This application claims the priority benefit of Taiwan application serial No. 98105651, filed on Feb. 23, 2009. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
1. Field of the Invention
The present invention is related to an antenna and particularly to an antenna with double groundings.
2. Description of Related Art
In view of the research of wireless communication, different systems have diversified frequencies and bandwidths, and require different designs of radiation patterns and polarizations of the wave radiated by the antenna from time to time. In addition, the environment of mobile communication is full of interference and variables. An antenna not only needs to coordinate the frequency, bandwidth, pattern of radiation wave, and polarization, but is required to overcome problems, such as interference of multipath, transition of radiation wave polarization, change of radiation wave pattern, and size, weight, and shape of the antenna. Among the above, the interference of multipath causes fading during the transmission of signal and greatly reduces the reliability of the wireless communication system.
At present, the means to overcome the fading problem is to use spatial diversity, pattern diversity, and polarization diversity of the antenna. In view of the design, a circularly polarized antenna has no particular polarization direction when receiving or transmitting radiation waves, and thus is able to overcome the influence of phase difference resulting from multipath interference. For this reason, antennas of satellite communication systems, global positioning systems, microwave AV monitor systems, electronic charging systems, microwave remote control and microwave measuring systems, and so forth all adopt circular polarization design for transmitting signals.
However, in the current communication products, the design of the circularly polarized antenna, which has a structure of
The present invention provides an antenna with double groundings which is designed to include two ground parts for generating two orthogonal linearly polarized waves, and thereby forms a radiation wave approximating to circular polarization. Based on the technical means of the present invention, the gain of circular polarization radiation wave is achieved and the arrangement of the antenna becomes more flexible.
The present invention provides an antenna with double groundings which uses two ground parts in parallel to a feeding part for generating a radiation wave approximating circular polarization.
The present invention provides an antenna with double groundings, including a body part, a feeding part, a first grounding part, and a second grounding part. Herein, the body part is electrically connected to the feeding part, the first grounding part, and the second grounding part, and the body part is corresponding to a resonance length for transmitting and receiving a radiation wave. In addition, a current path from the first grounding part to the feeding part along the body part is ½ times of the wavelength at operating frequency. A relative distance is maintained between the second grounding part and the first grounding part. It is noted that the resonance length is in a range of ⅓˜⅕ times of the wavelength at operating frequency.
In an embodiment of the present invention, the relative distance between the first grounding part and the second grounding part is ¼ times of the wavelength at operating frequency.
In an embodiment of the present invention, the body part includes a first conductive element, a second conductive element, and a third conductive element. More specifically, each of the first conductive element, the second conductive element, and the third conductive element has a first end and a second end. The first end of the second conductive element is electrically connected to the first end of the first conductive element, and further, the first end of the third conductive element is electrically connected to the second end of the first conductive element. Moreover, the second conductive element is electrically connected to the feeding part, the first grounding part, and the second grounding part.
In an embodiment of the present invention, the second conductive element of the antenna with double groundings is electrically connected to the feeding part via a feeding point, and a current path from the feeding point to the second end of the third conductive element is equal to the resonance length.
In an embodiment of the present invention, the first grounding part and the second grounding part of the antenna with double groundings are arranged on one side of the feeding part along a direction towards the second end of the second conductive element, and the widths of the first conductive element, the second conductive element, and the third conductive element are equal to one another.
In an embodiment of the present invention, the first grounding part and the second grounding part of the antenna with double groundings are respectively disposed on two sides of the feeding part, and the width of the third conductive element is larger than the width of the second conductive element. Furthermore, in the antenna with double groundings, a ratio of the width of the third conductive element to the width of the second conductive element is in a range of 1.5 to 2.
In an embodiment of the present invention, the first grounding part and the second grounding part of the antenna with double groundings are arranged on one side of the feeding part along a direction towards the first end of the second conductive element, and the widths of the second conductive element and the third conductive element are respectively larger than the width of the first conductive element.
In an embodiment of the present invention, a ratio of the width of the second conductive element to the width of the first conductive element and a ratio of the width of the third conductive element to the width of the first conductive element are in a range of 1.5 to 2.
From another aspect, the present invention further provides an antenna with double groundings, including a body part, a feeding part, a first grounding part, and a second grounding part. Specifically, the body part is electrically connected to the feeding part, the first grounding part, and the second grounding part. In addition, the body part with a feeding point extends a resonance length for transmitting and receiving a radiation wave. The feeding part is electrically connected to the body part via the feeding point. The first grounding part and the second grounding part are arranged in parallel to the feeding part. Herein, a current path from the first grounding part to the feeding part along the body part is ½ times of the wavelength at operating frequency, and a relative distance between the first grounding part and the second grounding part is ¼ times of the wavelength at operating frequency. It is noted that the resonance length is in a range of ⅓˜⅕ times of the wavelength at operating frequency.
Based on the above, the antenna of the present invention is designed to include two ground parts for generating two orthogonal linearly polarized waves and thereby forms a radiation wave approximating to circular polarization. Accordingly, the antenna with double groundings of the present invention has advantages in terms of miniaturization and is applicable to the transmission of radiation wave between global positioning systems, electronic products, and satellites.
To make the above features and advantages of the present invention more comprehensible, embodiments accompanied with drawings are described in detail as follows.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
In the following paragraphs, elements having identical or similar functions and structures are assigned with the same reference numbers and terms for consistency.
To be more detailed, the first conductive element 311 has two ends, which are respectively marked as A01 and A02; the second conductive element 312 has two ends, respectively marked as A03 and A04; the third conductive element 313 has two ends, respectively marked as A05 and A06; the feeding part 320 has two ends, respectively marked as A07 and A08; the first grounding part 331 has two ends, respectively marked as A09 and A10; and the second grounding part 332 has two ends, respectively marked as A11 and A12.
As shown in
In view of the configuration of the elements in the planar inverted-F antenna 300, the first grounding part 331, the second grounding part 332, and the feeding part 320 are arranged in parallel to one another. In addition, in the aspect of the second end A04 of the second conductive element 312, the second grounding part 332, the first grounding part 331, and the feeding part 320 are sequentially disposed on one side of the second conductive element 312 along a direction B1 towards the first end A03 of the second conductive element 312. From the aspect of the feeding point P31, the feeding part 320, the first grounding part 331, and the second grounding part 332 are sequentially arranged on one side of the second conductive element 312 along a direction B2 towards the second end A04 of the second conductive element 312.
Referring to
Furthermore, a current path from the first grounding part 331 to the feeding part 320 along the body part 310, i.e. the current path going from the end A10 through the first grounding part 331, the body part 310, and the feeding part 320 to the end A08, is ½ times of the resonance length (equal to λ/8). A relative distance D21 between the second grounding part 332 and the first grounding part 331, i.e. a vertical gap between the first end A12 of the second group part 332 and the first end A10 of the first grounding part 331, is ¼ times of the wavelength at operating frequency (equal to λ/16).
In view of the whole operation, the first grounding part 331 and the second grounding part 332 are to adjust an impedance matching of the planar inverted-F antenna 300. Moreover, based on the design of the first grounding part 331 and the second grounding part 332, the planar inverted-F antenna 300 is able to generate two orthogonal linearly polarized waves for forming a radiation wave approximating to circular polarization. For instance, the radiation wave patterns of the planar inverted-F antenna 300 in spatial directional angles theta (θ) and phi (ψ) are illustrated in
On the contrary, if the planar inverted-F antenna 300 in this embodiment only has one ground part, either the first grounding part 331 or the second grounding part 332, instead of two groundings, the pattern of the radiation wave would have apparent nulls, as shown in
In other words, because of the design of the first grounding part 331 and the second grounding part 332, the planar inverted-F antenna 300 of this embodiment is able to generate two orthogonal linearly polarized waves for forming the radiation wave which approximates to circular polarization. Moreover, a circular polarization wave does not have a specific polarization direction when receiving or transmitting radiation waves, and no null is formed. Accordingly, the intensity of signal is maintained and the reception of the antenna would not be influenced. For the above reasons, the planar inverted-F antenna 300 of the embodiment is applicable to the transmission of radiation wave between global positioning systems, electronic products, and satellites.
Specifically, in this embodiment, the body part 310′ includes a first conductive element 311′, a second conductive element 312′, and a third conductive element 313′. The current path D12 on the body part 310′ goes from a feeding point P32 through the ends A01 and A02 to the end A06. In view of the configuration of the elements in a planar inverted-F antenna 300′, the second end A07 of the feeding part 320 is electrically connected to the second conductive element 312′ via the feeding point P32. The first grounding part 331, the second grounding part 332, and the feeding part 320 are arranged in parallel to one another. In addition, the first grounding part 331 and the second grounding part 332 are respectively disposed on two sides of the feeding part 320. In other words, the second grounding part 332, the feeding part 320, and the first grounding part 331 are sequentially arranged on one side of the second conductive element 312′ along the direction B1 towards the first conductive element 311′.
With reference to
In addition, similar to the first embodiment, the body part 310′ is corresponding to a resonance length, and the resonance length is ⅓˜⅕ times of the wavelength at operating frequency, preferably ¼ times of the wavelength at operating frequency of a radiation wave received or transmitted by the body part 310′. A current path from the first grounding part 331 to the feeding part 320 along the body part 310′ is ½ times the resonance length. A relative distance D21 between the second grounding part 332 and the first grounding part 331 is ¼ times of the wavelength at operating frequency. Based on the design of the first grounding part 331 and the second grounding part 332, the planar inverted-F antenna 300′ of this embodiment is able to generate two perpendicular linearly polarized waves for forming the radiation wave which approximates to circular polarization. Details of this embodiment have been described in the above embodiments and therefore not repeated hereinafter.
Specifically, in this embodiment, the body part 310″ includes a first conductive element 311″, a second conductive element 312″, and a third conductive element 313″. The current path D13 on the body part 310″ goes from a feeding point P33 through the ends A01 and A02 to the end A06. In view of the configuration of the elements in a planar inverted-F antenna 300″, the second end A07 of the feeding part 320 is electrically connected to the second conductive element 312″ via the feeding point P33. The first grounding part 331, the second grounding part 332, and the feeding part 320 are arranged in parallel to one another. Moreover, the first grounding part 331 and the second grounding part 332 are located on one side of the feeding part 320 along the direction B1 towards the first end A03 of the second conductive element 312″. Furthermore, the feeding part 320, the second grounding part 332, and the first grounding part 331 are sequentially disposed on one side of the second conductive element 312″ along the direction B1 towards the first conductive element 311″.
As shown in
In addition, similar to the first embodiment, the body part 310″ is corresponding to a resonance length, and the resonance length is ⅓˜⅕ time of the wavelength at operating frequency, preferably ¼ times of the wavelength at operating frequency of a radiation wave received or transmitted by the body part 310″. A current path from the first grounding part 331 to the feeding part 320 along the body part 310″ is ½ times of the resonance length at operating frequency. A relative distance D21 between the second grounding part 332 and the first grounding part 331 is ¼ times the resonance length. Based on the design of the first grounding part 331 and the second grounding part 332, the planar inverted-F antenna 300″ as described in this embodiment is able to generate two perpendicular linearly polarized waves for forming the radiation wave which approximates to circular polarization. Details of this embodiment have been described in the above embodiments and therefore not repeated hereinafter.
In conclusion of the above, the planar inverted-F antenna according to the present invention uses double groundings to generate linearly polarized waves and thereby forms the radiation wave which approximates circular polarization. Accordingly, the planar inverted-F antenna of the present invention has advantages in terms of miniaturization and is applicable to the transmission of radiation wave between global positioning systems, electronic products, and satellites.
Although the present invention has been disclosed by the above embodiments, they are not intended to limit the present invention. Any person having ordinary knowledge in the art may make modifications and variations without departing from the spirit and scope of the present invention. Therefore, the scope of protection sought by the present invention falls in the appended claim.
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