Patent Application
20180212304
The disclosure generally relates to an antenna system, and more particularly, it relates to an antenna system for generating different radiation patterns.
With the advancements being made in mobile communication technology, mobile devices such as portable computers, mobile phones, multimedia players, and other hybrid functional portable electronic devices have become more common. To satisfy consumer demand, mobile devices can usually perform wireless communication functions. Some devices cover a large wireless communication area; these include mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some devices cover a small wireless communication area; these include mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz.
Antennas are indispensable elements to mobile devices supporting wireless communications. However, in general an antenna can usually only generate a fixed radiation pattern. If the signal reception direction is aligned with a null of the antenna radiation pattern, it may face problems with reduced data transmission rates and poor communication quality. Accordingly, there is a need to propose a novel solution for solving the problems of the prior art.
In an exemplary embodiment, the disclosure is directed to an antenna system including a first tunable antenna. The first tunable antenna includes a first radiation element, a second radiation element, a transmission line, and a switch circuit. The transmission line includes a first segment, a second segment, and a phase-adjustment segment. The first radiation element is coupled through the first segment to a first feeding point. The second radiation element is coupled through the second segment to a second feeding point. The switch circuit is configured to switch between the first feeding point and the second feeding point, so that the first feeding point or the second feeding point is arranged for receiving a feeding signal. The phase-adjustment segment has a first end and a second end. The first feeding point is positioned at the first end of the phase-adjustment segment. The second feeding point is positioned at the second end of the phase-adjustment segment.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
In order to illustrate the purposes, features and advantages of the invention, the embodiments and figures of the invention are shown in detail as follows.
Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. The term “substantially” means the value is within an acceptable error range. One skilled in the art can solve the technical problem within a predetermined error range and achieve the proposed technical performance. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
The first radiation element 120, the second radiation element 130, the first segment 140, the second segment 150, and the phase-adjustment segment 160 may be made of conductive materials, such as metal materials. It should be understood that the shapes and types of the first radiation element 120, the second radiation element 130, the first segment 140, the second segment 150, and the phase-adjustment segment 160 are not limited in the invention. For example, both of the first radiation element 120 and the second radiation element 130 may form a monopole antenna, a dipole antenna, a patch antenna, or a chip antenna. The aforementioned transmission line (including the first segment 140, the second segment 150, and the phase-adjustment segment 160) may be a microstrip line, a stripline, or a CPW (Coplanar Waveguide).
The first tunable antenna 110 has a first feeding point FP1 and a second feeding point FP2. Each of the first radiation element 120 and the second radiation element 130 may substantially have a straight-line shape or a rectangular shape. The first radiation element 120 is coupled through the first segment 140 to the first feeding point FP1. The second radiation element 130 is coupled through the second segment 150 to the second feeding point FP2. The phase-adjustment segment 160 is positioned between the first feeding point FP1 and the second feeding point FP2. The phase-adjustment segment 160 is configured to change the feeding phases relative to the first radiation element 120 and the second radiation element 130. Specifically, the phase-adjustment segment 160 has a first end 161 and a second end 162. The first feeding point FP1 is positioned at the first end 161 of the phase-adjustment segment 160. The second feeding point FP2 is positioned at the second end 162 of the phase-adjustment segment 160. The switch circuit 170 is configured to switch between the first feeding point FP1 and the second feeding point FP2, such that either the first feeding point FP1 or the second feeding point FP2 is arranged for receiving a feeding signal SF. A signal source 199 may be an RF (Radio Frequency) module for generating the feeding signal SF or processing a reception signal. The signal source 199 is coupled through the switch circuit 170 to either the first feeding point FP1 or the second feeding point FP2, so as to excite the first tunable antenna 110. In some embodiments, the phase-adjustment segment 160 substantially has an inverted U-shape, and the switch circuit 170 is at least partially disposed in a notch 165 of the inverted U-shape of the phase-adjustment segment 160, thereby reducing the total size of the first tunable antenna 110. In alternative embodiments, the phase-adjustment segment 160 has a different shape, such as a straight-line shape, a W-shape, or a C-shape. By switching between the first feeding point FP1 and the second feeding point FP2, the first tunable antenna 110 can generate different radiation patterns due to the changes in feeding phases, and therefore it can receive or transmit wireless signals in a variety of directions.
In some embodiments, the antenna system 100 covers an operation frequency band from 5150 MHz to 5875 MHz, so as to support the application of WLAN (Wireless Local Area Networks) 5 GHz. It should be noted that the aforementioned operation frequency band is adjustable in response to different requirements. In some embodiments, the element sizes of the antenna system 100 are as follows. The length L1 of the phase-adjustment segment 160 may be equal to 0.25 wavelength (λ/4) of the central frequency of the operation frequency band, so as to provide a feeding phase difference which is almost equal to 90 degrees. Since the switch circuit 170 can contribute a little feeding phase difference, the length L1 of the phase-adjustment segment 160 may be slightly shorter than 0.25 wavelength (λ/4) of the central frequency of the operation frequency band in other embodiments. The distance D1 between the first radiation element 120 and the second radiation element 130 may be substantially equal to 0.25 wavelength (λ/4) of the central frequency of the operation frequency band. The length L2 of each of the first radiation element 120 and the second radiation element 130 may be substantially equal to 0.25 wavelength (λ/4) of the central frequency of the operation frequency band. The above ranges of element sizes are calculated and obtained according to many experiment results, and they help to optimize the radiation pattern and the impedance matching of the antenna system 100.
Specifically, the first tunable antenna 310 further includes a dielectric substrate 380, a metal trace 390, and a ground plane 395. The dielectric substrate 380 has a top surface E1 and a bottom surface E2. The first radiation element 320 and the second radiation element 330 are disposed on the top surface E1 of the dielectric substrate 380. For example, each of the first radiation element 320 and the second radiation element 330 may be an L-shaped metal piece. The first radiation element 320 and the second radiation element 330 may be disposed on the top surface E1 of the dielectric substrate 380. The end of the first radiation element 320 and the end of the second radiation element 330 may extend toward each other. On the other hand, the metal trace 390 is disposed or printed on the top surface E1 of the dielectric substrate 380, and the ground plane 395 is disposed or printed on the bottom surface E2 of the dielectric substrate 380. The metal trace 390 may substantially have a meandering shape. The ground plane 395 may substantially have an inverted T-shape. The metal trace 390 has a vertical projection on the bottom surface E2 of the dielectric substrate 380. The whole vertical projection of the metal trace 390 may be inside the ground plane 395. With such a design, the aforementioned transmission line (including the first segment 340, the second segment 350, and the phase-adjustment segment 360) may be a microstrip line, which is formed by the metal trace 390 and the ground plane 395 together. It should be noted that the shape of the ground plane 395 can be fine-tuned and minimized according to the shapes of the first segments 340, the second segment 350, and the phase-adjustments segment 360. Since the ground plane 395 occupies only a small area of the bottom surface E2 of the dielectric substrate 380, it can prevent the radiation performance of the first radiation element 320 and the second radiation element 330 from being affected by a ground plane that is too large. The antenna system 300 can be implemented using a general manufacturing process of PCB (Printed Circuit Board), and therefore it has the advantages of low complexity and low cost. Other features of the antenna system 300 of
The phase-adjustment segment 660 may substantially have a straight-line shape. The length L3 of the phase-adjustment segment 660 may be shorter than or equal to 0.25 wavelength (λ/4) of a central frequency of an operation frequency band of the antenna system 600, so as to provide a feeding phase difference which is almost equal to 90 degrees. A third feeding point FP3 is positioned at a central point of the phase-adjustment segment 660 (e.g., the central point between the first feeding point FP1 and the second feeding point FP2). The switch circuit 670 is configured to switch between the first feeding point FP1, the second feeding point FP2, and the third feeding point FP3, such that the signal source 199 is coupled through the switch circuit 670 to the first feeding point FP1, the second feeding point FP2, or the third feeding point FP3. Accordingly, the first feeding point FP1, the second feeding point FP2, or the third feeding point FP3 is arranged for receiving a feeding signal SF from the signal source 199. Similarly, as mentioned in the embodiment of
Please refer to
In some embodiments, the third feeding point FP3 and the three-to-one switch circuit 670 of
In some embodiments, the aforementioned switch circuit performs a process for selecting a feeding point according to a control signal. The control signal may be generated by a processor module. For example, the processor module can control the switch circuit to switch to all of the feeding point combinations one after another, and finally select a specific feeding point combination corresponding to the maximum RSSI (Received Signal Strength Indicator), thereby optimizing the communication quality of the antenna system. The processor module can be implemented by a hardware circuit or by executing a computer software program. For example, the processor module may be a Wi-Fi module, and its control signal may be transmitted through a GPIO (General-Purpose Input/Output) interface to the switch circuit, but they are not limited thereto.
The invention proposes a novel antenna system for switching between feeding points, such that its one or more tunable antennas can generate different radiation patterns. Specifically, the invention can equalize the RSSI of each tunable antenna, so as to increase the throughput of the whole antenna system. According to the practical measurement, if the antenna system 400 of
Note that the above element sizes, element shapes, and frequency ranges are not limitations of the invention. An antenna designer can fine-tune these settings or values according to different requirements. It should be understood that the antenna system of the invention is not limited to the configurations of
Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 106140531 | Nov 2017 | TW | national |
This application claims the benefit of U.S. Provisional Application No. 62/449,113, filed on Jan. 23, 2017, the entirety of which is incorporated by reference herein. This application further claims priority of Taiwan Patent Application No. 106140531 filed on Nov. 22, 2017, the entirety of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62449113 | Jan 2017 | US |
