Multiband PIFA antenna for portable devices

摘要

A multiband PIFA (planar inverted-F) antenna. A preferred embodiment makes use of a spiral slot. The spiral slot is formed to cause multiple frequency dependent nulls in the antenna's electric field modal distribution. The preferred embodiment antenna has a single element patch radiator formed on a dielectric support in an inverted-F relationship with a first ground plane. The dielectric support may be part of a device housing or internal board, e.g., a PCB board. The patch radiator includes a spiral slot. A feed is made to the single element patch radiator in a location relative to the spiral slot to ensure that portions of the single element patch radiator enclosed by the spiral slot are fed as a series extension of another portion of said patch radiator. According to a preferred embodiment, the patch radiator may be formed from a single conductive sheet, plating or deposit along with the shorting post and feed. A majority of its surface area is formed in a primary plane and its remaining surfaces define, generally perpendicular from the primary plane, a feed extending from a first edge of the primary plane and a shorting post extending from a second edge of the primary plane. A tab may be formed to add radiator surface area and may extend, for example, perpendicular from a third edge of the primary plane.