We propose a novel technique for estimating the number of people in a video sequence; it has the advantages of being stable even in crowded situations and needing no ground-truth data. By analyzing the geometrical relationships between image pixels and their intersection volumes in the real world quantitatively, a foreground image directly indicates the number of people. Because foreground detection is possible even in crowded situations, the proposed method can be applied in such situations. Moreover, it can estimate the number of people in an a priori manner, so it needs no ground-truth data unlike existing feature-based estimation techniques. Experiments show the validity of the proposed method.

The phaseless antenna measurement technique is advantageous for high-frequency near-field measurements in which the uncertainty of the measured phase is a problem. In the phaseless measurement, which is expected to be used in the frequency band with a short wavelength, a slight positional deviation error of the probe greatly deteriorates the measurement result. This paper proposes a phase retrieval method that can compensate the measurement errors caused by misalignment of a probe and its jig. And this paper proposes a far-field estimation method by phase resurrection that incorporated the compensation techniques. We find that the positioning errors are due to the random errors occurring at each measurement point because of minute vibrations of the probe; in addition, we determine that the stationary depth errors occurring at each measurement surface as errors caused by improper setting of the probe jig. The random positioning error is eliminated by adding a low-pass filter in wavenumber space, and the depth positioning error is iteratively compensated on the basis of the relative residual obtained in each plane. The validity of the proposed method is demonstrated by estimating the far-field patterns using the results from numerical simulations, and is also demonstrated using measurement data with probe-positioning error. The proposed method can reduce the probe-positioning error and improve the far-field estimation accuracy by more over than 10 dB.

This paper describes a dielectric phase shifter (DPS) using contact-less connector. As the main feature of this structure, an array of difference length strip conductor etched on a dielectric substrate placed on the microstrip patch resonators gives tightly coupling between input and output port. A sliding dielectric substrate provides phase shift for between input and output port. In this paper, the characteristics of DPS are calculated by finite difference time domain (FDTD) method, and are verified by experiments.

Often, the major requisites of short-range communication systems are low power consumption and low cost, rather than high data-transmission speeds. This paper proposes low-cost and extremely low-power radio communication devices that use a basic one-chip microcomputer for short-range transmission and reception. In the proposed transmitter, a rectangular wave is generated at external I/O ports as carrier by the basic one-chip microcomputer and is then filtered and radiated by an antenna circuit. In the proposed receiver, the received signal is detected by a radio IC and is subsequently digitally processed by a microcomputer with a built-in A/D converter. The proposed transmitter and receiver are demonstrated, and the system performance is experimentally evaluated.

This paper presents a DC output voltage-boosting antenna with high input impedance in wide frequency band for RF (radio frequency) energy harvesting of FM broadcasting signals. Target input power level of -20dBm is used to design a loop antenna for DC output voltage-boosting. The RF energy harvesting on YNU campus provides 924mV DC output for a single rectenna and 1.72V DC output for twin rectennas by receiving several FM broadcasting wave simultaneously.

This paper presents a framework of multimode fully digital receiver implementation using direct RF-to-digital conversion. In this architecture the entire band including multiple RF systems is directly converted to digital by a wideband high speed ADC, and the RF systems can be easily switched by only digital signal processing with the minimum analog RF components. The digital RF front-end consists of parallel processing blocks for parallel data streams considering practical ADC's configuration. The RF signals are converted into baseband through digital IF stage and the data rates are made down by two steps of decimation. In this paper, a principle investigation into a dualmode system implementation is presented for simplicity. The circuit resource and the robustness to the spurs (spurious outputs) of an NCO (numerically controlled oscillator) in the proposed design will be presented. The proposed architecture was implemented with an FPGA on the developed prototype system and the operations were also verified.

This paper presents a mathing circuit of a T-shaped ridge waveguide by means of loaded probes. The reactance of the loaded probes for the matching between the ridged waveguide and the coaxial-cable is calculated by the impedance matrix of a source and loaded probes.

In a two-layer self-diplexing antenna fed at two ports, theoretical analysis has already shown that the isolation characteristics can be improved by adjusting the angle between the feed locations of the transmitting and receiving antennas. In this letter, we experimentally investigate the isolation characteristics of the self-diplexing array antenna. First, calculated and experimental results for each feed location of the element antenna are compared and good agreement is found. Second, experimental results with a 19-element planar array indicate that a self-diplexing antenna with suitably chosen feed configuration is effective in improving the isolation in a phased array antenna.

Numerical modeling of realistic engineering problems using the FDTD technique often requires smaller cell size, higher simulation accuracy and less computation resources. In this paper, we describe a high performance three-dimensional FDTD algorithm by using non-uniform mesh that allows flexible cell size to improve the accuracy of modeling, and computation resource also can be reduced greatly. In this paper, we will first explain the detailed formulation and algorithm of Non-Uniform Mesh. Next, examination of the reflection error from fine-coarse boundary because of the discontinuity is carried out. Then some test geometry are solved by using both uniform mesh and non-uniform mesh FDTD scheme to validate the results and check the accuracy of solution. We also examine the calculation accuracy due to mesh size ratio, and then investigation of how to determine the fine mesh region surrounding the object for a most small computation error will be carried out in this paper. In addition, the algorithm is demonstrated for several different antenna geometry.

This paper presents a method of synthesizing covariance matrix elements of array input signal for high resolution 2-D Direction-Of-Arrival (DOA) estimation via antenna (sensor) switching. Antenna array generally has the same number of array elements and receiver modules which often leads large receiver hardware cost. Two of the authors have already studied a way of antenna switching to reduce receiver cost, but it can be applied only for periodic incident signals like sinusoid. In this paper, we propose two simple methods of DOA estimation from sparse data by synthesizing covariance matrix elements of array input signal via antenna switching, which can also be applied to DOA estimation of antiperiodic incident signals. Performance of the proposed approach is evaluated in detail through some computer simulation.

Computing the Eigen Value Decomposition (EVD) of a symmetric matrix is a frequently encountered problem in adaptive (or smart or software) antenna signal processing, for example, super resolution DOA (Direction Of Arrival) estimation algorithms such as MUSIC (MUltiple SIgnal Classification) and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Technique). In this paper the hardware architecture of the fast EVD processor of symmetric correlation matrices for the application of an adaptive antenna technology such as DOA estimation is proposed and the basic idea is also presented. Cyclic Jacobi method is well known for the simplest algorithm and easily implemented but its convergence time is slower than other factorization algorithm like QR-method. But if considering the fast parallel computation of the EVD with a hardware architecture like ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), the Jacobi method can be a appropriate solution, since it offers a quite higher degree of parallelism and easier implementation than other factorization algorithms. This paper computes the EVD using a Jacobi-type method, where the vector rotations and the angles of the rotations are obtained by CORDIC (COordinate Rotation DIgital Computer). The hardware architecture suitable for ASIC or FPGA with fixed-point arithmetic is presented. Because it consists of only shift and add operations, this hardware friendly feature provides easy and efficient implementation. In this paper, the computational load, the estimate of circuit scale and expected performance are discussed and the validation of fixed-point arithmetic for the practical application to MUSIC DOA estimation is examined.

This paper presents a scheme for accurately detecting the number of incident waves arriving at array antennas. The array antenna and MIMO techniques are developing as 4th generation mobile communication systems and wireless LAN technologies, and the accurate estimation of the propagation environment is becoming more important. This paper emphasizes the accurate detection of the number of incident waves; one of the important characteristics in multidirectional communication. There are some recent papers on accurate detection but they have problems of estimation accuracy or computational cost in severe environment like low SNR, small number of snapshots or waves with close angles. Hence, AIC and MDL methods based on statistics and information theory are still often used. In this paper, we propose an accurate estimation method of the number of arrival signals using the orthogonality of subspaces derived from preliminary estimation of signal subspace. The proposed method accurately estimates the number of signals also in severe environments where AIC and MDL methods can hardly estimate. We evaluate the performance of these methods through some computer simulation and experiments in anechoic chamber.

This paper presents a low cost and portable DOA (Direction Of Arrival) estimation system for surveillance using a modifed beamspace MUSIC (MUltiple Signal Classification) by a quasi-orthogonal multi-beam. This is instead of DFT processing and hardware system consisting of chip-sized phase shifters, a single ADC (Analogue to Digital Converter) and a single TR (TRanceiver) module for an antenna array. In the beamspace MUSIC, generated beampatterns have orthogonal properties. This proposed system cannot make such a beampattern due to the variable range limitation of phase shifter, then we use the quasi-orthogonal beam obtained by the calculation of correlation coefficient for beampattern. We demonstrate the proposed system using 4-element microstrip array antenna and chip-sized phase shifters. The DOA experiment in anechoic chamber confirms the proposed system performance.

Two design parameters, SNR and correlation, are key factors for enhancing channel capacity in MIMO systems. Achieving high SNR and low correlation is desirable in antenna design. This paper discusses the relation between channel capacity and these two parameters, and presents simple formulas of this relation for propagation channels and antenna coupling of mobile terminals. According to these guidelines, indoor base station antennas are designed and examined using propagation measurements. We also present a suitable antenna design for mobile terminal antennas and based on a realistic propagation model, predicted the channel capacity of the antenna.

The use of directional antenna and polarization diversity techniques has been reported to achieve good MIMO performance. Low-profile, small structures are required to configure the MIMO antenna with these techniques. First, we assume downlink transmission in indoor MIMO systems and present the design guidelines for the radiation pattern to obtain large channel capacity by the ray-tracing method. We then propose a uni-directional, dual-polarized MIMO antenna with a thickness of 0.24λ based on the design guidelines. The proposed antenna consists of dipole antennas mounted horizontally to the ground plane and cavity backed slot antennas for vertical polarization. We apply the proposed antenna to 2 2 MIMO transmission and demonstrate the effectiveness of channel capacity enhancement in an actual environment. The improvement factor is revealed to be +16.2% with place averaged value compared to sleeve antenna configuration.

This paper reviews the antenna system for Japanese celullar systems and PHS (Personal Handphone System). The unique features of the Japanese cellualr system are multi-band operation, compact diversity antennas, electronic beam tilting, and indoor booster systems. The original antennas for the above purpose will be described. The PHS is also a unique mobile communication system in Japan, and is mainly used for high speed, low cost data transmission. Its original antennas are also presented in this paper.

Urban area suffers severe multipath effects due to its complex infrastructure environment and sector antenna is a popular choice as a base station antenna in those areas. Within sector antennas, omni cell antenna is utilized as supporting antenna to cover low reception areas between them. This paper proposes a slant 45° dual polarized omnidirectional antenna to operate as the omni cell antenna in those environments. The frequency band covers the IMT band, ranging from 1920MHz to 2170MHz with directivity focusing in horizontal plane. The antenna structure consists of a loop slot antenna array as excitation element which is placed inside a cylindrical slot antenna as parasitic element. Good performance is achieved in both S-parameter and directivity results, with a gain of more than 4 dBi and a gain difference of less than 1.5dB. The measurement results also agree well with the simulation results and the final design confirms that the proposed antenna works effectively as a slant ±45 ° dual polarized omnidirectional antenna.

This paper presents an analysis of a multi-hole directional coupler attached to an overmoded circular waveguide. The directional coupler is analized as a boundary value problem, and is solved numerically by a virtual cavity method. The approximate analysis of a small hole coupling coefficient is verified by this analysis. Numerical results indicate that the mutual coupling between holes is not negligible for calculating the directivity of the directional coupler.

In this paper, a new array geometry is proposed which is capable of performing underdetermined Direction-Of-Arrival (DOA) estimation for the circular array configuration. DOA estimation is a classical problem and one of the most important techniques in array signal processing as it has applications in wireless and mobile communications, acoustics, and seismic sensing. We consider the problem of estimating DOAs in the case when we have more sources than the number of physical sensors where the resolution must be maintained. The proposed array geometry called Nested Sparse Circular Array (NSCA) is an extension of the two level nested linear array obtained by nesting two sub-circular arrays and one element is placed at the origin. In order to extend the array aperture, a Khatri-Rao (KR) approach is applied to the proposed NSCA which yields the virtual array structure. To utilize the increase in the degrees of freedom (DOFs) that this new array provides, a subspace based approach (MUSIC) for DOA estimation and l1-based optimization approach is extended to estimate DOAs using NSCA. Simulations show that better performance for underdetermined DOA estimation is achieved using the proposed array geometry.