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S. H. H. Mashhadi

Bio: S. H. H. Mashhadi is an academic researcher from Northwestern Polytechnical University. The author has contributed to research in topics: Dielectric resonator antenna & Beamwidth. The author has an hindex of 2, co-authored 6 publications receiving 10 citations.

Papers
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Journal ArticleDOI
TL;DR: A novel widebeam aperture-coupled cylindrical dielectric resonator antenna that excites fundamental and high order hybrid modes inside the DR to achieve wide beamwidths in the two principal planes simultaneously.
Abstract: A novel widebeam aperture-coupled cylindrical dielectric resonator antenna is proposed, which consists of multi-layered cylindrical ceramic disks joined together to achieve the required height. The proposed antenna is fed by wide aperture slot, which, along with optimum dielectric resonator height, excites fundamental and high order hybrid modes inside the DR to achieve wide beamwidths in the two principal planes simultaneously. Then, a new frequency, which is called the limited frequency and denoted as $f_{\mathrm {L}}$ , is defined. Based on $f_{\mathrm {L}}$ , dimensions of the wide slot are determined. Finally, the antenna is manufactured and measured. Its operating frequency band ranges from 5.49 GHz to 7.2 GHz. The antenna yields broadbeam in the frequency band from 6.1 to 6.7 GHz and achieves a 3-dB beamwidth from 124° to 149° in the E-plane and from 112° to 126° in the H-plane.

12 citations

Journal ArticleDOI
TL;DR: In this article, a broadbeam aperture-coupled coplanar parasitic rectangular dielectric resonator antenna is proposed which yields broadbeam in both working planes simultaneously, where the antenna consists of a main radiating rectangular DRS element centered over a wide feed slot and two parasitic rectangular DSR elements one on each side of the main DRS with an optimum gap in between.
Abstract: A novel broadbeam aperture-coupled coplanar parasitic rectangular dielectric resonator antenna is proposed which yields broadbeam in both working planes simultaneously. The antenna consists of a main radiating rectangular dielectric element centered over a wide feed slot and two parasitic rectangular dielectric elements one on each side of the main radiating element with an optimum gap in between. The dielectric height and wide slot both play an important role in enhancing the beamwidth in two principal planes simultaneously. It is validated that inclusion of parasitic elements enhances the broadbeam bandwidth in addition to frequency bandwidth. First three azimuthal modes are excited out of which first two modes TEx 111 and TE x 112 are desired. The proposed antenna is compared with single element rectangular dielectric resonator antenna. To validate the proposed design, a prototype is fabricated and measured. The simulated and measured operating frequency bands of the proposed antenna respectively are 4.8 to 6.9 GHz and 5 to 6.8 GHz. The measured Eand H-plane beamwidths range from 115◦ to 144◦ and from 115◦ to 124◦, respectively, yielding a wider coverage area.

6 citations

Journal ArticleDOI
TL;DR: A novel broadbeam aperture-coupled step-walled rectangular dielectric resonator antenna that consists of a central widest ceramic plate with two plates on each side with decreased widths creating stepped or staircase like walls is proposed.
Abstract: Wide angular coverage antennas despite being a requirement for many recent safety applications are a design challenge. Applications like Automotive Radars, GPS and telemetry all need an antenna wit...

5 citations

Journal ArticleDOI
TL;DR: In this article, a resonant cavity antenna with low sidelobe levels over an enhanced bandwidth is presented, which uses a pair of complementary FSS layers to increase the radiation bandwidth of the antenna.
Abstract: A novel resonant cavity antenna (RCA) with low sidelobe levels over an enhanced bandwidth is presented. Radiation bandwidth of the antenna is increased by using a pair of complementary FSS layers, ...

3 citations

Proceedings ArticleDOI
04 Aug 2019
TL;DR: In this article, an acute isosceles triangular dielectric resonator antenna is proposed which yields wide beamwidths in E- and H-plane, simultaneously, using a wide aperture slot, which simultaneously excites the first two lower order modes.
Abstract: A novel ${\text{TM}}_{101}^{\text{z}}$ acute isosceles triangular dielectric resonator antenna is proposed which yields wide beamwidths in E- and H-plane, simultaneously. The antenna is fed by a wide aperture slot, which simultaneously excites the first two lower order modes. Then Mode-I frequency is identified using HFSS Eigen Mode solver. With the use of Mode-I frequency, dielectric resonator height is calculated which is a key parameter for identifying the broadbeam yielding band of frequencies. Its optimal value is found out to be 0.105λm. Proposed antenna operates in frequency band of 2.03 GHz to 3 GHz and yields E- and H-plane beamwidths ranging from 134° to 138° and 120° to 123°, respectively. The antenna is broadbeam in the frequency band from 2.03 GHz to 2.3 GHz.

Cited by
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01 Nov 1984
TL;DR: In this article, a substrate-superstrate printed antenna geometry which allows for large antenna gain is presented, asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed.
Abstract: Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.

568 citations

Journal ArticleDOI
Zhengyi Yang1, Na Kou1, Shixing Yu1, Fei Long1, Lili Yuan1, Zhao Ding1, Zhengping Zhang1 
TL;DR: In this paper, a reconfigurable polarization conversion method based on a metasurface turned by PIN diodes is proposed, which consists of one layer of a dielectric and two layers of metal surfaces.
Abstract: A novel reconfigurable polarization conversion method based on a metasurface turned by PIN diodes is proposed herein. The proposed metasurface consists of one layer of a dielectric and two layers of metal surfaces. When the diode is in an OFF-state, a wideband linear to circular (LTC) polarization converter is realized. The results show that the metasurface can achieve LTC polarization conversion in the frequency range of 11.8–24.1 GHz, and the axial ratio (AR) reveals that the 3-dB bandwidth is approximately 68.5%. When the diode is in the ON-state, a dual-band linear to linear (LTL) polarization converter is realized, with the 3-dB bandwidths of 10.5–13.9 GHz and 17.7–27.2 GHz, achieving a polarization converter ratio (PCR) greater than 90%. The dc bias circuit of the PIN diode is etched on the reflectance surface. Therefore, no additional feeding lines are introduced, which can decrease the impact on the active metasurface; this metasurface has practical applications in microwave communication systems.

37 citations

Journal ArticleDOI
TL;DR: In this paper, a dual-band dielectric resonator antenna exhibiting circular polarization at a high-frequency band of (7.85 GHz-7.93 GHz) in addition to linearly polarized lower frequency bands of (5.12 GHz-5.49 GHz) was designed for weather radar applications.
Abstract: This paper documents a novel design of dual-band dielectric resonator antenna exhibiting circular polarization at a high-frequency band of (7.85 GHz–7.93 GHz) in addition to linearly polarized lower frequency band of (5.12 GHz–5.49 GHz) using new materials, sapphire, and TMM13i for antenna design. With sapphire and TMM13i being immune to physical change, the novel design is suitable for weather radar applications. The obtained circular polarization reduces signal attenuation. A four-layered structure with sapphire and TMM13i stacked alternatively with aperture coupled feed is presented. Additionally, the corners of the patch have been truncated, and a slot has been etched in order to obtain the dual-band resonance and circular polarization respectively. The design is simulated using Ansys HFSS and fabricated for measurements. The VSWR (Voltage standing wave ratio) is measured to be less than 2 for both the bands. The simulated and measured gains of the antenna are 5.2 dBi and 4.9 dBi, respectively.

6 citations

Book ChapterDOI
01 Jan 2020
TL;DR: In this paper, a compact (17 × 20 × 1) mm3 coplanar waveguide-fed multi-band antenna has been designed, which consists of a U-slot over the rectangular patch structure and frequency shifting strips.
Abstract: In this paper, a compact (17 × 20 × 1) mm3 coplanar waveguide-fed multi-band antenna has been designed. This antenna consists of a U-Slot over the rectangular patch structure and frequency shifting strips. Various U-Slot structures have been studied in this work for the analysis of the antenna performances. A comparison table between the proposed antenna and similar antennas has been given in the result section. The proposed antenna resonates at 28 GHz, with a bandwidth of 2.62 GHz. Design and simulation of structures are carried out with the help of ANSYS HFSS software and other antenna parameters like field distributions, gain, directivity, impedance bandwidth, resonant frequencies, return loss, and VSWR are also reported in this study.

4 citations

Dissertation
01 Jan 2012

4 citations