Jeong Phill Kim

Miniaturization of lowpass filters by using artificial transmission lines

In this paper, a miniaturization method of lowpass filters by using artificial transmission lines (ATLs) is proposed. Instead of the published lumped element modeling, much more robust modeling of ATL based on ABCD parameters is used for the analysis and design of lowpass filters (LPFs). From two different conventional LPFs based on Richards transformation and Kurodas identity, miniaturized LPF configurations are derived with main transmission lines and stubs replaced by various ATLs. Two LPFs with a cut-off frequency of 2 GHz and 0.2 dB ripple are designed and fabricated. Reasonable agreement between the measured and the specifications is observed. In addition, two proposed LPF configurations show a size reduction ratio of 29.1% and 37.7%, respectively, compared with the corresponding conventional LPFs.

Multilayer directional filters with transmission zero characteristics

A new type of directional filter with a pair of transmission zeros in the stop-band is presented. It has also been showed that these transmission zeros can be properly controlled by adjusting the connecting transmission linepsilas electrical length or the amount of coupling (C).

An efficient optimization design of a manifold multiplexer using an accurate equivalent circuit model of coupling irises of channel filters

In this paper, an efficient optimization design method for a manifold multiplexer is proposed. For an efficient optimization, equivalent circuit models for coupling irises of channel filters are presented. Equivalent circuit models are obtained from the results of electromagnetic field (EM) analysis. To validate the presented optimization design method, a manifold multiplexer for Ka-band satellite applications is designed and realized. The good agreement between theoretical result and measured one is shown.

On the Generalization of Taylor and Bayliss n-bar Array Distributions

Taylors asymptotic analysis theory is used to design the generalized Taylor and Bayliss patterns. Such a design technique allows generating array factors with arbitrary sidelobe level and envelope taper. For both the Taylor and Bayliss patterns, array excitation is obtained by the Elliotts pattern zero matching technique. A few examples are provided to validate the presented theory. Also, variation of different array characteristics with respect to the sidelobe tapering is explained through graphical data.

Design of Various Compact Branch-Line Couplers by Using Artificial Transmission Lines

In this paper, a compact and easy to fabricate branch-line couplers, which can be used for tight and weak couplings with high directivity, is proposed. For these purpose, various artificial transmission lines (ATLs) are incorporated. Design of 3 dB and 10 dB couplers are designed and their characteristics are measured. Good electrical performance and circuit miniaturization indicate the validity of the present theory

Network analysis and design theory of aperture-coupled cavity-fed back-to-back microstrip directional coupler

A network analysis and design theory of an aperture-coupled cavity-fed back-to-back microstrip directional coupler was presented for the efficient and optimized design. For this purpose, an equivalent network was developed, and simple but accurate calculation of circuit element values was described. Based on this equivalent circuit, design equations of the coupler were derived and applied to design a 10 dB directional coupler. The hybrid optimization method based on the genetic algorithm and the Nelder-Mead method was invoked to treat several design parameters simultaneously. Good agreements between the measured and the specifications fully validated the proposed network analysis and design procedure.

Theoretical analysis of surface mountable triple-mode ceramic cavity

A novel surface-mountable ceramic cavity has been considered. The high-permittivity ceramic filling of the basic triple-mode waveguide cavity makes the proposed structure physically small. Integrated microstrip to ceramic filled waveguide transitions provide effective coupling between ceramic cavity and planar circuit. A key point of the suggested theory consists of utilization of weighted Gegenbauer polynomials as the basis functions for the Galerkins procedure. Such a choice of basis functions guarantees high accuracy and efficiency for the entire simulation algorithm. As an application example, a three-pole L-band filter with advanced high-quality factor is demonstrated.