the vertical width W (and thus the thickness of the multi-layer PCB 110).
As illustrated, the antenna 120′ differs from the antenna device 120 in that the antenna 120′ further includes an electrically floating parasitic patch 131. The parasitic patch 131 is only capacitively coupled to the antenna patch 121 and without any conductive coupling to ground or some other fixed potential. The parasitic patch 131 is arranged in a plane offset from the antenna patch 121, on the opposite side of the extension patch 125. Accordingly, the antenna patch is sandwiched between the extension patch 125 and the parasitic patch 131. As can be seen from
Similar to the antenna patch 121, the conductive strips 132A, 132B, 132C, 132D and the conductive vias 133 of the parasitic patch 131 may be arranged in a mesh pattern and form a substantially rectangular conductive structure extending the plane perpendicular to the PCB layers and in parallel to the edge of the multi-layer PCB 110. Also in this case, the grid spacing of the mesh pattern may be selected to be sufficiently small so that, at the intended wavelength of the radio signals to be transmitted by the antenna 120′, differences as compared to a uniform conductive structure are negligible. It is noted that various kinds of grid structures may be utilized, e.g., based on an irregular spacing of the conductive strips 132A, 132B, 132C, 132D and regular spacing of the vias 133, based on regular spacings both in the horizontal direction and vertical direction, or based on irregular spacings both in the horizontal direction and vertical direction. It is noted that also vias 133 which are not-aligned in the vertical direction could be utilized in the grid structure. Further, it is noted that various numbers of the conductive strips and/or vias may be used in the parasitic patch 131.
As further illustrated, the extension patch 125 is spaced by a distance G1 from the antenna patch 121. The parasitic patch 131 is spaced by a distance G2 from the antenna patch 121.
As in the case of the antenna 120, the distance G1 and the length L of the extension patch 125 may be set with the aim of optimizing the antenna 120′ for a certain wavelength range. The distance G2 and the size of the parasitic patch 131 (e.g., vertical width and/or horizontal width) may be set to optimize the bandwidth of the antenna 120′. In a typical scenario, the vertical width and horizontal width of the parasitic patch 131 are similar to the vertical width and horizontal width of the antenna patch 121, i.e., the parasitic patch 131 has substantially the same size as the antenna patch 121. Simulations of the antenna 120′ with the additional parasitic patch 131 have shown that an increased bandwidth of more than 1 GHz and a lowered cross-polarization level between horizontal direction and vertical direction of less than 15 dB can be achieved.
Further, the circuit includes a number of phase shifters 911, 912, 913, 914, 915, 921, 922, 923, 924, 925, one phase shifter corresponding to each antenna 120′ and polarization direction. In particular, the phase shifter 911 provides a phase shift PhaseH1 for a first of the antennas 120′ and the horizontal polarization direction, the phase shifter 912 provides a phase shift PhaseH2 for a second of the antennas 120′ and the horizontal polarization direction, the phase shifter 913 provides a phase shift PhaseH3 for a third of the antennas 120′ and the horizontal polarization direction, the phase shifter 914 provides a phase shift PhaseH4 for a fourth of the antennas 120′ and the horizontal polarization direction, and the phase shifter 915 provides a phase shift PhaseH5 for a fifth of the antennas 120′ and the horizontal polarization direction. Similarly, the phase shifter 921 provides a phase shift PhaseV1 for the first of the antennas 120′ and the vertical polarization direction, the phase shifter 922 provides a phase shift PhaseV2 for the second of the antennas 120′ and the vertical polarization direction, the phase shifter 923 provides a phase shift PhaseV3 for the third of the antennas 120′ and the vertical polarization direction, the phase shifter 924 provides a phase shift PhaseV4 for the fourth of the antennas 120′ and the vertical polarization direction, and the phase shifter 925 provides a phase shift PhaseV5 for the fifth of the antennas 120′ and the vertical polarization direction. By controlling the phase shifts applied by the phase shifters 911, 912, 913, 914, 915, 921, 922, 923, 924, 925, a directivity of the phased antenna array may be controlled, e.g., in terms of transmission direction, reception direction, beam width, or the like. This may be accomplished independently for the horizontal polarization direction and the vertical polarization direction.
As illustrated, the communication device 1000 includes one or more antennas 1010. These antennas 1010 include at least one antenna of the above-mentioned patch antenna type, such as the antenna 120 or the antenna 120′. Further, the communication device 1000 may also include other kinds of antennas. Using concepts as explained above, the antennas 1010 are integrated together with radio front end circuitry 1020 on a multi-layer circuit board 1030, such as the above-mentioned multi-layer PCB 110. As further illustrated, the communication device 1000 also includes one or more communication processor(s) 1040. The communication processor(s) 1040 may generate or otherwise process communication signals for transmission via the antennas 1010, For this purpose, the communication processor(s) 1040 may perform various kinds of signal processing and data processing according to one or more communication protocols, e.g., in accordance with a 5G cellular radio technology.
It is to be understood that the concepts as explained above are susceptible to various modifications. For example, the concepts could be applied in connection with various kinds of radio technologies and communication devices, without limitation to a 5G technology. The illustrated antennas may be used for transmitting radio signals from a communication device and/or for receiving radio signals in a communication device. Further, it is to be understood that the illustrated antenna structures may be subjected to various modifications concerning antenna geometry. For example, the illustrated rectangular antenna patch shapes could be modified to more complex shapes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/062768 | 6/6/2016 | WO | 00 |
