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For analysis, the simplest array comprises two isotropic antenna elements with same amplitude and same phase. A phase shifter in one branch provides the degree of freedom for basic pattern adjustment. We seek orthogonal patterns with respect to the element spacing, d, and the phase shift, δ. Approximate orthogonality (finite, but small correlation coefficient between patterns) is still useful in adaptive...
A synthesis methodology for the design of multifunction interleaved array with controlled sidelobes is proposed. The technique is based on the exploitation of binary analytical sequences with prescribed autocorrelation features derived from Almost Difference Sets (ADSs). The proposed method is theoretically introduced and a set of representative numerical results is presented to assess its features...
A fully analytical technique for concurrently designing the transmit and receive antennas of frequency-modulated continuous-wave (FMCW) radars is proposed. The approach is based on the interleaving of two sub-arrays according to a binary sequence derived from almost difference sets (ADSs). Thanks to the ADS autocorrelation properties, controllable sidelobes are achieved for the overall radiating systems...
This paper derives a new expression of the correlation coefficient for two omni-directional antennas in terms of the easy-to-measure S-parameters. The omni-directional antennas can be monopole or dipole antennas and they are aimed for use in MIMO communication systems whose capacity performance is significantly affected by signal correlation. With this new expression, it can greatly reduce the computational...
This paper investigates the three dimensional (3-D) spatial correlation characteristics of uniform concentric ring arrays (UCRAs) deployed in antenna systems. Closed-form formulas of the 3-D spatial correlation functions are derived. UCRAs with two different geometric structures and uniform distribution angular energy distribution are considered. It is found that the 3-D spatial correlation is a function...
A planar near field resonant parasitic (NFRP) antenna for multiple-input multiple-output (MIMO) applications in the WLAN 2.4/5.2/5.8 GHz frequency bands is presented. The NFRP antenna can create tri-band functions by incorporating three different parasitic elements. Nearly complete impedance matching to a 50Ω source is shown at the desired resonant frequencies. Additionally, NFRP antenna array configurations...
In this correspondence, the effect of mutual coupling and transmit correlation on the sum-rate capacity of a multiuser system is investigated for the case of the two-user MISO broadcast channel. Mutual coupling between antenna elements of the antenna array and transmit correlation are taken into account via the coupling matrix and the correlation matrix, respectively. A closed form formula for the...
In this work, a practical technique for building compact linear antenna arrays based on orthogonal radiations is presented. This approach utilizes passive couplers to separate out different orthogonal eigenmodes of linear arrays with closely-spaced elements as individual radiation mechanisms. In this way, undesired effects due to mutual coupling and spatial correlations can be avoided. Consequently,...
We experimentally characterize nomadic peer-to-peer channels in a multi-wall indoor office environment. In particular, we derived models of path-loss, shadowing and fading statistics at 3.8 GHz in fixed scenarios, and compare them with existing results. Highlights of the paper include a multi-wall path-loss model, the separation between obstruction, nomadic, and dynamic shadowing, a dynamic shadowing...
The joint characterization of the multiple links becomes important for mesh topologies, relaying, distributed antennas, cooperative transmission, virtual MIMO etc. For that purpose simultaneous measurements are needed. Since a suited measurement setup requires multiple channel sounders, a very few of such campaigns have been conducted. A single-sounder approach can be considered as an attractive,...
Multiple input multiple output (MIMO) communication architecture has spectral efficiencies far beyond those offered by conventional techniques, and is greatly to increase the channel capacity. In this paper, we investigate the MIMO channel capacity in correlated channels using the uniform angular distribution, numerical simulations are performed with Matlab to verify the proposed formula. We prove...
MIMO antenna design is one of biggest issues in the LTE deployment. The multiple antennas should be designed compactly without sacrificing radiation efficiency and spatial correlation. Such multiple antennas can be achieved with polarization antennas or decoupling elements. Conventionally, these antenna parameters are designed empirically. In this paper, a method to optimize multiple antenna directivities...
This paper presents the method to minimize the inter-element mutual coupling in a pair of suspended plate antennas by optimization of the orientation and feed configuration of antenna elements. By reducing the interelement mutual coupling, the envelope correlation coefficient can be suppressed for multiple-input multiple-output (MIMO) antenna systems.
An alternative approach, based on an iterative least square optimization technique, for the design of antenna array exhibiting equal side lobes in their radiation pattern. New and generalized expression for the array factor of all physically realizable linear antenna arrays with progressive phase shifts are introduced. The algorithm is based on the statistically computed signal analysis. By considering...
This paper investigates three algorithms for estimating the direction of arrival (DOA) of incoming wireless signals. The algorithms studied are Minimum Variance Distortionless Response (MVDR), MUltiple SIgnal Classification (MUSIC) and Maximum Likelihood (ML). The goal was to study these algorithms under the following conditions: a sparse sensor array, unknown nonuniform noise and the presence of...
In this paper, we propose a codebook construction method for multiple-input multiple-output (MIMO) beamforming systems operating under the per-antenna power constraint (PAPC). Under the PAPC which limits the individual power of each transmit antenna, it is known that only phase steering information is required to form the optimal beamforming vector at the transmitter. For systems with non-reciprocal...
The problem of optimizing the placement of the antennas for an optimum combining receiver equipped with a linear antenna array of fixed length is addressed. A Rayleigh fading model is considered where the complex channel gains of both the desired user and the interfering users are assumed to be correlated due to the mutual proximity of the antennas. The average output signal-to-interference-plus-noise...
Mutual coupling between elements in compact transmit antenna arrays is taken into account in performance prediction and system design of multiple-input multi-output (MIMO) systems. The transmitter-end coupling matrix comprised of array impedance matrix and effective load impedance matrix is derived. The impact of transmitter-end mutual coupling on spatial correlation, radiated power, and system capacity...
We analyse the spatial diversity of dense antenna arrays in the plane and show how it can be characterised by the eigenvalue spectrum of the spatial autocorrelation kernel. We show how this diversity spectrum can be calculated for any spatial fading statistics represented by the power azimuth spectrum (PAS). Numerically calculated diversity spectra provide estimates of the possible diversity gains...
This paper proposes a novel propagation based spectrum sensing method that utilizes beamforming for systems equipped with antenna arrays. Since rays are known to arrive in clusters, the arrival angles of the dominant ray clusters can be exploited to improve the spectral sensing performances. Moreover, from site-specific propagation characteristics, the dominant ray angles can be predicted without...
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