Patent Application
20240405406
This patent application is part of a project that has received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 674491.
The present invention relates generally to the field of electronic devices which require the transmission and/or reception of electromagnetic wave signals, and more particularly, to slim radiating structures in wireless electronic devices.
Wireless electronic devices typically handle one or more cellular communication standards, and/or wireless connectivity standards, and/or broadcast standards, each standard being allocated in one or more frequency bands, and the frequency bands being contained within one or more regions of the electromagnetic spectrum.
For that purpose, a typical wireless electronic device must include a radiating system capable of operating in one or more frequency regions with an acceptable radio-electric performance (in terms of for instance reflection coefficient, standing wave ratio, impedance bandwidth, gain, efficiency, or radiation pattern). The integration of the radiating system within the wireless electronic device must be effective to ensure that the overall device attains good radio-electric performance (such as for example in terms of radiated power, received power, sensitivity) without being disrupted by electronic components and/or human loading.
Additionally, a space within the wireless electronic device is usually limited and the radiating system has to be included in the available space. The radiating system is expected to be small enough to occupy as little space as possible within the device, which then allows for smaller devices, or for the addition of more specific components and functionalities into the device. At the same time, it is sometimes convenient for the radiating system to be flat since this allows for slim devices. Thus, many of the demands for wireless devices also translate to specific demands for the radiating systems thereof. This is even more critical in the case in which the wireless device is a multifunctional wireless device. Commonly-owned patent applications WO2008/009391 and US2008/0018543 describe a multifunctional wireless device. The entire disclosure of aforesaid application numbers WO2008/009391 and US2008/0018543 are hereby incorporated by reference.
For a good wireless connection, high efficiency is further required. Other more common design demands for radiating systems are the reflection coefficient (or standing-wave ratio, SWR) and the impedance which is supposed to be about 50 ohms. Other demands for radiating systems for wireless handheld or portable devices are competitive cost and a low SAR.
Furthermore, a radiating system has to be integrated into a device or, in other words, a wireless device has to be constructed such that an appropriate radiating system may be integrated therein which puts additional constraints by consideration of the mechanical fit, the electrical fit, and the assembly fit.
Of further importance, usually, is the robustness of the radiating system, which means that the radiating system does not change its properties upon smaller shocks to the device and the human loading.
Besides radio-frequency performance, small size and reduced interaction with human body and nearby electronic components, one of the current limitations of the prior-art is that generally the antenna system is customized for every particular wireless handheld device model. The mechanical architecture of each device model is different and the volume available for the antenna severely depends on the form factor of the wireless device model together with the arrangement of the multiple components embedded into the device (e.g., displays, keyboards, battery, connectors, cameras, flashes, speakers, chipsets, memory devices, etc.). As a result, the antenna within the device is mostly designed ad hoc for every model, resulting in a higher cost and a delayed time to market. In turn, as typically the design and integration of an antenna element for a radiating structure is customized for each wireless device, different form factors or platforms, or a different distribution of the functional blocks of the device will force to redesign the antenna element and its integration inside the device almost from scratch.
A radiating system for a wireless handheld or portable device typically includes a radiating structure comprising an antenna element which operates in combination with a ground plane layer providing a determined radio-frequency performance in one or more frequency regions of the electromagnetic spectrum. Typically, the antenna element has a dimension close to an integer multiple of a quarter of the wavelength at a frequency of operation of the radiating structure, so that the antenna element is at resonance or substantially close to resonance at the frequency of operation, and a radiation mode is excited on the antenna element.
Antenna elements operating in multiple frequency bands allocated at different regions of the electromagnetic spectrum usually present complex mechanical designs and considerable dimensions, mainly due to the fact that antenna performance is highly related to the electrical dimensions of the antenna element.
A further problem associated to the integration of the radiating structure, and in particular to the integration of the antenna element in a wireless device is that the volume dedicated for such integration has continuously shrunk with the appearance of new smaller and/or thinner form factors for wireless devices, and with the increasing convergence of different functionalities in a same wireless device. Therefore, from the conventional wisdom perspective, the trend in seeking for slimmer wireless device is incompatible with maximizing the performance of a traditional antenna device, which again, it is known to have a high correlation between antenna size (relative to the operating wavelengths) and performance.
Some techniques to miniaturize and/or optimize the multiband behavior of an antenna element have been described in the prior art. However the radiating structures described therein still rely on exciting a radiation mode on the antenna element for each one of the frequency bands of operation. This fact leads to complex mechanical designs and large antennas that usually are very sensitive to external effects (such as for instance the presence of plastic or dielectric covers that surround the wireless device), to components of the wireless device (such as for instance, but not limited to, a speaker, a microphone, a connector, a display, a shield can, a vibrating module, a battery, or an electronic module or subsystem) placed either in the vicinity of, or even underneath, the radiating element, and/or to the human loading. A multiband antenna system is sensitive to any of the above mentioned aspects because they may alter the electromagnetic coupling between the different geometrical portions of the radiating element, which usually translates into detuning effects, degradation of the radio-frequency performance of the antenna system and/or the radio-frequency performance of the wireless device, and/or greater interaction with the user (such as an increased level of SAR).
In this sense, a radiating system such as the one described in the present invention not requiring a complex and/or large antenna formed by multiple arms, slots, apertures and/or openings and a complex mechanical design is preferable in order to minimize such undesired external effects and simplify the integration within the wireless device.
Some other attempts have focused on antenna elements not requiring a complex geometry while still providing some degree of miniaturization by using an antenna element that is not resonant in the one or more frequency ranges of operation of the wireless device.
For example, WO2007/128340 discloses a wireless portable device comprising a non-resonant antenna element for receiving broadcast signals (such as, for instance, DVB-H, DMB, T-DMB or FM). The wireless portable device further comprises a ground plane layer that is used in combination with said antenna element. Although the antenna element has a first resonant frequency above the frequency range of operation of the wireless device, the antenna element is still the main responsible for the radiation process and for the radio-frequency performance of the wireless device. This is clear from the fact that no radiation mode can be excited on the ground plane layer because the ground plane layer is electrically short at the frequencies of operation (i.e., its dimensions are much smaller than the wavelength). For this kind of non-resonant antenna elements, a matching circuitry is added for matching the antenna to a level of SWR in a limited frequency range, which in this particular case can be around SWR≤6. Such level of SWR together with the limited bandwidth results in antenna elements which are only acceptable for reception of electromagnetic wave signals but not desirable for transmission of electromagnetic wave signals. With such limitations, while the performance of the wireless portable device may be sufficient for reception of electromagnetic wave signals (such as those of a broadcast service), the antenna element could not provide an acceptable performance (for example, in terms of reflection coefficient or gain) for a communication service requiring also the transmission of electromagnetic wave signals.
Commonly-owned patent applications WO2008/119699 and US2010/0109955 describe a wireless handheld or portable device comprising a radiating system capable of operating in two frequency regions. The radiating system comprises an antenna element having a resonant frequency outside said two frequency regions, and a ground plane layer. In this wireless device, while the ground plane layer contributes to enhance the electromagnetic performance of the radiating system in the two frequency regions of operation, it is still necessary to excite a radiation mode on the antenna element. In fact, the radiating system relies on the relationship between a resonant frequency of the antenna element and a resonant frequency of the ground plane layer in order for the radiating system to operate properly in said two frequency regions. Nevertheless, the solution still relies on an antenna element whose size is related to a resonant frequency that is outside of the two frequency regions. The entire disclosures of the aforesaid application numbers WO2008/119699 and US2010/0109955 are hereby incorporated by reference.
A different radiating system is disclosed in U.S. Pat. No. 6,674,411, in which a planar inverted-L antenna (i.e., a patch antenna) has a radiating element composed by a rectangular plate placed above and substantially parallel to a ground plane. The antenna is connected to a matching network that provides a match in one frequency band in a first frequency region, and in one frequency band in a second frequency region. Thus the antenna system is limited to single-band operation in both frequency regions. When operation in more bands is sought, the antenna system requires of a switched (active) matching network that provides non-simultaneous impedance matching in each frequency band. So in spite of having an antenna that occupies a large volume (20×10×8 mm3), not more than dual-band operation may be provided simultaneously.
For at least the above reasons, wireless device manufacturers regard the volume dedicated to the integration of the radiating structure, and in particular the antenna element, as being a toll to pay in order to provide wireless communication capabilities to the handheld or portable device.
In order to reduce as much as possible the volume occupied into the wireless handheld or portable device, recent trends in handset antenna design are oriented to maximize the contribution of the ground plane to the radiation process by using very small non-resonant elements. However, non-resonant elements usually are forced to include a complex radio-frequency system. Thus, the challenge of these techniques mainly relies on said complexity (combination of inductors, capacitors, and transmission lines), which is required to satisfy impedance bandwidth and efficiency specifications.
Commonly owned patent applications, WO2010/015365, and WO2010/015364 are intended for solving some of the aforementioned drawbacks. Namely, they describe a wireless handheld or portable device comprising a radiating system including a radiating structure and a radio-frequency system. The radiating structure is formed by a ground plane layer presenting suitable dimensions as for supporting at least one efficient radiation mode and at least one radiation booster capable of coupling electromagnetic energy to said ground plane layer. The radiation booster is not resonant in any of the frequency regions of operation and, consequently, a radio-frequency system is used to properly match the radiating structure to the desired frequency bands of operation.
More particularly, in WO2010/015364 each radiation booster is intended for providing operation in a particular frequency region. Thus, the radio-frequency system is designed in such a way that the first internal port associated to the first radiation booster is highly isolated from the second internal port associated to a second radiation booster. Said radio-frequency system usually comprises a matching network including resonators for each one of the frequency regions of operation and a set of filters for each one of the frequency regions of operation. Thus, said radio-frequency system requires multiple stages and the performance of the radiating systems in terms of efficiency may be affected by the additional losses of the components. As each radiation booster is generally intended for providing operation in a particular frequency region, the bandwidth capabilities may be limited for some applications requiring very wide bandwidth specially at the low frequency region, as for example for wireless devices operating at LTE700, GSM850 and GSM900.
Commonly owned patent applications WO2014/012796 and US2014/0015730 disclose a concentrated wireless device comprising a radiating system including a radiating structure and a radio-frequency system, such device operating two or more frequency regions of the electromagnetic spectrum. A feature of said radiating system is that the operation in at least two frequency regions is achieved by one radiation booster, or by at least two radiation boosters, or by at least one radiation booster and at least one antenna element, wherein the radio-frequency system modifies the impedance of the radiating structure, providing impedance matching to the radiating system in the at least two frequency regions of operation of the radiating system. The entire disclosure of aforesaid application numbers WO2014/012796 and US2014/0015730 are hereby incorporated by reference.
Commonly owned patent applications WO2014/012842 and US2014/0015728 disclose very compact, small size and light weight radiation boosters operating in single or in multiple frequency bands. Such radiation boosters are configured to be used in radiating systems that may be embedded into a wireless handheld device. Said patent applications further disclose radiation booster structures and their manufacturing methods that enable reducing the cost of both the booster and the entire wireless device embedding said booster inside the device. The entire disclosure of aforesaid application numbers WO2014/012842 and US2014/0015728 are hereby incorporated by reference.
Another technique, as disclosed in U.S. Pat. No. 7,274,340, is based on the use of two coupling elements. According to the invention, quad-band operation (GSM 1800/1900 and GSM850/900 bands) is provided with two coupling elements: a low-band (LB) coupling element (for the GSM850/900 bands), and a high-band (HB) coupling element (for the GSM1800/1900 bands), where the impedance matching is provided through the addition of two matching circuits, one for the LB coupling element and another one for the HB coupling element. In spite of using non-resonant elements, the size of the element for the low band is significantly large, being 1/9.3 times the free-space wavelength of the lowest frequency for the low frequency band. Due to such size, the low band element would be a resonant element at the high band. Additionally, the operation of this solution is closely linked to the alignment of the maximum E-field intensity of the ground plane and the coupling element. The size of the low band element undesirably contributes to increase the printed circuit board (PCB) space required by the antenna module. According to the invention, the bandwidth at the low frequency region is 133 MHZ (from 821 MHz to 954 MHz) that is insufficient for some applications requiring very wide bandwidth, especially at the low frequency region, as for example for wireless devices operating at LTE700, GSM850 and GSM900.
Therefore, a wireless device not requiring an antenna element and including a slim radiating system would be advantageous to make simpler the integration of the slim radiating structure into the wireless electronic device minimizing the amount of the electronic device that is allocated towards the slim radiating system, and to provide a suitable radio-frequency performance to operate in a wide range of communication bands. The volume freed up by the absence of a large and complex antenna element would enable smaller and/or thinner devices, as slim electronic devices, or even to adopt radically new form factors which are not feasible today due to the presence of an antenna element featuring a considerable volume. Furthermore, by eliminating precisely the element that requires customization, a standard solution is sought which should only require minor adjustments to be implemented in different wireless electronic devices.
It is an object of the present invention to provide an electronic device (such as for instance but not limited to a mobile phone, a smartphone, a phablet, a PDA, an MP3 player, a headset, a USB dongle, a laptop computer, a tablet, a gaming device, a GPS system, a digital camera, a wearable device as a smart watch, a PCMCIA, Cardbus 32 card, a sensor, or generally a multifunction wireless device which combines the functionality of multiple devices) containing a slim radiating system that covers a wide range of radio-frequencies and handles multiple communication bands while exhibiting a suitable radio-frequency performance.
It is another object of the invention to provide a slim radiating system suitable for being included within electronic devices, and more preferably within slim electronic devices.
It is another object of the invention to provide a standard slim radiating system which only requires minor adjustments to be included within different electronic devices.
Another object of the invention refers to the location (on the device) of radiation boosters and, more particularly, booster bars for obtaining the most favorable frequency bandwidth values.
An electronic device according to the invention may have a candy-bar shape, which means that its configuration is given by a single body. It may also have a two-body configuration such as a clamshell, flip-type, swivel-type or slider structure. In some other cases, the device may have a configuration comprising three or more bodies. It may further or additionally have a twist configuration in which a body portion (e.g. with a screen) can be twisted (i.e., rotated around two or more axes of rotation which are preferably not parallel). The electronic device may comprise a memory module, a processing circuitry module, a user interface module, a battery, and a wireless communication module.
The wireless communication module may include a slim radiating system, a radio-frequency transceiver circuit, a power amplifier circuit and a base-band module. The slim radiating system may be coupled to the power amplifier via a conductive path and to the radio transceiver circuit via a conductive path. The wireless communication module may include a multiplexing stage coupled to the slim radiating system via a conductive path.
A slim radiating system in accordance with the invention may include a slim radiating structure, a radio-frequency system, at least one internal conductive path and at least one external conductive path. The slim radiating structure may include a ground element and at least one radiation booster, which in some embodiments may be a booster bar, separated from the ground element by a gap.
A slim radiating structure may comprise a ground element and one, two, three, four or even more radiation boosters. In some preferred embodiments, said radiation boosters may be booster bars featuring an elongated shape. In preferred embodiments, each booster bar or radiation booster is separated from the ground element by a gap.
An aspect of the present invention relates to the use of the ground element (or ground plane layer) of the slim radiating system as a main source of radiation.
A radiation booster includes a dielectric material and in some embodiments, a single standard layer of dielectric material spacing two or more conductive elements. A single standard layer of dielectric material refers to dielectric material with a standard thickness, which is available off-the-shelf. For example, 0.025″ (0.635 mm), 0.047″ (1.2 mm), 0.093″ (2.36 mm) or 0.125″ (3.175 mm) are common/standard thicknesses for dielectric materials which are available in the market. Examples of dielectric materials may include fiber-glass FR4, Cuclad, Alumina, Kapton, Ceramic and for instance commercial laminates and substrates from Rogers® Corporation (RO3000® and RO4000® laminates, Duroid substrates and alike) or other suitable non-conductive materials.
The radiation booster may be formed by printing or depositing conductive material in a first and a second surface of the dielectric material (e.g. top and bottom) and adding several vias to electrically connect the conductive material in the first surface with the conductive material in the second surface. The conductive material in the first and second surfaces may have a substantially polygonal shape. Some possible polygonal shapes are for instance, but not limited to, squares, rectangles, and trapezoids. When the conductive material in said first and second surfaces has an elongated shape, for instance a rectangular shape, the radiation booster takes the form of a booster bar; a booster bar may also include vias that electrically connect the conductive material in the first surface with the conductive material in the second surface.
The elongated shape of a booster bar is characterized by two slim form factors: a slim width factor and a slim height factor. The slim width factor is a ratio between a length of the booster bar and a width of the booster bar. The slim height factor is a ratio between the length of the booster bar and a height of the booster bar.
The slim width factor characterizes the ratio between the length and the width of the booster bar, whereas the slim height factor characterizes the ratio between the length and the height of the booster bar. In a preferred embodiment, the value for the slim width factor and the slim height factor is greater than 2, for instance in one or more of those embodiments the value for the slim width factor is greater than 3, and preferably larger than 3.5, and the slim height factor is greater than 4. In another preferred embodiment, the value for the slim width factor is greater than 6 and/or the slim height factor is greater than 6. In another preferred embodiment, the value for the slim width factor is greater than 6 and/or the slim height factor is larger than 9. In some less preferred embodiments, the values for both the slim width factor and the slim height factor are between 1 and 2. The slim width factor and the slim height factor of a booster bar may take any of the values listed above yet being smaller than 25, and preferably smaller than 10.
A radiation booster may comprise one, two or more booster bars electrically connected, forming a booster element that fits in an imaginary sphere having a diameter smaller than ⅓ of a radiansphere corresponding to the lowest frequency of operation of the slim radiating system. Such a booster element may also be characterized by a slim width factor, a slim height factor, and a location factor. Any booster element according to the present invention may be limited by a slim width factor and a slim height factor, each of these factors being between 1 and 10, and preferably between 2 and 10.
An advantageous aspect of the invention refers to a booster bar built on a single standard layer of dielectric material that is manufactured at a competitive cost.
Another advantageous aspect of the invention refers to a booster bar having a slim width factor and/or slim height factor that enables the booster bar to occupy only a small portion within the electronic wireless device and making it suitable for its integration within slim electronic devices or flexible electronic devices.
Another advantageous aspect of the present invention refers to the location and slim form factors of a booster bar to guarantee the most advantageous frequency bandwidth for the available space.
A radiation booster, like for instance a booster bar, is separated from the ground plane layer by a gap. In the context of this document, the gap refers to a minimum distance between a point at an edge of the ground plane layer and a point at an edge of the bottom conductive surface of the radiation booster. The location of the radiation booster is characterized by a location factor that is a ratio between the width of the radiation booster and the gap. In a preferred example, the location factor is between 0.5 and 2. In another preferred example, the location factor is between 0.3 and 1.8.
Each radiation booster of the slim radiating system advantageously couples the electromagnetic energy from the radio-frequency system to the ground element in transmission, and from the ground element to the radio-frequency system in reception. The radiation boosters excite a radiation mode in the ground element enabling the radiation from the ground element.
The form factor of the radiation booster, together with its location in relation to the ground element, is configured to achieve a proper excitation of the radiation mode of the ground element. The location factor is selected to achieve the most favorable frequency bandwidth for a radiation booster with a certain form factor, particularly a booster bar.
Apart from the form factor of the radiation booster, the gap is also relevant for properly exciting a radiation mode in the ground plane layer and to achieve the most advantageous frequency bandwidth. The bandwidth of the slim radiating system may be degraded if the location factor is not properly selected.
The location factor and the slim form factors of a booster bar are selected to ensure the most favorable frequency bandwidth while minimizing/reducing the amount of space allocated towards the integration of the booster bar within the electronic device.
The slim radiating structure is mounted within the electronic device and is coupled to the radio-frequency system via a conductive path. The radiation booster is coupled to the ground element via a conductive path and is located at certain distance from the ground element. Said conductive path comprises a conductive element which may be linear or include a surface; the conductive element may comprise, for instance but not limited to, a metallic strip and/or a conductive trace.
In some embodiments, a slim radiating structure comprises one ground element or conductive material acting as a ground plane for the slim radiating structure. In some other embodiments, a slim radiating structure may comprise two, three or more ground elements or conductive materials acting as a ground plane for the radiating structure. In such embodiments, the plurality of ground elements may be electrically interconnected one to each other.
The at least one radiation booster for a slim radiating structure according to the present invention may have a maximum size at least smaller than 1/15 of the free-space wavelength corresponding to the lowest frequency of the first frequency region of operation. In some cases, said maximum size may be also smaller than 1/20, and/or 1/25, and/or 1/30, and/or 1/50, and/or 1/100 of the free-space wavelength corresponding to the lowest frequency of the first frequency region of operation. In some cases, the at least one radiation booster fits in an imaginary sphere having a diameter smaller than ⅓, or preferably smaller than ¼, or preferably smaller than ⅙, or even more preferably smaller than 1/10 of a radiansphere at said free-space wavelength. The radiansphere is defined as an imaginary sphere having a radius equal to the operating wavelength divided by two times π (pi).
Furthermore, in some examples, the at least one radiation booster also has a maximum size smaller than 1/15, and/or 1/20, and/or 1/25, and/or 1/30, and/or 1/50 of the free-space wavelength corresponding to the lowest frequency of the second frequency region of operation. In some cases, the at least one radiation booster fits in an imaginary sphere having a diameter smaller than ⅓, or preferably smaller than ¼, or preferably smaller than ⅙, or even more preferably smaller than 1/10 of a radiansphere at said free-space wavelength.
Additionally, in some of these examples the at least one radiation booster has a maximum size larger than 1/1400, 1/700, 1/350, 1/250, 1/180, 1/140, or 1/120 times the free-space wavelength corresponding to the lowest frequency of said first frequency region.
The maximum size of a radiation booster is preferably defined by the largest dimension of a booster box that completely encloses said radiation booster, and in which the radiation booster is inscribed. More specifically, a booster box for a radiation booster is defined as being the minimum-sized parallelepiped of square or rectangular faces that completely encloses the radiation booster and wherein each one of the faces of said minimum-sized parallelepiped is tangent to at least a point of said radiation booster. Moreover, each possible pair of faces of said minimum-size parallelepiped sharing an edge forms an inner angle of 90°. In those cases in which the radiating structure comprises more than one radiation booster, a different booster box is defined for each of them.
In some preferred examples, the area defined by the two largest dimensions of a booster box is advantageously small compared to the square of the wavelength corresponding to the lowest frequency of the first frequency region; in particular, a ratio between said area and the square of the wavelength corresponding to the lowest frequency of the first frequency region may be advantageously smaller than at least one of the following percentages: 0.15%, 0.12%, 0.10%, 0.08%, 0.06%, 0.04%, or even 0.02%. In some of these examples, a ratio between the area defined by the two largest dimensions of a booster box and the square of the wavelength corresponding to the lowest frequency of the second frequency region may also be advantageously smaller than at least one of the following percentages: 0.50%, 0.45%, 0.40%, 0.35%, 0.30%, 0.25%, 0.20%, 0.15%, 0.10%, or even 0.05%.
Moreover, in some embodiments according to the present invention, the at least one radiation booster will entirely fit inside a limiting volume equal or smaller than L3/25000, and in some cases equal or smaller than L3/50000, L3/100000, L3/150000, L3/200000, L3/300000, L3/400000, or even smaller than L3/500000, being L the wavelength corresponding to the lowest frequency of the first frequency region of operation.
A slim radiating system according to the invention is configured to handle multiple communication bands, and to provide coverage and an acceptable level of reflection coefficient in a wide range of communication bands in one or more frequency regions of operation exhibiting a suitable radio-frequency performance. The slim radiating system is designed to transmit and receive radio-frequency signals in multiple communication bands of interest, including frequency bands that may be added, for instance, through the deployment of future cellular telephone bands and/or data service bands.
In the context of this document, a frequency band preferably refers to a range of frequencies used by a particular cellular communication standard, a wireless connectivity standard or a broadcast standard, while a frequency region preferably refers to a continuum of frequencies of the electromagnetic spectrum. For example, the GSM 1800 standard is allocated in a frequency band from 1710 MHz to 1880 MHz while the GSM 1900 standard is allocated in a frequency band from 1850 MHz to 1990 MHz. A device operating the GSM 1800 and the GSM1900 standards must have a radiating system capable of operating in a frequency region from 1710 MHz to 1990 MHz. As another example, a wireless device operating the GSM 850 standard (allocated in a frequency band from 824 MHz to 894 MHZ) and the GSM 1800 standard must have a radiating system capable of operating in two separate frequency regions.
Some frequency bands that the slim radiating system may be configured to transmit and receive signals in are, for example, GSM 850 (824-894 MHZ), GSM 900 (880-960 MHz), GSM 1800 (1710-1880 MHZ), GSM 1900 (1850-1990 MHz), WCDMA 2100 (1920-2170 MHZ), CDMA 1700 (1710-2155 MHZ), LTE 700 (698-798 MHZ), LTE 800 (791-862 MHZ), LTE 2600 (2500-2690 MHz), LTE 3500 (3.4-3.6 GHZ), LTE 3700 (3.6-3.8 GHZ), WiFi or WLAN (2.4-2.5 GHz and/or 4.9-5.9 GHZ), etc. A wireless handheld or portable device according to the present invention may operate one, two, three, four or more cellular communication standards, wireless connectivity standards, and/or broadcasts standards, each standard being allocated in one, two or more frequency bands, and said frequency bands being contained within one, two or more frequency regions of the electromagnetic spectrum.
The slim radiating system is designed to provide an acceptable level of reflection coefficient in the frequency regions of operation. A slim radiating system according to the present invention is configured to operate in at least one frequency region. In some embodiments, the slim radiating system is configured to operate in a first frequency region comprising at least a first frequency band, and a second frequency region comprising at least a second frequency band. Such radiating system is configured to satisfy the radio-frequency bandwidths and frequency coverage goals. A slim radiating system according to the present invention may advantageously feature an impedance bandwidth in the first frequency region larger than 5%, 10%, 15%, or even larger than 20%. In addition, such radiating system may also feature an impedance bandwidth in the second frequency region larger than 5%, 10%, 15%, 20%, 25%, 30%, 35%, or even larger than 40%. The impedance bandwidth is defined as the difference between the highest and lowest frequencies of a frequency region, divided by the central frequency of the same frequency region.
Due to the small size of the radiation boosters, the radiation boosters and booster bars may be electrically short at some or all frequencies of operation. A slim radiating structure according to the present invention may feature a first resonant frequency, measured at an internal path, at a frequency higher (i.e. above) than the highest frequency of the first frequency region of operation when said radio-frequency system is disconnected. Moreover, when the radio-frequency system is disconnected, the input impedance of the slim radiating structure measured at the internal path may have an important reactance, in particular a capacitive reactance, within the frequencies of said first frequency region. In this case, a ratio between the first resonant frequency of the slim radiating structure and the highest frequency of the first frequency region is advantageously greater than 1.2. In some cases, said ratio may be even greater than one or more of the following values: 1.5, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, or 3.0. In some examples, a ratio between said first resonant frequency and the lowest frequency of the first frequency region of operation is advantageously greater than 1.3, or even greater than one or more of the following values: 1.4, 1.5, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, or 3.0.
In some embodiments, the first resonant frequency of the slim radiating structure, measured at an internal path when the radio-frequency system is disconnected, is above the highest frequency of the second frequency region, wherein a ratio between said first resonant frequency and said highest frequency of the second frequency region may be larger than one or more of the following values: 1.0, 1.1, 1.2, 1.4, 1.6, 1.8, or 2.0. In some other embodiments, said first resonant frequency is within the second frequency region. In some other examples, said first resonant frequency is above the highest frequency of the first frequency region and below the lowest frequency of the second frequency region.
In the context of this document, a resonant frequency associated to a radiation booster of the slim radiating structure preferably refers to a frequency at which the input impedance of the slim radiating structure, the impedance being measured at the internal path coupling the radiation booster to the radio-frequency system when the radio-frequency system is not connected, has an imaginary part equal or substantially equal to zero.
The radio-frequency system may comprise one or more matching circuits that modify the impedance of the slim radiating structure providing impedance matching to the slim radiating system, at an external path, in one or more frequency regions of operation of the slim radiating system.
A radio-frequency system according to the invention may include at least one matching network with a plurality of stages, for instance, two, three, four, five, six or more stages. A stage comprises one or more circuit components (for example but not limited to, inductors, capacitors, resistors, jumpers, short-circuits, delay lines, or other reactive or resistive components). In some cases, a stage has a substantially inductive behavior in the frequency region or regions of operation of the slim radiating system, while another stage has a substantially capacitive behavior in said frequency region/s, and yet a third one may have a substantially resistive behavior in said frequency region/s. In an example, a stage may substantially behave as a resonant circuit (such as, for instance, a parallel LC resonant circuit or a series LC resonant circuit) in at least one frequency region of operation of the slim radiating system. The use of stages having a resonant circuit behavior allows one part of a given matching network be effectively connected to another part of said matching network for a given range of frequencies, or in a given frequency region, and be effectively disabled for another range of frequencies, or in another frequency region.
In some examples, the at least one matching network alternates stages connected in series (i.e. cascaded) with stages connected in parallel (i.e. shunted), forming a ladder structure. In some cases, a matching network comprising two stages forms an L-shaped structure (i.e. series-parallel or parallel-series). In some cases, a matching network comprising three stages forms either a pi-shaped structure (i.e. parallel-series-parallel) or a T-shaped structure (i.e. series-parallel-series).
In some embodiments, a radio-frequency system according to the present invention comprises a matching circuit in a ladder topology. Such matching circuit preferably comprises one reactive component per stage. In some other embodiments, a radio-frequency system according to the present invention comprises a matching circuit at least including a series LC resonant circuit and a parallel LC resonant circuit.
In a preferred embodiment, an electronic device comprises a slim radiating system configured to transmit and receive electromagnetic wave signals in at least one frequency region of the electromagnetic spectrum, and comprising a slim radiating structure, a radio-frequency system, at least one internal conductive path and at least one external conductive path. The slim radiating structure comprises at least one ground element and at least one booster bar. The at least one internal conductive path comprises a conductive element that couples the at least one booster bar to the radio-frequency system. The radio-frequency system comprises at least one matching circuit modifying the impedance of the slim radiating structure providing impedance matching to the slim radiating system in the at least one frequency region at the at least one external conductive path. The at least one booster bar has an elongated shape, and is characterized by a slim width factor greater than 3 and a slim height factor greater than 3, is separated from the at least one ground element by a gap and is characterized by a location factor between 0.5 and 2.
Another preferred embodiment relates to an electronic device including a slim radiating system that comprises a slim radiating structure, a radio-frequency system, an internal conductive path and at least one external conductive path; the slim radiating system is configured to transmit and receive electromagnetic wave signals in a first frequency region and a second frequency region. The slim radiating structure comprises at least one ground element, and one booster bar separated from the ground element by a gap and is characterized by a location factor between 0.3 and 1.8. The internal conductive path comprises a conductive element that couples the booster bar to the radio-frequency system. The radio-frequency system comprises a matching circuit that modifies the impedance of the slim radiating structure providing impedance matching to the slim radiating system in the first and second frequency regions at the at least one external conductive path. The first and second frequency regions are preferably separated so that the lowest frequency of the second frequency region is above the highest frequency of the first frequency region. Some preferred matching circuits for such preferred embodiment are described in
Further, an advantageous aspect of the invention refers to a radio-frequency system comprising a matching circuit that provides impedance matching to the slim radiating system in first and second frequency regions preferably not requiring a filtering circuit or component that separates frequencies of the first frequency region from frequencies of the second frequency region (e.g. a diplexer, a bank of filters, etc.) for providing impedance matching in the first frequency region and second frequency region independently (i.e. in two separate branches or paths). Thus preferred matching circuits may provide impedance matching in said first and second frequency regions with one branch.
According to the present invention, some preferred matching circuits preferably comprise seven or less components, for instance: two, three, four, five, six or seven. Such matching circuits preferably do not comprise active circuits or components.
In some embodiments in which the slim radiating system is configured to transmit and receive signals in a first frequency region and a second frequency region, a ratio between the lowest frequency of the second frequency region and the lowest frequency of the first frequency region may be greater than 1.5. In some of these embodiments, said ratio may be also greater than 1.8, 2.0, 2.2, or 2.4. In addition, in some embodiments in which the slim radiating system is configured to operate signals from first and second frequency regions, a ratio between the lowest frequency of the second frequency and the highest frequency of the first frequency region may be greater than 1.2, 1.5, 1.8, 2.0, 2.2, or 2.4.
Accordingly, an advantageous aspect of such radio-frequency system is its efficiency in that impedance matching in the first and second frequency regions may be provided with one matching circuit using a reduced number of components, which consequently introduces lower losses in the radio-frequency system and makes it more robust against the tolerances of the components. Moreover, by not including filtering circuits such as diplexers, the radio-frequency system avoids the insertion losses characterizing such type of circuits and the necessity of having two separate matching circuits, which consequently makes the radio-frequency system have less components and the slim radiating system smaller in terms of area occupied in the device.
In a third preferred embodiment, an electronic device includes a slim radiating system comprising a slim radiating structure, a radio-frequency system, first and second internal conductive paths and at least one external conductive path; the slim radiating system is configured to transmit and receive electromagnetic wave signals in a first frequency region and a second frequency region. The slim radiating structure comprises at least one ground plane layer, first and second radiation boosters, each of the first and second radiation boosters being separated from the ground plane layer by a gap. The first internal conductive path comprises a conductive element that couples the first radiation booster to the radio-frequency system, and the second internal conductive path comprises a conductive element that couples the second radiation booster to the radio-frequency system. The radio-frequency system comprises a matching circuit coupled to the first and second internal conductive paths and to the external conductive path, the matching circuit modifies the impedance of the slim radiating structure providing impedance matching to the slim radiating system in the first and second frequency regions.
In some cases, the slim radiating system may comprise a first external conductive path and a second external conductive path, and the radio-frequency system may include a diplexer circuitry that advantageously filters signals from first and second frequency regions, said signals being matched in impedance in the first and second frequency regions by the matching circuit within the radio-frequency system. A first port of the diplexer is connected to the matching circuit, and the two remaining ports of the diplexer are connected to the first and second external conductive paths. The first and second external paths comprise, respectively, signals for frequencies from the first frequency region, and signals for frequencies from the second frequency region.
A further aspect of the present invention relates to a test platform for electromagnetically characterizing radiation boosters. Said platform comprises a substantially square conductive surface on top of which, and substantially close to the central point, the element to be characterized is mounted perpendicular to said surface in a monopole configuration, said conductive surface acting as the ground plane.
The substantially square conductive surface comprises sides with a dimension larger than a reference operating wavelength. In the context of the present invention, said reference operating wavelength is the free-space wavelength equivalent to a frequency of 900 MHz. A substantially square conductive surface according to the present invention is made of copper with sides measuring 60 centimeters, and a thickness of 0.5 millimeters.
In the test configuration as set forth above, a booster bar according to the present invention may be characterized by a ratio between the first resonance frequency and the reference frequency (900 MHz) being larger than a minimum ratio of 3.0. In some cases, said ratio may be even larger than a minimum ratio such as: 3.4, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8, 6.0, 6.2, 6.6 or 7.0.
A booster bar according to the present invention may also be characterized by a radiation efficiency measured in said platform, at a frequency equal to 900 MHz, being less than 50%, preferably being less than 40%, 30%, 20%, or 10%, and in some cases being less than 7.5%, 5%, or 2.5%. All those are quite remarkably low efficiency values considering the additional 1:3 frequency mismatch and beyond obtained in some of the embodiments as described above. Such a frequency shift would introduce further mismatch losses that would result in an overall antenna efficiency below 5%, and quite typically below 2%, which would be ordinarily considered unacceptable for a mobile phone or wireless application. Still, quite surprisingly, when combining at least one booster bar with the radio-frequency system of a slim radiating system according to the present invention, said slim radiating system recovers the efficiency required for the performance of a typical wireless device.
Embodiments of the invention are shown in the enclosed figures.
Further characteristics and advantages of the invention will become apparent in view of the detailed description of some preferred embodiments which follows. Said detailed description of some preferred embodiments of the invention is given for purposes of illustration only and in no way is meant as a definition of the limits of the invention, made with reference to the accompanying figures.
Illustrative wireless electronic devices including a slim radiating system in accordance with the present invention are shown in
In
In the examples of
The size and shape of the booster bar is characterized by a slim width factor and a slim height form factor. The slim width factor is a ratio between the length and the width of the booster bar, and the slim height factor is a ratio between the length and height of the booster bar, being the slim width factor and the slim height factor preferably larger than 3. In this example, where the booster is configured to operate in one or more frequency bands within the 600 MHZ-6 GHz range (e.g. GSM 850 (824-894 MHz), GSM 900 (880-960 MHz), GSM 1800 (1710-1880 MHz), GSM 1900 (1850-1990 MHz), WCDMA 2100 (1920-2170 MHz), CDMA 1700 (1710-2155 MHZ), LTE 700 (698-798 MHZ), LTE 800 (791-862 MHZ), LTE 2600 (2500-2690 MHz), LTE 3500 (3.4-3.6 GHz), LTE 3700 (3.6-3.8 GHz), WiFi (2.4-2.5 GHz and/or 4.9-5.9 GHZ)), the length is 10 millimeters, the width is 3.2 millimeters and the height is 3.2 millimeters, being the slim width factor 3.125 and the slim height factor 3.125, all those dimensions in these and other embodiments, within a typical tolerance of, for instance+/−1%-3% and in some occasions up to a 10% variation. The booster bar is separated from the ground plane by a gap 313; the gap is taken as the minimum distance between the bottom conductive layer and the ground plane layer. The gap distance plus the booster bar's width 311 is characterized as the depth of the radiation booster. The location of the booster bar in relation to the ground plane layer is characterized by a location factor. The location factor is a ratio between the width of the booster bar and the gap, being the location factor preferably in the range of between 0.5 and 2. In this example, the width is 3.2 mm and the gap is 3.3 mm, being the location factor 0.96 and the depth 6.5 mm, all those dimensions within a typical tolerance of, for instance +/−10% variation.
One way to characterize the radio-frequency performance of the slim radiating system entails the use of a reflection coefficient plot; a reflection coefficient of less than-4.4 dB is generally acceptable.
Another example of a slim radiating structure is shown in
A wireless electronic device comprising a slim radiating system that includes slim radiating structure 1300 may advantageously provide penta-band operation: two frequency bands in the first frequency region, like for example the frequency bands corresponding to the GSM 850 and GSM 900 cellular communication standards (i.e. the first frequency region comprising the 824 MHz to 960 MHz frequency range), and three frequency bands in the second frequency region, like for example the frequency bands corresponding to the GSM 1800, GSM 1900 and WCDMA 2100 cellular communication standards (i.e. the second frequency region comprising the 1710 MHz to 2170 MHz frequency range). In another example, a device according to the present invention could provide triple-band or quad-band operation with at least two frequency bands in the first frequency region, and at least another two frequency bands in the second frequency region, wherein first and second frequency regions do not overlap in frequency. Such device could operate, for instance but not limited to, the GSM 850 and GSM 900 cellular communication standards, and the GSM 1800 and GSM 1900 cellular communication standards.
In
Inductors 1503, 1531 and 1541 corresponding to the first stage of matching circuits 1500, 1510, 1530, 1540 and 1550 may preferably have a value in the range of 0.1 nH to 80 nH.
Matching circuits 1500, 1510, 1520, 1530, 1540, and 1550 are suitable for being used as matching circuit 203a and 203d shown in
A ratio between the lowest frequency of the second frequency region and the lowest frequency of the first frequency region is, for this particular case, greater than 1.5 and even greater than 2.0. In addition, a ratio between the first resonant frequency of the slim radiating structure measured at an internal path, when disconnected from the radio-frequency system, and the lowest frequency of the first frequency region is greater than 1.3, also greater than 2.0, and even greater than 2.4.
A booster bar such as 1900 is configured to be used in slim radiating systems according to the present invention, and in particular in each and every embodiment of the present invention. As such, a slim radiating system comprising a slim radiating structure, a radio-frequency system and at least one external conductive path, wherein the slim radiating structure comprises a radiation booster like, for example, 1900 and a ground plane layer, may be configured to transmit and receive electromagnetic wave signals in at least one frequency region, or in at least two frequency regions. The radio-frequency system comprises a matching circuit configured to provide impedance matching to the slim radiating system in said at least one or at least two frequency regions at the at least one external path.
The electrical length of conductive element 2003 may be shorter than 10% of the free-space wavelength corresponding to the lowest frequency of the first frequency region, and preferably it may be shorter than 5% of said free-space wavelength.
In
The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. So even though that in the illustrative examples described above in connection with the figures some particular designs of booster bars with specific values for the slim width factor, the slim height factor, and the location factor have been used, many other designs of boosters bars in accordance with the invention having for example different slim width factor, slim height factor, and/or location factor could have been equally used in the slim radiating structures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14178369.6 | Jul 2014 | EP | regional |
| 14189253.9 | Oct 2014 | EP | regional |
| 14191145.3 | Oct 2014 | EP | regional |
| 15165167.6 | Apr 2015 | EP | regional |
This application is a continuation of U.S. patent application Ser. No. 18/454,180 filed Aug. 23, 2023, which is a continuation of U.S. patent application Ser. No. 17/701,247 filed Mar. 22, 2022, now abandoned, which is a continuation of U.S. patent application Ser. No. 16/274,013 filed Feb. 12, 2019, issued as U.S. Pat. No. 11,349,195 on May 31, 2022, which is a continuation of U.S. patent application Ser. No. 15/875,817 filed Jan. 19, 2018, issued as U.S. Pat. No. 10,236,561 on Mar. 19, 2019, which is a continuation of U.S. patent application Ser. No. 14/807,449 filed Jul. 23, 2015, issued as U.S. Pat. No. 9,960,478, on May 1, 2018, which claims priority under 35 U.S.C. § 119 (c) from U.S. Provisional Patent Application Ser. No. 62/028,494, filed Jul. 24, 2014, U.S. Provisional Patent Application Ser. No. 62/064,716, filed Oct. 16, 2014, U.S. Provisional Patent Application Ser. No. 62/072,671, filed Oct. 30, 2014, and U.S. Provisional Patent Application Ser. No. 62/152,991, filed Apr. 27, 2015, the entire contents of which are hereby incorporated by reference. In addition, this application claims foreign priority under 35 U.S.C. § 119 (a)-(d) to Application No. EP 14178369.6 filed on Jul. 24, 2014, Application No. EP 14189253.9 filed on Oct. 16, 2014, Application No. EP 14191145.3 filed on Oct. 30, 3014, and Application No. EP 15165167.6 filed on Apr. 27, 2015, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62152991 | Apr 2015 | US | |
| 62072671 | Oct 2014 | US | |
| 62064716 | Oct 2014 | US | |
| 62028494 | Jul 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 18454180 | Aug 2023 | US |
| Child | 18734703 | US | |
| Parent | 17701247 | Mar 2022 | US |
| Child | 18454180 | US | |
| Parent | 16274013 | Feb 2019 | US |
| Child | 17701247 | US | |
| Parent | 15875817 | Jan 2018 | US |
| Child | 16274013 | US | |
| Parent | 14807449 | Jul 2015 | US |
| Child | 15875817 | US |
