BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a preferred embodiment of the antenna structure in accordance with the present invention.
FIG. 2 is a perspective view showing a resonator in FIG. 1 in accordance with the present invention.
FIG. 3 is a top view showing a feed-in/feed-out component in FIG. 1 in accordance with the present invention.
FIG. 4 is a graph showing the relation between frequency and return loss of the preferred embodiment of the antenna in accordance with the present invention.
FIG. 5 is a radiation pattern of the antenna in accordance with the present invention in the XY-plane at the frequency of 5.3 GHz.
FIG. 6 is a radiation pattern of the antenna in accordance with the present invention in the XY-plane at the frequency of 5.7 GHz.
FIG. 7 is a radiation pattern of the antenna in accordance with the present invention in the XY-plane at the frequency of 6.1 GHz.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the following, the present invention will be described in detail with reference to the attached drawings and component numerals, and it can be carried into effect by those skilled in the art after reading it.
With reference to FIGS. 1 and 2, an antenna structure 1 in accordance with the present invention is used to receive and transmit signals, which mainly comprises a resonator 11 and a feed-in/feed-out component 12. The resonator 11 can receive electromagnetic signals in the space or transmit electromagnetic signals into the space. The feed-in/feed-out component 12 is used to import or export the signals received or transmitted by the resonator 11.
In the above-mentioned antenna structure in accordance with the present invention, the resonator 11 is a column structure. Part of the exterior surface of the resonator 11 is coated with a metal layer 11a, which is made of conductive material, and a connector 11b is formed at the bottom end of the metal layer 11a, to be electrically connected to the feed-in/feed-out component 12. In particular, as FIG. 2 shows, the resonator 11 is a rectangular column with a resonator width a, a resonator length b and a resonator height h. The connector 11b is a metal strip connector with a connector height hc and a connector width wc. The resonator width a, the resonator length b and the resonator height h of a preferred embodiment are 5.7 mm, 3.3 mm and 12 mm, respectively. The metal layer 11a is formed on the three adjacent surfaces of the column of the resonator 11. The distance from the bottom end of the metal layer 11a to the bottom edge of the rectangular column of the resonator 11 is the connector height hc of the connector 11b. Part of the bottom end of the metal layer 11a extends and forms the connector 11b to the bottom edge of the rectangular column of the resonator 11. The connector height hc and the connector width wc of the preferred embodiment are 0.5 mm and 3.75 mm, respectively.
The coating area or coating height of the metal layer 11a of the above-mentioned resonator 11 is used to adjust the resonant frequency of the resonator 11.
With reference to FIGS. 1 and 3, in the above-mentioned antenna structure in accordance with the present invention, the feed-in/feed-out component 12 is made up of a wire pattern 122 coated or printed on a substrate 121. Wherein the substrate 121 with a substrate thickness t is made of a dielectric material such as FR4, Teflon, Duriod, fiberglass, aluminum oxide, ceramic materials, and so on; and, the wire pattern 122 is made of metal, with a grounding length LG and a grounding width WG, respectively. The wire pattern 122 comprises a grounding part 122a, parallel slot lines 122b and open-circuited slot lines 122c, and defines a resonator foot-print region 122d. The grounding part 122a is made of conductive material. It is used to ground the feed-in/feed-out component 12, and to electrically connect with the connector 1b. The parallel slot lines 122b and the open-circuited slot lines 122c are the part of the wire pattern 122 that conductive material is removed. The parallel slot lines 122b are made up of two parallel slot lines, with a parallel slot length L, a parallel slot width g1 and a parallel slot spacing w. The open-circuited slot lines 122c are made up of two open-circuited slot lines, with an open-circuited slot width g2 and an open-circuited slot length s. Each open-circuited slot line 122c is vertically extended from the end of the parallel slot line 122b close to the resonator foot-print region 122d, and the distance between the open-circuited slot line 122c and the backside of the resonator 11 is d. The wiring pattern 122 may incur a coupling effect of the electromagnetic signals associated with the resonator 11. In particular, as FIG. 3 shows, the feed-in/feed-out component 12 according to the preferred embodiment is coated or printed on a rectangular substrate 121, on which the feed-in/feed-out length, feed-in/feed-out width, and feed-in/feed-out height are 75 mm, 75 mm, and 0.5 mm, respectively. The parallel slot spacing w, which is the distance between the parallel slot lines 122b, is 0.5 mm. The parallel slot length L is 39 mm. The inner end of each parallel slot line 122b turns 90 degrees and extends toward the other parallel slot line 122b to form the open-circuited slot line 122c. An open-circuited slot opening, which is between the two ends of the two open-circuited slot lines 122c, is approximately 0.25 mm long. In addition, the distance d between the backside of the resonator 11 and the open-circuited slot line 122c is 0.5 mm.
The open-circuited slot width g2 and the open-circuited slot length s of the above-mentioned open-circuited slot lines 122c are used to adjust the impedance matching. The open-circuited slot length s is chosen slightly shorter than the parallel slot spacing w, and the open-circuited slot width g2 is chosen close to the parallel slot width g1.
Furthermore, the dimensions of the rectangular column of the resonator 11 and the open-circuited slot length s of the open-circuited slot lines 122c are used to adjust the impedance matching and the resonant frequency. When the distance d between the open-circuited slot line 122c and the backside of the resonator 11 is about one-seventh to one-sixth of the resonator width a of the rectangular column of the resonator 11, the antenna structure is optimized.
With reference to FIG. 4, the relevant parameters according to another preferred embodiment are: the resonator width a is 3.3 mm; the resonator length b is 5.7 mm; the resonator height h is 12 mm; the parallel slot spacing w is 10 mm; the parallel slot width g1 is 0.5 mm; the open-circuited slot width g2 is 0.5 mm; the distance d between the backside of the resonator and the open-circuited slot line is 0.5 mm; the open-circuited slot length s is 5.375 mm; the connector height hc is 0.5 mm; the connector width wc is 3.75 mm; the parallel slot length L is 39 mm; the grounding length LG is 75 mm; the grounding width WG is 75 mm; and the substrate thickness t is 0.6 mm. FIG. 4 shows the relation between frequency and return loss of the preferred embodiment of the antenna structure in accordance with the present invention, wherein the solid line shows the data measured from experiments, and the dash line shows the data simulated by a software package. FIG. 4 shows that the bandwidth measured from experiments is close to the simulated bandwidth.
FIGS. 5-7 are the radiation patterns of the antenna structure in accordance with the present invention in the XY-plane at the frequencies 5.3 GHz, 5.7 GHz, and 6.1 GHz, respectively, wherein the scale from the origin to the perimeter in radial direction is 40 dB. Curve 501 shows the Eθ component measured from experiments, and curve 502 shows the Eφ component measured from experiments. Curve 503 shows the Eθ component simulated by software, and curve 504 shows the Eφ component simulated by software. It is apparent from the figures that the radiation pattern of the antenna structure in accordance with the present invention has omnidirectional characteristic, and the frequency bandwidth is greater than that of conventional antennas.
The above-presented description is only intended to illustrate the preferred embodiment in accordance with the present invention, and must not be interpreted as restrictive to the present invention. Therefore, it is apparent that a variety of modifications and changes may be made without departing from the scope of the present invention, which is intended to be defined by the appended claims.
Patent Application
20080048915
