BANDWIDTH ENHANCEMENT OF WWAN/LTE TABLET COMPUTER ANTENNA USING EMBEDDED PARALLEL RESONANT CIRCUIT

摘要

By embedding a printed parallel resonant circuit, the lower-band bandwidth of the proposed internal tablet computer antenna is greatly enhanced. This bandwidth-enhancement technique allows the proposed antenna to cover the eight-band wireless wide area network/ long term evolution operation in the 704-960 and 1710-2690 MHz bands with a small size of 12 × 60 × 3.8 mm~3 in the tablet computer. The main radiator of the antenna comprises a patch monopole, a longer shorted strip, and a shorter shorted strip. The latter two shorted strips form the outer boundary of the antenna and are parasitically excited by the patch monopole. The parallel resonant circuit is formed by embedding a chip-inductor-loaded narrow strip in-between the longer shorted strip and the patch monopole, with the narrow strip whose front terminal connected to the patch monopole and end section gap-coupled to the longer shorted strip. This embedded circuit can lead to the generation of a parallel resonance seen at the antenna's feeding point. By controlling the parallel resonance to be at the high-frequency tail of the resonant mode at about 800 MHz contributed by the longer shorted strip, an additional resonance can be generated, which can result in dual-resonance excitation of the original single-resonance mode. Thus, a wide antenna's lower band is obtained. Further, the patch monopole can contribute a resonant mode to combine additional resonant modes contributed by the two-shorted strips to form a wide antenna's upper band. Details of the proposed antenna with the embedded parallel resonant circuit are described in the article.