• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.699-706
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• 2010

We have studied to obtain the slanted finger interdigital(SFIT) type filter was formed on the Langasite substrate and was evaporated two IDT electrode by Aluminum-Copper alloy respectively. We can fabricate that the block weighted type IDT as an input transducer of the filter and the withdrawal weighted type IDT as an output transducer of the filter from the results of our computer-simulation. Also, we have performed to obtain the properly design conditions about phase shift conditions of the SPIT type filter. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflectors are $5000\;{\AA}$ and $3.6{\mu}m$ respectively. At the first sample, we have employed that the distance from the hot electrode to the reflectors is $2.4{\mu}m$ distance from the ground electrode to the reflectors is $1.8{\mu}m$ and the distance from the hot electrode to the ground is $1.5{\mu}m$ respectively. At the other sample, we have also employed that the distance from the hot electrode to the reflectors and the distance from the ground electrode to the reflectors are $2.4{\mu}m$. Frequency response of the fabricated SAW filter has the property that the center frequency is about 190MHz and bandwidth at the 3dB is probably 7.3 MHz. And we could obtain that return is less than -20dB, ripple characteristics is probably 3dB and triple transit echo(TTE) is less than -22dB after when we have matched impedance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.457-459
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• 2003

A new hairpin type bandpass fille. (BPF) with novel type of resonators on Teflon substrate is designed, measured, and compared with its simulation results. The proposed filter seems to have advantages of low cost and low loss, thus being very useful for 12 GHz RF applications.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.73-77
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• 2018

This paper proposes a dual-band bandpass filter using stepped-impedance resonators (SIRs) with parallel coupled structures. The proposed filter adopts U-shaped SIRs with parallel coupled lines (PCLs) that have interdigital and comb-line shorted ends. The central PCLs build an upper passband and a transmission zero, and the two U-shaped SIRs build a lower passband. Four resonators and coupling structures are theoretically analyzed to derive its scattering parameters. A novel dual-band bandpass filter is designed and fabricated using the induced scattering characteristics. The measured results show that the fabricated dual-band bandpass filter has an insertion loss of less than 1.02 dB in the lower band of 2.45 GHz and of 3.01 dB in the upper band of 3.42 GHz, and a band-to-band isolation of more than 40 dB, from 3.14 to 3.2 GHz.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.3
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• pp.31-36
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• 1998

In this paper, Image Rejection Interdigital Filter(IRIF) for 5.8GHz wireless LAN was designed and implemented. When the input signal is -30dBm in the 4~8㎓ frequency band, the insertion loss including all kinds of loss is 6.3dB in the center frequency 5.775GHz. Therefore, it was showed practically insertion loss of about -3.3dB. Especially, image signal rejection is about -l7dB in the image frequency 6.475GHz. and skirt characteristics of the high frequency band is very excellent. Therefore, it was confirmed that the proposed IRIF is suitable for RF image signal rejection in the 5.8GHz wireless LAN system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1767-1775
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• 2003

The SAW device is extensively used as a electro$.$mechanical band­pass filter in which a two­pairs of interdigital transducers are provided over the surface of the piezoelectric substrate. For the design requirement, the central frequency and the bandwidth of the passband, and the attenuation level of the stopband region are specified. The configuration is made so as to satisfy the specification given. The central frequency is mainly determined by the distance between the pair of the finger electrodes. The design is considered as an optimization problem with which the error norm, the distance between the desired characteristics and the calculated for a given model is to be minimized. The delta function model and the electrical equivalent circuit model are utilized to represent the SAW filter characteristics. Genetic algorithm is used for optimization in which apodization of the transducer fingers is chosen as a design variable.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2662-2670
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• 2009

The effect of the reflector type for the SAW filter on the characteristics of the slanted finger IDT filter have been studied by computer simulation. The IDT was evaporated by Aluminum-Copper alloy. The design condition was optimized by the phase shift of the SAWfilter for WCDMA. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness are $5,000{\AA}$, and the width and the space of reflector are $3.6{\mu}m$ and $2.0{\mu}m$, respectively. Frequency response of the fabricated SFIT filter has the property that the center frequency is about 190MHz and bandwidth at the 3dB is probably 8.2MHz. And we could obtain that the return loss is less then 16dB, the ripple characteristics is probably 4dB and the triple transit echo is less then 18dB after when we have matched impedance.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.719-719
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• 2006

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1061-1067
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• 2004

In this study, ferroelectric (Ba,Sr)TiO$_3$ and high temperature superconductor YBCO thin films were fabricated by PLD (Pulsed Laser Deposition) method and tuneable bandstop filters were implemented with two different IDC(Interdigital Capacitance) gap patterns, 20${\mu}{\textrm}{m}$ and 30${\mu}{\textrm}{m}$ using these two thin film layers. The resonant frequency was changed by DC bias voltage. By comparing measured results with simulation, the dielectric properties of ferroelectric thin film have been extracted. The permittivity was 820 ～ 900 at 30 K and had an acceptable error range but the loss tangent had a great difference, 0.018 in 30${\mu}{\textrm}{m}$ IDC gap pattern and 0.037 in 20 ${\mu}{\textrm}{m}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.4
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• pp.325-331
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• 2002

In this paper, surface acoustic wave(SAW) bandpass filters using slanted finger interdigital electrode transducers(IDTs) are investigated. The slanted finger IDTs are used to design SAW filters with good shape factor, a flat passband, and good out-of-band rejection characteristic. For the filter design, input-output IDT structure was simulated with modified impulse model; uniform-withdrawal weighting IDTs, withdrawal-withdrawal weighting IDTs. SAW filters of uniform-withdrawal weighting IDTs structure were designed and fabricated on $128^{\circ}LiNbO_3$ piezoelectric substrates. Implemented SAW filter has a fractional bandwidth of 30%, center frequency of 70MHz and shape factor of $1.12\pm0.01$.

• Progress in Superconductivity
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• v.2 no.2
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• pp.92-96
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• 2001

We have fabricated a modified hairpin-type YBa$_2$Cu$_3$O$_{7-{\delta}}$ (YBCO) 2-pole microstrip bandpass filter with the center frequency of 5.8 GHz. We designed a hairpin-type filter with interdigital-coupled inner poles to improve the filter performance. Compared to a typical hairpin-type filter of the same size, the center frequency, the bandwidth and the insertion loss appeared smaller by 14.5% ,29.6%, and 0.55 dB, respectively. The dimensions of the filter were 13.7mm ${\times}$3.3 mm. YBCO films deposited on r-cut sapphire buffered with a CeO$_2$thin layer were used fur making the filter.