This article presented a dual-band monopole antenna fed by a coplanar waveguide (CPW) for wireless device applications in the 802.11b/a wireless local area network (WLAN) standards. The antenna consists of a rectangular radiator, two rectangular slots cut on both sides of the radiator, a semiring slot on the radiator, and a CPW feed for easy integration with other components on the printed circuit board. Parametric studies are carried out on the semiring slot and rectangular slots. The rectangular radiator generates two resonant bands at about 2.4 GHz for the 802.11b standard and 5.5 GHz for the upper band of the 802.11a. The semiring slot forms a resonator/bandstop filter to separate the radiator into two parts, hence generating another resonant band at around 5 GHz to cover the lower band of the 802.11a standard. The two rectangular slots improve impedance matching for the 802.11a standard. Simulation and measurement results of the proposed antenna show good agreements. Results show that the proposed dual-band antenna has good performances in terms of radiation pattern, peak gain, and radiation efficiency. The bandwidth for the 802.11a standard can be easily adjusted using dimensions of the semiring and rectangular slot, giving an easy way for engineers to design antennas for wireless device applications for the WLAN standards.

This paper proposes a self-optimized coverage coordination scheme for two-tier femtocell networks, in which a femtocell base station adjusts the transmit power based on the statistics of the signal and the interference power that is measured at a femtocell downlink. Furthermore, an analytic expression is derived for the coverage leakage probability that a femtocell coverage area leaks into an outdoor macrocell. The coverage analysis is verified by simulation, which shows that the proposed scheme provides sufficient indoor femtocell coverage and that the femtocell coverage does not leak into an outdoor macrocell.

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MCMs for RF and wireless systems often use metal filled via holes to improve isolation between the stripline and microstrip interconnects. In this paper, results from a 3D-FEM electromagnetic characterization of microstrip and stripline interconnects with metal filled via fences for isolation are presented. It is shown that placement of a via hole fence closer than three times the substrate height to the transmission lines increases radiation and coupling. Radiation loss and reflections are increased when a short via fence is used in areas suspected of having high radiation. Also, via posts should not be separated by more than three times the substrate height for low radiation loss, coupling, and suppression of higher order modes in a package. Index Terms-microstrip, stripline, coupling, crosstalk, MCM, microwave transmission lines I. INTRODUCTION RF and wireless package designs must become smaller to satisfy the demands of the commercial and government markets. Simultaneously, the package must house data processing, biasing, and memory circuits in addition to the RF circuits to reduce the overall system size and complexity. Even more ambitious systems being developed by NASA include microelectromechanical (MEM) gyroscopes, active pixel sensors, and other micromachined scientific instruments with the already mentioned electronic circuits to create entire systems in a package. While the size of the package is being reduced and the complexity increased, the cost must also be reduced. To achieve these utopian goals, many MultiChip Module (MCM) technologies have been proposed [1-5], but Low Temperature Cofired Ceramic (LTCC) may be the ideal packaging technology. The material used in LTCC packages has a moderate dielectric constant, 4<_<8, which permits wider microwave transmission lines and thus lower conductor loss than circuits on Si, GaAs, or Alumina. In addition, it has a low loss tangent of 0.002 at I0 GI-/z, which results in low dielectric attenuation. LTCC packages comprise many 0.1-0. i5 mm thick ceramic layers with transmission lines on each layer [2,6]. Vertical interconnects between the layers are easily manufactured by laser or