Browsing by Author "Chen, Hui-Chun"

Now showing 1 - 3 of 3

Modified vertically installed planar couplers for ultrabroadband multisection quadrature hybrid
(2006-08-01)
Chen, Hui-Chun
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
In this letter, we describe a five-section ultrabroadband 1-9 GHz microstrip quadrature hybrid (90 degrees, - 3 dB coupler), which uses two types of modified vertically installed planar (VIP) couplers and is suitable for conventional printed circuit board realization. The modified VIP couplers provide not only a way to implement tight coupling value with reduced modal phase velocity difference but also a layout flexibility to minimize the discontinuity between sections. An experimental circuit is designed and fabricated with a passband ripple of +/- 0.5 dB, a return loss of less than -20 dB, and an isolation of better than 20 dB over the frequency of 1-9 GHz. Very good agreement between the simulated and measured results is obtained.
Printed circuit board bandpass filters with octave bandwidth and very wide upper stopband
(2007-12-01)
Chen, Hui-Chun
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
Bandpass filters with broad bandwidth (up to 70%), very wide upper stopband (nearest spurious passband occurs up to five times of passband center frequency (f(0))), good stopband rejection performance (better than -30 similar to-40 dB in the whole stopband region), and matching with the conventional low cost printed circuit board process with low dielectric constant substrates are proposed in this paper. The proposed filters are designed using parallel-coupled vertically installed planar stepped-impedance resonators (VIPSIRs), which adopt the inherent nature of very tight coupling of VIP coupled line and extremely high impedance of VIP line. The extremely tightly coupled line enables the proposed filters having very wide passband and the extremely high impedance of VIP line leads to extremely large low-to-high impedance ratio that pushes the nearest spurious passband up to 5f(0). Both VIP coupled line and VIP high impedance line are analyzed and characterized by the design charts. The design procedures based on the design charts are verified by several experimental examples. The measured results agree very well with the simulated ones.
Suspended Substrate Stripline Bandpass Filters with both Broad Passband and Wide Upper Stopband
(2007)
Chen, Hui-Chun
;
Chang, Chi-Yang
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents broadband filters with broad bandwidth (up to 70%), very wide upper stopband (nearest spurious passband occurs up to five times of passband center frequency (f(0))), good stopband rejection performance (better than -30 similar to-4dB in the whole stopband region), and easy reproduced by the conventional low cost printed circuit board (PCB) process with low dielectric constant substrates. The proposed filters using suspended substrate stripline stepped impedance resonators (SIRs) with ground aperture technique to realize the extremely tightly coupled low impedance coupled-line sections as well as the extremely high-impedance uncoupled-line sections. The extremely tightly coupled tines enable the proposed filters to have very wide passband and the extremely high-impedance lines lead to large low-to-high impedance ratio that push the nearest spurious passband up to 5f(0). Furthermore, it has been shown that the equivalent circuit model accompanied with the design charts could accelerate the design procedures but keep the accuracy of the results. The design procedures have been described in detail and have applied to designed examples. A good agreement between simulation and measurement has been observed for the given examples.