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Helmet antennas have been investigated for various applications, such as military, construction, and disaster prevention. In their radio system operated at the low frequency, the half wavelength circular loop antenna, the folded dipole antenna, and the inverted-F antenna have been proposed. Since these antennas are arranged in proximity to the human head, the radiation efficiency is reduced and the...
This paper presents direction of departure (DOD)-based localization technique suitable for indoor environment. Localization is performed by estimating direction from known multiple beacons, where each of them comprises two antennas and 180° hybrid. DOD estimation is performed only from received signal strength indicator (RSSI), which does not have phase information. Indoor measurement campaign has...
The aim of this study is to develop an accurate and reliable method of estimating field distributions in train cars so as to advance radio link design of wireless LANs operated inside the cars. This paper describes effects of absorption and shielding caused by a large number of passengers on propagation characteristics of RF leakage from wireless access point operating in a bullet train. Field distributions...
A corrugated horn antenna with a dielectric lens for high gain performance is proposed in this paper. The proposed antenna consists of a corrugated conical horn antenna and a dielectric lens at the aperture. The material used for the dielectric lens is Teflon having the relative permittivity of 2.1. The proposed antenna provides wide bandwidth to cover the X band(8∼12GHz) and high gain performance...
In estimating DOA of incident waves with high accuracy, we often have to take into consideration the angular spread of each wave due to reflection, diffraction, and scattering. As a method of estimating DOA and AS simultaneously, SAGE-DOA-Matrix method was proposed which uses DOA-Matrix method along with SAGE algorithm. In this paper, we further improve the estimation performance of the method by...
A near-field far-field (NF-FF) transformation technique for RCS measurement is proposed. This technique employing two dimensional plane-wave expansion enables us to measure RCS from two dimensional near-field measurement. It cause significant reduction of near-field measurement cost for relatively thin measurement targets. In comparison with other 2-D transformation techniques, this technique promised...
A compact monopolar patch antenna is presented in this paper. The antenna has a wide bandwidth and a monopole-like radiation pattern. To reduce the whole size of the antenna, a substrate with high dielectric constant is adopted. Besides, three types of shorting pins and a triangle slot are added to the patch to widen the impedance bandwidth. The proposed antenna operates from 2.29 to 2.59 GHz for...
In this paper, we present a detection range enhanced antenna for mobile ultra-high frequency (UHF) RFID (Radio-frequency identification) applications. For the detection rage enhancement, triple polarization switching is used with a pair of parallel dipoles and a feeding network. The pair of parallel dipoles placed orthogonally each other to make a three polarization states by controlling the switches...
In this paper, we demonstrate a waveguide slot array antenna by integration of T-shaped filters using the diffusion bonding of laminated thin metal plates. The excellent performance of the T-shaped filter has been experimentally verified by the in-band transmission and the out-of-band rejection of the fabricated antenna.
A system composed of a grid array antenna (GAA) and parasitic monopoles is analyzed. The analysis is performed using an integral equation with the method of moments to reveal the radiation pattern, axial ratio, half-power beam-width and gain. It is found that the parasitic monopoles contribute to transforming a linearly polarized beam from the GAA into a circularly polarized beam. It is also noted...
In this paper, a novel single-layer broadband subwavelength multi-resonance element is proposed to design a dual circularly polarized (CP) reflectarray with a dual linearly polarized (LP) feed. The simulated results show an adequate phase range over 3600 and low mutual coupling between the two orthogonal polarizations of the element. Also, a superior bandwidth performance has been verified, compared...
A novel slot antenna designed on the road surface for machine-to-machine (M2M) RFID communication is presented. A corrugated ground plane with perturbed surface impedance is used underneath the antenna's radiator to adjust the antenna's radiation pattern, which otherwise will be highly affected by the properties of the road surface. The proposed antenna configuration is verified by full-wave simulations...
In this short paper we briefly revise the criteria defining near and far field. After an extension of the radian sphere notion to finite size sources, we generalize the amplitude and phase criteria for arbitrary source structures. Next we identify with a representative example the wavelength distance where the near field has reached the shape of the far field directivity, then we quantify the difference...
A long range wireless power system operating at 2.45 GHz is developed. The system is comprised of: 1) high gain horn antennas, 2) iteratively tuned matching/filtering network, 3) high efficiency rectifier, and 4) optimized load. An iterative technique is then used to match the antenna to the rectifier to greatly improve the efficiency. The rectifier is built around a single shunt diode rectifier topology...
This paper proposes an optical beam scanning antenna consisting of switched beam waveguide and leaky waveguide. Azimuth angle is changed by switching propagating direction inside waveguide and elevation scanning is given by sweeping the wavelength of tunable laser from 1500 to 1600 nm. The proposed antenna geometry is described in detail and wide angle beam scanning method in elevation plane is presented...
A new back-to-back patch antenna with orthogonal polarization by proximity coupled feed is proposed for repeater use. Two rectangular patches are arranged relative to the ground plane. The proposed patch antennas have bi-directional radiation patterns with orthogonal polarized wave. Good input impedances, axial ratio, isolations and radiation patterns were obtained by simulation.
A novel feeding way tor balanced antennas, loop antennas and spiral antennas, is presented. The author invented recently a circularly polarized simple loop/spiral antenna (CSA), which is configured only by twisting a loop like a cross shape. The CSA can radiate good circular polarization (CP), if it is fed by a good balanced feeder. The strict balance of currents is needed that CSA radiates good CP...
In this paper, a novel communication system for limited area communication is proposed. In the proposed system, sum pattern and differential pattern is used. A main beam of the sum pattern is directed to the direction of the desired user and signal for communication is transmitted using the main beam. On the other hand, a null of the differential pattern is also directed to the desired user and a...
A computational electromagnetics platform that can be used to study interactions between electromagnetic fields and human tissues is presented. The developed platform uses pre-existing triangle-represented geometry models and associated dielectric properties to create a finite-difference time-domain (FDTD) computation environment beyond the open-source MATLAN toolbox. Compared with most commercial...
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