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In this paper, a new printed ultra-wideband (UWB) power divider with notched band using square ring multiple-mode resonator (SRMMR) is presented. The characteristics of the proposed SRMMR are investigated by using even- and odd-mode analysis. Then, the initial UWB performance is achieved by introducing SRMMR to the basic Wilkinson power divider. Finally, a pair of parallel coupled lines is embedded into the SRMMR to achieve a desired notched band inside the UWB passband. The central frequency and the bandwidth of the notched band can be easily controlled by the electrical length and coupling coefficient of the coupled lines. To validate the design concept, a novel printed UWB power divider with notched band centered at frequencies of 5.8 GHz is designed and measured. The simulated and measured results indicate that it has a low insertion loss and good return loss performance at all the three ports, and a high isolation between the two output ports across the UWB bandwidth from 3.1 to 10.6 GHz with a small size of 0.46λg × 0.69λg ,w hereλg is the guided wavelength at 6.85 GHz.

A new microstrip ultra-wideband (UWB) bandpass fllter (BPF) with dual sharply rejected notched bands based on E-shaped resonator is proposed in this paper. The basic UWB BPF is designed using two microstrip interdigital coupled lines and one rectangular patch multiple-mode resonator (MMR). Then, to achieve dual band-notched performance, the proposed dual-mode E-shaped resonator is investigated and coupled to the rectangular patch multiple-mode resonator of the basic UWB BPF. To validate the design theory, a microstrip UWB BPF with two notch-bands centered at the frequencies of 5.8GHz and 8.0GHz, respectively, is designed and fabricated. Both simulation and experimental results are provided with good agreement.

A novel compact ultra-wideband (UWB) bandpass fllter (BPF) with triple sharply notched bands and wide upper stopband is proposed. The basic UWB BPF is composed of two microstrip interdigital coupled lines and one multiple-mode resonator (MMR). Then, to achieve triple band-notched performance, the proposed triple-mode stepped impedance resonator (TMSIR) is studied and coupled to the interdigital coupled lines of the basic UWB BPF. To validate the design theory, a microstrip UWB BPF with three notched bands respectively centered at 5.2GHz, 5.8GHz, and 6.8GHz is designed and fabricated. Both simulated and experimental results are provided with good agreement.

A miniaturized Gysel power divider/combiner (PDC) based on planar artiflcial transmission line (ATL) is presented in this paper. This planar ATL is composed of microstrip equivalent quasi- lumped elements and their discontinuities, and the ATL is capable of synthesizing microstrip line with various characteristic impedances and electrical lengths. For demonstration, the simulated and experimental results of proposed PDC @ 1GHz implemented on microstrip are given. Experimental results of the designed PDC agree well with the theoretical predictions. The proposed Gysel PDC circuit not only demonstrates low insertion loss at the fundamental frequency with compact size and high frequency suppression features, but also maintains Gysel PDC's high power-handling advantage. The occupied sizes of the proposed Gysel PDC are merely about 40% of the conventional Gysel PDC.

A novel approach to design microstrip ultra-wideband (UWB) bandpass fllter (BPF) using modifled genetic algorithm (MGA) is proposed in this paper. To achieve high e-ciency and accuracy, conventional GA is modifled. By improving the fltness evaluation, selection, crossover, and mutation, the two possible drawbacks of conventional GA, i.e., slow rate of convergence and local-best solution, are overcome. The modifled genetic algorithm is then applied to simultaneously search for the appropriate circuit topology and the corresponding electrical parameters with UWB characteristic. To demonstrate the efiectiveness of the novel approach, a new microstrip UWB BPF is designed and fabricated. Measurement results agree well with the design index and full-wave EM simulated results.