BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a portable electronic device, and in particular relates to a portable electronic device satisfying HAC requirements with a decreased SAR value.
2. Description of the Related Art
SAR and HAC are indices that measure the extent of radiation influence upon human health and hearing aid equipment, respectively. A high SAR value resulting from electromagnetic wave radiation may cause human health problems. Thus, mobile phones must pass SAR requirements (e.g. FCC & CE requirements). Mobile phones with excessive HAC values hinder audiphone's functions. Thus, 50% of the mobile phones sold in North America by a manufacturer must pass HAC requirements.
To pass SAR and HAC requirements, several conventional solutions are applied in mobile phone design: (a) board end power or antenna radiation efficiency is decreased to reduce radiation energy; (b) electric field distribution is modified by adding a metal element corresponding to an antenna; or (c) the antenna is disposed away from a radiation interference area thereof (e.g. away from amplifier.) However, the conventional solutions may deteriorate communications quality, reduce design flexibility, or increase hardware costs.
BRIEF SUMMARY OF THE INVENTION
A detailed description is given in the following embodiments with reference to the accompanying drawings.
An antenna is provided. The antenna includes a radiator, a feed conductor and a ground conductor. The radiator includes a body and a parasitic element. An aperture is formed on the body, and the body encloses the aperture. The parasitic element is connected to the body and extended into the aperture, wherein the parasitic element is connected to the body at a parasitic location. The feed conductor is connected to the body, wherein a signal, fed to the body by the feed conductor, travels on the body, and passes the parasitic location to the parasitic element. The ground conductor is connected to the body.
In one embodiment, a path length from the feed conductor to the parasitic location is ¼λ, wherein λ is a wavelength of the signal.
In another embodiment, a path length from the feed conductor to the parasitic location is ½λ, wherein λ is a wavelength of the signal.
In one embodiment, a portable electronic device is provided, wherein the feed conductor and the ground conductor electrically connect the body (antenna) to a circuit board thereof, and the antenna modifies an electric field distribution of the circuit board.
The antenna of the embodiment of the invention modifies an electric field distribution on a ground layer of a circuit board, and reduces the electric field intensity around the amplifier to improve HAC and SAR performance. In one embodiment of the invention, the HAC performance can be improved to level M3 (68.5 V/m). Additionally, the antenna can be disposed near the amplifier of a portable electronic device, without negatively effecting HAC requirement of the portable electronic device.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
FIG. 1A shows an antenna of a first embodiment of the invention transmitting a first signal;
FIG. 1B shows the antenna of the first embodiment of the invention transmitting a second signal;
FIG. 2 shows detailed structure of a parasitic element of the first embodiment of the invention;
FIG. 3 shows a modified example of the first embodiment;
FIG. 4A shows a portable electronic device utilizing the antenna of the embodiment;
FIG. 4B shows the antenna of the embodiment disposed near an amplifier of the portable electronic device;
FIG. 5A shows an antenna of a second embodiment of the invention transmitting a first signal;
FIG. 5B shows the antenna of the second embodiment of the invention transmitting a second signal;
FIG. 6 shows detailed structure of a parasitic element of the second embodiment of the invention; and
FIG. 7 shows a modified example of the second embodiment.
DETAILED DESCRIPTION OF THE INVENTION
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
FIG. 1A shows an antenna 100 of a first embodiment of the invention transmitting a first signal. With reference to FIG. 1A, the antenna 100 comprises a radiator 110, a feed conductor 120 and a ground conductor 130. The radiator 110 comprises a body 111 and a parasitic element 112. An aperture 113 is formed on the body 111, and the body 111 encloses the aperture 113. The parasitic element 112 is connected to the body 111 and extended into the aperture 113, wherein the parasitic element 112 is connected to the body 111 at a parasitic location 114. The feed conductor 120 is connected to the body. The first signal (for example, high frequency signal ranging from 1700 MHz to 3000 MHz), fed to the body by the feed conductor 120, travels on the body 111 along a resonance path 101, passes the parasitic location 114 to the parasitic element 112, and travels on the parasitic element 112 along a parasitic path 102. The ground conductor 130 is connected to the body 111. A path length from the feed conductor to the parasitic location (path length of the resonance path 101) is ¼λ, wherein λ is a wavelength of the first signal.
FIG. 1B shows the antenna 100 of the first embodiment of the invention transmitting a second signal. With reference to FIG. 1B, the second signal (for example, low frequency signal ranging from 800 MHz to 1000 MHz), fed to the body by the feed conductor 120, travels on the body 111 along a resonance path 103 enclosing the aperture 113.
With reference to FIG. 2, the parasitic element 112 is substantially L-shaped. The parasitic element 112 comprises a first section 1121 and a second section 1122, the first section 1121 is connected to the second section 1122, the first section 1121 extends in a first direction Y, the second section 1122 extends in a second direction X, the first direction Y is perpendicular to the second direction X, and an end of the first section 1121 is connected to the parasitic location 114. In this embodiment, a line width of the first section 1121 is greater than a line width of the second section 1122. A slot 115 is formed between the parasitic element 112 and the body 111. The parasitic element 112 further comprises a bent portion 1123, and the bent portion 1123 is formed on a free end of the second section 1122. A notch 116 is formed on a side of the parasitic element 112 for resistance matching.
FIG. 3 shows a modified example of the first embodiment, wherein the shape of the body 111 is modified, and a slot 117 is formed on a side of the body 111 to increase the resonance path 103.
FIG. 4A shows a portable electronic device 10 utilizing the antenna 100 of the embodiment. The portable electronic device 10 comprises a housing 1 and a circuit board (print circuit board) 2. The feed conductor and the ground conductor electrically connect the body (antenna 100) to the circuit board 2. The antenna 100 modifies an electric field distribution of the circuit board 2 to reduce an HAC value of the portable electronic device 10. With reference to FIG. 4B, in the embodiment of the invention, the antenna 100 can be disposed near an amplifier 3 of the portable electronic device 10, without negatively effecting HAC recruitment of the portable electronic device 10.
The antenna of the embodiment of the invention modifies an electric field distribution on a ground layer of the circuit board, and reduces the electric field intensity around the amplifier to improve HAC and SAR performance. In one embodiment of the invention, the HAC performance can be improved to level M3 (68.5 V/m). Additionally, the antenna can be disposed near the amplifier of the portable electronic device, without negatively effecting HAC recruitment of the portable electronic device.
FIG. 5A shows an antenna 100′ of a second embodiment of the invention transmitting a first signal. With reference to FIG. 5A, the antenna 100′ comprises a radiator 110′, a feed conductor 120 and a ground conductor 130. The radiator comprises a body 111 and a parasitic element 112′. An aperture 113 is formed on the body 111, and the body 111 encloses the aperture 113. The parasitic element 112′ is connected to the body 111 and extended into the aperture 113, wherein the parasitic element 112′ is connected to the body 111 at a parasitic location 114′. The feed conductor 120 is connected to the body. The first signal (high frequency signal), fed to the body by the feed conductor 120, travels on the body 111 along a resonance path 101′, passes the parasitic location 114′ to the parasitic element 112′, and travels on the parasitic element 112′ along a parasitic path 102′. The ground conductor 130 is connected to the body 111. A path length from the feed conductor 120 to the parasitic location 114′ (path length of the resonance path 101′) is ½λ, wherein λ is a wavelength of the first signal.
FIG. 5B shows the antenna 100′ of the second embodiment of the invention transmitting a second signal. With reference to FIG. 5B, the second signal (low frequency signal), fed to the body by the feed conductor 120, travels on the body 111 along a resonance path 103′ enclosing the aperture 113.
With reference to FIG. 6, similar to the first embodiment, the parasitic element 112′ is substantially L-shaped. The parasitic element 112′ comprises a first section 1121′ and a second section 1122′, the first section 1121′ is connected to the second section 1122′, the first section 1121′ extends in a first direction Y′, the second section 1122′ extends in a second direction X′, the first direction Y′ is perpendicular to the second direction X′, and an end of the first section 1121′ is connected to the parasitic location 114′. In this embodiment, and a line width of the first section 1121′ is greater than a line width of the second section 1122′. A slot 115′ is formed between the parasitic element 112′ and the body 111. A notch 116′ is formed on a side of the parasitic element 112′ for resistance matching.
FIG. 7 shows a modified example of the second embodiment, wherein the shape of the body 111 is modified, and a slot 118 and a slot 119 are formed on a side of the body 111 to increase the resonance path 103′.
Resistance matching and bandwidth of the antenna of the invention can be modified by changing the shapes of the body, the aperture and the parasitic element. The path length from the feed conductor to the parasitic location can be within a range from ½λ to ¼λ.
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. To 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.
Patent Application
20110043421
