In this article, novel 2-element and 4-element planar ultra- ideband (UWB) antenna arrays with bidirectional radiation patterns based on identical UWB antenna elements for UWB communications applications have been proposed, simulated and experimentally investigated. Each array is constructed by means of feeding omni-directional printed UWB monopole antennas with a UWB power divider. The proposed 2-element antenna array yields an impedance bandwidth of 110% (3.1–10.6 GHz) covering the whole UWB frequency bandwidth while the impedance bandwidth is multi-band in case of the 4-element antenna array because of the increasing effect of mutual coupling among antenna elements. The calculated gain of the 2-element and 4-element array is quite stable with about 3 and 6 dB higher than that of the single element, respectively. Both measured and calculated E-plane radiation patterns of the array and the single element are almost the same while the H-plane radiation patterns of the array are distinctively bidirectional compared to the omni-directional pattern of the single element.

The design and realization of a new in-phase and quadrature-phase power splitters for ultra wideband (UWB) applications are described in this paper. The in-phase power splitter is first designed and then the quadrature-phase power splitter (QPS) is developed using the designed in-phase power splitter, a conventional microstrip transmission line (MS) TL, and a well-synthesized metamaterial (MM) TL. The phase response of the MM TL is synthesized to achieve the desired 90◦ phase difference over an UWB frequency range. Two splitters were designed, implemented for UWB operation and experimentally demonstrated. To examine the performances of the proposed splitters, even-odd mode analysis, numerical simulations and experimental measurements were carried out. The comparison between simulated and experimental results shows a good agreement. Results show that the proposed in-phase power splitter has good insertion loss with equal power split, acceptable return loss at all ports and satisfactory isolation performances within the whole UWB frequency range. The proposed QPS has an output amplitude imbalance of less than 2.4 dB and a phase error of less than +15◦ from 3.0–9.0 GHz (100% FBW).

A novel microstrip fed ultra-wideband (UWB) antenna with different band rejection techniques is presented in this paper. The antenna consists of a maple-leaf shaped radiator fed by a microstrip line with a finite ground plane on the other side of the substrate. The size of the UWB antenna is 30.5 x 35.5 mm2 which is only about 0.3 x 0.35 λ2 at 3 GHz. The calculated impedance bandwidth of the proposed antenna ranges from 3 GHz to 14 GHz with relatively stable radiation patterns. Two different techniques have been implemented to achieve band-notch characteristic in the 5.0-6.0 GHz WLAN frequency band. The first one uses an H-shaped slot cut away from the radiating patch while the other one uses two rectangular slits in the ground plane creating defected ground structure (DGS).

This letter presents a printed monopole antenna with two steps and a circular slot for ultra-wide band (UWB) applications. The proposed antenna is fabricated and tested. The proposed antenna has a wide frequency bandwidth of 8.4 GHz starting from 3 GHz up to 11.4 GHz for a return loss (S11) of less than -10 dB and gain flatness over the frequency range. Measured results show also that the proposed antenna features satisfactory radiation characteristics within the achieved impedance bandwidth. By introducing a simple and proper narrow slot in the radiating element, frequency-notched characteristics can be obtained and a good band-notched performance in the 5–6 GHz band can be achieved.

This paper describes the design and experimental implementation of a discrete-time fixed-order H∞ controller for a DC motor speed and position control. To provide a model for the DC motor, two system identification techniques are employed. In the first one a model for DC motor speed control is identified in open-loop based on black box modeling whereas in the other one a model for position control is identified in closed-loop based on grey box modeling. An extension of HIFOO toolbox to discrete-time controller design developed recently is used to synthesize the controller. The performance of the designed controller in comparison with various control strategies is demonstrated. The paper aims at demonstrating simple modeling and control synthesis techniques with the help of available software tools to design low-complexity controllers in terms of design and implementation. Consequently, cheap hardware can be utilized for several applications.

This paper describes the design and experimental implementation of a discrete-time fixed-order H∞ controller for a DC motor speed and position control. To provide a model for the DC motor, two system identification techniques are employed. In the first one a model for DC motor speed control is identified in open-loop based on black box modeling whereas in the other one a model for position control is identified in closed-loop based on grey box modeling. An extension of HIFOO toolbox to discrete-time controller design developed recently is used to synthesize the controller. The performance of the designed controller in comparison with various control strategies is demonstrated. The paper aims at demonstrating simple modeling and control synthesis techniques with the help of available software tools to design low-complexity controllers in terms of design and implementation. Consequently, cheap hardware can be utilized for several applications.

This paper describes the design and experimental implementation of a discrete-time fixed-order H∞ controller for a DC motor position control. Based on grey box modeling, a model of the DC motor is identified. An extension of HIFOO toolbox to discrete-time controller design developed recently is used to synthesize the controller. The performance of the designed controller in comparison with various control strategies is demonstrated. The paper aims at demonstrating simple modeling and control synthesis techniques with the help of available software tools to design low-complexity controllers in terms of design and implementation. Consequently, cheap hardware can be utilized for several applications.