National Radio Research Agency
National Radio Research Agency
National Radio Research Agency | Date: 2015-05-15
An apparatus for measuring an antenna radiation pattern comprises a lower bearing unit; a hollow mast which is installed in the vertical direction; a hollow vertical bar, the length of which is vertically adjustable in a state; a goniometer which is horizontally coupled to the upper part of the vertical bar; a horizontal shaft which is positioned at the upper part of the goniometer; a first mounting unit, the length of which is vertically adjustable in a state; a second mounting unit having a vertical shaft which is coupled to the horizontal shaft by vertically penetrating one end of the horizontal shaft, the second mounting unit being installed on the upper end of the vertical shaft; and a support unit of which one end is coupled to the horizontal shaft and the other end is coupled to the outer periphery of the mast.
Yang J.G.,National Radio Research Agency |
Kim N.J.,National Radio Research Agency |
Yeom I.S.,Seoul National University of Science and Technology |
Keum H.S.,Electromagnetic Wave Technology Institute of RAPA |
And 3 more authors.
Measurement: Journal of the International Measurement Confederation | Year: 2017
This study has proposed a method of measuring the characteristics of electromagnetic (EM)-wave absorption and diffraction using MM absorbers (MAs). Metamaterials (MMs) can absorb or affect EM waves towards desired directions. There are a number of ongoing studies on the development of MAs for EM waves. However, as of yet no method of quantitatively evaluating the EM waves absorbed by MM has been clearly defined. It has been explained that the EM characteristics caused by MMs can be explained using Poyntings vector theorem. However, it is necessary to develop a practical alternative to the use of this theorem, because the theoretical evaluations have limitations due to the ideal properties of an antenna for measurement of EM waves and the size of MMs. Thus, this study has suggested that factors to be considered in measuring the characteristics of EM waves absorbed by MMs include distance between MM and antenna, performance characteristics of antenna, conditions of test field, measuring instrument, and measuring system. With a measurement system established, the MMs EM characteristics, which are represented by the amounts of EM waves absorbed and controlled by MMs, can be measured by generating EM waves from the antenna and comparing the differences between when there is a MM absorber and when there is no MM absorber at a location which is a certain distance (far-field) away from the source of the EM waves. This study has shown the amounts of EM waves absorbed by and controlled by MMs by using antennas with 2.4 and 4 GHz bandwidths. © 2016 Elsevier Ltd
News Article | May 15, 2017
Samsung has confirmed it will soon release refurbished versions of the ill-fated Galaxy Note 7 - the phablet that caught fire in several cases last year - but certification for the new phone may prove a problem for Samsung. South Korea is rumored to be the first market the company will release the new Galaxy Note 7 in, but the latest report claims the company has yet to apply for certification from two Korean agencies. The company will need permission from the Korean Agency for Technology and Standards as well as the National Radio Research Agency to be able to release the device in South Korea. A representative for the National Radio Research Agency confirmed customer's safety will come first when it comes to certification. The representative told The Korea Herald, “If Samsung makes such a request, we plan to examine and verify the safety of the device by putting users’ safety as the top priority.” That may be a major stumbling block for the company considering the issues Samsung had with the original Galaxy Note 7. Samsung hopes to help limit the environmental impact of disposing of millions of Galaxy Note 7 devices it currently has in storage by releasing a refurbished version. Rumors so far suggest the new Galaxy Note 7 will have the same specs as we saw on the original device, but will pack a slightly smaller 3,200mAh battery to ensure the device doesn't catch fire again. Whether the new Note 7 will come to the US, UK or Australia is currently unclear, but we can be pretty certain Samsung will be releasing the long rumored Galaxy Note 8 worldwide later this year though.
News Article | May 11, 2017
Samsung already confirmed that a refurbished version of the Galaxy Note 7 will return to stores this year in certain markets, without specifying a firm release date or pricing for the handset. A new report from Korea indicates that the launch is now imminent, and the phone is expected to be priced about 50% cheaper than the original. Don't Miss: Amazon just slashed $20 off each of its three most popular Kindles Citing a report in Chosun Ilbo, The Investor says the phone will be released in Korea as soon as this month. Samsung recently gained approval from the FCC in the United States and plans to soon apply for safety certification with the local regulator, the National Radio Research Agency. The approval process takes up to a month which means the phone could be in stores in early June at the soonest. In a comment, Samsung confirmed the Galaxy Note 7R — that’s the name for the safe Galaxy Note 7 version — will launch before the Galaxy Note 8 debuts. “We have not yet decided on the phone’s launch schedule,” a Samsung official said. “We plan to launch the phone before the Galaxy Note 8 that comes out later this year.” Leaked information indicates the Galaxy Note 7R will sport a smaller 3,200 mAh battery and run Android 7.1.1 out of the box. Comparatively, the original handset had a 3,500 mAh battery pack and launched with Android 6.0.1 on board. While Samsung seems ready to unleash the Galaxy Note 7R in its home market, it’s unknown at this time which other markets will receive the handset, or if it’s heading to the US or not. What we do know is that Samsung has around 3 million Galaxy Note 7 units in its warehouses that need to be disposed of one way or another. Watch news, TV and more Yahoo View, available on iOS and Android. See the original version of this article on BGR.com
Choi D.-G.,National Radio Research Agency |
Kim K.-H.,National Radio Research Agency |
Choi J.,Hanyang University
IEICE Transactions on Communications | Year: 2015
New Target Specific Absorption Rate (SAR) Values, Calculated Using A Proposed Reference Dipole Antenna And The Reference Flat Phantom, Are Presented For An SAR Validation Test At 150 MHz. The Reference Flat Phantom Recommended By The International Electrotechnical Commission (IEC) Standard For 150 MHz Requires A Significant Amount Of Liquid Owing To Its Large Size. We Conduct A Numerical Analysis In Order To Reduce The Size Of The Flat Phantom. The Optimum Size Of The Flat Phantom Is 780 (L1) X 540 (W) X 200 (H) Mm3, Which Is Approximately A 64% Reduction In Volume Compared To The Reference Flat Phantom. The Length Of The Reference Dipole Antenna Required For The Optimized Flat Phantom (extrapolated From The Reference Values At 300 MHz) Becomes 760 Mm. The Calculated And Measured Return Losses (S11 ) Of The Antenna At 150 MHz Are 24.1 DB And 22 DB, Respectively. The Calculated And Measured Results For The Return Loss Of The Dipole Antenna Agree Well And Satisfy The IEC Standard (> 20 DB). The Target SAR Values Derived From The Numerical Analysis Are 1.08 W/kg For 1 G Of Tissue And 0.77 W/kg For 10 G Of Tissue For An SAR Validation Test At 150 MHz. Copyright © 2015 The Institute Of Electronics, Information And Communication Engineers.
Kim K.J.,Yonsei University |
Choi W.C.,Yonsei University |
Yoon Y.J.,Yonsei University |
Bae S.-H.,National Radio Research Agency
2015 International Workshop on Antenna Technology, iWAT 2015 | Year: 2015
The 8×8 array applicator for 915 MHz hyperthermia proposed. Proposed array applicator is 8×8 lattice array with and without phased feeding. 8×8 lattice array with same phase is for superficial hyperthermia. 8×8 lattice array with phased feeding is for ultra-superficial hyperthermia, which has deeper treatment area. 8×8 lattice array without phased feeding has 61 % effective treatment area of array size in 2 cm depth from skin surface. 8×8 lattice array with phased feeding has penetration enhancement from 34 mm to 49 mm. © 2015 IEEE.
Park J.,National Radio Research Agency |
Kim W.N.,National Radio Research Agency |
Kang B.-G.,National Radio Research Agency |
Yeon H.,National Radio Research Agency
2014 31th URSI General Assembly and Scientific Symposium, URSI GASS 2014 | Year: 2014
The existing calibration methods of EMI antenna have to use three antennas. Even standard antenna method replacing the standard antenna by the calibrated antenna needs a common transmitting antenna. In this paper, a simple calibration method which uses only two antennas is discussed. The method requires a information for electric fields at receiving location. Standard antennas knowing antenna factors can determine such electric fields. Calculable standard dipole antenna has theoretical antenna factors and site insertion losses calculated by Numerical Electromagnetic Code in free space or in open area test site with infinite perfect conducting plane. Formula of new calibration method using the standard antenna are derived. Antenna factors measured by new method in open area test site of National Radio Research Agency (NRRA) are compared to the theoretical values. The results show good agreements within 0.09 dB from 30 MHz to 1 GHz. © 2014 IEEE.
Bae S.-H.,National Radio Research Agency |
Cha D.-H.,National Radio Research Agency
2014 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), USNC-URSI 2014 - Proceedings | Year: 2014
TVWS service is expected to be introduced in the near future. It should have to be capable of providing the broadcasting and TVWS services. However, it is difficult to share between broadcasting service and TVWS service in dense urban areas of the propagation environment. To date, there is no propagation prediction model for analysis of the two services. Recommendation ITU-R P.1546, propagation prediction method, is one of the candidates to analyze the both services. Recommendation ITU-R P.1546 is a point-to-area propagation prediction model, which is 30 ∼ 3000 MHz of the frequency band corresponding to the intervals 1 ∼ 1000 km distance. But it lacks accuracy for urban propagation model less than 1 km. © 2014 IEEE.
Khuyen B.X.,Hanyang University |
Tung B.S.,Hanyang University |
Dung N.V.,Hanyang University |
Yoo Y.J.,Hanyang University |
And 5 more authors.
Journal of Applied Physics | Year: 2015
We numerically and experimentally demonstrated a metamaterial perfect absorber (MPA) in MHz region based on a planar sandwiched metal-dielectric-metal structure. First, the single-peak perfect absorption was obtained at 400MHz. The ratios of the periodicity of unit cells and the thickness to the absorption wavelength are 1/12 and 1/94, respectively. The advantage of structural design and the mechanism for the low-frequency MPA are described in detail by the comparison between calculation, simulation, and experiment. Influence of the incident angle of electromagnetic (EM) wave for both transverse-electric (TE) and transverse-magnetic (TM) polarization on absorption was also investigated, and the absorption was maintained to be above 95% at incident angles up to 30°. Finally, we propose a self-asymmetric structure, which induces the dual-band perfect absorption in the same range of frequency. The EM behavior of the excitation modes and the mechanism of the dual-band MPA are clearly explained. Especially, when two resonance modes are finely controlled to be close enough, the bandwidth (full width at half maximum) of MPA is enhanced to be nearly wider twice than that in case of single-peak perfect absorption. The enhanced bandwidth is still well preserved by varying the incident angle up to 30°for both TE and TM polarization. The results were also confirmed by both simulation and experiment. Our work is promising for potential practical applications in the radio range, such as radio-frequency shielding devices, single/dual-frequency filters, and switching devices. © 2015 AIP Publishing LLC.
News Article | October 28, 2016
The only iPhone 7 Series cell phone case on the market that is designed to protect users from excessive radiation is available now, as part of the RF Safe Cooperation’s new three component iPhone 7 Safety Package. The case is designed with a cell phone radiation shielded flip cover to protect the user from microwave exposure. RF Safe, global leader in EMF safety, has launched its next generation iPhone 7 safety package, also featuring the RF Safe AirTube Headset, and RF Safe Ferrite Bead, a simple clip on device to provide cell phone radiation shielding for wired headsets. “Radiation safety is often like safely operating a motor vehicle. You use a blinker, seat belt, and headlights to maintain a safe driving experience,” says RF Safe founder, John Coates, “With cell phone radiation, it’s critical to have user knowledge of the wireless device to maintain proper distances and correctly use RF shielding.“ Health experts have been issuing warnings to consumers about the damaging impact cell phone radiation could have. The American Academy of Pediatrics (AAP) recently reinforced recommendations to utilize hands-free kits and limit usage. According to a recent report by ZDNet, an assemblyman of the National Radio Research Agency of South Korea claims that the new iPhone 7 and iPhone 7 Plus have twice the average special absorption rate (SAR) value in comparison to Samsung phones. Bluetooth technology powers the new iPhone 7 AirPods. Dr. Joel Moskowitz, a professor at the UC Berkeley School of Public Health, recently warned consumers that over time these emissions wear down the blood-brain barrier, which is essential for keeping out chemical toxins. With the AirPod, most of the wireless communications will emanate from the ear canal itself, according to details outlined by Apple last week. Apple’s W1 wireless chip, a focal point of the updated wireless technology, is housed in the bulbous portion of the AirPod that nestles into the ear canal. “You are putting a microwave-emitting device next to your brain,” says Moskowitz. With the AirPod sending high-tech radiation right into your ear, RF Safe says it could pose serious, long-term dangers, particularly for children. The RF Safe AirTube Headset features air tube acoustic technology, reducing microwave exposure to the head. iPhone users will experience the newest innovation in radiation safe cell phone headsets, and rich live sound without any electrical components in their ears. $1 from all pink RF Safe products will be donated help fund breast cancer research for National Breast Cancer Awareness Month. Since 1998 RF (Radio Frequency) Safe has been dedicated to evolving the wireless industries safety standards, by engaging in the business of design, testing, manufacture, and sale of safety technologies to mitigate harmful effects of cell phone radiation.