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In this paper, we formulate and experimentally demonstrate direction of arrival (DoA) estimation with a two-port composite right/left handed (CRLH) leaky-wave antenna (LWA) using the multiple signal classification (MUSIC) algorithm. The CRLH LWA consists of a cascade of metamaterial unit cells, periodically modulated using varactor diodes. By changing the voltages across series and shunt varactors,...
We explore the effect of loading a reverberation chamber on the calculation of the correlation coefficient of two-element antenna arrays (similar to the type used in multiple-input multiple-output (MIMO) wireless devices). The changes in correlation coefficient with loading are compared to the changes in a squared, mismatch-corrected version of the transmission coefficient 〈|Sxy|2〉 as a function of...
Reverberation chamber is used to characterize the diversity gain based on its properties of diffuse field. First, we isolate the effects on diversity gain due to different factors, resulting in a composite power imbalance. Then, we describe the power correlation as a function of the complex correlation when the K-factors on different channels are not identical. By using Monte Carlo simulations, we...
The synergetic integration of heterogeneous terrestrial and aerospace networks will play an important role in the evolution of wireless communications systems. In this direction, high-altitude platforms (HAPs) could act as relay stations in the stratosphere transferring information from an uplink to a downlink channel. This paper presents a novel transmission scheme for the delivery of mobile-to-mobile...
Equipping base stations (BSs) with very large antenna arrays is a promising way to increase the spectral and energy efficiency of mobile communication systems without the need for new cell sites. However, the prominently theoretical works on this topic are based on several crucial assumptions about the wireless channel which have not been sufficiently validated by measurements. In this paper, we report...
In this paper we present some channel measurement results of distributed multiple-input multiple-output (D-MIMO) systems inside a MD-82 aircraft. Channel capacity and spatial correlation are analyzed from the measured channel matrix. Capacity results of 7 different systems (six D-MIMO systems and a SISO system) are discussed. It is found that D-MIMO systems yield significant capacity gains as compared...
A four-element antenna array for a USB dongle multiple-input multiple-output (MIMO) antenna working in dual 2.4/5.2 GHz frequency bands is presented. For achieving reasonably low mutual coupling and good return loss characteristics of the antenna array, the positions of the antenna element are optimised within a compact low cost FR4 PCB board with dimensions of 25 × 50 × 0.8mm3. The array is evaluated...
MIMO system is a technique known as obtaining the high channel capacity. However, the channel capacity is reduced due to the presence of a direct path. Previous studies have shown that high SNR leads to significant capacity enhancement with high correlation environment [1]. Low correlation can be achieved by use of the orthogonality of the received signals in the LOS environment [2,3,4]. This paper...
Radio technology has been developed extensively for mobile communications and wireless LANs. In a wireless communication channel, we have multipath propagation due to reflections and scatterings. When the delay difference between multipath waves is large, we have frequency selective fading. Thus far, a frequency correlation defined for a single antenna has been used for evaluating the frequency selectivity...
Two types of methods are used to develop MIMO-OTA (over-the-air) measurement systems. One is a fading emulator based method that involves the arrangement of a number of actual radiation antennas that represent scattering objects. The other involves the use of a radio echoic chamber named “reverberation chamber” (RC) consisting of six metallic walls [1]. An RC has the advantage of being able to easily...
The scattering parameter formulation for the envelope correlation in an (N, N) MIMO antenna array has been modified to take the intrinsic antenna power losses into account. This method of calculation provides a major simplification over the use of antenna radiation field patterns. Its accuracy is illustrated in three examples, which also show that the locations of the correlation minima are sensitive...
A critical factor in the deployment of multiple input multiple-output systems is the cost of multiple analog transmit/receive chains. This problem can be mitigated by antenna subset selection at the transmitter/receiver. With antenna selection, a small number of analog radio frequency chains are multiplexed between a much larger number of transmit/receive antenna elements. In this paper, we present...
This paper focuses on calibration of uniform linear array (ULA) for high frequency surface wave radar. A novel algorithm is proposed based on spatial correlation properties of the calibration source. We can estimate amplitude from the main diagonal elements of spatial correlation matrix, and obtain DOA (direction of arrival) estimate of the calibration source by two-dimension FFT. The spatial correlation...
Modern wireless communications systems fall on the use of multiple antennas at both link ends in order to achieve increased spectral efficiency and high data rates. Recent works have studied the interaction between the antenna array model and the wave propagation scenario in order to provide insight into spatial degrees of freedom of multiple-antenna communication systems. This paper presents a polarization-sensitive...
Wireless communication using very-large multiple-input multiple-output (MIMO) antennas is a new research field, where base stations are equipped with a very large number of antennas as compared to previously considered systems. In theory, as the number of antennas increases, propagation properties that were random before start to become deterministic. Theoretical investigations with independent identically...
We propose a new algorithm, for parameter estimation that is applicable to imaging using moving and synthetic aperture arrays. The new method results in higher resolution and more accurate estimation than commonly used methods when strong interfering sources are present inside and outside the field of view (terrestrial interference, confusing sources).
We present the main features of the Atacama Large Millimeter/submm Array (ALMA) 64-antenna correlator sub-system and describe some original parts of the design. All correlator parts have been constructed, 3 quadrants are delivered to the 5000-m high site and 2 have been commissioned for ALMA Early Science. The basic observing modes are described and the huge flexibility embedded in the design is underlined.
The Epoch of Reonization (EoR) represents a major frontier of cosmic evolution yet to be explored. Red-shifted emission from the 21cm hyperfine transition of neutral hydrogen provides a unique tracer of the primordial intergalactic medium. But with foregrounds that exceed the expected EoR signal by more than five orders of magnitude, the level of calibration needed for detecting this signal is unprecedented...
In this paper the correlation coefficient between two inverted L-antennas (ILA) in wide frequency range is investigated. The coefficient has been calculated by using expression in terms of far-field radiation patterns in the azimuth plane. Novel theoretical expressions are obtained for this coefficient in the case of a couple of parallel short horizontal dipoles in a uniform angle of arrival (AoA)...
We have analysed the performance of multimode antennas arrays in double directional finite scatterers channel model with and without mutual coupling and compared the results with Omni directional antenna arrays. We have shown that multimode antennas are more suited as array elements as they perform better with regards to capacity and spatial correlation as a function of separation due to the more...
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