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leaky-wave-antennas
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Closed form formula for longitudinal slot of LWAs with minimum side lobe level
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 1820-1824 ; 9781509059638 (ISBN) ; Bayderkhani, R ; Alijani, M. G ; Neshati, M. H ; Sharif University of Technology
Abstract
In this paper a closed-form expression is introduced to calculate slot shape of long slot leaky wave waveguide antennas at its fundamental mode of operation with minimum side lobe level (SLL). The derived equation is a function of geometrical parameters of the structure. This is an advantage because they show a clear relationship between geometrical parameters of the antenna and radiated field that allows intelligent modification of the pattern. The Gaussian slot is used to obtain the best radiation pattern with lowest SLL. The results obtained by introduced formula are compared with the full wave commercial simulator such as HFSS software which confirms the accuracy of the introduced...
Frequency scanning in the uniform leaky-wave antenna based on nonradiative dielectric (NRD) waveguide
, Article 2011 19th Iranian Conference on Electrical Engineering, ICEE 2011, 17 May 2011 through 19 May 2011 ; May , 2011 ; 9789644634284 (ISBN) ; Sorkherizi, M. S ; Tadjalli, A ; Hosseini, S. R ; Sharif University of Technology
2011
Abstract
A leaky wave antenna of uniform configuration based on nonradiative dielectric wave guide (NRD) is studied. Non radiative dielectric wave guide is a modification of H-guide suitable for millimetre wavelengths. Wave propagation, power leakage, radiation pattern and frequency scanning feature of this kind of antenna is analyzed. Analysis is held on U band of frequencies using HFSS software
Dirac leaky wave antennas
, Article 5th International Conference on Millimeter-Wave and Terahertz Technologies, MMWaTT 2018, 18 December 2018 through 20 December 2018 ; Volume 2018-December , 2019 , Pages 1-5 ; 21570965 (ISSN); 9781538677179 (ISBN) ; Memarian, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Dirac leaky-wave antennas (DLWAs) are derived from photonic crystals exhibiting Dirac cone dispersion around their Γ-point. DLWAs provide high directive beams and continuous frequency beam scanning, non-fluctuating leakage constant and real non-zero Bloch impedance at and around broadside, due to the closed and linear Dirac dispersion relation around broadside. These features, along with their inherent compatibility for higher frequency designs (larger unit cells compared to metamaterials), make DLWAs an ideal candidate for the upper microwave, mm-wave and terahertz frequencies, and for applications such as radar, 5G, spectroscopy, etc. In this review, we cover the recent developments on...
Analytical study of open-stopband suppression in leaky-wave antennas
, Article IEEE Antennas and Wireless Propagation Letters ; Volume 19, Issue 2 , 2020 , Pages 363-367 ; Memarian, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
In the majority of leaky-wave antennas (LWAs), the lack of broadside radiation is due to the existence of an open-stopband (OSB) at broadside. In this letter, we present a study on the OSB suppression in LWAs. In particular, we start from a simple unit cell comprising a planar waveguide having alternating open and short sidewalls. The analytical and simulated band structures testify consistently that OSB suppression can indeed be realized by proper design, analytically studied using mode-matching, and further supported by full-wave simulations. An LWA is then implemented using the substrate integrated waveguide (SIW) technology, which provides interesting features such as a high directive...
Analytical study of Dirac type dispersion in simple periodic waveguide structures for leaky-wave applications
, Article IEEE Access ; Volume 10 , 2022 , Pages 25707-25717 ; 21693536 (ISSN) ; Memarian, M ; Eleftheriades, G. V ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
In this work, we present a study on the existence of Dirac type dispersion in the simplest of periodic metallic waveguide structures. It is shown that periodic repetitions of two dissimilar waveguides (WGs) can be properly designed to lead to a Dirac type dispersion. A simple theory using circuit modeling is presented to find the condition for Dirac point operation. In addition, mode-matching followed by full-wave simulations validate that the band structure matches that of the theory and shows that a Dirac dispersion can be realized. A Dirac Leaky-Wave Antenna (DLWA) is then implemented using this simple arrangement in substrate-integrated-waveguide (SIW) technology. This DLWA has the...
Analysis and Design of Antenna for Automotive Radar with Pencil Beam Based on Dirac Leaky-Wave Antennas
, M.Sc. Thesis Sharif University of Technology ; Memarian, Mohammad (Supervisor)
Abstract
Expansion of communication and the emergence of new fields such as the Internet of Things, has led to the development of smart cars and especially self-driving cars. The antennas used in the radar of these cars are of special importance for a better understanding of the environment around the car. The important parameters for the design of antennae for automotive radar are: good resolution, narrow beam width, the ability to change the angle of the main beam, etc. Among the most common antennas used in these radars are directional antennas, for this reason phased array antennas and leaky wave antennas are suitable options for this application. In general, the complexity and difficulty in the...
Design and Realization of a Microstrip Antenna Array for Both Automotive Radar Application and 5G Communications at 78/28 GHZ Band
, M.Sc. Thesis Sharif University of Technology ; Farzaneh, Forouhar (Supervisor)
Abstract
With the advancement of automotive technology, the use of automotive radar for collision avoidance and pedestrian detection has been increasingly become universal. In this thesis, our goal is to design a dual-band radar antenna for obstacle detection and a 5G omnidirectional antenna for communication purposes in self-driving cars. We will first introduce the automotive radar and its operation. Next, the FMCW radar, which is simultaneously effective for speed, distance and direction estimation is introduced. Then we introduce the leaky wave antenna as the frequency scanning antenna. This is realized in an SIW waveguide technology. The main issue in this part is the achievement of high...
Parallel-plates-based dirac leaky wave antennas
, Article IET Microwaves, Antennas and Propagation ; Volume 15, Issue 15 , 2021 , Pages 1877-1890 ; 17518725 (ISSN) ; Memarian, M ; Ahmadian, M ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
In this work, the authors experimentally show Dirac Leaky Wave Antennas (DLWAs) at upper microwave frequencies. For the first time, DLWAs are implemented using simple Parallel plate waveguide (PPW) technology, while yielding desirable radiation features and continuous beam scanning through broadside, as well as extremely low profile, with significant ease of fabrication, making them well suited for Ku band applications such as satellite communication, radar and emerging fifth-generation (5G). A planar Dirac photonic crystal in PPW is shown with a closed bandgap and linear dispersion around broadside. In this work, 1D and 2D PPDLWAs are designed that provide scannable fan and pencil beams,...
Dirac Leaky Wave Antenna for the Microwave and the mm-Wave Band
, M.Sc. Thesis Sharif University of Technology ; Memarian, Mohammad (Supervisor)
Abstract
Novel Dirac Leaky Wave Antennas (DLWAs) based on Substrate Integrated Waveguide (SIW) are presented in this thesis, for millimeter wave frequencies. These DLWAs provide interesting features such as radiating through broadside, beam scanning and ease in fabrication that are well suited for emerging fifth generation (5G) and IoT applications. In this thesis, it is shown that a Dirac photonic crystal can be realized in SIW technology composed of air columns inside a host SIW waveguide, exhibiting a closed bandgap and linear dispersion around broadside. Phase and attenuation constants are controlled to obtain directive beam and scanning in a wide range of angles (from -30˚ to 20˚). This DLWA...
Input impedance and radiation pattern of a resonant dipole embedded in a two-dimensional periodic leaky-wave structure
, Article IET Microwaves, Antennas and Propagation ; Volume 9, Issue 14 , 2015 , Pages 1567-1573 ; 17518725 (ISSN) ; Borji, A ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
Array scanning method (ASM) is employed to study the input impedance and radiation pattern of a two-dimensional periodic leaky-wave antenna (LWA). The antenna consists of a narrow horizontal strip dipole of arbitrary length underneath a two-dimensional (2D) periodic screen of metallic patches, which acts as a partially reflective surface (PRS), and backed by a ground plane. First, the Green's function in the presence of the 2D array of metallic patches is calculated by means of the ASM and then the current distribution and input impedance of the source dipole are calculated through the electric field integral equation and method of moments. The far-field pattern is computed using the...
Dirac leaky wave antenna for millimetre-wave applications
, Article IET Microwaves, Antennas and Propagation ; Volume 14, Issue 9 , 2020 , Pages 874-883 ; Memarian, M ; Eleftheriades, G. V ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Dirac dispersion cones enable remarkable wave phenomena in electronics as well as electromagnetic systems. In this work, the authors experimentally demonstrate for the first time the Dirac leaky wave antennas (DLWAs) at millimetre-wave (mm-wave) frequencies. The demonstrated DLWAs are implemented in the substrate integrated waveguide technology, delivering unprecedented features at high frequencies such as radiation at, and continuous beam scanning through broadside, with ease of fabrication, making these designs well suited for mm-wave applications such as emerging fifth generation and Internet of Things, radar and imaging. It is shown that a planar Dirac photonic crystal can be realised...