The design of a circular slot antenna for obtaining broadband circularly polarized (CP) radiation using a coplanar waveguide (CPW) feed is presented. The operation of the proposed antenna is achieved by protruding metallic mono‐strip from the circular ground plane towards the slot center at ϕ = 0° and feeding antenna using a 50‐Ω CPW with a protruded single strip at ϕ = 270°. In this design, the impedance bandwidth and 3 dB axial‐ratio bandwidth can reach as large as 50 and 36%, respectively. The peak of antenna gain is about 3.9 dBi, with gain variations <1 dBi for the frequencies within CP bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2728–2733, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22881

The design of a circularly polarized slot antenna fed by a single microstrip line is presented. The circularly polarized radiation is achieved by means of using a shorted square‐ring slot. This proposed antenna has the fundamental resonant frequency of 2.4 GHz with the minimum return loss of −50.44 dB. The impedance bandwidth is 930 MHz or 38.7% referred to the resonant frequency, and it also has the 3‐dB axial‐ratio (AR) bandwidth of 310 MHz or 12.9% referred to the resonant frequency. In addition, this proposed antenna shows good performance of circular polarization (CP) radiation with the range of the lower 3‐dB AR value covering elevation angles between −40 to 40 degrees. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1684–1687 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22517

A novel design of a broadband circularly polarized square slot antenna fed by a single coplanar waveguide is proposed and discussed. The circularly polarized radiation is achieved by means of using an outer rectangular ring and an inner rectangular ring at the center of a square slot. The proposed antenna has the fundamental resonant frequency of 2.44 GHz with the return loss of −40.93 dB, and it has the bandwidth of 3 dB axial ratio of 420 MHz or (17.21%). Details of the results are presented and discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2456–2459, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21951

A novel tungsten nitride (WNx) film for diffusion barrier applications has been prepared by nitridation of a fine grain chemical vapor deposited tungsten (CVD-W) film. The fine grain CVD-W is deposited at 300 °C in a low pressure chemical vapor deposition reactor with a SiH4/WF6 flow rate of 12.5/5 sccm under a total gas pressure of 100 mTorr. The subsequent nitridation process is executed in nitrogen plasma at 300 °C without breaking vacuum. The thickness of WNx layer as examined by secondary ion mass spectroscopy is 50 nm after 5 min exposure to nitrogen plasma. X-ray photoelectron spectroscopy spectra shows that the atomic ratio of tungsten to nitrogen in WNx layer is 2:1. According to the analysis by Auger electron spectroscopy and the measurement of n+p junction leakage current, the Al/WNx/W/Si multilayer maintains excellent interfacial stability after furnace annealing at 575 °C for 30 min. The effectiveness of W2N barrier is attributed to stuffing grain boundaries with nitrogen atoms which eliminates the rapid diffusion paths in fine grain CVD-W films.