A. Djaiz

ULTRA WIDEBAND CPW-FED APERTURE ANTENNA WITH WLAN BAND REJECTION

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 3GHz to 10.6GHz. In order to avoid interference

Design of UWB filter -antenna with notched band at 5.8GHz

In this paper, an UWB integrated filter-antenna system with notched band at 5.8 GHz has been presented. The design of the proposed integrated filter-antenna is based on cascading an UWB notched filter with an UWB antenna. The two parts of the system have already been matched to each others. The antenna-filter has a small size (68 × 27mm2). The system bandwidth meets the UWB requirements.

A New Ultra-Wideband Beamforming for Wireless Communications in Underground Mines

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 two- layer 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 ultra- wideband communication systems in confined areas.

Switched-beam antenna based on EBG periodic structures

This paper presents the design and the fabrication of a new switched beam antenna based on Electromagnetic BandGap (EBG) periodic structures. For this purpose, two different frequency selective surfaces are analyzed and their geometric and electromagnetic (EM) dualities are assessed. Then, these FSS structures are used to achieve EBG structures with controllable features. These agile structures are considered for the design of a switched beam antenna. The antenna is operating at 1.8GHz and presents a gain of 10dBi with 60° of beam-width in azimuth plane and the possibility to generate and switch between six different beams and cover 360°. Finally experimental results are presented and discussed. This system is suitable for smart antenna systems.

Ultra-Wideband Bandpass Filters Using Multilayer Slot Coupled Transitions

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.

Novel ultra-wideband Butler matrix for wireless underground mines

The main cause of degradation of communication quality in underground mines is multipath fading [1]. This multipath phenomenon arises when a transmitted signal undergoes reflection from various obstacles in the propagation environment which degrades the transmission quality and limits the frequency efficiency [1]. Smart antennas are one resolution to overcome this problem [2]. One of the most widely-known of switched beam networks, which is a part of smart antenna, is Butler matrix [2]. It is a passive feeding NXN network with beam steering capabilities for phased array antennas with N outputs connected to antenna elements and N inputs or beam ports.

A new two-layer bandpass filter using stepped impedance hairpin resonators for wireless applications

In this paper, we propose a new compact two-layer band-pass filter using stepped impedance hairpin resonators. This structure is composed of four resonators located on two microstrip stacked layer substrates, and the couplings between the resonators on the upper layer and those on the lower one are obtained by using two coupling apertures etched on a common ground plane placed between the two layers. A full-wave simulator is used to design the proposed structure and calculate the aperture coupling coefficients. To demonstrate the proposed design, a four-order band-pass filter prototype was fabricated and measured. The simulated results are compared with the measured data, and a good agreement is reported.

A design and fabrication of a new stacked bandpass filter using multilayer microstrip structure for wireless applications

This paper presents a new microstrip multilayer configuration in order to reduce the size of the microwave bandpass filters. To validate this approach, simulations and experimental investigations were made, and a compact stacked four-pole bandpass filter was designed, implemented and tested at 2.44 GHz. The experimental and simulated results on the filter are presented and discussed, and the comparison between them indicates a fairly good agreement. By using this multilayer configuration technique in the microwave filter design, a filter size reduction of about 50% can be easily achieved, which makes these compact filters well suited for mobile handset.

Design and Implementation of a Miniaturized CPW-FED Antenna with Enhanced Bandwidth

In this paper, the design and implementation of a new small antenna using a CPW-FED technology for further reducing the size and increasing the bandwidth are presented. The proposed antenna is designed and analyzed based on meandered parallel resonant arm to decrease the antenna area. In addition, a superstrate layer is added for further antenna miniaturization and bandwidth enhancement. For validation, an experimental prototype was built and tested. Obtained simulation and measurement results show that this miniaturized antenna operating at 2.45 GHz achieves a bandwidth of 220 MHz for 10-dB of return loss. Both simulation and measurement radiation patterns are stable across the operating frequency range, and show a good agreement.

Design of a new mm-wave antenna fed by CPW inductively coupling for mining communication

A new concept of coplanar waveguide (CPW) exciting of mm-wave slot antenna has been presented. The antenna feeding is ensured by the coupling from the coplanar line to the slot radiating element via an inductively excitation located within the ground plane to which the coplanar line is connected. Simulated results show good performances in terms of bandwidth and gain at 60 GHz. Through the adjustment of different parameters of the exciting slots, good impedance matching is achieved. This kind of antenna can be integrated easily with other active devices. The designed antenna is suitable for wireless communication in underground mine.