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The authors have investigated on the spatial fading emulator comprised of multiple antenna elements emulating the spatially distributed scatterers to generate the fading in the reproducible manner since 2001. This paper presents the history of early development until 2010 when MIMO OTA test was a very popular topic. The motivation, ideas and achievement are reviewed and summarized, because some important...
This paper presents a disk-loaded monopole stacked with patch antenna (DLMP) with a low-profile structure. The DLMP has three driven ports, each of which can create independent radiation patterns with orthogonally polarized characteristics. A design example is presented to achieve an overall height of 10 mm at 2 GHz. The calculated results show that the DLMP has well-defined monopole mode and patch...
This paper presents a polarization-controlled MIMO antenna to realize ultra high-speed and high-capacity mobile communications. The proposed antenna is comprised of three orthogonal dipoles, which can be controlled using a weight function created based on the variation of cross polarization power ratio (XPR) and the antenna inclination angle. By adjusting a phase shift between the antenna elements...
This paper presents a bilateral fading emulator for MIMO-OTA testing with a function of controlling the correlation of base station. On the basis of the Jakes theory, a methodology for achieving the spatial correlation of a base station antenna by setting the initial phases of scatterers in the two-dimensional channel model is introduced. The experimental results show that the designed correlation...
Since the evaluation of multiple-input multiple-output (MIMO) antennas requires full information of its complex radiation patterns as well as propagation channels, its design procedures and analyses are cumbersome and complicated in general. In this letter, the accuracy of a closed-form capacity formula for mean MIMO channel capacity is investigated, where the -parameter of the antenna is needed...
This paper presents an automatic impedance-matching algorithm that can sequentially realize a simultaneous conjugate-matching state for all the elements in an N-element array antenna. The analytical results show that the converged solution obtained from the proposed algorithm agrees well with the solution calculated by the analytical deterministic equation, confirming the validity of the proposed...
This paper investigates the mutual interactions between MIMO antenna radiation and multipath characteristics to obtain useful knowledge that can be employed in the design of a three-dimensional OTA system. In investigating factors that may affect the MIMO channel capacity, we focus on two key parameters, the incident wave power distribution in the elevation direction and the radiation pattern of terminal...
Decoupling method of 2 × 2 MIMO by connecting two element antennas between feed points are developed. Especially its method of connecting by capacitor or inductor with susceptance value is noted. In this paper, mechanism of decoupling method by connecting antennas is analyzed and a new decoupling method using branch elements without connecting the antennas is proposed.
The regression based channel capacity (REC) has been proposed for a simple and efficient evaluation of compact MIMO antennas. By entering the mean effective gains (MEG), correlation of MIMO array elements, and incident wave SNR to the developed regression formula, one can readily estimate the 2 × 2 MIMO channel capacity without a large amount of computer and human resources. The validity of the REC...
A simple and efficient method of the evaluation of MIMO channel capacity has been proposed. First, the channel capacity of a half wavelength dipole array antenna was calculated using a Monte Carlo method by changing incident wave SNR, power difference between two elements, and correlation coefficient. Using the calculated results, a polynomial function of estimating the channel capacity was given...
In the plan for future cellular systems, such as the LTE-advanced system, they are to be allocated a very wide frequency band. Hence, the wideband characteristics must be considered when a handset MIMO antenna is designed for such systems. In the literature [1], the authors have shown that there is a significant impact of a matching circuit on the channel capacity of a MIMO antenna over a wide frequency...
The use of a MIMO array in a small handset often affects system performance due to mutual coupling between the elements. This has motivated many researchers to conduct extensive studies on the effects of mutual coupling, and to optimize the impedance matching conditions to increase the channel capacity. However, there has been little study on enhancing channel capacity using a practical impedance...
This paper presents a radio frequency (RF) controlled spatial fading emulator for the evaluation of a handset MIMO antenna. The RF-controlled fading emulator can control RF signals directly in the spatial domain to produce an accurate radio propagation channel model, which includes the uniform and non-uniform angular power spectra (APS) in the horizontal plane. Fading correlation and MIMO channel...
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