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A compact ultra-wideband (UWB) antenna with size of 17 × 10 × 1 mm3 in low-temperature co-fired ceramic (LTCC) technology is designed, fabricated, and tested. It achieves impedance bandwidth of 6.7 GHz from 3.5 to 10.2 GHz. The measured antenna radiation patterns at 6.85 GHz are also presented. The antenna is further studied for a single-package solution of UWB radio transceivers. The integration is analyzed with an emphasis on the connection of the antenna to the transceiver die. The final integrated UWB antenna has size of 20 × 10 × 1.2 mm3 and achieves impedance bandwidth of 6.7 GHz from 5.05 to 11.75 GHz with available radiation patterns. It also achieves the radiation efficiency of >96% and the gain of 2.5 to 4.3 dBi over the simulated UWB frequency range. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 789–793, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23209

The preparation, characterization and application of metal organic framework (MOF) supported noble metal catalysts have drawn a great interest with the rapid progresses in the syntheses of MOFs and MOF based composites. There are several principal objectives for the investigation of MOF supported catalysts, including (1) the designable frameworks provide us a very clear model for the fundamental catalytic studies; (2) the extremely large surface area and the extremely high porosity of MOFs are always attractive for the catalytic applications; (3) the designable or the controllable porous structure with uniform pore size is excellent for the preparation of designable catalyst, a dream of chemists and chemical engineers worldwide; (4) the MOFs can be easily modified by various functional groups; (5) MOF based composites (with graphene and other materials) can be easily fabricated; (6) the needs for novel catalysts keep growing; (7) the member of the MOF family increases remarkably recently with the improvement of thermal and chemical stability of MOFs; (8) the hybrid of noble metal catalysts and MOFs is leading to many unusual catalytic properties. In this perspective, we summarize the recent advances in the preparation and application of MOF supported noble metal catalysts. To prepare this kind of new catalysts, two general methods have been reported: the precursor way and the metal nanoparticle way. The former is based on metal ions or metal precursors like inorganic salt (nitrate or chloride) or metallorganic compound. The metal ions or metal precursors have to be loaded into the MOF framework via chemical vapor infiltration, solution impregnation and incipient wetness infiltration or to be pre-incorporated on the organic linkers before the synthesis of MOF. The second way is based on the pre-synthesized metal nanoparticles. To do so, the pre-synthesized metal nanoparticles have to be directly involved in the synthesis of MOFs from the beginning. The characteristics of two ways have been discussed. Because of the unique properties and the structure of MOFs, the loading of metal or metal ion with the assistance of organic solvent is very helpful for the confinement of nanoparticles within the cavities of MOF frameworks or for control of size and location of nanoparticles. The structure control of catalyst together with size and location control still remains a significant challenge.

A series of solvents were examined for the ligand free Pd(II)-catalyzed Suzuki reaction of 4-bromotoluene with phenylboronic acid. It was found that the PdCl2/i-PrOH system could efficiently inhibit the homo-coupling of phenylboronic acid and give a cross-coupling product in high yields. The substrates with a wide variety of functional groups were tolerated in the system. A possible mechanism for this system was proposed.

Wireless body area network (WBAN) has begun to receive attention recently. Ultra wideband (UWB) is a promising technology for WBAN applications. This article presents the results of UWB radio channel measurements performed on human bodies from 3.1 to 10.6 GHz in indoor environments. The measurements were devised to generate the radiographs of path loss and delay spread for the first time. The radiographs contain both qualitative and quantitative information on the channel. They clearly display the influence of the body on the channel and thus reveal where the network nodes should be strategically placed on the body in the design of the UWB WBAN systems. They directly give such channel parameters as path loss and delay spread. They also reflect variations of the channel on and in close proximity to the body. In addition, the measurements were made in an anechoic chamber to expose the impact of the body and to study the effect of different environments on the channel. It is shown that for the UWB channel on the body the path loss exponent n = 2.7 can be used, while for the UWB channel through the body the path loss exponent increases to n = 3.7. The maximum value of the rms delay spread is 12 ns. The rms delay spread values are less than 6 ns 50% of the time. The number of multipath components increases with the separation between transmit and receive antennas. Because of the nonreflecting mechanism, the path loss is larger and the delay spread is smaller in the anechoic chamber environment. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1365–1371, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22411

A novel integrated-circuit-pressed ceramic-package antenna is proposed for the first time. The antenna is intended for use in the single-chip solutions of wireless transceivers using deep submicron complementary metal-oxide semiconductor (CMOS) technology. The prototype antenna printed on a dual-in-line integrated-circuit-pressed ceramic package is comparatively studied at 2.4 GHz with and without CMOS chip loading. The results show that CMOS chip loading greatly increases the impedance bandwidth, but slightly decreases the radiation efficiency of the antenna. The loaded antenna achieves an impedance bandwidth of 15.7% and a radiation efficiency of 64 ± 4%, which are sufficient for most applications. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 143–147, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20233

This Letter presents the measured time-delay characteristics of UHF radio propagation channels in room environments. The measurements used the swept-frequency technique with a different calibration method. The measured frequency bands include 2.4 GHz, 1.8 GHz, and 900 MHz. The particular interest is devoted to 2.4 GHz; the other two frequency bands were selected for comparison purpose. A simple channel model is derived from the measurement results. The in-room wideband propagation model is believed to be useful for BER simulation, modem scheme evaluation, and system design. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 115–119, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10248

An ultra-wideband (UWB) planar volcano-smoke slot antenna realized using low-temperature cofired ceramic (LTCC) technology is reported in this paper. The antenna, developed for a single-package solution of UWB radio, hasimple single-layer structure and a small footprint of 23 × 23 mm2. The result shows that the prototype antenna achieves an impedance bandwidth of 9 GHz (with return loss S11 < −10 dB from 3 to 12 GHz). The antenna radiation pattern at frequencies 3.5, 6.85, and 10.1 GHz and gain versus frequency are also presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 220–222, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20257

For microcellular system design, we have enhanced a well-known waveguide model for propagation-loss prediction along an LOS propagation path in a tunnel. It is reported in this letter. The enhancement involves a more accurate calculation of the tilt loss, the distinction of the two propagation regions, and the suggestion of using the free-space model for one region and the waveguide model for the other. The enhancement is demonstrated with examples. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 10–12, 2001.

Pyridine was used as a solvent for homocoupling of aryl bromides catalyzed by nickel chloride/triarylphosphine in the presence of zinc and recycled easily. Triphenylphosphine was the best ligand for nickel in this coupling reaction.

This paper presents a fully integrated concurrent dual-band CMOS low-noise amplifier (LNA). The LNA is implemented in a standard 0.18-μm 6M1P CMOS process and is designed from the system viewpoint to provide higher gain at the higher band, for the first time, to compensate the higher-band signal's extra loss over the air transmission. The LNA drains 5.3 mA of current from a 1.8-V supply voltage and achieves voltage gains of 16 and 22.5 dB, input return losses of 28 and 27 dB, and noise figures of 3.0 and 3.1 dB at 2.4 and 5.2 GHz, respectively. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 52–53, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11124