• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1214-1218
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• 2010

A new compact UWB bandpass filter with sharp-rejection and low insertion-loss is designed in this paper, using the parallel transmission line with SIR structure. An Example filter is firstly theoretically designed by the proposed synthesis procedure, the optimized by EM simulator, fabricated in microstrip line and finally characterized by a network analyzer. A good agreement between the simulation results and prototype validates the proposed UWB bandpass filter. The designed filter also realized a sharp rejection of higher order with a relatively small size which is proper for the UWB communication system.

• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.582-588
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• 2012

In this paper, a highly miniaturized and performed UWB bandpass filter has been newly designed and implemented by embedding all the passive elements into a multi-layered PCB substrate with high dielectric $SrTiO_3$ composite film for 3.1 - 4.75 GHz compact UWB system applications. The high dielectric composite film was utilized to increase the capacitance densities and quality factors of capacitors embedded into the PCB. In order to reduce the size of the filter and avoid parasitic EM coupling between the embedded filter circuit elements, it was designed by using a $3^{rd}$ order Chebyshev circuit topology and a capacitive coupled transformation technology. Independent transmission zeros were also applied for improving the attenuation of the filter at the desired stopbands. The measured insertion and return losses in the passband were better than 1.68 and 12 dB, with a minimum value of 0.78 dB. The transmission zeros of the measured response were occurred at 2.2 and 5.15 GHz resulting in excellent suppressions of 31 and 20 dB at WLAN bands of 2.4 and 5.15 GHz, respectively. The size of the fabricated bandpass filter was $2.9{\times}2.8{\times}0.55(H)mm^3$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.47-52
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• 2008

In order to enhance the rejection performance of the UWB bandpass filter based on the Composite Right- and Left-Handed Transmission-line(CRLH-TL) Metamaterial cell, we propose the lowpass filtering concept that fits into the design objectives : Keeping metamaterial property and miniaturization. So the bandpass filter itself is made far less than a quarter-wavelength and a pair of symmetric comprises lowpass filtering blocks are placed before and after the center CRLH filter which comprises tile interdigitated coupled lines and short-circuited stob. The design result will show the size of 'guided wavelength/8', the fractional bandwidth over 100%, the insertion loss much less than 1 dB, a flat Group-Delay and a good return loss performance, as expected.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.36-40
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• 2013

A novel design method of ultra wideband bandpass filter using CRLH transmission line with Dumbell type DGS is presented in this paper. Defected Ground Structure and microstrip interdigital capacitor are used to design the ultra wideband (UWB) filter. CRLH transmission line has composite characteristics of low pass and high pass filter. As control of cutoff frequency of low pass and high pass response on CRLH transmission line, we can get characteristic of UWB filter. We designed and simulated for CRLH transmission lines with one, two, four, and eight cells. A UWB filter using four cells CRLH is designed and fabricated to verify the results. The characteristics of designed filter have center frequency of 5GHz and relative bandwidth of 88%.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.371-375
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• 2013

The design of a new compact UWB bandpass filter is proposed, which has cascaded center-tapped microstrip composite right/left-handed transmission-line zeroth-order resonators (CRLH-TL ZORs). In an attempt to reduce the size, instead of the conventional half-wavelength resonators or periodic and multiple CRLH-TL cells, only one cell ZOR geometry is adopted as each resonator in the filter. Additionally, two center-tapped ZORs are coupled to increase the slope of the skirt. Besides, stepped impedance matching parts are placed in the paths to the input and output ports to enhance passband and stopband performances. The proposed filter is shown to have the overall size of $0.69{\lambda}_g{\times}0.70{\lambda}_g$, the insertion loss much less than 1 dB, and an acceptable return loss performance in the predicted and measured results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.102-106
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• 2008

A new compact UWB bandpass filter with sharp-rejection, low insertion-loss and flat group-delay is developed In this paper, using the transversal filtering combined with SIR(stepped impedance resonator) concept. To form the required passband, multiple out-of-band transmission zeros are created around band-edges, securing very low insertion loss in the very wide frequency range. Also it is found to be beneficial to realize a sharp rejection of higher order with a relatively small overall size and simultaneously have very smoothly varying group-delay which is proper for the UWB applications. The validity of the proposed technique is proven theoretically and experimentally.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.928-935
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• 2018

In this paper, a compact fully printable bandpass filter is suggested for a low-frequency channel 3.2 GHz ~ 3.7 GHz in the Ultra-Wideband (UWB) communication system. It is featured with a small geometry of $0.5{\lambda}_g/15$ and a low insertion loss despite using FR4 as a cheap substrate of a high dielectric loss. This is made possible by generating zeroth-order-resonance (ZOR) from one cell comprising two series resonances obviously separated from one shunt resonance as a third-order bandpass filter. Especially, the series resonance elements are combined with spur-lines bent by 90 degrees, which makes the port-impedance matched well and eliminates spurious hikes in the stopband, while the overall size remains almost unchanged. The design is carried out by setting up the equivalent circuit and the circuit simulation is checked by the full-wave EM analysis. The structure is manufactured and measured to show that the circuit modeling and EM simulation results agree with the measured data.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.41-47
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• 2009

In this paper, a band pass filter with a rejection band is proposed for UWB(Ultra Wide Band) communication system. First, low pass filter accessed cut off frequency of 10.2 GHz was designed using structure stepped impedance. And high pass filter accessed cut of frequency of 3.2 GHz was designed using parallel short-stub. There was implemented composite connection of designed low pass filter and high pass filter. The relative dielectric constant, the height, the loss tangent of the PCB substrate were ${\varepsilon}_r$=2.2, h=0.508 mm and loss tangent = 0.0009 respectively. The fabricated band pass filter shows a compact size of 3 cm. The fabricated band pass filter was characterized using 37169A VNA(Vector Network Analyzer). And measured result were obtained 7.5 GHz of bandwidth and -10 dB of return loss and -3 dB of insertion loss from pass band. The result of the research can be used for the UWB communications and MIC/MMIC, RFIC system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.323-332
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• 2009

In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.

• Journal of electromagnetic engineering and science
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• v.9 no.3
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• pp.164-173
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• 2009

In this paper, two new circuit structures for European and U.S. ultra-wide band(UWB) bandpass filters(BPFs) with sharp roll-off characteristics are introduced. We show first that the ultra-wide bandpass property is obtained from a $\lambda$/4 open T resonator with a capacitively coupled $\lambda$/4 short-circuited line, which provides two attenuation poles at lower and upper cutoff frequencies. Then, two identical capacitively coupled input/output lines, which can be $\lambda$/4-length open ends or $\lambda$/2-length short ends, with the T-resonator, are adopted to suppress lower and higher frequency components outside of the pass band. There is coupling between the input and output lines providing two additional transmission zeros in the lower and upper transition bands of the filter. Since the coupling between the T-resonator with the $\lambda$/4 short-circuited line and the input/output lines limits the bandwidth of the filter to the European UWB band, both the $\lambda$/4 short-circuited line and the input/output lines are inserted between the two stacked T-resonators for the U.S. UWB band. The filter structures are simulated with ADS and HFSS and realized with low-temperature co-fired ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results.