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Al In N ∕ Ga N heterostructures have been proposed to possess advantageous properties for field-effect transistors (FETs) over AlGaN∕GaN [Kuzmík, IEEE Electron Device Lett. 22, 501 (2001); Yamaguchi et al., Phys. Status Solidi A 188, 895 (2001)]. A major advantage of such structures is that AlInN can be grown lattice-matched to GaN while still inducing high charge carrier densities at the heterointerface of around 2.7×1013cm−3 by the differences in spontaneous polarization. Additionally, it offers a higher band offset to GaN than AlGaN. We grew AlInN FET structures on Si(111) substrates by metalorganic chemical vapor phase epitaxy with In concentrations ranging from 9.5% to 24%. Nearly lattice-matched structures show sheet carrier densities of 3.2×1013cm−2 and mobilities of ∼406cm2∕Vs. Such Al0.84In0.16N FETs have maximum dc currents of 1.33A∕mm for devices with 1μm gate length.

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A triple-band dipole antenna with wideband balun integration is proposed in this article. This antenna consists of two dipoles, a wideband balun and feeding line. These three parts are integrated into a compact design, which has a small size of 30 Â 25 Â 0.8 mm 3 based on the substrate having a dielectric constant of 2.55. The simulated results show that triple bands of 2.40-2.59 GHz, 3.42-3.80 GHz, and 5.06-5.95 GHz are attained by this antenna, and can cover the bands of WLAN/WiMAX. The simulated and measured radiation patterns at different center frequency are also demonstrated and the designs of dipoles and balun are also provided, which exemplify omnidirectional characteristics in the H-plane.

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