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A. H. Majeed

Bio: A. H. Majeed is an academic researcher from Nahrain University. The author has contributed to research in topics: Radiation pattern & Monopole antenna. The author has an hindex of 4, co-authored 15 publications receiving 99 citations. Previous affiliations of A. H. Majeed include University of Basrah & University of Bradford.

Papers
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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

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TL;DR: In this paper, a compact dielectric resonator antenna (DRA) with band-notched characteristics for ultra-wideband applications is presented, which increases the reflection coefficient by 235 dB and reduces the gain by 612 dB.
Abstract: In this paper, a compact dielectric resonator antenna (DRA) with band-notched characteristics for ultra-wideband applications is presented A comprehensive parametric study was carried out using CST Microwave Studio Suite TM 2011 to analyze and optimize the characteristics of the proposed antenna Three shapes for the coupling slot were investigated Simulation results show that the proposed DRA had a −10 dB impedance bandwidth of 23% from 997 GHz to 12558 GHz, and a maximum gain of 723 dBi The antenna had a notched band centered at 1057 GHz, which increased the reflection coefficient by 235 dB, and reduced the gain by 612 dB The optimized designs were verified by experimental tests on fabricated samples

17 citations

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TL;DR: In this paper, balanced dual-segment cylindrical dielectric antennas with ultra-wideband (UWB) operation were proposed and a T-shaped slot and L-shaped microstrip feeding line was suggested to furnish a balanced coupling mechanism for feeding two DRAs, and the performance of the proposed antenna was analyzed and optimised against the target frequency band.
Abstract: This study reports on balanced dual-segment cylindrical dielectric antennas with ultra-wideband (UWB) operation. A T-shaped slot and L-shaped microstrip feeding line was suggested to furnish a balanced coupling mechanism for feeding two DRAs, and then the performance of the proposed antenna was analysed and optimised against the target frequency band. The proposed antenna was then modified by adding a C-shaped strip to increase the gain. The performances of both balanced antennas were characterised and optimised in terms of antenna reflection coefficient, radiation pattern, and gain. The antennas cover the frequency range from 6.4 to 11.736 GHz, which is 58.7% bandwidth. A maximum gain of 2.66 dB was achieved at a frequency of 7 GHz with the first antenna, with a further 2.25 dB increase in maximum gain attained by adding the C-shaped strip. For validation, prototypes of the two antennas were fabricated and tested. The predicted and measured results showed reasonable agreement and the results confirmed good impedance bandwidth characteristics for UWB operation from both proposed balanced antennas.

15 citations

Journal ArticleDOI
TL;DR: In this paper, a dual-segmented dielectric resonator (DR) antenna design was proposed for wideband applications in the X-band region, where two DRs coupled to an S-shaped slot introduce interesting features.
Abstract: A new low-cost dual-segmented dielectric resonator (DR) antenna design is proposed for wideband applications in the X-band region. Two DRs coupled to an S-shaped slot introduce interesting features. The antenna performance was characterised in terms of the reflection coefficient, gain, and radiation pattern, and detailed simulation studies indicate excellent antenna performance from 7.66 to 11.2 GHz (37.5% fractional bandwidth) with a maximum gain of 6 dBi at 10.6 GHz, whereas the fabricated prototype has a matched bandwidth from 7.8 to 11.85 GHz (41% fractional bandwidth) and maximum gain of 6 dB i . The antenna is compact, size 1 × 0.83 × 0.327 times the wavelength at 10 GHz. The two DR segments may be located on the same side or on opposite sides of the substrate, giving, respectively, improved gain or more uniform field patterns. Experimental testing of the prototype performance showed reasonable agreement with the predicted performance.

8 citations

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TL;DR: In this article, a new approach to the design of an UWB monopole antenna with dual band-notched characteristics is presented, where the antenna has the form of an elliptical monopole over a ground plane having a U-shaped and C-shaped slots on the radiating patch.
Abstract: In this paper, a new approach to the design of an UWB monopole antenna with dual band-notched characteristics is presented. The antenna has the form of an elliptical monopole over a ground plane having an elliptical slot to achieve the UWB. The dual-band notch function is created by inserting a U-shaped and a C-shaped slots on the radiating patch, thus no extra size is needed. The proposed antenna shows a good omnidirectional radiation pattern across the band from 3.2 to more than 14 GHz. The dual band-rejection is for 4.88-5.79GHz centered at 5.4GHz and 7.21-8.46 GHz centered at 7.8 GHz. The antenna prototype using the FR-4 substrate with e r =4.3 has a compact size of 25mm×25 mm ×1.45mm. The fabricated prototype showed experimental results comparable to those obtained from the simulations.

5 citations


Cited by
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1,011 citations

Journal ArticleDOI
TL;DR: A review paper concerning wide-band and ultra-wideband (UWB) antennas used for wireless communication purposes in terms of the materials as well as a numerical analysis is presented.
Abstract: A review paper concerning wide-band and ultra-wideband (UWB) antennas used for wireless communication purposes in terms of the materials as well as a numerical analysis is presented. These antennas which are taken into account are listed as wide-band microstrip antenna, wide-band monopole antenna over a plate, wide-slot UWB antenna, stacked patch UWB antenna, taper slot (TSA) UWB antenna, metamaterial (MTM) structure UWB antennas, elliptical printed monopole UWB antenna, and flexible wearable UWB antenna. The antennas’ performance is compared based on their size and how they can be applicable for portable communication device applications. This review paper furnishes a proper direction to select varieties of figures in terms of impedance bandwidth, gain, directivity, dimensions, time domain characteristics, and materials affecting these antenna’s characteristics.

63 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive investigation of research carried out on dielectric resonator antennas (DRAs) in the last three and half decades, in an application-oriented approach, is presented.
Abstract: This survey article outlines a comprehensive investigation of research carried out on dielectric resonator antennas (DRAs) in the last three and half decades, in an application-oriented approach. DRAs have created a remarkable position in antenna engineering for their adept characteristics like high efficiency, low loss, wide bandwidth, compact size, 3-dimensional modeling flexibility, etc. The use of DRAs for different commercial and defense applications associated with the wireless communication is highlighted in this article. To make a smooth and effective survey article, all the application-oriented DRAs available in the open literature are classified in five different categories like microwave bands, specific frequency, technology, millimeter-wave, and miscellaneous types. The ultimate aims of this review article are as follows: (i) highlights the usability of DRAs for different commercial and defense applications, (ii) helpful for the antenna industries/manufacturers to find out the best DRA for any specific application as per their requirement, and (iii) points out research gap in some application domains which will be quite helpful for future antenna researchers. In the authors' opinion, this survey may be helpful to DRA researchers as such a survey process is not available in the open literature.

52 citations

Journal ArticleDOI
TL;DR: In the class of printed broadband antennas with unbroken ground plane, the proposed antenna achieves minimum volume with good bandwidth and radiation properties, suitable for target scanning applications.
Abstract: A broadband and compact stacked microstrip patch antenna has been developed using stacked configuration. The antenna comprises two parasitic patches stacked above the driven patch fed by shifted microstrip feed and a step transformer between feed and patch to achieve broadband coupling. Cross polarization has been improved by inserting a vertical slot in the direction of feed. The antenna occupies very low volume of ${\mathbf{0}}.{\mathbf{36}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{39}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{096}}{\lambda _{\mathbf{o}}}$ (radiating elements volume), while overall dimensions with ground plane are ${\mathbf{0}}.{\mathbf{7}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{7}}{\lambda _{{\mathbf{o}}}}\,\times\,{\mathbf{0}}.{\mathbf{096}}{\lambda _{\mathbf{o}}}$ . The overall bandwidth achieved is 35% (4.9–7.05 GHz) and a peak gain of 8.2 dBi with average gain of 6 dBi. Antenna radiation patterns are quite unidirectional with ${\mathbf{F}}\text{/}{\mathbf{B}} > {\mathbf{21}}$ dB and significantly low cross-polarization levels, suitable for target scanning applications. In the class of printed broadband antennas with unbroken ground plane, the proposed antenna achieves minimum volume with good bandwidth and radiation properties.

51 citations

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TL;DR: In this paper, a novel ultrawide band planar antenna with band notched characteristics is presented, which is achieved by loading a pair of metamaterial inspired rectangular split ring resonator (SRR) near the feed line and by etching the SRR slots on a radiating patch.
Abstract: A novel compact size ultrawide band planar antenna with band notched characteristics is present. The band rejection characteristic is achieved by loading a pair of metamaterial inspired rectangular split ring resonator (SRR) near the feed line and by etching the SRR slots on a radiating patch. The simulated and measured results reveal that the proposed antenna exhibits the impedance bandwidth over the ultrawide band (UWB) frequency range from 3.1 to 14 GHz with the voltage standing wave ratio less than 2 except for band stop bands at 3.29 to 3.7 GHz (WiMAX band), 3.7 to 4.10 GHz (C-band), 5.1 to 5.9 GHz (WLAN band), and 7.06 to 7.76 GHz (downlink X-band satellite communication), respectively. The proposed antenna fabricated on low-cost FR-4 substrate has compact size of 24 × 20 × 1.6 mm3. The simulation results are compared with measured results and demonstrate good agreement with stable gain over pass bands. The proposed antenna also exhibits dipole-like radiation pattern in E-plane and omni-directional pattern in H-plane. These results led to conclusion that the presented antenna is a suitable candidate for ultrawide band UWB applications with desired band notch characteristics.

45 citations