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A distinctive low-profile 2 × 2 MIMO antenna system for Wi-Fi 7 applications is presented in this paper that is compact, easily manufactured and with excellent performance. Because of its compact size and good RF performance, the design can be placed in hidden locations for various applications such as the automotive field in the front side mirrors or front dashboard, and consumer products in laptops and internet wireless routers. The proposed design can cover the entire tri-bands of Wi-Fi 7 (2400-2495 MHz, 5150-5895 MHz, 5945-7125 MHz) using a loaded low-profile Planar Inverted-F Antenna (PIFA) with distinct dimensions and slots across its geometry. The element design and the MIMO system is simulated and a properly made prototype was fabricated to present the results in terms of reflection coefficients, current distribution, combined radiation patterns, passive isolation, ports efficiencies, and Envelope Correlation Coefficient (ECC). The design shows relatively good RF properties across the entire three bands, hence making it an attractive solution to be used for Wi-Fi 7 technology to satisfy the needs of larger omnidirectional coverage area, wider channel bandwidth, and better transmission rates with low interference. [ABSTRACT FROM AUTHOR]

This paper compares the performance of a modified double exponential filter (DEF) with respect to a Kalman filter for automotive applications that rely solely on position estimation via a global-positioning-system receiver. The performance of these two filters was initially analyzed in simulations for both Gaussian and non-Gaussian noise sources on the position estimates. The analysis was extended to include a field data collection on a vehicle in an urban-canyon environment. The modified DEF exhibited better 2-D position accuracy in both the non-Gaussian simulation and the field data collection efforts. Index Terms--Double exponential filter (DEF), global positioning system (GPS), Kalman filter (KF), navigation, telematics.

A novel null-steering method that minimizes the effect of radio frequency interference (RFI) and the effect of antenna phase center variation (PCV) and group delay (GD) is proposed. PCV and GD are important to characterize for global navigation satellite system (GNSS) antenna arrays used in satellite based landing architectures, since they directly affect the pseudo-range and accumulated Doppler observables. The proposed method is denoted as the Beam Subtraction method (BS). The BS method is compared against a conventional null-steering (CNS) method applied to a large aperture antenna array. Simulation results reveal noticeable improvement in both the PCV and GD curves as a function of azimuth and elevation angles when using the BS method compared to the CNS thus reducing the error on the range measurements as well as improving system availability in the presence of RFI. Index Terms--Group delay, multipath limiting antenna, null steering, phase center variation.

The carrier-to-noise density ratio (C/[N.sub.0]) is considered an important parameter describing the GPS receiver performance. This paper compares the performance of two popular coarse-acquisition (C/A) C/[N.sub.0] algorithms appearing in literature: the variance summing method (VSM) [1, 2], and the power ratio method (PRM) [3, 4], 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 L1 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/[N.sub.0] level while the simulated one contained variable C/[N.sub.0] levels. The effect of adding AWGN on the C/[N.sub.0] estimate was directly proportional with the noise power. The C/[N.sub.0] estimates suffered more when the CWI frequency was closer to the IF of the receiver. The PRM suffered from saturation at higher C/[N.sub.0] levels. The VSM showed good tracking at high C/[N.sub.0] levels and better immunity to limited quantization levels, while its C/[N.sub.0] estimate suffered from rapid fluctuations in power levels when sudden power steps occurred.

Multipath (MP) is the dominant error source in Global Positioning System (GPS) code-based position solutions requiring high accuracy. A technique is introduced here to mitigate error due to ground-reflected NIP signals. The technique uses two orthogonal dipoles to capture the direct GPS signal and the ground-reflected GPS signal. Adjusting the amplitude and phase of the received voltage between the two dipoles can reduce the impact of MP error. Theoretical derivations of this technique are performed for a GPS signal upon reflection from dry soil, seawater, and fresh water. The theoretical results are verified with a real world experiment on the aforementioned surfaces. GPS pseudo-range (PR) and carrier-to-noise ratio (C/No) measurements for specific satellites are used to verify the predicted theoretical results.

Various multiple-input multiple-output (MIMO) antenna systems for automotive applications are presented in this paper using two uniquely designed elements: 1) a low profile wideband Planar Inverted-F antenna (PIFA), and 2) a compact wideband monopole in the sub-6GHz 5G systems and Vehicle-to-Everything (V2X) communications that cover the frequency range from 617MHz to 6GHz. The proposed MIMO systems can be used in a low-profile or shark fin style housing placed on the vehicle's roof. Each MIMO system achieves satisfactory performance across the whole band with suitable physical dimensions. The envelope correlation coefficient (ECC) and diversity gain (DG) are calculated using MATLAB in each MIMO configuration as they represent the two key factors in the MIMO performance. Simulation results are presented along with measured data on a 1-meter rollededge ground plane (GND) and on a vehicle's roof from properly cut metal sheet prototypes. The results are discussed in terms of VSWR, passive isolation between elements, combined radiation patterns, port-efficiencies, ECC, and DG. [ABSTRACT FROM AUTHOR]

In this paper, three Vehicular multiple-input multiple-output (MIMO) 5G antenna systems have been constructed from using a newly developed 5G cellular branched Monopole element are presented. The MIMO systems operates in the 5G frequency bands (617MHz-5GHz) with a compact structure that allows for up to four elements to be integrated in the same Sharkfin. The 3 configurations of MIMO systems have been simulated using HFSS, measured on a 1-meter ground plane (GND), then measured on a vehicle roof and the individual antenna parameters in terms of reflection coefficient and efficiency have captured. The MIMO antenna systems performance in terms of passive isolation, combined radiation pattern, envelope correlation coefficient (ECC), and diversity gain (DG) have been reported and discussed. [ABSTRACT FROM AUTHOR]

A Ground-Based Augmentation System (GBAS) monitors the signals of Global Navigation Satellite Systems and broadcasts differential correction signals. It relies on Multipath Limiting Antennas (MLAs) that can receive signals over almost the entire upper hemisphere while greatly attenuating signals reflected from the ground. The current Federal Aviation Administration (FAA)-approved system utilizes an MLA that is approximately 182.9 cm tall. In this paper, a substitute MLA is designed that is only 97.05 cm tall (approximately 44% reduction). The size reduction is accomplished by reducing the number of array elements from 19 to 11. We developed a novel self-cardioid antenna element that allows for this reduction. [ABSTRACT FROM AUTHOR]

In this research we propose two orthogonally placed FR4 printed planar monopole antenna elements for use in the automobile roof top shark fin antenna for LTE MIMO applications. The discussed MIMO antenna system is designed to cover the worldwide LTE frequency band from 698MHz to 2700MHz. The goal of this research is to achieve satisfactory MIMO performance across the whole band while staying within physical constraints of the shark fin style antenna. The target reflection coefficient (S11) of each element is -6dB. Because of physical constraints of the automotive shark fin design antenna MIMO decorrelation is achieved by cross polarization and small distance separation. Correlation better than -12dB is targeted and achieved in higher bands, while in lower frequency bands antennas would not benefit from MIMO performance. Numerical simulation of the MIMO antenna system is performed using FEKO in order to verify the design parameters. Simulation findings are confirmed by manufacturing antennas and testing in the lab. [ABSTRACT FROM AUTHOR]

A theoretical model is presented for the shielding effectiveness of a waveguide containing an insert consisting of several smaller hexagonal or "honeycomb"- shaped waveguides. FEKO, an electromagnetic modeling software package, is used to create computer-aided design (CAD) models of physical waveguides, and to find solutions for the TE11 mode of propagation for each model using the Finite Element Method (FEM). S-parameters are used to characterize the shielding effectiveness of the waveguide models through simulation in FEKO and measurement of waveguide samples in the laboratory. The results obtained by each method are compared and discussed. [ABSTRACT FROM AUTHOR]

In this work, SAR values in passenger and driver head and body regions due to the presence of one or more cellphones were determined via simulation for the situation in which all vehicle passengers are children. Additionally, the adult driver has access to a hands free cellphone as part of increased in-vehicle connectivity. The FEKO tool, using the Method of Moments, was utilized for simulations. [ABSTRACT FROM AUTHOR]