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The radio holography method performs the direction-of-arrival (DOA) estimation of radio waves with a relatively simple array system because it uses a reference antenna. This paper proposes a new radio holography method in which cyclic correlations of digital-modulation signals are introduced for the DOA estimation of desired signals only. The DOA estimation accuracy of the method is evaluated by computer...
By introducing diversity techniques to the transmitting array of MIMO radar, the performance of MIMO radar in target estimation can be enhanced. This paper utilizes compositely the transmission beam diversity and spreading code diversity, and also propose the algorithm for the diversity technique. The computer simulation shows the effectiveness of the proposed method.
Thicknesses of window glasses, radomes, plastic cases of wireless systems are comparable with the wavelength in the millimeter-wave band. The reflections from the dielectric plate surfaces are canceled out of phase when the thickness is identical to a half of the wavelength. The reflection loss is minimum at the resonant frequency. However, they are not canceled at any other frequencies except integer...
5G, the next generation of wireless communications, is focusing on modern antenna technologies like massive MIMO, phased arrays and mm-wave band to obtain data rates up to 10 Gbps. In this paper, we have proposed a new 64 element, 8×8 phased series fed patch antenna array, for 28 GHz, mm-wave band 5G mobile base station antennas. The phased array steers its beam along the horizontal axis to provide...
A partially parallel-feeding system of traveling-wave waveguide slot array has an advantage to reduce the frequency dependence of excitation phase of slots cut on the waveguide, which results in broadband feature of gain and radiation pattern. However, a conventional narrowband post-loaded radiating slot for array element limits the overall bandwidth of the array. A broadband wall-surrounded slot...
A center-feeding travelling-wave microstrip array antenna is designed to realize a high-gain and broadband two-dimensional array antenna in quasi millimeter-wave band. Microstrip antennas suffer from high feeding-loss in high frequency band. Therefore, center-feeding and travelling-wave operation are applied. To reduce manufacturing errors in etching process, we propose elliptically shaped radiating...
Electromagnetic waves penetrate window glasses, radomes and cases of electric devices for wireless systems. The thickness of the dielectric plate is a similar dimension to the wavelength in high-frequency band. The reflections from the surfaces of the dielectric plate are canceled out of phase only when the thickness is identical to a half wavelength. However, they are not a half in general, then,...
This paper deals with the near-field DOA-Matrix method with SAGE algorithm, which is applied for source localization using a uniform linear array antenna. In this paper, we investigate the effect of spatial smoothing processing (SSP) on the performance of the near-field DOA-Matrix method with SAGE algorithm. The computer simulation using electromagnetic field analysis shows the SSP improves the source...
A beam-switching antenna which is composed of several independent antennas with different beam directions is one of the realistic solutions of an electronic beam-scanning antenna, because it does not need any special feeding circuits. Excitation phases of radiating elements in traveling wave antennas are controlled by changing the connection point along the feeding line. As the radiating elements...
Many investigations on the metamaterials are reported. It is known that the directions of the Poynting vector and the wavenumber vector are opposite in Double Negative Medium (DNM). Therefore, to visualize the Poynting vector and the wavenumber vector is useful to recognize the peculiar phenomenon of DNM. In this paper, we propose a method to obtain the Poynting vector and the wavenumber vector from...
Multiple-Input Multiple-Output (MIMO) radar which applies MIMO communication technology in the radar has attracted attention as a kind of high-resolution radar. In this paper, target direction is estimated by applying the MUSIC method to the minimum redundancy MIMO radar which has been used as the adaptive beamforming array. Furthermore, the Root-MUSIC method which has been limited to the uniform...
In estimating DOA of incident waves with high accuracy, we often have to take into consideration the angular spread (AS) of each wave due to reflection, diffraction, and scattering. As a method of estimating DOA and AS simultaneously, DOA-Matrix method was proposed. In this paper, we extend the array configuration from the linear array to the planar array for simultaneous estimation of DOA and AS...
An 8×8 element array antenna is composed of the E-plane waveguide parallel-feeding circuit in the lower layer and the 2×2 slotted cavities in the upper layer. The E-plane waveguide parallel-feeding circuit consists of two plates and assembled at the center of the broad wall of the waveguide to achieve low-loss property and wide bandwidth simultaneously. The 2×2 slotted cavities are designed to obtain...
A compact planar transmission-line transition direct-connecting from a waveguide to four microstrip-lines is designed in the submillimeter-wave band. Microstrip array antennas are fed from the back at the center of the antenna for wide frequency bandwidth. To reduce the size of the center feeding circuit, the direct connection of all four microstrip lines into the waveguide is advantageous for radiation...
The high-resolution DOA estimation with an array antenna is utilized as an important technique for source localization in mobile communication or radio monitoring. This paper deals with MUSIC with circular array which can perform DOA estimation in all directions of azimuth. Uniform circular array (UCA) and minimum redundancy circular array (MRCA) are compared in DOA estimation and the effectiveness...
This paper deals with the near-field DOA-Matrix method for source localization using a uniform linear array antenna. In general, the mutual coupling between array elements degrades the DOA estimation accuracy. In this paper, we investigate the influence of mutual coupling in source localization using the near-field DOA-Matrix method and the improved method.
The cyclic method performs the direction-of-arrival (DOA) estimation of the desired signals by using cyclic correlations of digital-modulation signals. This paper proposes a cyclic method which uses in-phase combining of multiple cyclic correlations (MCC) and the forward and backward spatial smoothing processing (FB-SSP). Also, the way of reducing the computation load in FB-SSP is provided. Computer...
This paper proposes a novel antenna configuration for wireless power transfer system with magnetically coupled resonance. The computer analysis shows high transmitting efficiency with wider receiving area of the proposed antenna.
A microstrip-to-waveguide transition can be used for connecting antennas and backed RF circuits. Loss of the transition due to the leakage from the gap between the substrate and the waveguide has been a serious problem in the millimeter-wave band. A choke structure is provided in the gap at the quarter wavelength away from the waveguide edge to suppress the leakage. The effect to use the choke structure...
Rotman-lens is widely used in multi-beam antennas for beam forming networks which give required beam directions. Discrete beam-scanning can be fulfilled by switching beams. However, a part of the radiated power from the input port to the Rotman-lens which delivers outside of the output port arrangement becomes loss to the dummy ports. Therefore, optimizing the connection angle and the tapered width...
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