Abstract: A dual-band monopole antenna mainly comprises a microwave substrate, a first horizontal radiating metallic line, a second horizontal radiating metallic line, a vertical radiating metallic line, a feeding point, and a ground plane. The microwave substrate includes a first surface and a second surface. The first horizontal radiating metallic line is printed on the first surface. The second horizontal radiating metallic line is printed on the first surface. The vertical radiating metallic line is printed on the first surface, wherein the first horizontal radiating metallic line and the second horizontal radiating metallic line respectively intersect the vertical radiating metallic line at different positions. The feeding point is disposed on the vertical radiating metallic line, and a ground plane is printed on the second surface of the microwave substrate.

Abstract: A dual-frequency planar antenna disclosed herein utilizes a main radiating device to produce a resonance mode and excites a parasitic radiating device to produce another resonance mode by the coupling of energy. These two modes can provide sufficiently broad bandwidths, and the present invention is simple in design, which makes it cost effective. Therefore, the planar antenna of the present invention is a competitive alternative for wireless communication applications.

Abstract: A planar inverted-F antenna with a first operating bandwidth and a second operating bandwidth comprises a ground surface, a radiating device, a shorting device, a dielectric material, and a feeding device. The dielectric material is for isolating the radiating device from the ground surface. The feeding device is for transmitting a microwave signal. The radiating device further includes a first radiating element, a second radiating element, and a third radiating element. The first operating bandwidth is formed by the first resonance mode of the first radiating element and the second radiating element. The second operating bandwidth is formed by the second resonance mode of the first radiating element and the second radiating element and the first resonance mode of the third radiating element.