1. Field of the Invention
The present invention relates to a planar dual polarization antenna and a complex antenna, and more particularly, to a planar dual polarization antenna and a complex antenna of broadband, wide beamwidth, high antenna gain, better common polarization to cross polarization (Co/Cx) value, smaller size, and meeting 45-degree slant polarization requirements.
2. Description of the Prior Art
Electronic products with wireless communication functionalities, e.g. notebook computers, personal digital assistants, etc., utilize antennas to emit and receive radio waves, to transmit or exchange radio signals, so as to access a wireless communication network. Therefore, to facilitate a user's access to the wireless communication network, an ideal antenna should maximize its bandwidth within a permitted range, while minimizing physical dimensions to accommodate the trend for smaller-sized electronic products. Additionally, with the advance of wireless communication technology, electronic products may be configured with an increasing number of antennas. For example, a long term evolution (LTE) wireless communication system and a wireless local area network standard IEEE 802.11n both support multi-input multi-output (MIMO) communication technology, i.e. an electronic product is capable of concurrently receiving/transmitting wireless signals via multiple (or multiple sets of) antennas, to vastly increase system throughput and transmission distance without increasing system bandwidth or total transmission power expenditure, thereby effectively enhancing spectral efficiency and transmission rate for the wireless communication system, as well as improving communication quality. Moreover, MIMO communication systems can employ techniques such as spatial multiplexing, beam forming, spatial diversity, pre-coding, etc. to further reduce signal interference and to increase channel capacity.
The LTE wireless communication system includes 44 bands which cover from 698 MHz to 3800 MHz. Due to the bands being separated and disordered, a mobile system operator may use multiple bands simultaneously in the same country or area. Under such a situation, conventional dual polarization antennas may not be able to cover all the bands, such that transceivers of the LTE wireless communication system cannot receive and transmit wireless signals of multiple bands. Therefore, it is a common goal in the industry to design antennas that suit both transmission demands, as well as dimension and functionality requirements.
Therefore, the present invention provides a planar dual polarization antenna to solve current technical narrow-beamwidth problems.
An embodiment of the present invention discloses a planar dual polarization antenna, for receiving and transmitting at least one radio signal, comprising a first patch plate; a metal grounding plate comprising a first pattern slot and a second pattern slot, wherein a first rectangle and a second rectangle enclosing an angle constitute a shape of the first pattern slot, the first rectangle and the second rectangle meet at a pivot vertex, and the first pattern slot and the second pattern slot are symmetric with respect to a centerline of the first patch plate; and a first dielectric layer disposed between the first patch plate and the metal grounding plate.
An embodiment of the present invention further discloses a complex antenna for receiving and transmitting at least one radio signal, comprising a first planar dual polarization antenna layer comprising a plurality of first patch plates; a metal grounding plate comprising a plurality of rectangular regions, wherein each rectangular region of the plurality of rectangular regions is disposed corresponding to one of the plurality of first patch plates, each rectangular region of the plurality of rectangular regions comprises a first pattern slot and a second pattern slot, a first rectangle and a second rectangle enclosing an angle constitute a shape of the first pattern slot, the first rectangle and the second rectangle meet at a pivot vertex, and the first pattern slot and the second pattern slot are symmetric with respect to a centerline of the first patch plate; and a first dielectric layer disposed between the first planar dual polarization antenna layer and the metal grounding plate.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Briefly, the length L1 of the metal grounding plate 120 along the symmetry axis axis_y is longer than the width W1 of the metal grounding plate 120 along the direction x, thereby increasing 3 dB beamwidth in the horizontal plane. The pattern slots 124a, 124b of the metal grounding plate 120 is utilized to balance the asymmetry of the length L1 and the width W1 and thus improve common polarization to cross polarization (Co/Cx) value.
Specifically, to increase the beamwidth in horizontal plane (i.e., the xz plane), the width W1 of the metal grounding plate 120 along the direction x must be shortened to make the antenna pattern in horizontal plane diverge. It turns out that the length L1 of the metal grounding plate 120 along the symmetry axis axis_y is longer than the width W1 of the metal grounding plate 120 along the direction x. Since the length L1 is not equal to the width W1, resonance lengths in the vertical direction and in the horizontal direction will differ. The pattern slots 124a, 124b of the metal grounding plate 120, however, could balance the asymmetry due to the uneven quantities between the length L1 and the width W1. The pattern slots 124a, 124b substantially have a boomerang shape 20. Please refer to
Please note that the planar dual polarization antenna 10 as shown in
Technically, because an LTE base station is generally located near the ground, and because of the distance between an LTE base station and a user, the radiation power of the complex antenna 30 should be concentrated in vertical plane (i.e., the yz plane) within plus or minus 10 degrees elevation angle with respect to the horizon. In such a situation, the patch plates DPP_1, DPP_2 vertically aligned to form a 1×2 array antenna can ensure that antenna gain meets system requirements. Moreover, the length L1 of the rectangular regions SC1, SC2 along the symmetry axis axis_y is longer than the width W1 of the rectangular regions SC1, SC2 along the direction x, thereby increasing 3 dB beamwidth in horizontal plane (i.e., the xz plane). Table 1 is an antenna characteristic table for the complex antenna 30. As can be seen from Table 1, the complex antenna 30 meets LTE wireless communication system requirements for maximum gain and front-to-back (F/B) ratio. Furthermore, as the width W1 of the metal grounding plate 320 shrinks from 100 mm to 70 mm, the beamwidth in horizontal plane can increase to 69.5 to 73.0 degrees.
To further improve common polarization to cross polarization (Co/Cx) value of the complex antenna 30, the structure of the metal grounding plate 320 may be modified. Please refer to
In other words, with the array antenna structure, antenna gain of the complex antenna 40 increases. And the width W1 of the rectangular regions SC3, SC4 is shortened to increase beamwidth. In order to balance the asymmetry between the length L1 and the width W1, the rectangular regions SC3, SC4 further respectively comprise the pattern slots PSL_1a, PSL_1b, PSL_2a, PSL_2b and thus improve common polarization to cross polarization (Co/Cx) value.
Simulation and measurement may be employed to determine whether the complex antenna 40 meets system requirements. Specifically,
Please note that the planar dual polarization antenna 10 and the complex antenna 30, 40 are exemplary embodiments of the invention, and those skilled in the art can make alternations and modifications accordingly. For example, portions of the feeding transmission lines 102a, 102b, FTL_1a, FTL_1b, FTL_2a, FTL_2b and the slots 122a, 122b, SL_1a, SL_1b, SL_2a, SL_2b may be modified according to different considerations, which means that degrees of the included angles enclosed by two adjacent portions can be either obtuse or acute angles, length ratios or width ratios may be changed, and the shape and the number of portions may vary. Also, having a shape “substantially conforming to a cross pattern” recited in the present invention relates to the patch plate 140, 160, UPP_1, UPP_2, DPP_1, DPP_2 being formed by two overlapping and intercrossing rectangular patch plates. However, the present invention is not limited thereto, and any patch plate having a shape “substantially conforming to a cross pattern” are within the scope of the present invention. For example, a patch plate extends outside a square side plate; alternatively, a patch plate extends outside a saw-tooth shaped side plate; alternatively, a patch plate further extends outside an arc-shaped side plate; alternatively, edges of a patch plate are rounded. The dielectric layers 110, 130, 150, 310, 330, 350 can be made of various electrically isolation materials such as air. The patch plate 160, the planar dual polarization antenna layer 360 and the dielectric layer 150, 350 in fact depend on bandwidth requirements and may therefore be optional. The complex antennas 30, 40 are 1×2 array antennas, but not limited thereto and can be 1×3, 2×4 or m×n array antennas.
Besides, the length L2 of the rectangle 200a of the boomerang shape 20 as shown in
On the other hand, to reduce the beamwidth in horizontal plane (i.e., the xz plane), the width of the metal grounding plate along the direction x may be enlarged.
To sum up, by adjusting the ratio of the length to the width of the rectangular regions of the metal grounding plate, beamwidth increases. In order to balance the asymmetry of the length and the width, the metal grounding plate comprises pattern slots, which improves common polarization to cross polarization (Co/Cx) value.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Number | Date | Country | Kind |
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103126252 | Jul 2014 | TW | national |