• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1086-1096
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• 2011

In this paper, we present the trisection band-pass filter with a transmission zero at 2.63 GHz, which has a center frequency of 2.44 GHz, relative bandwidth of 5 %, and return loss of 18 dB, based on a multi-port ElectroMagnetic simulation. The coupling matrix for the trisection filter is calculated and this filter is transformed into band-pass filter prototype through a lossless 2-port circuit transformation. The J-inverter values and slope parameters of each individual resonator are computed using an EM simulation Y-parameters of the filter with multi port. The dimensions of desired filter are determined by matching the computed J-inverter and susceptance slope parameters to those of the prototype band-pass filter. Undesired cross-couplings are found to occur which does not appear in the prototype trisection filter. To overcome the problem of undesired couplings, the filter was optimized to satisfy the same frequency response of prototype filter. The validity of the proposed design method was verified through the implementation of the designed and optimized filter.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.775-782
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• 2022

In this paper, a novel small-diameter cylindrical post capacitor inserted into an evanescent-mode rectangular waveguide (EMRWG) is proposed for easier tuning. In order to feed the EMRWG, the proposed structure uses a single ridge rectangular waveguide with the same width and height as the waveguide at the input and output ends. The inserted post capacitor are made up a circular groove formed in the center of the lower part of the broad wall of the EMRWG, and a concentric cylindrical post inserted into the upper part. First, the equivalent circuit model for the proposed structure is presented. When the EMRWG and the single ridge waveguide are combined, the joint susceptance and the turns ratio of the ideal transformer are calculated by two simulations using HFSS (3d fullwave simulator, Ansoft Co.) respectively. The susceptance and resonance characteristics of the inserted post were analyzed by using the obtained parameters and the characteristics of the EMRWG. A 2-post filter with a center frequency of 4.5 GHz and a bandwidth of 170 MHz was designed using a WR-90 waveguide, and the simulation results by using the HFSS and CST, equivalent circuit model were in good agreement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.4
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• pp.46-52
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• 2009

In this paper, a novel VCO (Voltage Controlled Oscillator) structure is proposed to achieve the characteristic of low phase noise and a wide frequency tuning range. The proposed scheme adopts an impedance transforming technique to change a series resonance into a parallel resonance for maximizing the susceptance slope parameter. The manufactured VCO shows a frequency tuning bandwidth of 600MHz from 10.1GHz to 10.7GHz with a tuning voltage varying from 0 to 9V, an excellent phase noise below -119dBc/Hz@1MHz offset. The harmonic suppression is measured above 28dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.694-704
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• 2011

In this paper, we present a design of a 5th order Chebyshev interdigital band-pass filter using inverter and susceptance slope parameter values obtained from EM simulated multi-port Y-parameters. The shifted length of the resonator is determined when the frequency of the transmission zero is separated far away from the center frequency. For the initial dimensions of the interdigital filter, the filter is decomposed into the individual resonators, and the dimensions are obtained using EM Simulation of the decomposed resonators. However, the interdigital filter with the dimensions determined from the EM simulation of the decomposed resonators shows slightly distorted response from the desired frequency response due to the coupling between non-adjacent resonators. To obtain a EM simulation dataset, EM simulation for this filter is carried out by parameter sweep with constant ratio for the initial values. In this dataset, it is determined the final values for the filter by optimization. The fabricated filter by PCB shows an upper-shift of center frequency of about 70 MHz, which was caused by permittivity changed and tolerance of fabrication.