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Author

Abdulkareem S. Abdullah

Bio: Abdulkareem S. Abdullah is an academic researcher from University of Basrah. The author has contributed to research in topics: Antenna (radio) & Microstrip antenna. The author has an hindex of 10, co-authored 43 publications receiving 378 citations.


Papers
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Journal ArticleDOI
TL;DR: Both measured and simulated return loss characteristics of the optimised antenna show that it satisfies the requirement of 2.4/5.8 GHz WLAN and 3.5 GHz WiMAX antenna applications.
Abstract: In this study, the authors present a simple reconfigurable multiband antenna with two PIN diode switches for worldwide interoperability for microwave access (WiMAX)/wireless local area networks (WLAN) applications. The antenna permits reconfigurable switching in up to ten frequency bands between 2.2 and 6 GHz, with relative impedance bandwidths of around 2.5 and 8%. The proposed antenna has been simulated using computer simulation technology microwave studio software and fabricated on an FR-4 substrate. It is compact, with an area of 50 × 45 mm 2 , and has a slotted ground substrate. Both measured and simulated return loss characteristics of the optimised antenna show that it satisfies the requirement of 2.4/5.8 GHz WLAN and 3.5 GHz WiMAX antenna applications. Moreover, there is good agreement between the measured and simulated results in terms of radiation pattern and gain.

105 citations

Journal ArticleDOI
TL;DR: In this article, a planar monopole antenna is proposed for ultra-wideband applications, which consists of a ring patch and a partial ground plane with a defective ground structure of rectangular shape.
Abstract: A compact planar monopole antenna is proposed for ultra-wideband applications. The antenna has a microstrip line feed and band-rejected characteristics and consists of a ring patch and a partial ground plane with a defective ground structure of rectangular shape. An annular strip is etched above the radiating element and two slots, one C-shaped and one arc-shaped, are embedded in the radiating patch. The proposed antenna has been optimised using bio-inspired algorithms such as the particle swarm optimisation and the firefly algorithm, based on a new software algorithm (Antenna Optimizer). Multi-objective optimisation achieves rejection bands at 3.3-3.7 GHz for Worldwide Interoperability for Microwave Access, 5.15-5.825 GHz for the 802.11a wireless local area network system or HIPERLAN/2, and 7.25-7.745 GHz for C-band satellite communication systems. Validated results show wideband performance from 2.7 to 10.6 GHz with S 11 <; -10 dB. The antenna has compact dimensions of 28 × 30 mm 2 . The radiation pattern is comparatively stable across the operating band with a relatively stable gain except in the notched bands.

56 citations

Journal ArticleDOI
TL;DR: In this article, the authors presented a new circular polarization reconfigurable antenna for 5G wireless communications, containing a semicircular slot, was compact in size and had a good axial ratio and frequency response.
Abstract: This paper presented a new circular polarization reconfigurable antenna for 5G wireless communications. The antenna, containing a semicircular slot, was compact in size and had a good axial ratio and frequency response. Two PIN diode switches controlled the reconfiguration for both the right-hand and left-hand circular polarization. Reconfigurable orthogonal polarizations were achieved by changing the states of the two PIN diode switches, and the reflection coefficient |S11| was maintained, which is a strong benefit of this design. The proposed polarization-reconfigurable antenna was modeled using the Computer Simulation Technology (CST) software. It had a 3.4 GHz resonance frequency in both states of reconfiguration, with a good axial ratio below 1.8 dB, and good gain of 4.8 dBic for both modes of operation. The proposed microstrip antenna was fabricated on an FR-4 substrate with a loss tangent of 0.02, and relative dielectric constant of 4.3. The radiating layer had a maximum size of 18.3 × 18.3 mm2, with 50 Ω coaxial probe feeding.

55 citations

Journal ArticleDOI
TL;DR: In this paper, a compact dielectric resonator antenna (DRA) for wideband applications is proposed, which consists of two cylindrical DRA resonators that are asymmetrically located with respect to the center of a rectangular coupling aperture.
Abstract: A compact dielectric resonator antenna (DRA) for wideband applications is proposed. Two cylindrical dielectric resonators that are asymmetrically located with respect to the center of a rectangular coupling aperture are fed through this aperture. By optimizing the design parameters, an impedance bandwidth of about 29%, covering the frequency range from 9.62 to 12.9 GHz, and a gain of 8 dBi are obtained. Design details of the proposed antenna and the results of both simulation and experiment are presented and discussed.

46 citations

Journal ArticleDOI
TL;DR: In this paper, a compact sensing/communicating antenna configuration for interweave cognitive radio (CR) systems is presented, where the sensing antenna is an ultra-wide band (UWB) planar monopole antenna, while the communicating antenna is a reconfigurable microstrip antenna etched on the backside of the UWB antenna radiating patch.
Abstract: This paper presents a compact sensing/communicating antenna configuration for interweave cognitive radio (CR) systems. The sensing antenna is an ultra-wide band (UWB) planar monopole antenna, while the communicating antenna is a reconfigurable microstrip antenna etched on the backside of the UWB antenna radiating patch. Based on the current distribution of the UWB sensing antenna, the position and the shape of the communicating antenna are optimized to effectively reduce the mutual coupling between the antenna ports. A frequency reconfigurability from (5-6) GHz is achieved by attaching a varactor diode to the radiating patch of the communicating antenna. The simulated and measured results show good radiation and frequency domain characteristics of the proposed antenna. It is found that the communicating antenna has reflection coefficient values less than -18dB at the resonant frequencies. The mutual coupling between the sensing and communicating antennas is found less than -20dB.

18 citations


Cited by
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01 Jan 2012
TL;DR: A novel multiple-input multiple-output (MIMO) transmission scheme which combines spatial modulation (SM) and space-time block coding (STBC) to take advantage of the benefits of both while avoiding their drawbacks is proposed.
Abstract: A novel multiple-input multiple-output (MIMO) transmission scheme, called space-time block coded spatial modulation (STBC-SM), is proposed. It combines spatial modulation (SM) and space-time block coding (STBC) to take advantage of the benefits of both while avoiding their drawbacks. In the STBCSM scheme, the transmitted information symbols are expanded not only to the space and time domains but also to the spatial (antenna) domain which corresponds to the on/off status of the transmit antennas available at the space domain, and therefore both core STBC and antenna indices carry information. A general technique is presented for the design of the STBC-SM scheme for any number of transmits antennas. Besides the high spectral efficiency advantage provided by the antenna domain, the proposed scheme is also optimized by deriving its diversity and coding gains to exploit the diversity advantage of STBC. A low-complexity maximum likelihood (ML) decoder is given for the new scheme which profits from the orthogonality of the core STBC. The performance advantages of the STBC-SM over simple SM and over V-BLAST are shown by simulation results for various spectral efficiencies and are supported by the derivation of a closed form expression for the union bound on the bit error probability.

258 citations

Journal ArticleDOI
TL;DR: In this paper, an electric ring resonator (ERR) incorporated into the coplanar waveguide feedline is proposed for use in the planar configuration of the ultrawideband (UWB) antenna.
Abstract: The ultrawideband (UWB) planar antenna is designed as a circular metallic patch fed by a coplanar waveguide (CPW). This antenna provides the impedance bandwidth of the wideband response from 2.5 to 12 GHz. To achieve the notched characteristics at desirable frequencies, the electric ring resonator (ERR) incorporated into the CPW feedline is proposed for use in the planar configuration of the UWB antenna. The notched frequency band is controlled by dimensions of the ERR structure. The single-notched band can be obtained by placing a single ERR beneath the CPW structure. For implementation of the multinotch band, a modified multimode structure of the ERR is examined. Reconfigurability of the first notched band is provided by using a digital variable capacitor (DVC) instead of ERR's quasi-lumped capacitance. The results of simulations and measurements are in a good agreement.

125 citations

Journal ArticleDOI
TL;DR: This work reviews some recently proposed reconfigurable antenna designs suitable for use in wireless communications such as cognitive-ratio (CR), multiple-input multiple-output (MIMO), ultra-wideband (UWB), and 4G/5G mobile terminals.
Abstract: Reconfigurable antennas play important roles in smart and adaptive systems and are the subject of many research studies. They offer several advantages such as multifunctional capabilities, minimized volume requirements, low front-end processing efforts with no need for a filtering element, good isolation, and sufficient out-of-band rejection; these make them well suited for use in wireless applications such as fourth generation (4G) and fifth generation (5G) mobile terminals. With the use of active materials such as microelectromechanical systems (MEMS), varactor or p-i-n (PIN) diodes, an antenna’s characteristics can be changed through altering the current flow on the antenna structure. If an antenna is to be reconfigurable into many different states, it needs to have an adequate number of active elements. However, a large number of high-quality active elements increases cost, and necessitates complex biasing networks and control circuitry. We review some recently proposed reconfigurable antenna designs suitable for use in wireless communications such as cognitive-ratio (CR), multiple-input multiple-output (MIMO), ultra-wideband (UWB), and 4G/5G mobile terminals. Several examples of antennas with different reconfigurability functions are analyzed and their performances are compared. Characteristics and fundamental properties of reconfigurable antennas with single and multiple reconfigurability modes are investigated.

111 citations

Journal ArticleDOI
TL;DR: Different types of effective implementation techniques for reconfigurable antennas used in various wireless communication systems such as satellite, multiple-input multiple-output (MIMO), mobile terminals and cognitive radio communications are investigated.
Abstract: Due to the fast development of wireless communication technology, reconfigurable antennas with multimode and cognitive radio operation in modern wireless applications with a high-data rate have drawn very close attention from researchers. Reconfigurable antennas can provide various functions in operating frequency, beam pattern, polarization, etc. The dynamic tuning can be achieved by manipulating a certain switching mechanism through controlling electronic, mechanical, physical or optical switches. Among them, electronic switches are the most popular in constituting reconfigurable antennas due to their efficiency, reliability and ease of integrating with microwave circuitry. In this paper, we review different implementation techniques for reconfigurable antennas. Different types of effective implementation techniques have been investigated to be used in various wireless communication systems such as satellite, multiple-input multiple-output (MIMO), mobile terminals and cognitive radio communications. Characteristics and fundamental properties of the reconfigurable antennas are investigated.

86 citations