Search

This paper presents the proposal and design of multistate diplexer on uniform- and stepped stub-loaded resonators, that is, a three-state diplexer (TSD) and a four-state diplexer (FSD). The two proposed diplexers have an attractive application in a frequency-hopping system with miniaturization in their overall size. Next, three and four sets of second-order bandpass filters are applied to form the three and four filtering channels, respectively. These filtering channels are then used to comprise these multiple-state diplexers. In this way, compact size and high-frequency selectivity have been well achieved. For the purpose of demonstration, the prototypes of TSD and FSD are fabricated and measured. The measured results are found in good agreement with the simulated results.

A triple-band bandpass filter (BPF) using stub loaded quarter-wavelength triple-mode resonators is presented in this letter. Based on the resonance characteristics analysis, it is found that the fundamental mode and the third harmonic in the quarter-wavelength resonator can be independently controlled by the length of quarter-wavelength resonator and the length of short-circuited stub. Furthermore, a new mode is achieved by a novel technique of loading an open-circuited stub on a short-circuited stub. Finally, triple-band BPF is designed, fabricated, and measured to verify the design principle. Good agreement is achieved between the theoretical, simulated and measured results.

A highly integrated three-state diplexer (TSD) on a single planar elliptical structure is for the first time presented in this paper. Three resonant modes are investigated in a planar elliptical resonator, e.g., two TM11 degenerate modes and one TM21 mode. These three resonant modes are designed to form three filtering channels, which are further combined to generate three states of a diplexer, namely, TSD. The planar elliptical triple-mode resonator is fed by three microstrip lines to form a triple-mode TSD. In order to validate the concept, the designed planar TSD is fabricated and measured. The measured results are in good agreement with the simulated ones.

A helical resonator with two-sectional different pitches is proposed in this paper. The frequency ratios of the first two resonant modes of the helical resonator can be tuned to desirable values in a certain range by adjusting the pitches. The proposed resonator is applied to design dual-band bandpass helical filters. To achieve control over dual-band filtering characteristics, a feeding structure with step-rectangular plate and a coupling window with three apertures are also proposed to realize the expected external quality factors and coupling coefficients in the two bands. To validate the design, a second order and a fourth order dual-band helical filters are fabricated and measured. The measured results show good agreement with simulation ones.

This paper presents a novel modified coaxial cavity resonator and its application to bandpass filters (BPF) with compact size. Unlike the conventional coaxial cavity resonator, the proposed resonator is made up of multi-metal-slices-loaded on the inner coaxial conductor within a single rectangle cavity. The technique with multi-metal-slices is applied to enhance the self-inductance and self-capacitance of the coaxial cavity resonator which leads to size reduction. Based on the research of position and size for the loading multi-metal-slices, an efficient way to load is proposed, Compared to the conventional coaxial cavity resonator, the central frequency can be reduced. Finally, a simulation example of BPF using this technique is presented to validate this attractive design concept.

A compact triple-mode dielectric resonator (DR) bandpass filter (BPF) based on a single waveguide cavity is proposed, while three resonant modes of a single cavity are classified as a TM mode and a pair of hybrid degenerate modes (HE modes). Two HE degeneration modes in a single metal cavity are excited by using an off-centered DR approach. They work together to constitute a three-pole passband with a fractional bandwidth of 2.7% at the central frequency of 2.53 GHz. To verify the proposed idea, the proposed triple-mode DR BPF is fabricated by using silver plated aluminum metal cavity, and the simulated and measured results are in good agreement. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1645–1647, 2016

In this article, a double-T-shaped stub centrally loaded uniform impedance resonator (UIR) is introduced and its resonant characteristics are well clarified, which provided a simple approach for triple-mode wideband bandpass filter (BPF) design. The double-T-shaped stub consists of a T-shaped stub at the center of UIR and two shunt uniform-impedance stubs at the T-shaped stub. Furthermore, loading technique for zero-voltage point is employed to guide design procedure from UIR to the proposed resonator. The resonant frequencies of the first three modes for the resonator can be free to adjust by the length of the UIR and the two kinds of stub. Finally, a compact wideband BPF is designed, fabricated, and measured. The measured results are in good agreement with the full-wave simulation results. The realized wideband filter exhibits a 3 dB fractional bandwidth of 69.1% with good in-band filtering performance, wide stopband, and sharp out-of-band rejection skirt.