Abstract: A method and apparatus for modeling radio propagation is provided. In the method, when a wall having a thickness is modeled as a line having no thickness, an error in a shade area is minimized by considering the thickness of a wall while maintaining simplicity in a ray-tracing method.

Abstract: A probe and an antenna, more particularly, a probe and antenna using a waveguide, which reduces the multiple reflection of electromagnetic waves. The probe includes: and the antenna each include a waveguide and a resonance unit is entirely or partially disposed in the inside of the waveguide, and comprising the resonance unit including a conductor.

Abstract: A method of assigning a frequency channel using efficient spectrum sensing in a multiple Frequency Assignment system includes a channel sensing process, wherein a base station of a secondary user classifies multiple frequency channels licensed to a primary user into a plurality of channel state sets according to usage states, periodically senses channel states by changing a sensing period according to the types of classified channel state sets, and manages the sensed channel states as frequency channel state set information; a channel state set broadcasting process; and a channel assigning process. Accordingly, a frequency channel can be assigned to a secondary user requesting channel assignment using frequency channel state set information without a primary user experiencing interference noise.

Abstract: A CR apparatus for performing communication in a CR network includes: a communication unit configured to measure a channel estimation signal, transmit measured channel state information to a master device, and, when a QP of a reference channel arrives, make a communication channel transition to a candidate channel and perform communication; and a channel information management unit configured to receive and manage the channel state information measured by the communication unit and channel information comprising a candidate channel, into which a channel transition is to be made during a QP of the reference channel, received from the master device and control channel transition of the communication unit based on the channel information.

Abstract: Provided is a method of assigning a frequency channel using efficient spectrum sensing in a multiple Frequency Assignment (FA) system.

Abstract: Provided is an antenna for a base station and a repeater capable of electrically or mechanically controlling the individual operation of an element antenna constituting an array antenna or a sub-array antenna so as to adaptively cope with the change in the communication environment, and having an economic and high performance transmitting and receiving function, and a method of controlling a mode of the antenna. The multi-mode antenna includes a radiation portion having one or more array antenna and capable of selectively changing an antenna effective opening surface and changing a resistance direction of an antenna beam pattern, an active channel portion connected to the array antennas and including switches, transmission and receiving channels, and a signal combiner and splitter, and a modem and control portion connected to the active channel portion and having a control portion and a modem.

Abstract: An all-in-one multi-band antenna includes: a first antenna element configured to operate at a first frequency band, the first antenna element including a first ground, a first radiating part, and a first feed line and a first feed point through which a signal power is applied to the first radiating part; and a second antenna element configured to operate at a second frequency band, the second antenna element including a second ground, a second radiating part, and a second feed line and a second feed point through which a signal power is applied to the second radiating part, wherein the second radiating part is provided within a pseudo-cavity formed at a center portion of the first radiating part.

Abstract: A system for reducing a radiation field in a wireless power transmission system includes a signal generation unit, a power amplification unit, a signal detection unit, a standing wave ratio (SWR) calculation unit and a control unit. The signal generation unit receives power and generates a signal for wireless power transmission. The power amplification unit amplifies the wireless signal generated by the signal generation unit. The signal detection unit detects a radiation signal generated by the magnetic resonator with respect to output power of the power amplification unit. The SWR calculation unit calculates an SWR using the detected radiation signal. The control unit selects a frequency having a lowest SWR based on the SWR calculated by the SWR calculation unit, and controls the signal generation unit to generate the signal for the wireless power transmission using the selected frequency.

Abstract: An image reconstruction apparatus includes: a transmission signal generation unit configured to generate a transmission signal in an image reconstruction region, in order to acquire an image reconstruction value; an electromagnetic wave measurement unit configured to measure electromagnetic waves by receiving the transmission signal; an image reconstruction unit configured to update a parameter by using a matrix of matched system of a Sinc-Gauss-shaped basis function which is allocated to each node of a reconstruction mesh in the image reconstruction region, and generate an image reconstruction value; and an optimization determination unit configured to determine whether the parameter of the image reconstruction unit is optimized or not, and output the image reconstruction value or cause the image reconstruction unit to repetitively perform the calculation, wherein the reconstruction mesh has a grid structure of which the size is larger than that of a forward mesh and equal to the image spatial resolution.

Abstract: A method and an apparatus for controlling transmit power of a CR device are provided. The method includes acquiring CR environment information regarding a licensed user or an unlicensed user occupying an adjacent channel or an adjacent cell of the CR device; determining a transmit power value of the CR device using the CR environment information; and generating transmit power control information including the transmit power value. The method and apparatus guarantee reliable communication of the CR device and minimize interference with the licensed user.

Abstract: An electromagnetic absorber using resistive material includes a ground plane of a conductive material; a dielectric layer formed on the ground plane; and a pattern layer in which specific unit cell patterns made of a resistive material are periodically arranged on the dielectric layer. The electromagnetic absorber is applied to an electronic toll collection system, a transportation device, a building structure, an electronic device and an anechoic chamber.

Abstract: Provided is an isolation antenna for a repeater which can acquire high isolation by using loop and dipole antennas, which are positioned in opposite directions to each other based on a shielding means, in a unidirectional repeater generally used in broadcasting or wireless communications even though transmitting antenna/receiving antennas having a co-channel are set up closely to each other. The transmitting/receiving isolation antenna includes: a shielding means including an electric conductor; a first antenna of a dipole antenna type in one side of the shielding means; and a second antenna of a loop antenna type in an opposite side of the shielding means where the first antenna is positioned.

Abstract: Provided is an antenna system for tracking a satellite which includes a fixed body and a rotating body. The antenna system includes a transmitting/receiving unit having a transmitting channel and a receiving channel for signal power, a driving unit for enabling mechanical motion of the rotating body for satellite tracking, and a control unit for monitoring and controlling the operation of the driving unit. Accordingly, the various kinds of the components of the antenna system mounted and operated on the movable body can be minimized and the output of the transmitted signal required in the antenna system can be simply replaced, thereby simplifying the configuration of the system and reducing the production cost of the system. In addition, the STR having the tracking signal processing function in the digital mode as well as the general analog mode is mounted on the antenna system, thereby improving accuracy of satellite tracking.

Abstract: A resource reservation method between a master device and a slave device or between slave devices in a centralized network. In resource reservation between slave devices, optimal resources may be allocated by performing link measurement between the slave devices before allocating the resources.

Abstract: Provided is a method of sensing an operating channel by using a natural quiet period in a cognitive radio system. A requested QP is reduced by using a natural QP needed for communication that is intrinsic to a communication system, not by using a QP for cognitive radio.

Abstract: Provided is a hybrid beaconing method in which a centralized beaconing scheme and a distributed beaconing scheme are combined.

Abstract: There is a provided a method for managing a multiple frequency assignment using a terminals RX performance in an orthogonal frequency division multiple access (OFDMA) wireless regional area network (WRAN) system, including: a) measuring a bit energy/noise power spectral density (Eb/No) and a received signal strength indicator (RSSI) which are received in the terminal; b) informing the measured Eb/No and RSSI of a base station; c) calculating a round trip delay (RTD) in the base station; d) determining a terminal performance level based on the measured Eb/No, RSSI and the calculated RTD; and e) determining a frequency channel and modulation scheme based on the determined performance level.

Abstract: There is provided to a method for measuring antenna characteristics operating in an out-of-operational frequency range of a chamber, in the chamber having a predetermined operational frequency range, including the steps of: a) measuring reflected wave characteristics of the out-of-operational frequency range generated within the chamber; b) measuring the characteristics of a measurement target antenna operating in the out-of-operational frequency range of the chamber; and c) measuring final characteristics of the measurement target antenna by compensating the characteristic data of the measurement target antenna measured in the step b) for reflected wave data measured in the step a).

Abstract: An electromagnetic-wave suppression structure in a multilayer PCB or package structure is supplied with a power to be used therein by a power distribution network including a power plane and a ground plane. The multilayer PCB and package includes: an electromagnetic-wave suppression structure including an electromagnetic band-gap; and the electromagnetic-wave suppression structure is formed at a specific portion(s) of the power plane and/or the ground plane to suppress noises.

Abstract: Provided is a method for evaluating spectrum utilization efficiency in a radio system sharing frequency. The method for evaluating spectrum utilization efficiency of a frequency sharing radio system in a radio environment having a first radio system using at least one specific frequency in an allocated frequency band and a second radio system sharing the frequency band allocated by the first radio system, includes calculating net coverage per unit area based on a design parameter on the first radio system and a design parameter on the second radio system; and evaluating spectrum utilization efficiency based on the calculated net coverage per unit area.