Ultra-wideband antenna having a band notch characteristic
The present invention discloses an antenna for ultra-wideband (UWB) communication having a band-stop characteristic. According to an embodiment of the present invention, the UWB antenna is a patch antenna employing microstrip feeding. In order to expand a bandwidth at a low frequency band, a stub is formed in a radiating element. Furthermore, since steps are formed in a ground plane, an antenna characteristic at an intermediate frequency band can be improved and a UWB characteristic can be obtained. According to another embodiment of the present invention, the UWB antenna is a patch antenna employing microstrip feeding and has a recess formed in the ground plane, thereby implementing the UWB characteristic. The antenna of the present invention has an inverse U-shaped slot formed in the radiating element, thus implementing the band-stop characteristic at the UNII band. In addition, the antenna of the present invention has includes a ground plane having a small area and has omnidirectional radiating patterns accordingly.
1. A ultra-wideband (UWB) antenna, comprising:
a substrate;
a circular radiating element formed on a top surface of the substrate;
a ground plane formed on a bottom surface of the substrate, wherein at least one step is formed in the ground plane;
a feeding element connected to the radiating element; and
a stub formed at the radiating element to expand a bandwidth at a low frequency band, wherein the stub has a length ranging from 30° to 60° of a circular path with a radius greater than a radius of the circular radiating element.
2. The UWB antenna according to claim 1 , wherein the ground plane is formed not to overlap with the radiating element.
3. The UWB antenna according to claim 1 , wherein the feeding element is a microstrip feeding line.
4. The UWB antenna according to claim 1 , wherein a slot is formed in the radiating element to obtain a band-stop characteristic.
5. The UWB antenna according to claim 4 , wherein the slot has an inversed U-shape.
6. The UWB antenna according to claim 4 , wherein the slot has a length ranging from 13 to 16 mm.
7. The UWB antenna according to claim 4 , wherein the slot has a length of
(λ c /√{square root over (∈ r )})/2,
where ∈ r is a relative dielectric constant of the substrate and λ c is a wavelength corresponding to a center frequency f c of a stop band.
8. The UWB antenna according to claim 7 , wherein the center frequency f c of the stop band is in a range of 5 to 6 GHz.
9. A UWB antenna, comprising:
a substrate;
a rectangular radiating element formed on a top surface of the substrate, wherein a notch is formed at a bottom edge of the rectangular radiating element and wherein bandwidth of the antenna can be adjusted by controlling a length and width of the notch;
a ground plane formed on a bottom surface of the substrate; and
a feeding element connected to the radiating element, wherein a recess is formed in the ground plane.
10. A UWB antenna having a band-stop characteristic, comprising:
a substrate;
a radiating element formed on a top surface of the substrate;
a ground plane formed on a bottom surface of the substrate; and
a feeding element connected to the radiating element,
wherein a U-shaped slot is formed in the radiating element to obtain the band-stop characteristic, wherein the slot has a length of
(λ c /√{square root over (∈ r )})/2,
where ∈ r is a relative dielectric constant of the substrate and λ c is a wavelength corresponding to a center frequency f c of a stop band.