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For calibrating electric-field probe to evaluate the value of SAR (specific absorption rate) for devices at a frequency of 30 MHz, a shielded loop antenna is used as a reference antenna. To facilitate curve fitting for the calibration, near-field gain should be constant near the loop. In this paper, it is shown that the circumference of the loop can be selected as the near-field gain becomes approximately-constant...
An adjustable unequal power divider design is proposed. The design replaces two transmission lines of the two-section power divider by two T-equivalent circuits. By tuning the capacitors in the T-equivalent circuits, the power ratio can change from 1∶2 to 1∶3 or from 1∶3 to 1∶2. The circuit has been simulated by EM simulators and verified the performance by fabricated and measured the prototype layout...
Circuits designed and fabricated on a transparent and flexible substrate is presented in this paper. The proposed circuits were designed to operate at 2.4GHz and fabricated on commonly used PVC material. Using double-sided parallel-strip line on power divider and branch line designs, we obtained good simulated and measured results within the frequency of interest.
This paper proposes composed right/left handed transmission lines (CRLH-TL) consisting of arbitrarily-shaped conductor elements, which are designed by a genetic algorithm (GA). However, when the right/left handed transmission lines are constructed by these elements, the higher-order mode coupling between the adjacent elements often causes the unexpected transmission characteristics error and then...
This paper presents a design of a quasi-millimeter wave wideband antenna array consisting of a leaf-shaped bowtie antenna (LSBA) and series-parallel feed networks in which parallel strip and microstrip lines are employed. A 16-element LSBA array is designed such that the antenna array operates over the frequency band of 22–30GHz. In order to demonstrate the effective performance of the presented configuration,...
In this paper, we present a coupled-fed meandered loop antenna on a planar structure. The antenna is fabricated on the FR4 substrate of thickness of 1.6mm and permittivity of 4.4. The antenna with a total size of 30 mm × 13.75 mm × 1.6 mm is feed by a 50 Ohm mini-coaxial line. By using an L-shaped monopole connected on the coaxial line and the meander loop to generate multiple modes to form the required...
Recently, MIMO (Multiple-Input Multiple-Output) technology is introduced in small terminals. If MIMO technology is mounted on a compact body, decoupling methods must be needed. In preceding studies, a decoupling method of 2×2 MIMO by connecting two antennas has been developed. This paper proposes a decoupling method using branch shape of 2×2 MIMO without connecting two antennas.
Multi-input multi-output (MIMO) transmission with multiple antennas, which performs parallel transmission at the same time and frequency and enhances the channel capacity, has attracted attention. In the case of small mobile terminals, the limitation of spaces for the multiple antennas leads to degrade the improvement of the channel capacity in proportion to the number of the antennas. This paper...
An intruder detection method by using Multiple Input Multiple Output (MIMO) channels was proposed (MIMO sensor). Although the channel capacity on the MIMO transmission is severely degraded in time variant channels, we can take advantage of this feature in MIMO sensor applications. For the MIMO sensor, the accurate estimation of channel state information (CSI) is essential. Moreover, the transceiver...
This paper presents a localization method of multiple living-bodies suitable for multi-path environments. The time-variant Multiple-Input Multiple-Output (MIMO) channel is measured and the bistatic MIMO radar estimates multiple target locations from Fourier-transformed channel information. Measurements are carried out in an indoor environment, and it is shown the proposed method can estimate multiple...
Multiuser MIMO (MU-MIMO) improves the system channel capacity by employing the transmission between a base station (BS) and multiple user terminals (UTs). Block Diagonalization (BD) has been proposed as a practical algorithm in MU-MIMO broadcast channel. However, when the number of transmit antennas is equals to the total number of received antennas, the transmission rate by the BD algorithm is decreased...
The downlink non orthogonal multiple access (NOMA) was proposed by using successive interference cancellation (SIC) at the receiver that enables communication with the terminal over the number of base station antennas. Furthermore, technique using both random beamforming and SIC was proposed. In this paper, we propose the spatial multiplexing for multiple users exceeding degree of freedom at the base...
Some novel bandstop filters (BSF's) are proposed,including a sharp-rejection BSF via the combination of the conventional BSF and signal interference technique, a sharp-rejection dual-band BSF using signal-interaction concept with three paths. The measurement results have a good agreement with the simulation results.
Even though they are small in volume and light in weight, the foreign object debris (FOD) on the runways must be removed to ensure the safety and security of flights. To sense and detect those FODs, we have been proposing the novel millimeter-wave radar architecture to improve both the detection and cost performance of the radar system. The radar system is based on the radio-over-fiber technology...
As an alternative of parabolic reflectors, microstrip reflectarrays inherit their many merits as well as those of conventional antenna arrays. This work is focused on solving the problem of terahertz (THz) beam scanning by reflectarrays. The proposed reflectarray is demonstrated based on novel single-layered elements with a linear phase delay and multi-frequency phase-matching method. An operating...
Reflectarray antennas were used to improve wireless propagation channel in none-line-of-sight (NLOS) environment. Experiments for the elimination of blind spots propagation channel and enhancement of MIMO performance were investigated. It was demonstrated that the reflectarray can be used to enhance the communication quality and increase the multipath richness for MIMO communications.
Experimental investigation of electrical properties of Portland cement concretes (PCCs) at microwave frequencies is presented in this paper. An equivalent electric circuit including conductance and susceptance is used for modeling of electrical properties of PCC specimens at early ages. Experimental results demonstrate that electric conductance can be used to identify the different subsurface moisture...
This paper proposes an unified distributed spectrum sensing model for analyzing the overlay, underlay and hybrid overlay/underlay paradigms in a distributed cognitive radio network where there are one primary channel and multiple secondary user (SU) pairs, and the co-channel interference is present. At each SU, the energy detection scheme is employed to identify the usage of the primary channel and...
In this study an Indoor Positioning System (IPS) based on intelligent fingerprint-assisted has been proposed in order to calculate the reliable reference point data and development a positioning system learning mechanism through wireless network connection. Due the change in external environment, the traditional statistical approach will require more than 150 times of learning for the reference points,...
This paper describes characteristics of direct and scattered waves that are extracted from measurement channel data obtained using a 3.35 GHz vector channel sounder in an indoor environment. Each ray of the scattered waves is designated a number in order of the received level. The relationship between the ray number and the characteristics of each ray such as the received level, delay time, and azimuth...
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