Pifa

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  • Publicado : 11 de março de 2013
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Planar inverted-F antenna (PIFA) The Planar Inverted –F Antenna is popular type of antenna commonly suitable for portable wireless devices due of its low profile, small size, and built-instructure[1] besides the low cost and simplicity of its manufacturing process[2] . PIFA antennas, which resemble an inverted F, are resonant at a quarter-wavelength and usually have good SAR properties. DesignPIFA, which is based on a modification of the inverted F antenna – IFA, is typically made up of a rectangular element short circuited to a ground [3]. A basic PIFA design consists of a shortcircuit plate connecting this ground plane and the planar element. A feed wire, feeding the top plate, is also connected from where the signal will be supplied. A more complex design, prioritizing thereduction of the size, can be merely obtained shortening the antenna. A capacitive loading on top should be aggregated to compensate the effects of the shortening in the impedance (fig. 1).

𝑳𝟏 +𝑳𝟐 =
𝑖𝑓 𝑊 =1 𝐿1

𝝀 𝟒
𝐿1 + 𝐻 = 𝜆 4 𝜆 4

𝑖𝑓 𝑊 = 0

𝐿1 + 𝐿2 + 𝐻 =

where: 𝐿1 and 𝐿2 are the dimensionsof the top plate 𝑊 is the width of the short circuit plate 𝐻 is the height of the short circuit plate

Impedance Matching The impedance matching of the PIFA is obtained by positioning ofthe single feed and the shorting pin within the shaped slot, and by optimizing the space between feed and shorting pins. The main idea behind designing a PIFA is to avoid using any extra lumpedcomponents for matching network, and thus avoid any losses due to that.[4] Radiation Pattern The radiation pattern of the PIFA is the relative distribution of radiated power as a function of direction inspace. In the usual case the radiation pattern is determined in the far-field region and is represented as a function of directional coordinates. Radiation properties include power flux density, field...
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