• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.5
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• pp.185-189
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• 2005

This paper focuses on the design for Rx/Tx switch module of GSM(global standard mobile) band, characterization of a miniature, low power and dual-band implementation of the front-end switch module with low-pass filer And the effort to make agreement between the simulated design and the measured data for these solutions takes the place through accumulated design and manufacturing data library. We present the design, modeling and measurement of switch module integrating GSM Rx/Tx switching circuit and LPF(low pass filter) on a LTCC(low temperature co-fired ceramic) substrate. For GSM application, insertion and return loss of the low pass filter designed was less than 0.3 dB which was less than 12.7 dB at 900 MHz. The LTCC switch module contained 10 embedded passives and 3 surface mount components integrated on 4.6$\times$4.8$\times$1.2 mm, 6-layer multi-layer integrated circuit. The insertion loss of switch module measured at 900 MHz was 11 dB. In both of the design approach yielded excellent agreement between measured and simulated results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.262-268
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• 2010

In this paper, a high power active tunable bandpass filter made of dielectric resonators and varactor diodes is designed using the active capacitance circuit generating negative resistance for tuning cellular TX, RX band. An active capacitance circuit's series feedback circuit using GaAs HFET whose $P_{1dB}$ is 32 dBm is used for compensating the losses from the varactor diodes of the tunable bandpass filter. The tuning elements, the varactor diodes are used as the back-to-back configuration to achieve the high power performance, The designed active capacitance circuit improves the insertion loss characteristics. The designed 2-stage active tunable dielectric bandpass filter at cellular band can cover from 800 MHz to 900 MHz. The insertion losses at 836 MHz and 881.5 MHz with 25 MHz bandwidth are 0.48 dB and 0.39 dB, respectively. The $P_{1dB}$ of the designed bandpass filter at TX and RX band are measured as 19.5 dBm and 23 dBm, respectively.

• Journal of radiological science and technology
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• v.10 no.1
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• pp.13-23
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• 1987

Author has studied for finding the method of decreasing the radiation dose and increasing diagnostic range in chest X-ray radiography. The study for the added filter thickness from half value layer to 1/8 value layer by decreasing curve and research for the exposure factors, decreasing ratio of radiation dose, ratio of scatter ray and image quality in chest X-ray radiography. The results were as follows: 1. By using the rare earth intensifying screen system at 120 Kvp, the sensitivity is increased by times and the exposure ratio is decreased 0.22 by comparison with the $CaWO_{4}$ intensifying screen system at 80 Kvp. 2. By using Al added filter of 1/8 value layer, the scatter ray is increased more than no filter, But the scatter ray is decreased more in $G_{4}/RxOG$ intensifying system than in LT-II/Rx intensifying system. 3. At 120 Kvp, the image quality value of $G_{4}/RxOG$ system is increased more than LT-II/Rx system compared with slight decreasing image quality value at 80 Kvp. Concluded that by using the added filter could decrease the radiation dose by 1/3 and obtain effective image quality with the added filter at high voltage hard exposure.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.367-370
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• 1998

A hybrid-integrated SAW(surface acoustic wave) douplexer including transmitter(Tx) filter, receiver(Rx) filter an dantenna terminal has been studied. The prototype duplxer was designed for CDMA system application in the 800 MHz-band. Ladder type SAW filters consisting of one port SAW resonators wer integrated on epoxy substrate to demonstrate the feasiblity of antenna duplexer. In order to perform the duplexing function, a strip line for impedance transformaton with length of .gamma./4 was inserted at rx path. The fabricted duplexer has an insertion loss of 3.0 dB at Tx path and 3.7 dB at Rx path. The attenuation has more than 40dB.

• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.52-57
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• 2014

In this paper, designs and test results of X-band Tx and Rx filters for satellite communications are presented. The passbands are 7.9 ~ 8.4 GHz and 7.25 ~ 7.75 GHz for the Tx filter and the Rx filter respectively. Both of the filters require very high rejection performance between the two passbands. In order to make these filters in an in-line type, non-resonating node method was adopted and E-plane junction was used for the non-resonating node. Design procedures of circuit model design and full-wave electromagnetic model design are described. The test results show that all the performances meet requirements including temperature variations and the sizes are smaller than those of domestic commercial filters by about 30 ~ 40 %.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.245-248
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• 2001

In this paper, we have investigated the design technique and fabricated the surface acoustic wave (SAW) filter for duplexer, which consists of Tx. and Rx. filter, and antenna terminal. For Tx. and Rx. bandpass filters we used the one-port SAW resonators with n-section ladder structure. The structure is composed of couples of series-arm resonators and parallel-arm resonators. RF filter using ladder structure was designed and fabricated on 36$^{\circ}$Y-X LiTaO$_3$ substrates. Designed filters, insertion loss is less than 1.5dB, the bandwidth is more than 25MHz, rejection band level is less than -30dB and center frequency is 820MHz.

• Electrical & Electronic Materials
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• v.9 no.9
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• pp.933-941
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• 1996

In this study, the Tx(Transmitting) and Rx(Receiving) band pass filter for personal communication services was constructed and designed using .lambda./4 TEM mode dielectric resonators. Band pass filter was composed of ceramics resonators which has been developed using ($Zr_{0.65}$,$Sn_{0.35}$) $Ti_{1.04}$ $O_{4.04}$ ceramic and Unloaded-Q ( $Q_{o}$) of .lambda./4 TEM mode dielectric resonator with inner hole size 0.9mm and external size 3mm using silver electrode is 354.5 at 1.95GHz. For the band pass filter design and construction, the design theory and simulation results of band pass filter using J-inverter theory have been studied. The parameters which are evaluated by design theory are practically applied to the filter construction and the simulation results are in agreement with the measured results after fine tunnings.s.s.s.s.s.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.1048-1058
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• 1996

In this paper, a small duplexer is designed and implemented using a H-plane T-junction and Transmitting/Geceiving filte with a dual mode cavity resonator for Ku-band. Transmitting(TX) filter is designed at center frequeny 12.5 GHz and Receiving(RX) filter, at center frequency 14.5 GHz. Both filters have a 100 MHz bandwidth. This duplexer is reduced to about 40% by the conventional duplexer of cavity bandpass filter structure in size. Operating characteristics of duplexer is optimized in order not to distors matching characteristics of each filter when interfaced to a H-plane T-junction. Consequently, the responses of filter with H-plane T-junction nearly coincide with that of filter itself.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.38-46
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• 1996

The purpose of this study is to develop the miniaturized duplexer filter for mobile communications using high dielectric constant (${\varepsilon}$r > 100, 180) ceramic resonators. Duplexer filter was ocmposed of ceramic resonators which has been developed using BNT system and SCT system, respectively. Developed duplexer filter was formed to have Tx frequency band at 836.5 (($\pm$12.5)MHz and Rx frequency band at 881.5 ($\pm$12.5)MHz. Insertion loss at Tx frequency band was 1.41dB and 1.46dB, insertion loss at Rx frequency band was 3.49dB and 3.65dB, respectively. Especially, duplexer filters using dielectric cermaics with ${\varepsilon}$r = 180 were 8% smaller than commercially manufactured duplexer filters using dielectric ceramics with ${\varepsilon}$r = 90 by murata.

• Journal of electromagnetic engineering and science
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• v.6 no.2
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• pp.103-109
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• 2006

This paper suggests an efficient and comprehensive algorithm of the protection ratio derivation and illustrates some calculated results applicable to the initial planning of frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current microwave frequency band of 6.7 GHz including Tx spectrum mask and Rx filter response. According to results, fade margin and co-channel protection ratio reveal 41.4 and 75.2 dB, respectively, for 64-QAM and 60 km at BER $10^{-6}$. It is shown that the net filter discrimination with 40 MHz channel bandwidth provides 28.9 dB at the first adjacent channel, which yields 46.3 dB of adjacent channel protection ratio. In addition, the protection ratio of 38 GHz radio relay system is also reviewed for millimeter wave band applications. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also applied to frequency coordination in fixed millimeter wave networks.