Mohammad S. Sharawi

A Dual-Element Dual-Band MIMO Antenna System With Enhanced Isolation for Mobile Terminals

A novel dual-band 4-shaped printed multiple-input-multiple-output (MIMO) antenna system of two elements is designed and fabricated for Long Term Evolution (LTE) wireless handheld and portable terminals. The low frequency band covered is 803-823 MHz, and the high frequency band covered is 2440-2900 MHz. The isolation between the two elements was more than 17 dB in the low band after using a defected ground plane structure (DGS) between the two antenna elements. The overall size of the printed MIMO antenna system was 50× 100×1.56 mm3.

Printed Multi-Band MIMO Antenna Systems and Their Performance Metrics [Wireless Corner]

Multiple-input-multiple-output (MIMO) antenna systems are a key enabling technology for modern fourth-generation (4G) wireless systems. The need for higher data rates for multimedia applications within the limited bandwidth and power levels led the way to the use of multiple antennas at the receiver and transmitter ends. Printed MIMO antenna systems, supporting multiple bands, including the lower band of the 4G wireless standard (LTE), pose a challenge in terms of available size. In this work, we start by defining the new required metrics to characterize MIMO antenna systems. We then present several recent printed multi-band MIMO antenna systems, along with some isolation-enhancement mechanisms that are used in these closely packed antennas.

A CSRR Loaded MIMO Antenna System for ISM Band Operation

A 2 × 2 (four-element) multiple-input multiple-output (MIMO) patch antenna system is designed and fabricated for a 2.45-GHz ISM band operation. It uses complementary split-ring resonator (CSRR) loading on its ground plane for antenna miniaturization. This reduces the single-element antenna size by 76%. The total board size of the proposed MIMO antenna system, including the GND plane is 100 × 50 × 0.8 mm3, while the single-patch antenna element has a size of 14 × 18 mm2. The antenna is fabricated and tested. Measured results are in good agreement with simulations. A minimum measured isolation of 10 dB is obtained given the close interelement spacing of 0.17λ. The maximum measured gain for a single operating element is -0.8 dBi.

Isolation Improvement in a Dual-Band Dual-Element MIMO Antenna System Using Capacitively Loaded Loops

A dual-band dual-element multiple-input-multiple-output (MIMO) antenna system with enhanced isolation is proposed. The MIMO antenna system is based on printed 4-shaped antenna elements. Dual band isolation is achieved by using an array of printed capacitively loaded loops (CLLs) on the top side of the board for high band isolation improvement and a complementary CLL structure on the GND plane of the antenna for lower band isolation improvement. The lower band of operation covers 827{853MHz and the higher band covers 2.3{ 2.98GHz. Two prototypes were investigated to access the efiect of the isolation mechanism. Measured isolation improvement of 10dB was observed in the lower operating band while the improvement in the higher band was approximately 2.5dB. The isolation improvement was at the expense of 5% reduction in e-ciency. The measured gain patterns as well MIMO flgures of merits such as the correlation factor, TARC and MEG were investigated as well.

A Cognitive Radio Reconfigurable MIMO and Sensing Antenna System

A planar, compact, single-substrate, multiband, frequency-reconfigurable multiple-input-multiple-output (MIMO) antenna system is presented. The proposed antenna elements are integrated with an ultrawideband (UWB) sensing antenna to develop a complete antenna platform for cognitive radio (CR) applications. The dual-element MIMO antenna is integrated with p-i-n and varactor diodes for frequency reconfigurability. Two modes of selection are used for the MIMO antenna system reconfigurability along with varactor tuning to sweep the frequency over a wide band especially below 1 GHz. The proposed sensing antenna is used to cover a wide range of frequency bands from 720 ~ 3440 MHz. The complete system comprising the multiband reconfigurable MIMO antennas and UWB sensing antenna for CR applications is proposed with a compact form factor. The antenna system is developed on a single substrate area of dimensions 65×120×1.56 mm3.

GPS C/N/sub 0/ estimation in the presence of interference and limited quantization levels

The carrier-to-noise density ratio (C/N0) is considered an important parameter describing the GPS receiver performance. This paper compares the performance of two popular coarse-acquisition (C/A) C/N0 algorithms appearing in literature: the variance summing method (VSM) (Psiaki et al., 2003, Psiaki, 2001), and the power ratio method (PRM) (Van Dierendonck, 1996, Sayre, 2003), in terms of their estimates in 1) additive white Gaussian noise (AWGN), 2) narrowband continuous wave interference (CWI), 3) their response to quantization and saturation effects, and their 4) dynamic range. The algorithms were implemented as a part of a software receiver. Two LI GPS data sets are examined; one was obtained from a GPS raw data collection setup, while the other was obtained from a GPS signal simulator. The collected set was stored with almost constant C/N0 level while the simulated one contained variable C/N0 levels. The effect of adding AWGN on the C/N0 estimate was directly proportional with the noise power. The C/N0 estimates suffered more when the CWI frequency was closer to the IF of the receiver. The PRM suffered from saturation at higher C/N0 levels. The VSM showed good tracking at high C/N0 levels and better immunity to limited quantization levels, while its C/N0 estimate suffered from rapid fluctuations in power levels when sudden power steps occurred

An 800 MHz 2

A compact size 2 × 1 multiple-input-multiple-output (MIMO) antenna system operating in the 800 MHz band is proposed for long term evolution (LTE) handsets. The fabricated MIMO system has a typical isolation of 12 dB and a maximum gain of 2.2 dBi. Two isolation enhancement methods are investigated; one that looks into the depth of the ground split separating the two antennas, the other introduces extra splits within the arms of the GND plane. It is found that introducing extra splits within the arms of the GND plane of the proposed geometry enhances the isolation by at least 3 dB. The proposed MIMO antenna system is based on meander line antennas, and covers the band from 760-886 MHz. The size of the antenna system is 40 × 50 mm2.

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Kalman filter (KF) parameter tuning has been dealt with in a limited fashion and usually was left to engineering intuition due to unavailable measurements of process noise and high dimensionality of the problem. In this paper we present a simple Neural Network (NN) based approach to KF tuning problem. Since the approach trades number of KF runs required for the optimal filter tuning for KF performance, the result of the such tuning is the set of tuning parameters that gives suboptimal performance. Advantages of this approach are: 1) simple practical framework for optimal filter performance tuning, 2) the framework is independent of the type of a filter and 3) low number of filter runs required to obtain quasi optimal parameter set. The main disadvantage is the suboptimal filter performance that can be easily improved by increasing the number of filter runs. Two NN architectures were investigated, generalized regression neural network (GRNN) and regular radial basis networks (RBNN). RBNN showed much better performance for a given non-linear test function with a clear maximum peak. Performance measures along with computational efficiency for these methods were compared. A step-by-step tuning procedure is presented.

1 Compact MIMO Antenna System for LTE Handsets

Current high-speed PCB (printed circuit board) designs need extra care due to the frequency of operation and reduced rise time signals. We present the main issues and parameters that a PCB designer has to consider and analyze before a board layout is created. First order approximation equations for various parameters are presented, based on the geometry of the PCB traces. Some useful design practices are also mentioned. As the speed of operation increases, the variables that are neglected in the lower frequency/higher rise time situation become more significant. Such parameters increase the complexity of the design. Three-dimensional analysis becomes a must to calculate and model interconnects accurately. This is where field solvers and the role of the signal integrity engineer come into play.

Neural Network Based Approach for Tuning Kalman Filter

In this paper, a step-by-step procedure is devised for extracting the material parameters to facilitate and simplify the design procedure of metamaterial structures using commercial software packages. A parameter-retrieval method using the S parameters is used to calculate the curves for the complex permittivity and permeability of the metamaterial based on its unit element. The S parameters are extracted using HFSSTM, which is a Finite-Element-Method (FEM)-based full-wave simulator. The permittivity and permeability curves are calculated using a MATLAB script. Two different methods are used in HFSS to extract the S parameters: one using perfect electric and perfect magnetic (PE-PM) boundary conditions, and the second using the master-slave boundary conditions. Wave ports and Floquet ports are used to excite the structure. The results of the proposed procedure are validated by comparing the calculated curves with already published results.