Broad-Band Microstrip-to-CPW Transition via Frequency-Dependent Electromagnetic Coupling

Abstract

Abstract-An improved broad-band microstrip-to-coplanarwaveguide (CPW) transition is developed on a basis of the frequency-dependence characteristic of an electromagnetic surface-to-surface coupling. A self-calibrated method of moments is extended to model this unbounded two-port discontinuity with the two dissimilar microstrip/CPW feeding lines. Numerical results are provided to demonstrate its frequency response of transmission under varied strip/slot dimensions and further exhibit its attractive ultra-broad-band transmission with low radiation loss.

Ultra-wideband bandpass filter with hybrid microstrip/CPW structure

“…Let's start to construct and characterize a CPW MMR and a surface-to-surface microstrip/CPW coupling structure [10]. As shown in Fig.…”

“…Fig. 3(a) shows a hybrid microstrip/CPW surface-to-surface coupling structure that was initially studied in [10] to make up a broadband microstrip-to-CPW transition with the use of its frequency-dispersive and enhanced coupling extent. In this structure, the upper microstrip conductor is vertically coupled with the central strip conductor of the lower CPW on ground plane via electromagnetic coupling.…”

“…In this way, a CPW nonuniform or MMR is formed on the ground plane to excite and allocate the first three resonant modes occurring around the lower end, center and higher end of the concerned UWB passband. Meanwhile, a surface-to-surface [10] or broad-side [6] coupled microstrip/CPW structure is characterized, aiming to allocate its coupling peak with enhanced extent around the UWB's center or 6.85 GHz. This proposed UWB filter can address the two problematic issues which exist in the initial UWB filter [7], i.e., an insufficiently tight coupling degree between two side-to-side coupled microstrip lines and parasitic radiation loss from a wide strip conductor or patch in the central part of the MMR on the microstrip line.…”

A Novel Wideband Bandpass Filter Using Stub-Loaded Ring Resonator and Tapped Feed

“…Many techniques [8,9] have been reported using the two-layered structure to significantly enhance this concerned coupling strength, such as aperture-backed coupled lines [8] and broadside-coupled microstripto-coplanar-waveguide (CPW) transition [9]. However, the exact alignment of such a two-layer circuit is still a challenging problem in practical fabrication.…”

Novel broadband microstrip-to-CPW transition with easy transmission band control

“…Also, the microstrip-to-CPW transitions are very useful in RF devices such as couplers and filters [3,4]. Several techniques for microstrip-to-CPW transitions have been reported such as a via-hole and a metal post based on electrical contact [5], an electromagnetic surface-to-surface coupling [6], and a phase shifting technique [7]. Although the aforementioned transitions have broadband characteristic, those transitions are involved the difficulty of transmission band control for various RF circuits and integrated systems.…”