This brief introduces a novel concept of a virtual impedance for tri-band impedance matching. The proposed mathematical concept, when applied in practical realization, simplifies the design of tri-band matching to a great extent and also enhances the achievable frequency transformation ratios beyond 7.3. A good agreement between simulation and measurement results on a prototype, designed on RO5880 substrate, operating at three unrelated commercial frequencies of 1.8 GHz, 2.4 GHz, and 5.8 GHz demonstrate the effectiveness of the presented concept.

This article presents the design scheme of a wideband Wilkinson Power Divider (WPD) with two-stage architecture utilizing quarter-wave transmission lines and short-circuit stubs. The bandwidth of the proposed WPD is flexible and can be controlled using the design parameters. The proposed design achieves excellent isolation between output ports in addition good in-band performance. The analysis of the proposed circuit results in a simplified transfer function which is then equated with a standard band-pass transfer function to determine the parameters of transmission lines, stub’s impedances, and the value of the isolation resistors. Furthermore, it is also demonstrated that a simple alteration in the proposed circuit enables the design of a wideband DC isolated WPD that maintains a good in-band and isolation performance. A number of case studies have been included to highlight the flexibility of the proposed design. Two distinct prototypes are developed on different boards to demonstrate the wideband performance of the proposed design. An excellent agreement between the experimental and measured results for both the designs over a wide band including very good isolation between ports validate the proposed design.

This article proposes the design scheme of an ultrawideband Wilkinson Power Divider (WPD). A detailed even and odd-mode analysis is carried out to derive closed-form design equations for the determination of design parameters. The design equations demonstrate that the proposed design theory indeed exhibits a bandpass behavior. Moreover, an interesting feature is a simple equation-derived resistive isolation network for achieving a wideband isolation between the two output ports. The concept of a defected ground is also employed to achieve compactness in design and for achieving realizable values of the design parameters. After analyzing power division in terms of reflection and isolation, a prototype has been designed on RO4003C substrate. The simulated and measured results show excellent agreement with an ultra-wide fractional bandwidth of 82% and port-to-port isolation over a fractional bandwidth more than 100%.