Patent Application
20240283152
An antenna system of an electronic device can include a plurality of antenna types for wireless connectivity. Examples of electronic devices include, but are not limited to, mobile phones, tablets, base stations, network access points, customer-premises equipment (CPE), laptops, and wearable electronics.
Modern electronic devices such as notebook computers can suffer from compromised antenna performance due to space constraints in a smaller and thinner display housing. This poor antenna performance leads to more reflected radio frequency (RF) power, poor wireless connectivity, and a frustrating user experience.
The aforementioned challenges, among others, are addressed in some examples by the disclosed techniques for improving reflection performance and radiation pattern of a compact antenna system. For example, by using a central conductor of a coaxial cable as a ground path, an antenna height of the antenna system is effectively increased, and antenna performance can be maintained despite the space constraints. An outer conductor of the coaxial cable carrying RF signals can also radiate to free space, improving connectivity of the electronic device, and user experience can be enhanced.
Examples described herein provide an antenna system suitable for compact devices with good dual-band performance. For example, an electronic device can include a dielectric housing; a ground plane; a coaxial cable including a central conductor and an outer conductor; and an antenna printed circuit board (PCB) communicatively connected to the outer conductor of the coaxial cable and located within the dielectric housing, the antenna PCB including: an antenna microstrip feed located on the antenna PCB, a portion of the antenna microstrip feed forming a first part of a radiating antenna element; and an antenna feed point located on the antenna microstrip feed, wherein the outer conductor of the coaxial cable is communicatively connected to the antenna microstrip feed at the antenna feed point, wherein the central conductor is a ground path from the antenna PCB to the ground plane, and wherein the outer conductor is a second part of the radiating antenna element.
In another example, an electronic device can include a display panel; a RF transparent housing; an RF module; and an antenna system communicatively connected to the RF module, the antenna system including: a ground plane; and a coaxial cable including a central conductor and an outer conductor; and an antenna printed circuit board (PCB) communicatively connected to the outer conductor of the coaxial cable and located within a region of the RF transparent housing adjacent to an edge of the display panel, the antenna PCB including a planar antenna patch, wherein a portion of the antenna patch forms a first part of a radiating antenna element, wherein the central conductor forms a ground path from the antenna PCB to the ground plane, and wherein the outer conductor is a second part of the radiating antenna element.
In an additional example, an electronic device can include a dielectric housing; a ground plane; a coaxial cable including a central conductor and an outer conductor; and an antenna printed circuit board (PCB) communicatively connected to the outer conductor of the coaxial cable and located within the dielectric housing, the antenna PCB including: an antenna microstrip feed located on the antenna PCB; and an antenna feed point located in a central region of the antenna microstrip feed such that the antenna feed point separates the antenna microstrip feed into a first part of a radiating antenna element and a second part of the radiating antenna element, wherein the outer conductor of the coaxial cable is communicatively connected to the antenna microstrip feed at the antenna feed point, wherein the central conductor is a ground path from the antenna PCB to the ground plane, wherein the outer conductor is a third part of the radiating antenna element, and wherein the first part of the radiating antenna element has a first length and the second part of the radiating antenna element has a second length corresponding to two different wavelengths of RF signals.
Referring initially to
The antenna system 100 is located within a housing 110, such as the first housing. The housing 110 can include a RF-transparent portion 115 located along a perimeter edge (hereafter referred to as the RF window 115), allowing the antenna system to transmit and receive RF signals even if the housing 110 is a metal housing. In other cases, the housing 110 can be a dielectric housing which is at least partially RF-transparent. The dielectric housing 110 and/or RF window 115 can be polymer, glass, organic material (e.g., wood or bamboo), or other dielectric materials. The housing 110 further includes a display panel 125 of the electronic device, such as a Light Emitting Diode (LED) display panel, Liquid Crystal Display (LCD) panel, micro LED panel, or any other flat panel display technology.
An RF shield covers a back side of the display panel 125, forming a ground plane 120. The ground plane 120 can be a foil layer (e.g., copper foil) located behind the display panel 125, or the display panel can include a metal back plate.
An antenna printed circuit board (PCB) 130 is located adjacent to the display panel 125 within the perimeter edge of the housing 110. The antenna PCB 130 comprises an antenna microstrip feed 140 located on a first side of the PCB. The antenna PCB 130 can be a single or double-sided PCB, and in some cases includes an antenna microstrip feed 140 on either side. The antenna PCB 130 can also be a flexible (“flex”) PCB for more versatility, and to better fit inside a narrow space provided within the housing 110. In some cases, the antenna microstrip feed 140 can include a stripline feed, antenna stub, or another part of an antenna system implemented on the antenna PCB 130.
In certain implementations, the antenna PCB 130 can be omitted in favor of a different technology. For example, laser direct structuring (LDS) can be used to form the antenna microstrip feed 140 within a three-dimensional dielectric portion. Injection molding or other molding techniques can also be used to mold a dielectric layer around the antenna microstrip feed 140 without adversely affecting a radiation pattern of the antenna system 100. Resin, polymer, or other malleable dielectrics can be used to create a protective layer around the antenna microstrip feed 140 even when very little space is available inside the housing 110. It will be appreciated by those skilled in the art that molding can be performed as a final step of assembling the antenna system 100, contouring the dielectric to fill cavities in the housing 110 and sealing the various components in place.
The antenna microstrip feed 140 includes a first branch 140a and a second branch 140b which are separated by an antenna feed point 160a proximal to the center of the antenna PCB 130. The first branch 140a and the second branch 140b of the antenna microstrip feed 140 form a first part and a second part of a radiating antenna element of the antenna system 100. As is discussed herein, the first part and the second part of the radiating antenna element can correspond to different operating bands of a dual-band antenna system 100. In certain implementations, the antenna microstrip feed 140 can have only a first branch 140a forming a first part of a radiating antenna element for a single-band antenna system 100. The antenna microstrip feed 140 can further include one or more microstrip segments 140c on the antenna PCB 130. The first branch 140a, second branch 140b, and microstrip segments 140c of the antenna microstrip feed 140 are connected together by a coaxial cable 150.
The coaxial cable 150 comprises a central (inner) conductor 150a and an outer conductor 150b. The central conductor 150a and the outer conductor 150b are a pair of concentric cylindrical conductors separated by a dielectric medium. Portions of the coaxial cable 150 can be insulated by a rubber, vinyl, or other type of insulating jacket. The central conductor 150a is a solid conductor of a conductive material (e.g., copper or aluminum) and the outer conductor 150b can be a stranded conductor of the same conductive material which encircles the central conductor 150a. In some cases, each conductor 150a and 150b can be of a different conductive material. The central conductor 150a can also be a stranded conductor for greater flexibility of the coaxial cable 150. The dielectric medium can be one or more layers of polytetrafluoroethylene (PTFE), polyethylene foam, solid polyethylene, or another polymer known to one skilled in the art. In some cases, a cavity may exist between the central conductor 150a and the outer conductor 150b such that the conductors are separated by an air gap. Additional layers, such as an RF shielding layer, can be provided between the central conductor 150a and the outer conductor 150b. The coaxial cable 150 can be modified, such as by removing portions of the insulating jacket, outer conductor 150b, and/or dielectric, to connect the central conductor 150a and outer conductor 150b to the antenna microstrip feed 140.
The central conductor 150a of the coaxial cable forms a ground path from the antenna PCB 130 to the ground plane 120 to ground the antenna system 100. The outer conductor 150b of the coaxial cable is communicatively connected to the antenna microstrip feed 140 at the antenna feed point 160a. The outer conductor 150b is configured to carry RF signals between an RF module (e.g., an RF transceiver and/or front-end module) and the antenna PCB 130. Depending on whether the antenna system 100 is a single-band or dual-band system, the outer conductor 150b of the coaxial cable can form a second part or a third part of the radiating antenna element, allowing the RF signal to radiate to free space as it is transmitted between the RF module and the antenna feed point 160a.
The coaxial cable 150 is electrically connected to the antenna PCB 130 at least at the antenna feed point 160a, such as by soldering. The outer conductor 150b of the coaxial cable 150 can also be connected to the microstrip segments 140c of the antenna microstrip feed 140 by soldering. In addition to electrically connecting the branches 140a-b and segments 140c of the antenna microstrip feed 140, the coaxial cable 150 is mechanically mounted to the antenna PCB 130 by the outer conductor 150b. The coaxial cable 150 can be mounted to the antenna PCB 130 at the antenna feed point 160a and additional mounting points 160b corresponding to each of the one or more microstrip segments 140c. The antenna feed point 160a and additional mounting point(s) 160b can be two or more solder points used to electrically and mechanically connect the outer conductor 150b across the antenna PCB 130. In addition to soldering, an adhesive or a molded dielectric as discussed herein can be used to mount the coaxial cable 150 at the antenna feed point 160a and additional mounting point(s) 160b on the antenna microstrip feed 140.
Those skilled in the art will appreciate that the outer conductor 150b, representing a second part or a third part of the radiating antenna element, can effectively replace a portion of the antenna microstrip feed 140 (i.e., a “leg” of the antenna system 100) on the antenna PCB 130. Therefore, it is not necessary for the antenna microstrip feed 140 to be a single contiguous piece. The microstrip segments 140c provide a mounting point for the coaxial cable 150 and can be electrically connected by soldering to the outer conductor 150b, forming the second or third part of the radiating antenna element of the antenna system 100.
One advantage of the antenna system 100 of
The first branch 140a and the second branch 140b of the radiating antenna element can be parallel to the edge of the ground plane 120 such that the antenna height H1 is constant throughout the antenna system. (i.e., a first antenna height H11 measured from a proximal end of the first part of the radiating antenna element and a second antenna height H12 measured from a distal end of the second part of the radiating antenna element are equidistant to the proximal edge of the ground plane 120.) Because the coaxial cable 150 is routed along the antenna PCB 130 over the one or more microstrip segments 140c of the antenna microstrip feed 140, a space is provided on the antenna PCB 130 below the antenna microstrip feed 140 to maintain a RF line-of-sight corresponding to the antenna height H1. The coaxial cable 150 does not obstruct this RF line-of-sight between the antenna microstrip feed 140 and the ground plane 120.
In some cases, the first branch 140a and the second branch 140b of the radiating antenna element do not form a straight-line radiator, but can still be parallel to the edge of the ground plane 120. For example, the first branch 140a can have a first antenna height H1 and the second branch 140b can have a second antenna height H2. Alternatively, the radiating antenna element can have a curved portion along the antenna microstrip feed 140. The radiating antenna element can have a first height H1 at the proximal end of the first branch 140a and a second height H2 at the distal end of the second branch 140b, wherein antenna height is continuously varied between the two ends. The antenna height(s) and configuration of the antenna microstrip feed 140 can be adapted to allow the antenna PCB 130 to fit inside various types of housings 110.
The ground path of the central conductor 150a is shielded by the outer conductor 150b carrying RF signals, thereby preventing the ground path from inadvertently coupling RF emissions of the antenna system 100 to the ground plane 120. The coaxial cable 150 therefore does not interfere with or adversely affect a radiation pattern of the radiating antenna element. The coaxial cable 150 as described herein can improve performance of the antenna system 100 in scenarios where performance would otherwise be compromised by a grounded outer conductor coupling RF emissions, effectively reducing the antenna height H1. The coaxial cable 150 being grounded by the central conductor 150a can also allow the antenna PCB 130 to be made smaller without a corresponding reduction in antenna height and performance.
The length of the radiating antenna element can correspond to an operating band of an RF module 315 of the antenna system 100. For example, the RF module 315 can support Wi-Fi communication such as 2.4 GHz band Wi-Fi and/or 5 GHz band Wi-Fi. The RF module 315 can support any type of WLAN or WWAN connectivity known to one skilled in the art, including Wi-Fi, Bluetooth, ultra-wideband (UWB), 4G LTE, 5G NR, geolocation standards, and the like. The single-band inverted-F antenna 300a can be a fractional wavelength antenna, such as ½ wavelength, ¼ wavelength, ⅛ wavelength, ⅝ wavelength, or similar. The inverted-F antennas of the antenna system 100 as described herein can be used to provide coverage across multiple frequency bands and/or communication standards.
For example, the first branch 140a of the antenna microstrip feed 140 can have a length which is a multiple of 12.5 centimeters, forming a first part of the radiating antenna element configured for TX/RX operation in the 2.4-2.5 GHz Wi-Fi band. The second branch 140b of the antenna microstrip feed 140 can have a length which is a multiple of 5 centimeters, forming a second part of the radiating antenna element configured for TX/RX operation in the 5-7 GHz Wi-Fi band. For space savings within the housing 110, each branch of the antenna microstrip feed 140 can be a ¼ wavelength antenna or smaller. For example, the length of the first branch 140a can be less than about 3.12 centimeters and the length of the second branch 140b can be less than about 1.25 centimeters. These dimensions of the antenna microstrip feed 140 can be adjusted depending on the application of the antenna system 100 and the electronic device, providing coverage of relevant frequency bands and complementing any other antenna microstrip feeds 140 of the antenna system.
The outer conductor 150b can form a third part of the radiating antenna element at an end portion of the coaxial cable 150 between the antenna feed point 160a and the first leg 310. The length of the coaxial cable 150 can be selected for impedance matching with the first and second parts of the radiating antenna element. For example, the outer conductor 150b of the coaxial cable 150 can have a characteristic impedance of 50 ohms, 75 ohms, 300 ohms, or another impedance matched to the dual-band inverted-F antenna 300b. The RF module 315 is communicatively coupled to the outer conductor 150b of the coaxial cable 150 to transmit or receive RF signals by the dual-band inverted-F antenna 300b.
A parasitic element 320 is adjacent to and parallel with the straight-line portion of the radiating antenna element. The parasitic element 320 includes a second leg 330 to connect the parasitic element directly to the ground plane 120 at the edge of the antenna PCB 130. The parasitic element 320 can contribute to resonance effects of the dual-band inverted-F antenna 300c, and allows the antenna system 100 to achieve equivalent performance in a smaller footprint compared to the dual-band inverted-F antenna 300b of
A first frequency response 510 of the antenna system 100 of
In a first region 530a of the chart 500 corresponding to the 2.4-2.5 GHz Wi-Fi band, the first frequency response 510 shows a high degree of attenuation (as low as −20 dB) of reflected signals. However, the second frequency response 520 only shows −8 dB of attenuation in the first region 530a. Accordingly, at frequencies relevant to 2.4 GHz Wi-Fi operation, the antenna system 100 of
In a second region 530b of the chart 500 corresponding to the 5-7 GHz Wi-Fi band, the first frequency response 510 and the second frequency response 520 are more similar. At frequencies above 4 GHz, the two frequency responses start to diverge, with the first frequency response 510 measuring −9 dB, −12 dB, and −6 dB at 5 GHz, 6 GHz, and 7 GHz, respectively. In contrast, the second frequency response 520 measures −6 dB, −5 dB, and −3 dB at those same frequencies. Noise rejection in the second region 530b for the second frequency response 520 is narrowly centered around about 6.4 GHz, indicating a lower bandwidth, while the first frequency response 510 shows generally improved noise rejection over the wider range from 5-7 GHz. For at least these reasons, the antenna system 100 of
The principles the examples described herein can be used for any other system or apparatus including mobile phones, tablets, base stations, network access points, customer-premises equipment (CPE), laptops, and wearable electronics.
Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled,” as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word “connected,” as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number, respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
Moreover, conditional language used herein, such as, among others, “may,” “could,” “might,” “can,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain examples include, while other examples do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more examples or that one or more examples necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular example.
