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    Reduced active impedance variation by using time modulated array

    , Article 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, APSURSI 2019, 7 July 2019 through 12 July 2019 ; 2019 , Pages 1765-1766 ; 9781728106922 (ISBN) Mazaheri, M. H ; Fakharzadeh, M ; Akbari, M ; Safavi Naeini, S ; IEEE Antennas and Propagation Society (APS); The Institute of Electrical and Electronics Engineers (IEEE) ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    In this paper we investigate the active impedance of Time Modulated Array (TMA) as a low-cost and simple beamforming architecture. Since the antenna elements in TMA are periodically turned on and off, the active impedance of this structure has less variation compared to a phased array architecture. In this paper, we have compared the active impedance of a TMA structure and that of the phased array for different cases. The active reflection coefficient of the TMA is always below-10 dB, while the impedance of the phased array becomes unmatched for certain scan angles  

    Design and calibration procedure of a proposed V-band antenna array on fused silica technology intended for MIMO applications

    , Article International Journal of Microwave and Optical Technology ; Volume 13, Issue 4 , 2018 , Pages 317-329 ; 15530396 (ISSN) Salarpour, M ; Farzaneh, F ; Staszewski, R. B ; Sharif University of Technology
    International Academy of Microwave and Optical Technology (IAMOT)  2018
    Abstract
    A coplanar-fed wideband antenna array system to characterize MIMO channels in the 60 GHz band is proposed. The array consists of six U-slot patch elements with half-wavelength separation and is fed independently by individual transceivers. The system is designed and simulated on fused silica substrate to be integrated easily with RFICs and to achieve fine fabrication resolution (1um) for accurate mm-wave measurements. It can provide 11dBi peak gain at broadside and beam steering up to ±40° tilted from broadside over 57-63 GHz band. A new on-wafer calibration technique is developed to balance the amplitude and phase of all transceivers at the input of the array system which realizes high... 

    Synchronization-Phase Alignment of All-Digital Phase-Locked Loop Chips for a 60-GHz MIMO Transmitter and Evaluation of Phase Noise Effects

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 67, Issue 7 , 2019 , Pages 3187-3199 ; 00189480 (ISSN) Salarpour, M ; Farzaneh, F ; Staszewski, R. B ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    A phase-coherent technique for multiple all-digital phase-locked loops (ADPLLs) is presented and developed in this paper to target a 57-63-GHz multiple-input multiple-output (MIMO) transmitter (TX) with a digital beam-steering capability. The ADPLL TX chains are first fabricated in nanoscale CMOS and then time-synchronized and frequency-phase locked by a field-programmable gate array (FPGA) evaluation board. The calibration approach for phase alignment is carried out using a cancellation method to acquire the out-of-phase state within two ADPLLs. The accuracy of beam steering and phase alignment is investigated and analyzed based on a time-domain model for ADPLL to consider the impact of... 

    Performance Analysis and Optimization of Optically Steered Arrayed Antennas with Gratings

    , Ph.D. Dissertation Sharif University of Technology Shabani, Mostafa (Author) ; Akbari, Mahmood (Supervisor)
    Abstract
    It is well known that arrays of antennas make it possible to steer the radiation pattern without steering a physical structure. For the past few decades this has been considered for many civil and military communication systems. Recently, ultra-short pulses are considered for high resolution radars and ultra-wideband communication systems. Systems with short pulses and large antenna arrays may benefit from high resolution in both temporal and spatial domains. But the implementation of the ultra-wideband feeding circuits for such antenna arrays is a hard job even with state of the art electronics. Optical technology has been applied, successfully, to a number of radio applications such as... 

    Beam Steering in Circular Planar Array of Coupled Microwave Oscillators

    , M.Sc. Thesis Sharif University of Technology Tooni, Sakineh (Author) ; Banai, Ali (Supervisor)
    Abstract
    In this thesis, it is shown that by detuning the array peripheral elements, without using phase shifters, and locking the array to the common frequency there exists a phase difference between two adjacent elements which is constant along the array and is proportional to the amount of free running frequency detuning. By changing free running frequency and therefore resultant phase difference, one can control the array beam direction. Linear, ring, hexagonal and triangular array configurations have been analyzed so far. In this work we endeavor to explore a circular planar array with weak coupling. The aim is to yield an analytical relationship to determine the free running frequency of each... 

    Simultaneous microwave chirped pulse generation and antenna beam steering

    , Article Progress In Electromagnetics Research M ; Volume 22 , 2012 , Pages 137-148 ; 19378726 (ISSN) Shabani, M ; Akbari, M ; Sharif University of Technology
    2012
    Abstract
    A new structure is suggested for simultaneous microwave chirped pulse generation and array antenna beam steering. It is based on using a multi-channel fiber Bragg grating in a photonic microwave delay-line filter. The paper presents a feasibility study of the idea, discussing the main performance parameters of both signal generation and beam steering functions. Specifically, it focuses on the effects of wavelength tuning, resolution and accuracy. The study shows that custom off-the-shelf components could be used to implement an all optical system capable of generating chirped pulses while steering the radiation pattern of a small sized antenna array. The advantages of the structure for... 

    A mm-Wave MIMO transmitter with a digital beam steering capability using CMOS all-digital phase-locked loop chips

    , Article 2018 IEEE MTT-S International Microwave Workshop Series on 5G Hardware and System Technologies, IMWS-5G 2018, 30 August 2018 through 31 August 2018 ; 2018 ; 9781538611975 (ISBN) Salarpour, M ; Bogdan Staszewski, R ; Farzaneh, F ; Sharif University of Technology
    Abstract
    In this paper, we propose a mm-wave transmitter architecture intended for radar and 5G MIMO applications with beam steering over 57-63 GHz frequency band. Each transmitter chain comprises an all-digital phase-locked loop (ADPLL) CMOS IC chip intended to be dictated to a single antenna unit within an array. For demonstration purposes, each IC is embedded on a printed circuit board (PCB) to provide beam steering using highly accurate digital approach. The overall transmitter is connected to an antenna array with half wavelength spaced elements to maximize the beam scanning coverage. The ADPLL boards are fabricated and a calibration technique is carried out to align amplitude-phase of all... 

    Design procedure of a U-slot patch antenna array for 60 GHz MIMO application

    , Article 14th International Conference on Advanced Trends in Radioelectronics, Telecommunications and Computer Engineering, TCSET 2018, 20 February 2018 through 24 February 2018 ; Volume 2018-April , 2018 , Pages 612-615 ; 9781538625569 (ISBN) Salarpour, M ; Farzaneh, F ; Staszewski, R. B ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    In this paper, we present an antenna array with beam steering capability to characterize MIMO channels over 57-63 GHz frequency band. This uniform linear array is built of six U-slot patch elements which are spaced half wavelength to maximize the beam scanning coverage. Each element can be fed by an individual transceiver to establish a MIMO construction. The system is implemented in fused silica technology to be integrated easily with RFICs and to achieve excellent fabrication tolerance for accurate mm-wave measurements. It can provide 11dBi peak realized gain at broadside and beam steering up to ±40° from broadside in the whole frequency band. © 2018 IEEE  

    Asymmetrical 4×4 butler matrix and its application for single layer 8×8 butler matrix

    , Article IEEE Transactions on Antennas and Propagation ; Volume 67, Issue 8 , 2019 , Pages 5372-5379 ; 0018926X (ISSN) Tajik, A ; Shafiei Alavijeh, A ; Fakharzadeh, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    The design procedure and measured results of a novel 4 × 4 Butler matrix are presented in this paper. This asymmetrical structure provides fairly flexible phase outputs; therefore, the array radiation pattern can be rotated around the array normal axis. The structure of this modified Butler matrix is discussed in detail, and the explicit design formulas are derived to achieve the arbitrary main beams direction. Using the proposed design procedure, the Butler matrix can provide even broadside and endfire beams. In addition, this structure is employed to design two Butler matrices, which generate similar patterns as a conventional 8 × 8 Butler matrix, using only single layer circuits with... 

    5-6 GHz dual-vector phase shifter in 0.18 μm LID CMOS

    , Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 82-86 ; 9781728115085 (ISBN) Choopani, A ; Fakharzadeh, M ; Safarian, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    In this paper, a low power active phase shifter in 0.18 μm CMOS technology, operating from 5 to 6 GHz, for WLAN applications is presented. Design equations for this novel structure, which consists of two current steering stages, transconductance stage and DACs, are derived, thoroughly. This phase shifter has a range of 360° with 5.625° phase resolution. The power consumption is 35 mW. The RMS phase error is only 0.3°. The simulated power gain, input P1dB, and NF are 4 dB, -0.8 dBm and 6 dB, respectively  

    , M.Sc. Thesis Sharif University of Technology Razieh, Azad (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    In recent years due to the advances in semiconductor technology and the ability to implement small-scale manufacturing, communication at 60 GHz band receive more attention than ever has been. The use of this frequency band is not only about 7-9 GHz unlicensed broadband access provided, but getting smaller devices make it possible to use multiple antennas at the transmitter and receiver, and thus taking advantage of multiple input – multiple output systems. Antennas used in these systems should have features such as small size , low weight, high gain and bandwidth and also they should keep their high efficiency and gainat high frequency range (about a few GHz ). To achieve these features... 

    Evaluation of beam steering in circular planar array of coupled microwave oscillators

    , Article International Journal of RF and Microwave Computer-Aided Engineering ; Volume 21, Issue 4 , 2011 , Pages 383-391 ; 10964290 (ISSN) Tooni, S ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2011
    Abstract
    A Green's function to describe the time behavior of the locking phases in a circular planar array of mutually coupled microwave oscillators is proposed. Using this Green's function the dynamic behavior of the array can be described for any arbitrary free running frequency of elements of the oscillator array. Beam steering is realized via detuning the edge oscillators of the array from a reference frequency and the beam direction is controlled by the amount of detuning for each oscillator at the edge. Some detuning functions such as sinusoidal, triangular and rectangular ones have been applied and, the resulting array patterns are compared with one another  

    Continuum modelling of a circular planar array of coupled microwave oscillators

    , Article European Microwave Week 2009, EuMW 2009: Science, Progress and Quality at Radiofrequencies, Conference Proceedings - 39th European Microwave Conference, EuMC 2009, 28 September 2009 through 2 October 2009, Rome ; 2009 , Pages 1349-1352 ; 9782874870118 (ISBN) Tooni, S ; Banai, A ; Sharif University of Technology
    Abstract
    in this paper the phase distribution in an array of coupled oscillators arranged on a circular surface is discussed. Coupling is considered to be weak and each oscillator is coupled to its four nearest neighbours. In a continuum limit where the number of oscillators goes to infinity a theoretical formulation in polar coordinates is proposed to describe the dynamic behaviour of phases of the array elements. A Green's function for phase distribution of the array is proposed in terms of its normalized eigenfunctions. Beam steering can be done via detuning the edge oscillators. © 2009 EuMA  

    Geometrically modified einzel lenses, from the conventional cylindrical einzel lens to cubic and continuous einzel lens

    , Article IEEE Transactions on Plasma Science ; Volume 45, Issue 5 , 2017 , Pages 828-835 ; 00933813 (ISSN) Riazi, A ; Yasrebi, N ; Monjezi, H ; Rashidian, B ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    New geometrical counterparts to the conventional Einzel lens, cubic, and the continuous body electrostatic (CBE) lenses are introduced and their performances are investigated in terms of different aberrations and input beam properties. Design curves for the continuous body electrostatic lens are presented. Relative sensitivity is proposed as a figure of merit, based on which the focusing characteristics of the two new lenses are compared with that of a conventional Einzel, and a quadrupole lenses of the same size, as well. Moreover, performance and characteristics of the lenses are compared in terms of their corresponding sensitivities to the applied voltage and the incidence beam... 

    Error Analysis of Electronic Beam Steering in Coupled Oscillator Arrays

    , M.Sc. Thesis Sharif University of Technology Hajian, Hamid (Author) ; Banayi, Ali (Supervisor)
    Abstract
    Mutually coupled oscillator arrays have been considered. Detuning of free running frequencies of perimeter elements has been used in these arrays in order to steer the beam without phase shifters. Characteristic equations of transient and steady-state conditions of amplitude and phase of the elements of coupled oscillator arrays has been derived. Literature review is done in coupled oscillator arrays. Sensitivity analysis of beam pointing angle due to free running frequencies of elements in coupled oscillator arrays has been done and the various planar arrays has been compared. Sensitivity analysis of beam pointing angle due to phase error of elements in conventional phased array antennas... 

    Analysis and Design of a Multiple-Input Multiple-output (MIMO) Transmitter in the 60 GHz Band with a Beam Steering Capability Using All-digital Phase-locked Loop Chip

    , Ph.D. Dissertation Sharif University of Technology Salarpour, Mahdi (Author) ; Farzaneh, Forouhar (Supervisor)
    Abstract
    Multiple-Input Multiple-Output (MIMO) communications at millimeter-wave (mm-wave) frequencies (e.g., in the 60 GHz band) is a modern technology recently considered for various applications, such as emerging 5G services for multi-user MIMO (MU-MIMO) and high-resolution frequency-modulated continuous wave (FMCW) MIMO radars to support multi-gigabit throughputs in short-range environments via spatial multiplexing-diversity. Nevertheless, the impairments of communication channels in this frequency band, including significant propagation loss and severe blockage effect, are quite challenging to allow an efficient communication link. Hence, beamforming/beam steering can play a crucial role in 60... 

    An investigation on the performance of receiving optical beam-forming networks

    , Article Final Program and Book of Abstracts - iWAT 2010: 2010 International Workshop on Antenna Technology: Small Antennas, Innovative Structures and Materials, 1 March 2010 through 3 March 2010 ; March , 2010 ; 9781424448845 (ISBN) Shabani, M ; Akbari, M ; Sharif University of Technology
    2010
    Abstract
    Next generation wideband and ultra-wideband radar antenna arrays need efficient true-time delay networks for array control. Following the great interest for optical control of antenna array beam steering, performance analysis of optical beam-formers is a must. In this paper signal to noise ratio and dynamic range of simple optical beamforming structures with components off the shelf are investigated theoretically. Especially the effects of certain power combining components such as arrayed wave guide gratings, broadband passive optical combiners and microwave combiners inspected. It turns up that an efficient microwave combiner would surpass the optical combiners in both SNR and dynamic... 

    New methods of reducing the phase quantization error effects on beam pointing and parasitic side lobe level of the phased array antennas

    , Article 2006 Asia-Pacific Microwave Conference, APMC, Yokohama, 12 December 2006 through 15 December 2006 ; Volume 3 , 2006 , Pages 2114-2117 ; 4902339102 (ISBN); 9784902339109 (ISBN) Taheri, S ; Farzaneh, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    Abstract
    Usually the digital phase shifters are used to steer the beam of a phased array antenna, and the accuracy of beam steering and other properties of the radiation pattern is dependent on the number of bits of the phase shifter and its resolution. In this paper the results of simulations, accomplished using a number of phase feeding methods in order to reduce the phase quantization error effects are presented and three new methods are introduced and compared with the previous works. Copyright 2006 IEICE