Planar inverted F antenna and method of making the same

A multi-band antenna (1) used in wireless communications includes a radiating portion (2), a grounding portion (4), and a connecting portion (3). The radiating portion (2) includes a first radiating element (21) operating at 900 MHz frequency band and a second radiating element (22) operating at 1800 MHz frequency band. The connecting portion (3) connects the radiating portion (2) and the grounding portion (4). The grounding portion (4), the radiating portion (2), and the connecting portion (3) locate in the same plane.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an antenna, and more particularly to a planar inverted-F antenna (PIFA) used in a portable electronic device.

2. Description of the Prior Art

With the development of wireless communication, more and more portable electronic devices, for example note book, install an antenna system for working in a Wireless Local-area Network (WLAN). Transmitting and receiving signals plays an important role in wireless communication process. In recent years, a majority of WLAN bases on Bluetooth technical standard or 802.11 technical standard. Antenna in Bluetooth technical standard bases on 2.4 GHz frequency band, and in 802.11 technical standard bases on 2.4 GHz and 5 GHz. So, antenna in notebook mostly works in the above frequency bands at the present time.

However, user would not satisfy a portable wireless communication devices only working in WLAN in the future. It's desired to make portable wireless communication device working in Wireless Wide-area Network (WWAN). The portable wireless communication device working in WWAN can work and entertain in more broad area. WWAN adopts two techniques, GSM and CDMA at present. However, a portable wireless communication device can work in GSM unless it has an antenna working in the frequency band of GSM. Antennas in notebook and other portable wireless communication device mostly work in 2.4 GHz frequency and 5 GHz frequency now. However, antennas of the mobile phone working in GSM mostly cannot be set in notebook or other portable wireless communication device because of size or power.

For example, China Patent No. 2689482Y discloses a PIFA capable of working on three frequency bands. The antenna includes three radiating elements, respectively operating at 1800 GHz, 900 MHz, and 2450 MHz. So, the antenna can be set in notebook or other portable wireless communication device for working in GSM. However, this antenna adopts solid structure, that is, the radiating elements, connection element, and grounding element respectively locate in different planes. Complex configuration and taking up more space result in the antenna going against industrialization manufacture, wasting cost and breaching trend of miniaturization development of antenna.

Hence, in this art, a planar inverted-F antenna to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiment.

BRIEF SUMMARY OF THE INVENTION

A primary object, therefore, of the present invention is to provide a planar inverted-F antenna with simplified structure and reduced size.

A second object, therefore, of the present invention is to provide a method of manufacturing the antenna above.

In order to implement the above object and overcomes the above-identified deficiencies in the prior art, the planar inverted F antenna forming in a metal patch, comprises a first radiating element and extending in a first direction, a second radiating element and extending in a second direction different from the first direction, a grounding portion and spacing with the first radiating element and the second radiating element, an connecting portion connecting the first and the second radiating elements and the grounding portion, and a feeder line comprising a inner conductor for attaching to the connecting portion and a outer conductor for attaching to the grounding portion. The first radiating element has a first radiating portion and a second radiating portion being perpendicular to the first radiating portion. The connecting portion comprises a first portion, a second portion paralleling the first portion and s third portion connecting the first portion and the second portion.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to a preferred embodiment of the present invention.

Referring toFIG. 1, a planar inverted-F antenna1according to the present invention is made of a metal sheet and comprises a radiating portion2, a grounding portion4, and a connecting portion3connecting the radiating portion2and the grounding portion4.

The radiating portion2comprises a first radiating element21operating at a lower frequency and a second radiating element22operating at a higher frequency and extending along a first direction. The first radiating element21is of L-shape and comprises a first part210extending along the first direction and parallel to the second radiating element22and a second part211extending along a second direction from left end of the first part210toward the grounding portion4. The L-shape design of the first radiating element21is capable of avoiding adding the lateral size of the planar inverted-F antenna1. The connecting portion3comprises a first side section31parallel to the second part211of the first radiating element21and connecting the first radiating element21and the second radiating element22, a second side section32extending along the first direction from a lower end of the first side section31toward the second part211, and a third side section33extending along the second direction from left end of the second side section32to terminate the second side section32with the grounding portion4, respectively. The grounding portion4is a rectangular piece connecting the third side section33and parallel to the second side section32. A feeding point5locates on the second side section32near the third side section33. A feeding line6extends from feeding point5and connects the grounding portion4. The feeding line6comprises an inner conductor61soldered to the feeding point5, an inner insulating layer63enclosing the inner conductor61, a metal braiding layer62soldered to the grounding portion4and an outer insolating layer (not labeled).

The second, third side sections32,33of the connecting portion3and a longer edge of the grounding portion4together form a slot7with width equal to the length of the third side section33. High frequency of the second radiating portion22can arrive at a more wider frequency band and a more better radiation impression by changing the width of the slot7i.e. the length of the third side section33and location of the feeding point5.

The first radiating element21, the connecting portion3, and the grounding portion4together form a first planar inverted-F antenna receiving and transmitting lower frequency signal. The second radiating portion22, the connecting portion3, and the grounding portion4form a second planar inverted F antenna receiving and transmitting higher frequency signal.

FIGS. 2-5show the horizontally polarized and vertically polarized principle plane radiation patterns of the antenna1operating at the resonant frequency of 900 MHz and 1800 GHz. Note that each radiation pattern of the planar inverted-F antenna1is close to corresponding optimal radiation pattern and there is no obvious radiating blind area, conforming to the practical use conditions of an antenna.

Referring toFIG. 6, sets forth a test chart recording of Voltage Standing Wave Ratio (VSWR) of the antenna1as a function of frequency. Note that VSWR drops below the desirable maximum value “2” in the 880 M-920 MHz frequency band and in the 1710-2180 MHz frequency band, indicating acceptable efficient operation in these two wide frequency bands, which cover more than the total bandwidth of GSM (low frequency band includes 880-960 MHz, high frequency band includes 1710-1880 MHz) and be provided with more wider frequency band of the operating at high frequency.

The method of making the same of the planar inverted-F antenna1of the present invention comprises following steps. Firstly, selecting a rectangle metal piece. Secondly, calculating a required length of the radiating portion2according to the bands of 900 MHz and 1800 MHz. Thirdly, calculating a length and shape of the connecting portion3according to required impendence matching. Fourth, achieving the radiating portion2, the connecting portion3, and the grounding portion4by digging slots in the rectangle metal piece according to the calculations. Fifth, calculating the location of the feeding point5and providing the feeding line6connecting to the feeding point5according to impendence matching.