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A novel band‐stop filter (BSF) using coaxial‐fed slotted substrate integrated waveguide (SIW) is proposed in this article. The proposed BSF is designed using coaxial‐fed line with extended probes penetrating through the substrate and connecting each other, instead of using the main transmission line to dispose the resonators. The SIW cavities perform the resonators excited by the probes to produce a stopband. Then, two BSFs with one and two SIW cavities are firstly designed, both of them have SIW cavity resonator modes and lower‐band reflection zeroes. Then, two types of third‐order BSFs using two cavity resonators and one slot resonator are presented, the high selectivity is achieved by the RZs at both sides of the stopband. Finally, one of the proposed third‐order BSFs is fabricated and measured to verify the design method. [ABSTRACT FROM AUTHOR]

Two third‐order continuously tunable bandpass filters featuring single‐/dual‐band operations, respectively, are presented in this letter. One requires a set of three metallic posts in a single metallic cavity, while the other needs one more set to achieve the desired dual‐band operation. The length of each post is adjusted through a screw from its top to establish the center frequency of the passband. Moreover, the coupling among these three resonators can be controlled by varying their locations to determine the bandwidth of the passband. At the bottom of the cavity, grooves are created to linearize and extend the frequency tuning range. In addition, compared to traditional coaxial cavity filters, the proposed designs offer the advantages of ease in fabrication and low in weight. A practical example for the dual‐band design is presented for experimental verification. The simulated range for the tunable passband is from 0.8 to 3.2 GHz, which amounts to a fractional bandwidth of 120%. The simulated results agree well with the measured data. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel substrate-integrated waveguide (SIW) dual-band bandpass filter fabricated on a double-layer substrate is presented in this article. Each layer uses two rectangular cavities to create a passband, so the two individual bandpass filters are formed by setting the different locations of loaded posts for dual-band operation, that is, 4.6 and 5.3 GHz. In design, the coupling between the upper and lower layers is realized via two slots on the middle metal layer between two substrates. The double-layer structure not only provides a degree of freedom to control the center frequency of two passbands, but also improves the out-of-band rejection skirts with the help of produced transmission zeros. In final, the proposed SIW bandpass filter is fabricated to prove the predicted results in experiment, and good agreement is obtained. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:155-158, 2016 [ABSTRACT FROM AUTHOR]

An ultra-wideband (UWB) bandpass filter (BPF) using the hybrid microstrip and coplanar waveguide (CPW) structure is proposed in this article.The BPF composes of CPW feed lines and H-shaped microstrip resonator. By a CPW/microstrip back-to-back coupling structure, the UWB BPF was realized with the passband covering the entire UWB band (3.1-10.6 GHz). A narrow notched band achieved by etching slots on the lower impedance part of the H-shaped resonator to form an open circuit stub. At last, three U-slot DGSs are used to achieve a good upper-stopband rejection. The measured results are in good agreement with the simulated results. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1577-1581, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27663 [ABSTRACT FROM AUTHOR]

ABSTRACT 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 [ABSTRACT FROM AUTHOR]

In this article, a continuously microfluidically tunable filter using two microstrip resonators is proposed. By injecting different amount of water into the tubes, the resonant frequency as well as coupling intensity between two resonators can be controlled. As a result, the fractional bandwidth (FBW) of the proposed band can keep constant when tuning the frequency. As far as the authors know, most of the state‐of‐the‐art microfluidics tunable filters are discontinuous, and the tuning range is limited. In this article, the wide tuning capacity of the frequency is realized by placing some tubes between the microstrip resonators and the ground. By increasing or decreasing the amount of water in the pipes, the local dielectric constant and the equivalent electrical length of the transmission line are changed simultaneously. Therefore, it plays a key role in resonant frequency tuning. In the other hand, the coupling coefficient can be controlled by injecting the amount of water into the tube between the two resonators. Finally, through the analysis of computer simulation technology simulation and measurement, it can be seen that the tuning range of resonant frequency is up to 41.3%, with the central frequency varying from 1.33 to 1.88 GHz. The insertion loss is less than 3.09 dB and the return loss is higher than 15 dB, while the FBW is 3.4% ± 0.2%. The measurement matches well with the simulation results, verifying the proposed design methodology. [ABSTRACT FROM AUTHOR]

A dielectric‐loaded slot antenna with the characteristic of broadband, low profile, and low cross‐polarization is presented. The antenna incorporating a low permittivity (εl=4.1 ${\varepsilon }_{l}=4.1$) and multiple high permittivity (εh=22 ${\varepsilon }_{h}=22$) rectangle dielectric is fed by two rectangle slot, which generates three slot modes and achieves measured 10 dB impedance bandwidth of 88% $ \% $ from 1.57 to 4.04 GHz covering the long term evolution (1.71–2.69 GHz) and sub‐6G (3.3–3.6 GHz). Furthermore, the presented slot antenna with a footprint of 0.81 × 0.56λ02 ${\lambda }_{0}^{2}$ and a low profile of 0.09λ0 ${\lambda }_{0}$ (λ0 ${\lambda }_{0}$ is the wavelength in the air region at the center frequency) appears the performance of measured peak gain of 9 dB without using any dielectric resonator mode. On the basis of the single‐polarized design, the dual‐polarized design with a profile of 0.09λ0 ${\lambda }_{0}$ is investigated and fabricated. According to the measured results, the dual‐polarized prototype achieves a 10‐dB impedance of 60% $ \% $ from 1.6 to 3 GHz. [ABSTRACT FROM AUTHOR]