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A kind of low sidelobe and high gain microstrip antenna array with 32×8 units operating in the X-band is designed, which achieves the gain of 28 dBi and the sidelobe level of −25 dB at 9.37 GHz. The Chebeshev distribution is used in designing the current distribution on the surface of this antenna, which achieves a width of main lobe of 5° in E-plane and a main lobe width of 10° in H-plane. The amplitude...
With compact folded method, a kind of folded crossed dipole ultra wideband antenna is proposed with omnidirectional radiation characteristics on the horizontal direction in this paper. The antenna is comprised of orthogonal crossed semicircular metal discs with twice 90° folded on both ends. Horizontal size is reduced obviously compared with original crossed semicircular disc antenna. This antenna...
Scattering performance of a reflectarray using a log-periodic dipole array (LPDA) element is demonstrated numerically and experimentally. The LPDA element and the reflectarray are designed using method of moments (MoM). The designed 10 × 1 reflectarray was fabricated using a 3D printing technology. A bistatic radar cross section (BRCS) of the designed reflectarray was measured in a radio anechoic...
In the 5G system, high frequency bands over 6 GHz (6–100 GHz) will be a key factor in providing a very wide bandwidth. Because of high path losses, these bands are considered to use for small cells. To design radio links with high accuracy and evaluate 5G system performances for various scenarios, channel characteristics must be clarified. In this paper, we clarify channel characteristics in an outdoor...
This paper presented the design of a wearable EEG-based control network and emergency medical assistance system which works and is now under test by volunteers. The system can detect the user's blink control signal, heart rates and brain signal, etc. A new scheme to control the device for disabilities was proposed in the paper. A DSP was used to calculate and process these data which can also send...
In this paper, we investigate feasibility of orbital angular momentum (OAM) based analog transmission method. The method uses analog discrete Fourier transform (DFT) feed networks for mode generation as well as circular array antenna with right-hand and left-hand circular polarizations. The simulation revealed the designed array antennas enhance the capacity up to double of the single polarization...
In this paper, a planar 4-port antenna is designed to investigate the effect of user finger for mobile terminal application. The proposed array antenna covers a bandwidth of 2.5 GHz centered at 28 GHz. The effects of user's finger on the antenna are studied in four different positions on top of antenna elements, with six distances between antenna and user's finger. The losses due to the increased...
A novel angular independent dual-band FSS for multi-frequency communication is discussed in this letter. The proposed FSS with closely spaced response is consist of improved cross-shaped metal strips and a dielectric substrate. The unit cell size of the proposed FSS is 0.13λ×0.13λ where λ corresponds to the wavelength of the first resonant frequency. The proposed FSS exhibits dual stop band characteristics...
This paper presents a dual-band design of reflectarray antenna by using metallic elements for high energy efficiency at 28 and 60GHz bands. The dual-band operation is created by considering the frequency bands below and above the cutoff frequency of metallic waveguides. This frequency band separation differentiates the waveguide's characteristics as a resonant and non-resonant reflecting elements,...
We herein investigate the design of a tapered slot antenna (TSA) that is divided into a radiator and a feeding circuit (balun). We measured the differential component and common component of the surface current on the TSA in a previous study. Moreover, we measured the radiation patterns of the radiator and the balun in order to discuss the radiation of the TSA. In particular, the differential component...
A new multi-polarization reconfigurable omnidirectional antenna is proposed. The antenna consists of a top-loaded monopole for vertically polarized working state (VP), a circular loop for horizontally polarized working state (HP). The circularly polarized working state (CP) is achieved by exciting the monopole and the loop simultaneously with different phases. It is shown that the bandwidth overlapped...
Video Synthetic Aperture Radar (ViSAR) is a novel technique to continuously monitor moving targets in the interested area. From the video echo provided by the ViSAR system, the motion trail of the moving target can be easily obtained. Therefore, the echo of the moving target should be carefully studied, which is important in practical application for moving targets tracking in ViSAR system.
For mode multiplexing transmission using two-dimensional orthogonal field distribution, a beam switching circuit is designed and transmission between Tx and Rx antenna systems are calculated. Generation of orthogonal four modes by the beam switching circuit is presented in this paper. The simulated isolations between the orthogonal modes are over 20 dB at the center frequency.
In this paper, we propose a fast design procedure for the low scattering metasurface in the microwave region. Since there are numerous units with various geometric dimensions inside the metasurface aiming to generate a diffusion-like scattering pattern, it presents a large computation burden for the evaluation and optimization of the scattering behaviors of the whole metasurface. To overcome this...
The impact of rotor yaw angle on the diffraction loss of a radar beam due to scattering at a 3-blade rotor of a wind turbine (WT) is investigated. Simulation results for a C-band weather radar are based on 2D Fresnel-Kirchhoff diffraction approach considering negligible impact of the ground plane.
A passive W-band 19-channel spatial power splitter/combiner is presented, for the applications in grid amplifiers design. The design employs a linear array of chip-to-air-filled waveguide contactless connections, and are directly integrated within a single-layer. The meta-material-based gap waveguide is used; it enables a low-loss low-profile solution. The quasi-optical beamformer gives rise to a...
An adaptive radio system combining compact switchless reconfigurable antenna with Software Defined Radio is proposed. The system allows control of the direction of the transmitted signal solely by adjusting the baseband I and Q components of the modulated signal, while maintaining small antenna size through the use of compact multiport antenna. The system is demonstrated in a line-of-sight configuration...
One of the ways to obtain non-reciprocal response is a utilization of active components. Active components inherit non-linear responses and noise production. These “unwanted” accompanying response should be comprehended in advance, for metasurface application of this metamaterial structure in addition to planar microwave component, which are no needs to be considered in pure passive metamaerial structure...
The authors have been researching a 4×4 SVD-MIMO-OFDM system that adaptively changes transmitter weights and modulation schemes in accordance with feedback information received by a TDD. This report presents our evaluation of the effects of feedback delays due to the TDD on the BER performance of the proposed system. The computer simulation results revealed that the required normalized SNR of a system...
A novel satellite base station configuration based on the Distributed Array Antenna (DAA) technique is studied to eliminate mechanical satellite tracking equipment. A DAA controller integrates all antennas so each antenna's aperture can be downsized and its transmitting power reduced while realizing the required characteristics. This paper revealed the maximum gain achievable with the DAA base station.
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