Abstract: A multi-frequency printed antenna includes an insulating substrate, a feed strip, a ground strip, and a plurality of radiating and grounded conductive strips. The insulating substrate has a first surface and a second surface opposite to the first surface. The feed strip and the plurality of radiating conductive strips are formed on the first surface while the ground strip and the plurality of grounded conductive strips are formed on the second surface. The radiating conductive strips together with the grounded conductive strips form a multi-resonant mechanism to achieve a multi-frequency antenna radiation.

Abstract: A multi-frequency printed antenna includes an insulating substrate, a feed strip, a ground strip, and a plurality of radiating and grounded conductive strips. The insulating substrate has a first surface and a second surface opposite to the first surface. The feed strip and the plurality of radiating conductive strips are formed on the first surface while the ground strip and the plurality of grounded conductive strips are formed on the second surface. The radiating conductive strips together with the grounded conductive strips form a multi-resonant mechanism to achieve a multi-frequency antenna radiation.

Abstract: An improved planar inverted F-type antenna comprises a metal ground plane having a feeding metal bore formed thereon, and a flat metal plate in parallel with the metal ground plane. The flat metal plate further includes an open circuit end and a short circuit end and provides a feeding leg to pass through the feeding metal bore. The short circuit end connects the metal ground plane through a short circuit leg. The distance between the open circuit end and short circuit end of the flat metal plate is proximate a quarter of wavelengths. The flat metal plate is formed as an open-short circuit trapezoid-shaped structure. The trapezoid-shaped structure increases operative bandwidth of the antenna.

Abstract: A compact printed antenna includes a substrate and a printed circuit on the substrate. The printed circuit includes a ground metal, a helical metal, a short circuit leg and a feeding leg. The ground metal has a feeding structure. The helical metal includes a plurality of conductive apertures to connect a plurality of metal strips to form a flat helical structure. The helical metal is parallel with the ground metal and has a short circuit end and an open circuit end to form an open circuit-short circuit structure. The short circuit end connects the ground metal through the short circuit leg. The feeding leg is extended outwards from a selected location on the helical metal to further connect a matching circuit. By providing the compact printed antenna, the flat helical structure of the helical metal can be shrunk in size, an inductance to allow the antenna making desired adjustment for the input impedance can be generated, and the adjustment freedom upon coupled impedance for the antenna can be increased.

Abstract: An improved planar inverted F-type antenna comprises a metal ground plane having a feeding metal bore formed thereon, and a flat metal plate in parallel with the metal ground plane. The flat metal plate further includes an open circuit end and a short circuit end and provides a feeding leg to pass through the feeding metal bore. The short circuit end connects the metal ground plane through a short circuit leg. The distance between the open circuit end and short circuit end of the flat metal plate is proximate a quarter of wavelengths. The flat metal plate is formed as an open-short circuit trapezoid-shaped structure. The trapezoid-shaped structure increases operative bandwidth of the antenna.

Abstract: An indented planar inverted F-type antenna apparatus comprises a metal ground plane having a feeding metal bore formed thereon and a crenellated metal in parallel with the metal ground plane. The crenellated metal further has an open-circuit end and a short-circuit end. The short-circuit end can connect with the metal ground plane through a short-circuit leg. Further, the crenellated metal can include a feeding leg for extending to pass through the feeding metal bore. By providing the crenellated structure of the crenellated metal, the size of the antenna can be reduced and an irregular electric field can be generated between the crenellated metal and the metal ground so that various frequencies of signals can be obtained and also operating frequency band of the antenna can be extended.