Distributed multiband antenna and methods

摘要

A distributed multiband antenna intended for radio devices, and methods for designing manufacturing the same. In one embodiment, a planar inverted-F antenna (PIFA) configured to operate in a high-frequency band, and a matched monopole configured to operate in a low-frequency band, are used within a handheld mobile device (e.g., cellular telephone). The two antennas are placed on substantially opposing regions of the portable device. The use of a separate low-frequency antenna element facilitates frequency-specific antenna matching, and therefore improves the overall performance of the multiband antenna. The use of high-band PIFA reduces antenna volume, and enables a smaller device housing structure while also reducing signal losses in the high frequency band. These attributes also advantageously facilitate compliance with specific absorption rate (SAR) tests; e.g., in the immediate proximity of hand and head “phantoms” as mandated under CTIA regulations. Matching of the low-frequency band monopole antenna is further described.

主权项

1. A multiband antenna assembly comprising a lower and an upper operating frequency band, the multiband antenna assembly for use in a mobile radio device, the multiband antenna assembly comprising:
a substrate element comprised of a first end and a second opposing end, the substrate element comprising a conductive coating disposed thereon to form a ground plane, the conductive coating substantially covering the substrate element and extending from the first end towards the second opposing end, a portion of the second opposing end is exposed to form a clearance area without the conductive coating disposed thereon; a planar inverted-F antenna (PIFA) element configured to operate in the upper frequency band and being disposed above the ground plane and proximate to the first end of the substrate element; a monopole antenna configured to operate in the lower frequency band and being disposed proximate to the clearance area of the second opposing end, the clearance area configured to provide electrical isolation of the monopole antenna from the PIFA element, and further configured to reduce a ground plane clearance; and a feed apparatus configured to feed the monopole antenna and the PIFA element; wherein the monopole antenna further comprises:
a radiator element formed in a plane substantially perpendicular to the ground plane; anda non-conductive slot formed within the radiator element; and a matching circuit comprising:
a feed point;a ground;a stripline coupled from the ground to the feed point;a tuning capacitor coupled to the ground and the stripline; anda feed pad coupled to the stripline via an inductor; andwherein the feed pad is further coupled to the radiator element; wherein the PIFA element further comprises:
a first planar radiator formed substantially parallel to the ground plane;a parasitic planar radiator formed substantially coplanar to the first planar radiator;a non-conductive slot formed within the first planar radiator;a first feed point configured to couple the first planar radiator to the feed apparatus;a ground point configured to couple the first planar radiator to the ground plane; anda parasitic feed point configured to couple the parasitic planar radiator to the ground plane wherein a total efficiency for the multiband antenna assembly disposed proximate a head and a hand phantom is greater than 2.5 dB better in the upper frequency band as compared with a bottom mounted monopole antenna.