1. Field of the Invention
The invention relates to an antenna, and more particularly to a broadband dielectric resonator antenna.
2. Description of the Related Art
Conventional dielectric resonator antennas provide a narrow bandwidth. For increasing bandwidth, conventional dielectric resonator antenna combines different-shaped resonator structures. For example, conventional dielectric resonator antenna combines resonator structures with triangular or circular cross-sections for connecting bands thereof and increasing bandwidth. However, manufacturing processes of conventional dielectric resonator antenna are complicated, increasing costs and antenna height (size), and is hardly every utilized in portable electronic devices.
Another conventional dielectric resonator antenna combines a plurality of resonate modes to increase bandwidth. However, divergence field thereof changes with frequency by influence of high order resonate modes.
Additionally, another conventional dielectric resonator antenna comprises a plurality of openings formed in a resonator to intermit electric fields, decrease dielectric coefficient and increase bandwidth. However, manufacturing processes of conventional dielectric resonator antenna with openings are also complicated and costly.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The invention provides an antenna comprising a substrate, a feed conductor, a ground layer and a resonator body. The substrate comprises a first surface and a second surface. The feed conductor is formed on the first surface. The ground layer is formed on the second surface comprising an opening. The resonator body comprises a first resonator structure and a second resonator structure. The first resonator structure is disposed on the ground layer. The second resonator structure is disposed on the ground layer surrounding the first resonator structure, wherein a groove is formed between the first and the second resonator structures.
The antenna of the invention combines TE111y, TE112y and TE113y mode bands to provide bandwidth of 33%, and provides a bandwidth between 4.89 GHz to 6.86 GHz to satisfy requirement of WLAN 802.11 a with linear polarization and wider wave paddle. The antenna of the invention has smaller height and reduced cost, and can be incorporated with other planer circuits and easily produced in large scale by low temperature co-fired processes.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
a and 4b show dimensions of the antenna 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.
The first resonator structure 141 is cube-shaped. The second resonator structure 142 surrounds a rectangular area. The opening 131 is longitudinal extending pass bottoms of the first resonator structure 141 and the second resonator structure 142. The feed conductor 120 is longitudinal, and also extends pass bottoms of the first resonator structure 141 and the second resonator structure 142. The feed conductor 120 extends along a first axis z, the opening 131 extends along a second axis y, and the first axis z is perpendicular to the second axis y. The feed conductor 120 correspondingly passes a center of the opening 131.
The resonator body 140 is a dielectric resonator structure comprising low temperature co-fired ceramics or other high dielectric coefficient and low loss materials. The substrate 110 can comprise dielectric materials such as Teflon, glass fiber, Aluminum Oxide, ceramics, glass fiber plate (FR4), and microwave printed circuit board (Duroid).
When wireless signal is transmitted, the signal travels from the feed conductor 120, passes the opening 131 and is coupled to the resonator body 140. Because dielectric coefficient of the resonator structures 141 and 142 is much greater than dielectric coefficient of air in the groove 143, electric field is enhanced when power lines pass the groove 143. Therefore, quality factor of the resonator structures is reduced. Additionally, the antenna of the invention combines TE111y, TE112y and TE113y mode bands to provide bandwidth of 33%.
a and 4b show dimensions of the antenna 100 of the invention. The resonator body 140 has length a2, width b2 and height d. The groove 143 has first width g1, second width g2 and third width g3. The resonator structure 141 has length a1, width b1 and height d. The substrate 110 and the ground layer 130 have length Lg and width Wg. The feed conductor has width Wm, and extends over the opening 131 with length Ls. The opening 131 has length La and width Wa.
In the embodiment of the invention, the diameters of the resonator body 140 are a1=16.2 mm, b1=10 mm, a2=30.5 mm, b2=19 mm, d=4 mm, g1=0.5 mm, g2=4.5 mm and g3=0.2 mm. The diameters of the opening are Wa=2 mm and La=13.5 mm. The diameters of the ground layer 130 are Wg=Lg=60 mm. Thickness t of the substrate 110 is t=0.6 mm. The dielectric coefficient of the substrate 110 is 4.4. The dielectric coefficient of the resonator structures 141 and 142 is 20. The opening 131 separates from an edge of the resonator body 140 in a distance ds=12.5 mm. The feed conductor extends over the opening 131 with length Ls=5 mm.
In the embodiment of the invention, frequency of the antenna can be modified by tuning diameters (length a2, width b2 and height d) of the resonator body 140. Frequency of the antenna can be modified, and bandwidth thereof can be increased by tuning diameters (first width g1, second width g2 and third width g3) of the groove. Additionally, divergence field shape and divergence field bandwidth are also modified by tuning diameters of the groove. Input impedance can be modified by tuning diameters and positions of the opening and the feed conductor.
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. 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.
Number | Date | Country | Kind |
---|---|---|---|
TW96115557 | May 2007 | TW | national |