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Far-field pattern of an antenna above the earth is different from the characteristics in free space. We propose an estimation method of antenna far-field above the earth from near-field data in free space. The method reconstructs current distribution on a surface of an antenna from near-field data in free space and estimates the far-field pattern above the earth using the reconstructed current distribution...
This paper presents characteristics of a free access transmission line consisting of a paper substrate and foam instead of dielectric substrate for easy installation in body area network applications. We measure the coupling characteristics between two dipole antennas above the proposed transmission line to show its basic performance. The coupling level between two dipole antennas on body propagation...
A slim vertically polarized omni-directional feed circuit integrated loop slot antenna for mobile base station is proposed in this paper. Picocell antenna requires a compact and slim structure, because its construction space is limited in urban areas. The proposed antenna consists of loop slots and patches to improve omni-directional pattern and bandwidth. In order to enhance the directivity gain,...
CISPR25 test is used to characterize EMC performance of automotive component. To avoid miss detection of unwanted emission in this test, it is necessary to scan the measurement antenna along the wire. In this paper, we propose a no scanning method using two loop antennas placed near DUT and wire terminal. Simulation and measurement show that the proposed method picks up unwanted signal with the errors...
In this paper, a probe-positioning error estimation of phase retrieval method in planar near-field measurements in millimeter frequency band is presented. Not only is the accuracy of the estimation but also the tolerance of probe-positioning error necessary in high frequency measurements because of its short wavelength. Using phase retrieval method, the accuracy of the estimation is shown in simulation...
One of the most important field in array signal processing is direction-of-arrival (DOA) estimation, which is applicable in wireless and mobile communications. We consider the problem of estimating the DOA for reactance-based uniform circular arrays (UCAs). In this paper, a new technique of estimating DOAs is proposed for the reactance-based UCA antenna as well as a method to calculate optimal reactance...
Cylindrical near-field measurement is effective against spherical far-field measurement of long linear array antenna. Long measurement time is a problem of this method caused by a large amount of sampling points. This paper proposes a thinning sampling technique for sampling points reduction on cylindrical far-field estimation method. Near-field equivalent current is sparsely sampled. Number of sampling...
Phase retrieval technique is well used for antenna near field measurement in higher frequency bands and probe positioning errors have been discussed in detail for general problems. This paper revisits probe positioning errors in planar phaseless measurement focused on performance test of integrated millimeter wave antennas under the accuracy of practical measurement facilities. The error effects are...
This paper presents “Smart suit” for body area network. Body communication network need to be prepared for firefighters, astronauts and soldiers to transmit vital data, location and other information to a base and to receive instructions. Corrected data by on/in body sensors are transmitted to an antenna through cables in conventional suits. For easy sensor location and no physical connection with...
This paper presents experimental performance of Optical Leaky Wave Antenna (OLWA) using waffle waveguide (WWG). The antenna is fabricated by silicon photonics technology to achieve high directivity gain leaky waveguide antenna with small perturbation parameter of WWG. Narrow beam and one-dimensional beam scanning is demonstrated by sweeping input wavelength of OLWA. The measured WWG performance is...
Far field antenna pattern measurement requires very long distance for high gain antennas used in cellular base station systems. Its distance, more than tens of hundreds meters, is difficult to set up inside high accurate anechoic chamber. Near field measurement is an alternative pattern measurement with a drawback of time consuming to pick up 2D scanning plane. High speed and accurate measurement...
Wide band electrical parameter measurement for thin material samples is presented by two identical ridged waveguide horn antennas facing each other to propagate quasi-TEM mode between ridges. To suppress multi-reflection inside horns, absorber sheets put on the walls are designed to minimize standing wave in the waveguide. We demonstrate wide band shielding effectiveness measurements and show the...
To efficiently optimize antenna parameters, we need to know more physical insight of antenna operating principles. The theory of characteristic modes is one of the best methods to help us penetratingly understand the antenna's operating principles. This paper is devoted to apply the theory of characteristic modes to provide an in-depth physical insight into the behavior of some proposed antennas and...
This paper presents measurement techniques to reduce sampling points in Total Radiated Power (TRP) measurement by spherical scanned probes. For the sampling point reduction, this paper presents modified equi-angle to eliminate the effect of metric coefficient and generalized spiral scanning to pick up measured data uniformly. Data reduction rate is discussed by the measurement results. In addition,...
A wideband dual-polarized small antenna is proposed using a crossed tapered slot antenna. Antenna height is minimized by optimizing the antenna parameters and is lightweight not to use dielectric materials. Antenna geometry for easy fabrication is also provided by combining two TSAs with a slit and a large hole on each substrate. A MIMO emulator by this dual-polarized antenna is also demonstrated.
In this paper, a simplified specific absorption rate (SAR) measurement method using a broadband wave absorber phantom is investigated for handset antennas. The antenna factors are determined by using finite-difference time-domain (FDTD) analysis to obtain the electric-field intensity from the electric voltage of the probe in the wave absorber at 835 and 1,950 MHz. The measured electric-field intensity...
Wireless power transmission (WPT) by two short helical dipoles arrayed orthogonally is presented. For the electric resonance coupling WPT system, the short dipoles need for a matching circuit due to cancel its large capacitance at the operating frequency. In the proposed method, the loss is reduced by using the helical structure instead of matching circuit. Its power transmission characteristics are...
RFIDs are used to transmit data and electric power simultaneously in many applications such as product management, public transport ticket and so on. RFID was introduced in 13.56 MHz band by the electromagnetic induction coupling. It has an advantage of high transmission efficiency, while its drawback is short transmission distance and low data rate. To extend the RFID applications, the frequency...
In EMI (Electromagnetic Interference) test, the electric field intensity of radiated emission from EUT (Equipment Under Test) is measured. To find the maximum radiation by EUT, a receiving antenna is moved along a vertical pole, because the electric field intensity is seriously changed by the effect of ground reflection wave. In addition to this vertical movement, the main beam tilting is required...
In the wireless power transmission (WPT), the freedom of antenna's position is one of the important things. In the WPT systems using the magnetic resonance, the angle characteristic of two rectangular coils has been reported [1]. Furthermore, the study about the efficiency improvement by a transmission coil array for the decreasing of efficiency due to antenna position has been proposed [2]. Although...
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