Antenna structure

1. An antenna structure, comprising:

a dielectric substrate; and

a metal element, disposed on the dielectric substrate, and comprising a transmission element and a radiation element;

wherein a first triangular hollow region and a second triangular hollow region are formed on the radiation element;

wherein the antenna structure is capable of completely covering a wide operation frequency band from 690 MHz to 6000 MHz;

wherein each of the first triangular hollow region and the second triangular hollow region has an acute triangular shape;

wherein the acute triangular shape has a first interior angle from 50 to 60 degrees, a second interior angle from 76 to 90 degrees, and a third interior angle from 38 to 46 degrees;

wherein the dielectric substrate is planar and has an upper surface and a lower surface which are opposite to each other, and wherein the whole metal element is planar and is positioned on and parallel to the upper surface of the dielectric substrate.

2. The antenna structure as claimed in claim 1 , wherein the transmission element is a coplanar waveguide.

3. The antenna structure as claimed in claim 1 , wherein the radiation element comprises a common element, a first edge element, a second edge element, a first ground element, and a second ground element, wherein the first triangular hollow region is surrounded by the common element, the first edge element, and the first ground element, and wherein the second triangular hollow region is surrounded by the common element, the second edge element, and the second ground element.

4. The antenna structure as claimed in claim 3 , wherein each of the first edge element and the second edge element has a narrow and long straight-line shape.

5. The antenna structure as claimed in claim 3 , wherein the common element is coupled through the first edge element to the first ground element, and wherein the common element is further coupled through the second edge element to the second ground element.

6. The antenna structure as claimed in claim 1 , wherein the first triangular hollow region and the second triangular hollow region are symmetrical with respect to a central line of the metal element.

7. The antenna structure as claimed in claim 1 , wherein a length of the metal element is substantially from 0.4 to 0.6 wavelength of the lowest frequency of the wide operation frequency band.

8. The antenna structure as claimed in claim 1 , wherein a width of the metal element is substantially from 0.6 to 0.7 wavelength of the lowest frequency of the wide operation frequency band.