Patent Application
20120287014
(i) Representative Figure:
(ii) Brief description of reference numerals of the representative figure:
None
1. Field of the Invention
The subject application relates to a handheld device and a planar antenna thereof. More particularly, the planar antenna of the subject application comprises a screening element configured to make the planar antenna operating at two central frequencies and a switch configured to make the planar antenna operating at another two central frequencies.
2. Descriptions of the Related Art
As modern people's demands on the wireless communication become increasingly higher, handheld devices (e.g., mobile phones, notebook computers, tablet personal computers and wireless network routers) have gradually become indispensable to modern people's life. In order to meet the demands of modern people on the handheld devices, handheld device manufacturers all try to design the handheld devices to be more humanized or more adapted for people's needs. Among these designs, multi-frequency operability and a slim profile are most desired by the modern people.
In order to impart the handheld devices with the multi-frequency operability, the manufacturers have made great efforts to develop antennas with the multi-frequency operability in the recent years. Among these antennas, a planar inverted-F antenna (PIFA) with a slim profile has received the most attention. The conventional single-frequency planar inverted-F antenna has only a radiator of about ¼ wavelength as a resonant current path. If the single-frequency planar inverted-F antenna is to operate at more central frequencies, then other parasitic antenna elements and/or other branches must be added to form multiple current paths. In other words, if a common conventional antenna needs to transmit and receive two or more kinds of signals, it must have two or more radiator branches that transmit and receive signals at respective operating frequencies; however, as these radiators occupy much space and, meanwhile, the handheld devices for the antenna does not have a large enough clearance area, the transceiving quality of the antenna is degraded.
In design of the conventional multi-frequency planar inverted-F antennas, due to the increased number of antenna elements, an unexpected coupling effect may be generated between the antenna elements to increase the complexity in design of the antennas; meanwhile, also due to the increased number of the antenna elements, the overall volume of the antenna is increased and this results in various disadvantages. Furthermore, the conventional multi-frequency planar inverted-F antennas cannot be switched flexibly to operate at multiple central frequencies.
In view of this, an urgent need exists in the art to design a planar antenna, which has a small volume, a simple design and a capability of flexibly operating at multiple central frequencies.
An objective of the subject application is to provide a planar antenna, which has a small volume, a simple design and a capability of flexibly operating at multiple central frequencies. The planar antenna of the subject application has only one radiator, so it has a reduced volume compared to the conventional multi-frequency planar inverted-F antennas. In addition, as the planar antenna of the subject application can operate at multiple central frequencies without need of other parasitic antenna elements and/or other branches, the complexity in design of the planar antenna is also reduced.
To achieve the aforesaid objective, the subject application discloses a planar antenna, which comprises a radiator, a screening element and a switch. The radiator comprises: a first portion comprising a first contact point and a second contact point; a second portion comprising a third contact point, a fourth contact point electrically connected to the second contact point, and a fifth contact point; and a third portion comprising a sixth contact point. The screening element is electrically connected between the fifth contact point and the sixth contact point to make the planar antenna operating at a first high-frequency (HF) current path and a first low-frequency (LF) current path. The switch is electrically connected between the first contact point and the third contact point to make the planar antenna operating at a second HF current path and a second LF current path. When the switch is turned off, the planar antenna operates at a first HF central frequency corresponding to the first HF current path and a first LF central frequency corresponding to the first LF current path. When the switch is turned on, the planar antenna operates at a second HF central frequency corresponding to the second HF current path and a second LF central frequency corresponding to the second LF current path.
Another objective of the subject application is to provide a handheld device and a planar antenna thereof. The planar antenna is disposed within a clearance area of a substrate of the handheld device. Compared to the conventional multi-frequency planar inverted-F antennas, the planar antenna of the subject application has a reduced volume, so it can be disposed within the clearance area more effectively and the clearance area can be completely utilized to improve the communication quality of the handheld device. Accordingly, in case that the size of the clearance area is not reduced with the volume of the planar antenna, the subject application can reduce the influence of electronic elements, which are disposed outside the clearance area, on the planar antenna so as to improve the communication quality of the handheld device. On the other hand, in case that the size of the clearance area is reduced with the volume of the planar antenna, the subject application can make the internal spatial arrangement of the handheld device more flexible and minimize the influence of the electronic elements on the planar antenna so as to maintain the communication quality of the handheld device.
To achieve the aforesaid objective, the subject application further discloses a handheld device, which comprises a substrate and a planar antenna. The substrate includes a clearance area, and the planar antenna is disposed within the clearance area and configured to transmit and receive an RF signal. The planar antenna comprises a radiator, a screening element and a switch. The radiator comprises: a first portion comprising a first contact point and a second contact point; a second portion comprising a third contact point, a fourth contact point electrically connected to the second contact point, and a fifth contact point; and a third portion comprising a sixth contact point. The screening element is electrically connected between the fifth contact point and the sixth contact point to make the planar antenna operating in a first HF current path and a first LF current path. The switch is electrically connected between the first contact point and the third contact point to make the planar antenna operating in a second HF current path and a second LF current path. When the switch is turned off, the planar antenna operates at a first HF central frequency corresponding to the first HF current path and a first LF central frequency corresponding to the first LF current path. When the switch is turned on, the planar antenna operates at a second HF central frequency corresponding to the second HF current path and a second LF central frequency corresponding to the second LF current path. The detailed technology and preferred embodiments implemented for the present invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention.
The present invention mainly relates to a handheld device and a planar antenna thereof, and the planar antenna has a small volume, a simple design and a capability of flexibly operating at multiple central frequencies. The following embodiments are only for purpose of illustrating the present invention rather than to limit the scope of the present invention. It shall be appreciated that, in the following embodiments and the attached drawings, elements unrelated to the present invention are omitted from depiction. Furthermore, dimensional relationships among individual elements in the attached drawings are illustrated only for ease of understanding but not to limit the actual scale.
A first embodiment of the present invention is shown in
As shown in
Further speaking, as shown in
The screening element 133 is electrically connected between the fifth contact point 1313c and the sixth contact point 1315a so that the planar antenna 13 has a first high-frequency (HF) current path and a first low-frequency (LF) current path. Specifically, when the planar antenna operates in a first frequency band operating mode, the screening element 133 excludes the third portion 1315 from the first HF current path (i.e., the fifth contact point 1313c and the sixth contact point 1315a form an open circuit therebetween), and incorporates the third portion 1315 into the first LF current path (i.e., the fifth contact point 1313c and the sixth contact point 1315a form a short circuit therebetween). In other words, the screening element 133 allows the radiator 131 of the planar antenna to operate in a dual operating modes, i.e., to resonate at two primary central frequencies (e.g., one fundamental frequency and at least one harmonic frequency) simultaneously.
The switch 135 is electrically connected between the first contact point 1311a and the third contact point 1313a so that the planar antenna 13 has a second HF current path and a second LF current path. Specifically, when the switch 135 is turned on (i.e., the first contact point 1311a and the third contact point 1313a are electrically conducted to each other), the planar antenna operates in a second frequency band operating mode; and in this case, the second HF current path includes the conductor between the first contact point 1311a and the third contact point 1313a but excludes the third portion 1315; and the second LF current path includes both the conductor between the first contact point 1311a and the third contact point 1313a and the third portion 1315. Accordingly, in the precondition that the screening element 133 can make the radiator 131 of the planar antenna resonating at two primary central frequencies simultaneously, the switch 135 can further make the radiator 131 of the planar antenna resonating at another two primary central frequencies. It shall be appreciated that, the switch 135 may be a mechanical switch, an electronic switch or any other element configured to control conducting between the first contact point 1311a and the third contact point 1313a.
Furthermore, the first portion 1311 of the radiator 131 further comprises a feeding point 1317 electrically connected to a signal terminal (not shown) of the circuit board 113, and the second portion 1313 of the radiator 131 further comprises a ground point 1319 electrically connected to a ground terminal (not shown) of the circuit board 113; thus, the handheld device 1 can transmit and receive the RF signal via the planar antenna 13. Further speaking, when the switch 135 is turned off, the planar antenna 13 operates in the first frequency band operating mode (i.e., at a first HF central frequency corresponding to the first HF current path and a first LF central frequency corresponding to the first LF current path); and when the switch 135 is turned on, the planar antenna 13 operates in the second frequency band operating mode (i.e., at a second HF central frequency corresponding to the second HF current path and a second LF central frequency corresponding to the second LF current path).
Furthermore, the planar antenna 13 further comprises an RF choke 139, which is electrically connected between the feeding point 1317 of the first portion 1311 of the radiator 131 and a direct current (DC) output terminal of the circuit board 113 to block an RF signal flowing into the DC output terminal. In this embodiment, whether the diode element is turned on or off is controlled by a DC control signal outputted from the DC output terminal. On the other hand, the planar antenna 33 further comprises a DC blocker 141. The DC blocker 141 is a capacitor, which is electrically connected between the second contact point 1311b of the first portion 1311 of the radiator 131 and the fourth contact point 1313b of the second portion 1313 of the radiator 131 and configured to block the DC control signal flowing into the fourth contact point 1313b of the second portion 1313 via the second contact point 1311b of the first portion 1311. It shall be appreciated that, in other embodiments, the DC blocker 141 may be any other element or combination of elements that can block a DC current from passing therethrough, but is not limited to the capacitor.
Further speaking, when a voltage at the DC output terminal is lower than a preset value (threshold), the diode element is turned off (i.e., un-conducting), so an open circuit is formed between the first contact point 1311a of the first portion 1311 and the third contact point 1313a of the second portion 1313 of the radiator 131. In this case, the planar antenna 33 operates in the first frequency band operating mode. However, when the voltage at the DC output terminal is higher than the preset value, the diode element is turned on, so a current path is formed between the first contact point 1311a of the first portion 1311 and the third contact point 1313a of the second portion 1313 of the radiator 131. In this case, the planar antenna 33 operates in the second frequency band operating mode.
Similarly, the feeding point 1317 of the planar antenna 13 is electrically connected to an RF choke 139, and the RF choke 139 is electrically connected to a DC output terminal of the circuit board 113 to block an RF signal flowing into the DC output terminal. The DC output terminal outputs a DC control signal to control the ON or OFF state of the diode element. On the other hand, the DC blocker 141 is also a capacitor, which is electrically connected between the second contact point 1311b of the first portion 1311 and the fourth contact point 1313b of the second portion 1313 of the radiator 131 and configured to block the DC control signal flowing into the fourth contact point 1313b of the second portion 1313 via the second contact point 1311b of the first portion 1311.
According to the above descriptions, the planar antenna of the subject application utilizes the screening element 133 to generate a HF current path and a LF current path in each of the two operating modes respectively and utilizes the switch 135 to flexibly switch between the two operating modes. Thus, the planar antenna can operate at multiple central frequencies to transmit and receive RF signals of different frequency bands or of different communication systems. Further speaking,
Specifically, the subject application can provide a very large operable bandwidth by using only one radiator. Therefore, compared to the conventional antennas having the similar functionalities, the antenna of the subject application can have its volume reduced by about ⅓ and provide a better performance. Furthermore, as the planar antenna of the subject application has only one radiator but no other parasitic antenna elements and/or other branches, it has not only a reduced volume but also a relatively simple design as compared to the conventional multi-frequency planar inverted-F antenna; as a result, the planar antenna can be disposed within the clearance area of the handheld device more effectively to reduce the influence of other electronic parts of the handheld device on the characteristics of the planar antenna. On the other hand, in case that the size of the clearance area is reduced with the size of the planar antenna, the internal spatial arrangement of the handheld device can be made more flexible.
The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.
