Compact Dual Band PIFA for GPS and WiMAX

Abstract

ABSTRACT:A compact Planar Inverted F Antenna (PIFA) as the element for dual band operation in 1.48 GHz GPS and 3.2 GHz WiMAX band is proposed. PIFAs are quarter wavelength elements. Among various possible antennas, PIFAs have the advantages of low profile, compact size and are very suitable for present-day wireless communication application. A folded slit in the top plate is used to get the dual band operation. Comparison between two different orientations for folded slit is performed. A 50% miniaturization and gain improvement is achieved when the folded slit is near to the feed with an open end. The radiation pattern and current distribution on the PIFA are also plotted. KEYWORDS:PIFA, dual band, folded slit, miniaturization I.INTRODUCTIONMonopole antennas and helical antennas (whip antennas) were used as external antennas in early days. They are quarter wavelength elements and can have wide bandwidth. But they cause user interference because of the backward radiation. These were later replaced by internal antennas. Many applications require low profile antennas, especially portable devices such as laptops and mobile phones. Patch antennas and their derivatives are the best candidates for low profile application as internal antennas. Patch antennas are half wavelength elements. Their disadvantage of large dimension and narrow bandwidth led to the introduction of Planar Inverted-F Antenna (PIFA). PIFA have size less than quarter wavelength which is best suited as internal antennas in portable devices. But the main limitation is narrow bandwidth. By adjusting various parameters of PIFA their size can be made smaller and their bandwidth can be enhanced [1].In order to incorporate different standards into a single device, multi band and broadband antennas are required. When the operating frequencies are far apart multi band antennas are preferred over broadband because of the need of multiple filters in case of broadband. In this thesis, a single band PIFA for GPS is designed. Then the top plate is modified to obtain a dual band antenna operating at 1.5 GHz GPS and 3.3 GHz WiMAX. A folded slit structure on the top plate is used for obtaining dual band performance. Two different orientations of slits are compared. II.RELATED WORKSIn [2-6], dual band antennas with parasitic elements to generate higher bands are proposed. The total volume occupied by these antennas is larger than the proposed compact element. In [2], a slim dual-band PIFA in conjunction with Lshaped parasitic is proposed for GPS and WiMAX bands. The size of element is 100 x 24 mm² and the height is 9.8 mm. In [3], a compact dual band PIFA with two meandered metallic strips and one nearly rectangular patch to produce three resonances in the GSM and DCS band is proposed. Height of PIFA is 8.4 mm and the size of radiating element is 24 x 37 mm². In [4], a dual-band PIFA for DVB-T and WLAN applications with overall size of 217 x 12 mm² and height of 8 mm is proposed. The driven PIFA element acts as the primary element, governing the lowest resonant frequ...