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This paper propose an acceleration method of Compressed Sensing by both Kronecker product and zero element removal in estimation of both DOA and TOA. Numerical results show that the calculation time is greatly reduced is by proposed method.

This paper proposes a plural modulation schemeestimation method for using machine learning. The estimationaccuracy of the method is numerically verified. As the results, it isshown that the combination of modulation scheme in mixedsignals can be estimated by proposed method., 2020 International Symposium on Antennas and Propagation (ISAP) 25-28 Jan. 2021 Osaka, Japan

In the 5th generation mobile communication system, high frequency bands over 6GHz are used to realize high speed and large capacity communication. Because of high path losses, these bands are considered to use in small cells at low base station antenna. In this paper, measured data with moving using a channel sounder at 20GHz is analyzed for a low base station antenna installed in an urban street cell environment to clarify the radio wave propagation characteristics., 2020 International Symposium on Antennas and Propagation (ISAP) 25-28 Jan. 2021 Osaka, Japan

In this paper, introduction of Adaptive Array in BRT (Bus Rapid Transmit) Communications where the trial of autonomous driving is examined. As a result of examination, service area is expanded, and the effectivenessof Adaptive Array is demonstrated., 2020 International Symposium on Antennas and Propagation (ISAP) 25-28 Jan. 2021 Osaka, Japan

In this paper, effects of the relay station install location and the retransmission beam width on the service area expansion performance of a polarized MIMO gap-filler in a terrestrial broadcasting environment is examined. Numerical results show that the distribution of buildings is important to design the relay station parameter., 2020 International Symposium on Antennas and Propagation (ISAP) 25-28 Jan. 2021 Osaka, Japan

Recently, electromagnetic interference in AMradio receivers associated with noise generated from the powercontrol unit (DC-DC converters) in hybrid vehicles (HVs) hasbecomes a serious problem. To address this problem, a noisesuppression method thorough digital signal processing in anAM radio is proposed in the past research. However, themethod is only applicable to single desired signal. In this paper,the reduction performance by the method for multiple desiredsignals is confirmed., 2020 International Symposium on Antennas and Propagation (ISAP) 25-28 Jan. 2021 Osaka, Japan

In estimating the direction of arrival (DOA) of a radio wave using array antennas, the correlation matrix calculated from the received signals at each antenna element is generally used. In recent years, applied researches such as DOA estimation and radio propagation estimation using machine learning have been conducted. In this paper, a method for estimating the DOA using machine learning is proposed, and clarify the influence of each hyperparameter on the estimation accuracy., 2020 International Symposium on Antennas and Propagation (ISAP) 25-28 Jan. 2021 Osaka, Japan

Array antenna technology for wireless systems is highly integrated for demands such as multi-functionality and high-performance. This paper details recent technologies in Japan in design techniques based on computational electromagnetics, antenna hardware techniques in the millimeter-wave band, array signal processing to add adaptive functions, and measurement methods to support design techniques, for array antennas for future wireless systems. Prospects of these four technologies are also described.

Communication performance of Multi User MIMO system is degraded when the base station is interfered during channel estimation from other base stations (interference stations). This paper proposes two methods to reduce the interference using the interference channel, which is measured in advance. It is shown that the proposed methods reduce interchannel interference and high channel capacity is achieved even when interference occurs.

In this paper, the SAGE algorithm is applied to measured data acquired by the 20 GHz band channel sounder in a real urban street cell environment, and DOA (Direction of Arrival) is estimated. Then, the average arrival angles and angle spreads are calculated from the estimated results, and angle of arrival characteristics are evaluated. It is shown that the average angle of arrival gradually approaches to direction of transmitter as the distance between the transmitter and the receiver increases. Also, it is shown that the arrival angle spread in the azimuth plane tends to decrease as the distance between transmitter and receiver increases.

This paper proposes the variable reflection angle meta-surface using the double layered structure which can change the scatter pattern simply by sifting other layer. It is clarified that the gradients of the element vs. the reflection phase are changed by the relative position between two layers in double layered patch type FSS (Frequency Selective Surface). It is found that the reflection angle with range of about −34 deg. to −2 deg. is obtained in the proposed meta-surface.

Current major transmission scheme is OFDM transmission. This paper proposes a DOA estimation method using cyclostationarity of OFDM signal and evaluates its effectiveness. As a result, it is clarified that only the desired wave can be estimated by the proposed DOA estimation method. The accuracy of proposed method is improved when the guard interval is long or number of elements is large.

In this paper, cognitive radio considering an interference reduction by controlling secondary system is proposed. The channel capacity on secondary system and communication quality on primary system are improved by interference suppression and transmission power control on secondary system. The performance and effectiveness are clarified through numerical simulation.

A position estimation technique using electromagnetic wave has been proposed for object detection in wireless power transmission. However, the conventional position estimation method has a problem that cannot estimate the position of multiple objects. This paper proposes a multiple objects position estimation method using hyperbola, ellipse and circle. Positions of multiple objects can be estimated by finding the intersection of hyperbola, ellipse and circle.

In a polarized MIMO transmission, performances of the system deteriorates due to the difference between the transmission characteristics of horizontal polarization and vertical polarization. In this paper, we will examine the influence of a relay station position on channel capacity for relay transmission in polarized MIMO. As a result, it is clarified that a high channel capacity is stably obtained when the relay station and the reception point is in the line-of-sight environment.

TDL (Tapped Delay Line) array antenna is effective for a wide band signals. On the other hands, it is expected for wide angle null pattern formation. This paper shows the effectiveness of TDL array antenna for wide angle null pattern.

Restriction of communication area is preferable in view point of security. Two kinds of beams are used in a communication area restriction system which has been proposed by the authors; one is for transmitting and the other is for jamming [1]. In the conventional method, a binomial coefficient is used; however, sidelobe level is raised in case of virtual linear array. This paper proposes a new weighting method using gamma function for virtual linear array to reduce the sidelobe level. The result of analysis shows that the undesired radiation is reduced by the proposed method.

A position estimation technique using electromagnetic wave has been proposed for object detection in wireless power transmission. However, conventional position estimation method has a problem that position estimation accuracy varies with object position. This paper proposes a position estimation method using hyperbola obtained from time difference and ellipse obtained from path length. Due to the orthogonality between the hyperbola and the ellipse, it is enabled to accurate position estimation regardless of the object position. Moreover, effect of thermal noise at the receiver antennas and antenna spacing of the receiver on position estimation accuracy is shown.

This paper clarifies the effects of configuration of a MIMO base station antenna on the channel capacity in line-of-sight street cell environment. It is shown that the optimum beam width in the horizontal plane depends on the road width and the distance from the base station. Moreover, it is also shown that the channel capacity decrease as the service area becomes wider.

In this paper, a blind signal separation method for two incoming waves using eigenvector synthesis is proposed. The array weights to separate each waves are made from two eigenvectors. Numerical results show that the proposed method could improve the signal separation characteristics.

Restriction of communication area is preferable in view point of security. In this paper, a communication area restriction method is proposed. In the proposed method, binomial coefficient array for transmitting and for jamming is used. In the conventional method, the beam for jamming was formed using 2 elements; while in this paper, the beam is formed using 8 elements binomial array. As a result of analysis, it is shown that the undesired radiation is drastically reduced by the proposed method.

This paper describes a design method of a metasurface that consists of two types FSS (Frequency Selective Surface) and the ground plane to realize broadband reflected wave reduction. The ideal filtering characteristics of one FSS is clarified when the other FSS is a patch type FSS. A loop and patch type FSS is proposed to realize the ideal filtering characteristics. Then, a meta-surface with reflected wave reduction function is constructed with the patch type FSS and the proposed FSS. As a result, 48.9 % of a relative bandwidth within a reflection amplitude −10 dB or less is obtained by the proposed meta-surface.

A low-profile and decoupling dipole antenna array is achieved by combining patch type meta-surface with proposed parasitic cells. Based on the moment method analysis results, it is clarified that proposed parasitic cells can suppress mutual coupling of dipole antennas without additional impedance. In addition, the maximum decoupling effect of 13.3 dB is achieved.

This paper proposes the horizontally polarized omni-directional antenna with a cylindrical frequency selective surface (FSS). The FSS features the orthogonal polarization conversion function. Therefore, the vertically polarized wave radiated from a dipole antenna is converted to the horizontally polarized transmitted one. The simulation results by using the FDTD and the MoM show that this antenna has the good performance as the horizontally polarized omni-directional antenna.

Recently, electromagnetic interference in AM radio receivers associated with noise generated from the power control unit (DC-DC converters/inverters) and other power electronics devices, such as an electric power steering (EPS) control modules, in hybrid vehicles (HVs) has become a serious problem. In order to address this problem, most noise suppression methods use either noise filters (for noise sources) or shield wiring and ferrite cores (for noise propagation paths). We have proposed a noise suppression method through digital signal processing in an AM radio receiver. In this method, the received AM radio signal containing HV noise is first quadrature demodulated. Next, a replica signal of the noise is generated using the noise signal in the quadrature component. The replica signal is then subtracted from the AM radio signal containing the noise of the in-phase component. In this paper, first, we show the noise canceling method. And then, we construct a prototype of the radio receiver system based on the method. Finally, we demonstrate that the system can reduce the DC-DC converter noise and the EPS noise superimposed at the same time on the AM radio signal by more than 15 dB.

This paper proposes the spatial filter with FSS(Frequency Selective Surface) for orthogonal polarization conversion such as converting the vertical polarization to horizontal polarization. It is found that multilayered loop-slot type FSS having band-pass filter characteristics realize orthogonal polarization conversion. Furthermore, it is shown that the optimal number of layers of the FSS is three, and maximum value of relative bandwidth is 9.5%.