Abstract-In this paper, we present a new ultra wideband antenna design with band rejection for UWB applications. A CPW-fed circular patch radiates through a circular aperture, which ensures wideband impedance matching and stable omnidirectional pattern over an UWB frequency range, from 3 GHz to 10.6 GHz. In order to avoid interference with WLAN applications, at 5.8 GHz, the antenna is slightly modified to reject undesired band. A semi-circular slot ring is etched on the circular patch at the notch frequency, which creates an open circuit and avoids impedance matching and current propagation. A prototype was fabricated and measured, and the obtained experimental results agree with simulations and show an omnidirectional azimuth pattern over the entire bandwidth.

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In this article, a new ultra‐wideband (UWB)‐integrated antenna‐filter notched at HiPerLAN 5.8 GHz frequency is presented. This antenna filter system is composed of a rectangular slot fed with a microstrip rectangular patch by coupling effect and cascaded with an UWB interdigital hairpin resonator filter. The proposed components, antenna and filter, are matched with 50 Ω, to allow an easier connection, with no need to add additional matching circuit. To improve the selectivity of the antenna filter system, two wide sections of microstrip line was inserted between the input/output feed lines and the interdigital hairpin resonators of the UWB filter. To validate the proposed concept, a prototype was fabricated and tested. The experimental results are presented and discussed. The obtained results show a good agreement between experimental and full‐wave electromagnetic (EM) simulation results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1298–1302, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25963

Abstract-In this paper, a novel ultra-wideband switched-beam antenna system based on 4×4 two-layer Butler matrix is presented and implemented to be used in hostile environment, such as underground mines. This matrix is based on the combination of a broadband twolayer slot-coupled directional coupler and a multilayer slot-coupled microstrip transition. With this configuration, the proposed matrix was designed without using any crossovers as used in conventional Butler matrices. Moreover, this new structure is compact and offers an ultra-wide bandwidth of 6 GHz. To examine the performance of the proposed matrix, experimental prototypes of the multilayer microstrip transition and the Butler matrix were fabricated and measured. Furthermore, a three 4-antenna arrays were also designed, fabricated and then connected to the matrix to form a beamforming antenna system at 3, 5.8 and 6 GHz. As a result, four orthogonal beams are produced in the band 3-9 GHz. This matrix is suitable for ultrawideband communication systems in confined areas.

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stage of the LNA, respectively. The fabricated LNA has gain of 12.5 dB, noise figure of 2.72 dB, and IIP3 of Ϫ5 dBm, with power dissipation of 8 mW from 1.5 V supply voltage.

New Ultra-Wideband (UWB) bandpass filters are proposed and tested. The filters are composed of two microstrip -Conductor-Backed Co-Planar Waveguide (CBCPW) transitions and a multiple-mode resonator, constituted by a line section. The both cases, where the line section is a microstrip or a CBCPW are tested. First, simulated and experimental results for the transition are presented, showing that a wide operating band is obtained. Then, the results for the proposed filters that use this transition structure are presented. Simulated and measured data show that the filters can provide an operating band from 3.1 GHz to 10.6 GHz (−10 dB bandwidth), which is suitable for ultra-wideband systems. The group delay is about 0.3 ns over the most central band and less than 0.45 ns all over the operating band. In addition, using an optimization procedure, a bandwidth of 15 GHz can be achieved with the proposed filter which is more than what was fixed by Federal Communications Commission (FCC) for UWB radio systems. Moreover, a filter constituted by combining the two proposed filters was also designed and fabricated, to improve further the band rejection.