Daniel N. Aloi

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.

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 Methodology for the Evaluation of a GPS Receiver Performance in Telematics Applications

This paper presents a methodology to evaluate the position availability of automotive grade global positioning system (GPS) receivers intended for Telematics applications utilizing a multichannel GPS satellite signal simulator in a controlled laboratory environment. Initially, field testing of two distinct GPS receivers was conducted in an urban canyon environment and a foliage environment to assess each receivers position availability performance. Test scenarios were then developed on a multichannel GPS satellite signal simulator in order to create controlled and repeatable stimuli to the GPS receivers. The scenarios take into account the actual satellite constellations at the same day, time, and locations of the field data collections. Furthermore, the number of visible satellites and power levels was adjusted in order to stimulate the hardware tracking sensitivity, hardware acquisition sensitivity, dynamic range, and navigation filter design, all of which impact position availability for GPS receivers. Quantitative results demonstrated good correlation between the results obtained using the developed test scenarios and the results from the field testing. The proposed methodology will result in reducing validation cost and time to market for automotive Telematics products

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

Neural Network Based Approach for Tuning Kalman Filter

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.

Design and Implementation of Embedded Printed Antenna Arrays in Small UAV Wing Structures

Unmanned aerial vehicles (UAV) are extensively being used in exploration, surveillance and military applications. Such vehicles often collect data via special sensors and send the data back to the central station via wireless links. Embedded in wing structure printed antennas will eliminate the drag due to friction, and allow for extended load capability due to their extra light weight. In this work we present the design and implementation of a 4-element linear antenna array embedded in a small UAV wing structure. The antenna array operates in the 2.4 GHz ISM band. Simulations and measurements that characterize the performance of the antenna array are presented. Field measurements show the impact of utilizing beam-forming in enhancing the communication link throughput.

A vehicular rooftop, shark-fin, multiband antenna for the GPS/LTE/cellular/DSRC systems

A shark-fin rooftop multiband antenna for the automotive industry is proposed. The antenna system receives Right Hand Circularly Polarized (RHCP) satellite signals for the Global Positioning Systems (GPS) L1-Band and Vertically Linearly Polarized (VLP) signals for the Long Term Evolution (LTE), the cellular frequencies, the Universal Mobile Telecommunications Systems (UMTS) and the Dedicated Short Range Communications (DSRC) system. A ceramic patch antenna element was used for the GPS signals and a printed monopole utilizing printed ground sleeve technique for the cellular and LTE signals. A study of four potential DSRC antenna elements to determine the appropriate antenna element location within the antenna cover to obtain optimum performance is also presented and discussed in detail. The antenna module was measured on a 1-meter diameter ground plane and on a vehicle roof model. The design and measurements results are presented and discussed below.

Characterizing the performance of single-channel Pseudo-Doppler direction finding systems at 915 MHz for vehicle localization

In this work, we present a performance analysis of two-phase-based single-channel radio-frequency (RF) direction finding (DF) methods in two wireless environments: open field and an open parking lot. A wireless channel model is created for both environments, and a software receiver is used to process the incoming RF signal to estimate the angle of arrival (AOA). The channel and receiver models are compared against measurements from a hardware prototype. Results shows a 100% pass rate in the open field environment when the receiver is located at the exterior center roof of the car. The pass rate does not exceed 25% if the receiver module is placed inside the car or if the system is evaluated in the open parking lot environment. This paper shows that a phase-based single-channel DF approach will not perform reliably in a highly reflective wireless environment. Copyright

Full length article: Comparative analysis of single-channel direction finding algorithms for automotive applications at 2400 MHz in a complex reflecting environment

This paper presents an amplitude-based single-channel direction finding system for automotive applications and compares its performance against two different phase-based single-channel direction finding algorithms in a complex reflecting environment (parking garage) at 2400 MHz. All three direction finding algorithms utilize a multi-element receiving antenna array placed at two locations on a vehicle. The received complex electric fields at each antenna element within the receiving antenna array are used as inputs to the three direction finding algorithms, resulting in a direction of arrival estimate. The results from this research provide insightful information on the performance of various direction finding algorithms as a function of complex reflecting environment, transmitter height, receiving antenna array location, number of receiving antenna elements and pass rate acceptance criteria.