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In this paper we propose a Signal-to-Interference Ratio (SIR) based grouping scheme of interference alignment (IA) in order to increase the sum-capacity for K-user multipleinput multiple-output (MIMO) interference channel. As a feasibility proof of this scheme, two IA groups in a simple road environment model are considered and the achievable sumcapacity is evaluated.
This paper develops a novel frequency synthesizer using harmonics of the reference signal for the low power consumption and low phase noise requirements of advanced wireless systems. The innovation of our frequency synthesizer is developing an adaptive pulser whose output pulse-width is designed to decrease as the reference frequency increase for enhancing frequency synthesis range. The pulsed reference...
This paper presents beam shaping performance of beam adjustable microstrip antenna arrays (BA-MSAAs) with narrow-with rectangular patch elements. The BA-MSAA consists of a central patch element fed by a feeding line and two parasitic patches with variable reactance circuits (VRCs) adjacent to the center patch. Radiation pattern of the BA-MSAA is controlled by the reactance values of the VRCs. In order...
An L-shaped probe can generate circular polarization, combining with surrounding aperture, such as waveguides. And the waveguide antenna using L-shaped probe has broadband characteristics in axial ratio (AR) and input impedance, however cross-polarization (XPOL) is easily generated due to its asymmetrical structure resulting in a narrow azimuth range for circular polarization. This paper discussed...
This paper proposed a microstrip antenna with the operating bands of LTE700, LTE900 and LTE1800 for mobile device applications. This antenna was printed using FR-4 substrate material. The overall dimension of the antenna is 135 mm × 32 mm × 1.6 mm with 50 Ω impedance. The usage of ground plane can generate resonant modes to expand the bands at low frequency. Operating frequency bands of the antenna...
Electromagnetic field distributions established in a commercial aircraft, Boeing 777 class large passenger aircraft, due to a personal electric device are evaluated. We use FDTD technique and a large-scale parallel computing technique to precisely estimate the EMF distributions. In order to evaluate EMF characteristics including the whole structure of the aircraft such as the wings and engines, the...
This paper reports the performance analysis of a proposed auto-regressive (AR) model-based linear predictor algorithm with Kalman filtering (KF). The relationship between the optimum AR order and the channel correlation coefficient is investigated by means of the Akaike Information Criterion (AIC). Through our analysis, 2nd-order differential model based on the AR model-based linear predictor algorithm...
In order to overcome the increasing traffic problems of mobile terminals used on the upper floors of high-rise buildings, a three-dimensional cell configuration that has small cells on various floors is considered. It is necessary to clarify the fading characteristics of radio-waves from outdoor macrocell to the floors, in order to evaluate the wireless transmission technology for the three-dimensional...
Recently, in order to evaluate the performance of heterogeneous networks, outdoor-to-indoor propagation characteristics have been actively investigated. In this paper, we evaluate the performance of a theoretical analysis method that is a hybrid of ray-tracing and physical optics with respect to the calculation accuracy. This is the first investigation to focus specifically on the calculation part...
A new technique for estimating far-field gain as well as phase center of antennas operated in liquid is numerically demonstrated. It is easily derived that the distance characteristic of near-field gain for antennas operated in the liquid is the same as that in free space. Moreover, another expression for the nearfield gain for antennas operated in the liquid that the authors have proposed is proven...
Three measurement methods for a small antenna with reduced influence of a measurement cable are presented. Baluns are classed from a perspective of blocking effect for unbalanced current. Application of fiber optics and extended S-parameter method are also introduced. Measurement results show the effectivity of those methods.
We are developing a far field gain and an antenna factor estimation method for EMI broadband antennas using the amplitude center distance and time frequency analysis technique. Our method is using an amplitude center modified Friis transmission formula. In this paper, we show the measurement results of far field antenna factor of log-periodic dipole array antenna on an open area test site. In the...
Recently, S-parameter method that is the measurement method of the input impedance of the balanced antenna is proposed. It is a problem of this method that the jig influences measured value when the measurement frequency increases. To remove the influence of the jig, we have examined compensating method using the ABCD-matrix. In this report, to remove the influence of the jig, we propose a novel open...
The magneto-electric dipole was developed based on the idea of combining an electric dipole with a magnetic dipole to achieve a symmetrical radiation pattern with low back radiation. The idea is not new but all the antenna structures reported in the literature developed by this complementary antenna or Huygen's source concept are not very wideband in bandwidth and confined with linear polarization...
Circularly-polarized 2-by-2 antenna arrays based on the complementary source concept are designed for millimeter-wave applications at 60 GHz. Each antenna element consists of a slot and an electric dipole. Energy is coupled from a microstrip feeding network to the slots. Each slot radiates and simultaneously excites the dipole, achieving a complementary source. Two arrays are presented to demonstrate...
A folded dipole is known as a classical wideband antenna and usually analyzed by decomposing into two coupling modes: dipole mode and twin-lead stub mode, which can be seen as an effective 2-pole filter. A wideband microwave absorber surface can be formed by an array of receiving folded dipoles backed by a ground at λ/4, since the combination of the twin modes of folded dipole and the third coupling...
With the recent development of wireless communication technology, wireless body area network (WBAN) has received great attention. WBAN devices can be classified depending on location: in-body, on-body, and off-body. A repeater can be required in order to realize various wireless communication services such as in-body to on-body and on-body to off-body communications.
An unit-cell of Frequency Selective Surface (FSS) is designed in order to control the transmission characteristics of electromagnetic waves penetrated into the human body for microwave biomedical applications. The integration of water bolus and FSS not only assists the impedance matching in complex dielectric medium but also provides the optimal condition for the wave penetration. The proposed FSS...
We discuss recent developments in a finite-difference time domain (FDTD) algorithm for electromagnetic wave interaction with complex dispersive media, based on a quadratic complex rational function (QCRF). The QCRF is simple and accurate to consider frequency dispersive responses. Compared to the Debye, Drude, or Lorentz dispersion equation, the QCRF equation has more degrees of freedom and it is...
This paper presents a novel wideband differentially driven circularly polarized antenna. It consists of a ground plane, a half loop and a dipole. Circularly polarized radiation is realized by overlapping the far field of the half loop and dipole. The overall bandwidth of the antenna, restricted by its 3dB axial ratio and 3dB gain bandwidths, is from 5 to 6.9GHz or 32%. The peak gain within the bandwidth...
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