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- Alayon Glasunov, Andrés, et al.
(författare)
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Experimental characterization of the propagation channel along a very large virtual array in a reverberation chamber
- 2014
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Ingår i: Progress in Electromagnetics Research B. - 1937-6472. ; :59, s. 205-217
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Tidskriftsartikel (refereegranskat)abstract
- We show that the combined use of radio frequency absorbers and directive antennas can produce significant changes of the radio propagation channel properties along the positions of a virtual array inside a reverberation chamber. A multidimensional characterization of the channel was performed at 40 antenna positions with spacing of 0:233λ at 1 GHz. The average power, the Ricean K-factor, the coherence bandwidth, the r.m.s. delay spread, the mean delay, the beamforming power angle spectrum and array antenna correlation have been studied for different arrangements in the reverberation chamber. The analysis shows that the joint average over time and frequency channel behavior is, as expected, rather homogeneous along the very large array. However, individual realizations of the channel present a pronounced selective behavior in space, time and frequency with parameters varying along the positions of the virtual array suggesting that a heterogeneous behavior of the radio channels can be emulated in reverberation chambers. An important application of the presented study comprises testing of antenna array designs and algorithms in multipath environments. Further development may lead to Over The Air testing of Multiple Input Multiple Output antenna systems of various sizes, i.e., from small to very large arrays.
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| 2. |
- Alayon Glazunov, Andres, 1969-, et al.
(författare)
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On Some Optimal MIMO Antenna Coefficients in Multipath Channels
- 2011
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Ingår i: Progress in Electromagnetics Research B. - 1937-6472. ; 35, s. 87-109
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Tidskriftsartikel (refereegranskat)abstract
- This paper derives some optimum transmit and receive antenna coefficients in wireless multipath channels based on the spherical vector wave multimode expansion of the multiple-input multiple-output (MIMO) channel matrix. The derived antenna coefficients satisfy the following specific optimization criteria: (i) maximum MIMO mean effective link gain (link MEG) based on the multimode channel realizations or (ii) maximum MIMO link MEG based on the multimode correlation matrix or (iii) correlation minimization by diagonalization of the MIMO full-correlation matrix. It is shown that the proposed approach leads to matrix equations belonging to the nearest Kronecker product (NKP) problem family, which in general have no trivial solution. However, we show that exact solutions are provided to the posed NKP problems under the assumption of the Kronecker model for the MIMO full-correlation matrix. The results are illustrated by numerical examples. The proposed approach is a complement to existing antenna pattern analysis methods.
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| 3. |
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| 4. |
- Alayon Glazunov, Andres, et al.
(författare)
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On the Physical Limitations of the Interaction of a Spherical Aperture and a Random Field
- 2011
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Ingår i: IEEE Transactions on Antennas and Propagation. - : IEEE. - 0018-926X .- 1558-2221. ; 59:1, s. 119-128
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Tidskriftsartikel (refereegranskat)abstract
- This paper derives physical limitations on the interactions of antennas exciting TM or TE modes (but not both) and wireless propagation channels. The derivation is based on the spherical vector wave expansion of the electromagnetic field outside a sphere circumscribing the antennas. The result is an extension of the seminal work of Chu on the classical limitations on maximum antenna gain and radiation Q. Rather than maximizing antenna gain in a single direction we obtain physical limitations on the antenna gain pattern, which is directly translated to more condensed parameters, i.e., the instantaneous effective gain G(i) and the mean effective gain G(e) if instantaneous realizations or correlation statistics of the expansion coefficients of the electromagnetic field are known, spectively. The obtained limitations are on the maximum of G(i)/Q and G(e)/Q, which establish a trade-off between link gain and Q.
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| 7. |
- Alayon Glazunov, Andres, et al.
(författare)
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Physical Modeling of MIMO Antennas and Channels by Means of the Spherical Vector Wave Expansion
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we propose a new physically motivated model that allows to study the interaction between the antennas and the propagation channel for Multiple-Input Multiple-Output (MIMO) systems. The key tools employed in the model are the expansion coefficients of the electromagnetic field in spherical vector waves and the scattering matrix representation of the properties of the antenna. We derive the expansion of the MIMO channel matrix, H, in spherical vector wave modes of the electromagnetic field of the antennas as well as the propagation channel. We also introduce the channel scattering dyadic, C, with a corresponding correlation model for co- and cross-polarized elements and introduce the concept of mode-to-mode channel mapping, the M-matrix, between the receive and transmit antenna modes. The M-matrix maps the modes excited by the transmitting antenna to the modes exciting the receive antennas and vice versa. The covariance statistics of this M-matrix are expressed as a function of the double-directional power-angular spectrum (PAS) of co- and cross-polarized components of the electromagnetic field. Our approach aims at gaining insights into the physics governing the interaction between antennas and channels and it is useful for studying the performance of different antenna designs in a specified propagation channel as well as for modeling the propagation channel. It can furthermore be used to quantify the optimal properties of antennas in a given propagation channel. We illustrate the developed methodology by analyzing the interaction of a 2x2 system of slant polarized half-wavelength dipole antennas with some basic propagation channel models.
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