humidity conditions were presented. The array is intended to provide more reliable off-body communication links within the 2.45 GHz ISM band and to be worn by rescue workers or fire fighters, active in a disaster area. Compared to a nonuniform array, the ULA guarantees low mutual coupling between the radiating elements, a narrow main beam, low side lobes, and relatively easy steering. In general, when choosing a textile material as a substrate for a textile antenna array to integrate into a garment, the MR value of the textile material must be taken into account. Here, it was shown, under reproducible rH conditions realized in a climate test cabinet, that the array on Azzurri foam exhibits perfectly stable reflection coefficient characteristics of each individual antenna element. For the implementation on cotton, however, the resonance frequency decreases with increasing rH, and the ISM band is no longer covered, when the rH is above 70%. Thanks to the ETMPA topology of the individual patches, the relatively small number of radiating elements, and the rather large spacing of 3/4k between them, the mutual coupling is always low, even for the implementation on cotton, where the influence of rH is again noticeable. Hence, a low-cost array design with a large antenna aperture of about 50 cm and with limited steering capabilities centered around the broadside direction is obtained. When limiting the steering angle to 10 around the broadside direction, no grating lobes appear. ABSTRACT: A printed slot antenna comprising two quarterwavelength slots of different lengths and a half-wavelength slot for eight-band wireless wide area network/long term evolution operation in the tablet computer is presented. The two quarter-wavelength slots are open slots or monopole slots, and the half-wavelength slot is aligned inbetween the two quarter-wavelength slots. The three slots are excited using a two-strip feedline which is printed on the opposite surface of the printed slots. The proposed three-slot configuration can lead to two wide operating bands, with the lower one covering the 704-960 MHz band and the upper one covering the 1710-2690 MHz band. Good radiation efficiency for frequencies over the operating bands is obtained. The simulated body specific absorption rate values of the antenna in the bottom face, landscape and portrait orientations to the flat phantom in the body specific absorption rate testing model also meet the limit of 1.6 W/kg for 1-g tissue. Details of the results are presented.

The use of a parallel‐resonant (PR) slit for dual‐band bandwidth enhancement of a small‐size printed monopole slot antenna to achieve the wireless wide area network operation in the tablet computer is demonstrated. The antenna is easy to fabricate by printing on a thin FR4 substrate of size 10 × 45 mm2. The PR slit, mainly configured as a spiral shape to occupy a small area of about 6.5 × 6.5 mm2 on the FR4 substrate, generates two parallel resonances at about 1.2 and 2.5 GHz to, respectively, result in dual‐resonance excitation of the quarter‐wavelength and half‐wavelength modes of the monopole slot at about 0.9 and 1.9 GHz. In this case, two wide operating bands are obtained to, respectively, cover the 824–960 and 1710–2170 MHz bands. That is, with the dual‐band bandwidth enhancement contributed by the PR slit, the proposed antenna can cover the GSM850/900/1800/1900/UMTS bands with a small planar size. Details of the proposed antenna are described in the article. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:40–45, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27273

A study on the body SAR of the planar WWAN (wireless wide area network) monopole slot antenna for tablet device application is presented. The monopole slot antenna covers penta‐band WWAN operation in the 824∼960/1710∼2170 MHz bands with low near‐field emission such that its body SAR (specific absorption rate) values for 1‐g tissue in the bottom face, landscape and portrait orientations to the flat phantom meet the limit of 1.6 W/kg for practical applications. Effects of the monopole slot antenna disposed at various possible locations in the tablet device on the body SAR results are also analyzed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26094