• Title, Summary, Keyword: Radio frequency microwave

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Experimental Measurement System for 3-6 GHz Microwave Breast Tomography

  • Son, Seong-Ho;Kim, Hyuk-Je;Lee, Kwang-Jae;Kim, Jang-Yeol;Lee, Joon-Moon;Jeon, Soon-Ik;Choi, Hyung-Do
    • Journal of electromagnetic engineering and science
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    • v.15 no.4
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    • pp.250-257
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    • 2015
  • This paper presents an experimental measurement system for 3-6 GHz microwave tomography (MT) of the breast. The measurement system is constructed as a minimal test bed to verify key components such as the sensing antennas, radio frequency (RF) transceiver, sensing mechanism, and image reconstruction method for our advanced MT system detecting breast cancer at an early stage. The test bed has eight RF channels operating at 3 to 6 GHz for high spatial resolution and a two-axis scanning mechanism for three-dimensional measurement. The measurement results from the test bed are shown and discussed.

Use of Mobile Phones and Cancer Risk

  • Ayanda, Olushola S.;Baba, Alafara A.;Ayanda, Omolola T.
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.1
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    • pp.403-406
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    • 2012
  • Mobile phones work by transmitting and receiving radio frequency microwave radiation. The radio frequency (RF) emitted by mobile phones is stronger than FM radio signal which are known to cause cancer. Though research and evidence available on the risk of cancer by mobile phones does not provide a clear and direct support that mobile phones cause cancers. Evidence does not also support an association between exposure to radio frequency and microwave radiation from mobile phones and direct effects on health. It is however clear that lack of available evidence of cancer as regards the use of mobile phone should not be interpreted as proof of absence of cancer risk, so that excessive use of mobile phones should be taken very seriously and with caution to prevent cancer.

Application of Radio Frequency Microwave Technique for Glucose Detection (포도당 검출을 위한 라디오 주파수 마이크로파의 적용)

  • Kim Tae-Woo;Park Byoung-Soo;Cho Dong-Uk;Han Khil-Sung;Cho Tae-Kyung
    • The Journal of the Korea Contents Association
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    • v.4 no.4
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    • pp.171-178
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    • 2004
  • Radio frequency (RF) microwave can be used to predict glucose concentration in a sample. This paper presents preliminary results in determining the concentration by measuring relative permittivity in the solutions of distilled water, saline, human serum, and human blood containing glucose. It was shown that the microwave method has larger penetration depth of about 100times of NIR, than NIR technique in measuring glucose concentration for the tissue like a human muscle. The larger penetration depth of the method has advantages because it is more useful to detect glucose in a human body non-invasively. In the experiments, sensitivity for detecting glucose concentration in blood solutions was almost 57mg/dl at the frequency of approximately 5.8GHz.

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Determination of electron energy distribution functions in radio-frequency (RF) and microwave discharges (RF/마이크로웨이브 방전에서의 전자에너지 분포함수의 결정)

  • 고욱희;박인호;김남춘
    • Journal of the Korean Vacuum Society
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    • v.10 no.4
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    • pp.424-430
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    • 2001
  • An electron Boltzmann equation is solved numerically to calculate the electron energy distribution functions in plasma discharge which is generated by radio-frequency (RF) and microwave frequency electric field. The maintenance field strengths are determined self-consistently by solving the homogeneous electron Boltzmann equation in the Lorentz approximation expressed by 2nd order differential equation and an additional particle balance equation expressed by integro-differential equation. By using this numerical code, the electron energy distribution functions in argon discharge are calculated in the range from RF to microwave frequency. The influence of frequency of the HF electric field on the electron energy distribution functions and ionization rate are investigated.

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A K-band Hair-pin Oscillator Using a Frequency Doubler (주파수 체배기를 이용한 K-Band용 Hair-pin 발진기)

  • 현안선;김훈석;김종헌;이종철;김남영;정원채;홍의석
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.6
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    • pp.833-842
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    • 1998
  • In this paper, a K-band oscillator which is composed of a hair-pin resonator, a GaAs MESFET, and a frequency doubler, is suggested, implemented by HMIC(Hybrid Microwave Integrated Circuits) form, and characterized for its microwave performance. A $\lambda_g$/4 open stub is used in frequency doubler to suppress the fundamental frequency of 9 GHz which is the output of the hair-pin resonator oscillator and output matching network is optimized for its second harmonic freuency of 18 HGz. For the oscillator, the output power of -0.83 dBm, the fundamental frequency suppression of -23 dBc, and phase noise of -86 dBc/Hz at 18.20 GHz are obtained.

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Vector Network Analysis Using a One-Path, Frequency-Multiplied Photonic Link

  • Lee, Dong-Joon;Kwon, Jae-Yong;Kang, Jin-Seob;Whitaker, John F.
    • Journal of electromagnetic engineering and science
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    • v.10 no.4
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    • pp.282-289
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    • 2010
  • A simplified, practical vector network analyzer (VNA) that uses mature radio-over-fiber technology has been designed and demonstrated. The measurement concept allows the full S-parameters of a microwave device (or antenna) to be obtained while minimizing the detrimental effects of electrical cables, which are replaced with a photonic link. A variety of high-frequency light modulation schemes with frequency sweeping capabilities are presented to realize a one-path (single, forward), frequency-multiplied optical link for VNA applications. Using the photonic one-path link, full two-port S-parameters have been extracted based on five-term error modeling, which has half the error terms compared with the standard duplex configuration. The S-parameters of a microwave filter and antenna measured using frequency-multiplied optical links are found to be in good agreement with those obtained using a conventional VNA.

Interference Effect of Microwave Oven Noise to Wireless LAN Using a GTEM Cell (GTEM Cell을 이용한 전자레인지 잡음이 무선 랜에 미치는 간섭 영향 분석)

  • Chung, Yeon-Choon;Jeon, Sang-Bong;Kwun, Suk-Tai;Yun, Jae-Hoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.3
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    • pp.240-247
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    • 2009
  • In this paper, we proposed the method of the interference evaluation between the microwave oven noise and the wireless LAN(Local Area Network) by using the GTEM cell. We used microwave oven noise in time to assess the interference unintentional noise effects on wireless LAN and realized by combining an AM(Amplitude Modulation) modulator and a FM(frequency Modulation) modulator. Also the GTEM cell can be used to guarantee the reliability by the evaluations of the frequency and time responses. As measurement results for the APD(Amplitude Probability Distribution) of the interfering noise we analyzed the effect of microwave oven noise to the throughput of wireless LAN.

A reversible data hiding scheme in JPEG bitstreams using DCT coefficients truncation

  • Zhang, Mingming;Zhou, Quan;Hu, Yanlang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.1
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    • pp.404-421
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    • 2020
  • A reversible data hiding scheme in JPEG compressed bitstreams is proposed, which could avoid decoding failure and file expansion by means of removing of bitstreams corresponding to high frequency coefficients and embedding of secret data in file header as comment part. We decode original JPEG images to quantified 8×8 DCT blocks, and search for a high frequency as an optimal termination point, beyond which the coefficients are set to zero. These blocks are separated into two parts so that termination point in the latter part is slightly smaller to make the whole blocks available in substitution. Then spare space is reserved to insert secret data after comment marker so that data extraction is independent of recovery in receiver. Marked images can be displayed normally such that it is difficult to distinguish deviation by human eyes. Termination point is adaptive for variation in secret size. A secret size below 500 bits produces a negligible distortion and a PSNR of approximately 50 dB, while PSNR is also mostly larger than 30 dB for a secret size up to 25000 bits. The experimental results show that the proposed technique exhibits significant advantages in computational complexity and preservation of file size for small hiding capacity, compared to previous methods.

Performance A Analysis of OFDM/QPSK-DMR System Using BL-PSF over Microwave Channel Environments (Microwave 채널환경에서 BL-PSF를 적용하는 OFDM/QPSK-DMR 시스템의 성능분석)

  • Ahn, Jun-bae;Yang, Hee-jin;Oh, Chang-heon;Cho, Sung-joon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.9C
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    • pp.1279-1288
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    • 2004
  • In this paper, the DMR(Digital Microwave Radio) system-based OFDM(Orthogonal Frequency Division Multiplexing) scheme in microwave channel environments has been proposed and system performances have been evaluated. The existing single carrier DMR system has a complex system structure due to using high-level QAM(Quadrature Amplitude Modulation) modulation scheme and so charmel capacity is limited by sensitive effects from fading. Therefore, in the proposed DMR system, it uses that the OFDM scheme for enhancement of fading distortion and also uses that the band-limited pulse shaping filter instead of windowing for no additional data such as GI/GB and for using efficient of IFFT/FFT block. The performance of OFDM/QPSK-DMR system and single carrier DMR system are analysed by computer simulation using two-ray model under the microwave channel environments The computer simulation results confirm that the fade margin of the proposed OFDM/QPSK-DMR system is highly increased as the number of sub-carriers is larger.

Synthesis of Forsterite with High Q and Near Zero TCf for Microwave/Millimeterwave Dielectrics

  • Ohsato, Hitoshi;Ando, Minato;Tsunooka, Tsutomu
    • Journal of the Korean Ceramic Society
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    • v.44 no.11
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    • pp.597-606
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    • 2007
  • With the advent of ubiquitous age, the high quality dielectric materials have been required for the wireless communications available to the millimeterwave as well as microwave frequencies. The utilizable region for the frequency has been expanding to the millimeter-wave region because of the shortage of radio frequency (RF) resources. These high frequencies would be expected for ultra high speed LAN, ETS and car anti-collision system on the intelligent transport system (ITS) and so on. Silicates are good candidates for microwave/millimeterwave dielectrics, because of their low dielectric constant ${\epsilon}_r$ and high quality factor (High Q). Forsterite ($Mg_2SiO_4$) is one of the silicates with low ${\epsilon}_r$ of 6.8 and Q f of 240000 GHz. In this paper, we reviewed following three categories for synthesis of forsterite: (1) Synthesis of high Q forsterite (2) Adjust the temperature coefficient of resonant frequency $TC_f$ (3) Diffusion of $SiO_{4^-}$ and Mg-ions on the formation of forsterite.