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A triple-passband filter is proposed by exploiting the first three resonant modes in a single rectangular cavity: TE101, TE011, and TM110 modes. Triple-passband frequency response is realized by generating one transmission zero (TZ) between any of two adjacent modes so that each mode contributes one passband. Beside TZs between modes, the three resonant modes are excited by properly placing two coupling apertures at input/output ports of the cavity. When cascading two single cavities, three pairs of slots are used to independently control the coupling between two respective modes of different cavities. As a result, not only two TZs between different passbands but also a pair of additional TZs below the first passband and above the third passband could be realized, respectively, thereby attaining a high selectivity of a triple-passband filter. Finally, a dual-cavity filter with triple-passband and four out-of-band TZs is fabricated and tested. The measured results have verified the validity of the proposed design well. [ABSTRACT FROM AUTHOR]

An integrated method of broadband duplex–filtenna based on a 3-D metallic cavity structure is proposed in this paper. In our design, two broadband filtennas with different operation frequency bands share the same metallic cavity-backed resonator. The two operation bands are realized with fractional bandwidths (FBWs) of 24% and 18%. The whole total FBW of two bands achieves 57%, and there are radiated nulls at the transition band showing a good filtering property. By integrating these two filtennas, a duplex–filtenna is formed with unidirectional radiation property. The radiation gain of these two filtennas exhibits good filtering property. The filtenna gain frequency responses have two transmission zeros near the lower and upper cutoff frequencies of both lower and upper operation bands. To validate the proposed concept, one cavity-backed duplex–filtenna with low-profile metallic cavity is designed and fabricated. The measured results have verified the simulation results well, and the isolation between the two wideband channels exceeds 30 dB as predicted in theory. [ABSTRACT FROM AUTHOR]

In this paper, a wireless charging coil integrated with a Bluetooth antenna is proposed. The equivalent circuit model is developed to analyze this multifunctional coil. The outermost turn of the coil is appropriately designed in order to improve the radiation efficiency of the antenna. In this way, the radiation frequency of the coil is determined by the length of the outermost coil. Meanwhile, the inductance of the coil is adjusted to achieve high charging efficiency. When the coil is taken as a Bluetooth antenna, the measured reflection coefficient has achieved a fractional bandwidth of 8.3%, covering a frequency range of 2.3–2.5 GHz, with $\vert {S} _{11}\vert < -10$ dB. The measured radiation efficiency of the antenna is about 62% at 2.4 GHz. When the coil is applied, the system charging efficiency is about 61%. In particular, the entire circuit module is fabricated on the low-cost FR4 printed circuit board. It can be expected that both the radiation and charging efficiencies can further be improved by using low-loss substrate. [ABSTRACT FROM AUTHOR]

This paper proposes a quasi-elliptic filter with slot coupling and nonadjacent cross coupling based on the substrate integrated waveguide (SIW) cavity. The slots etched on the top metal plane of SIWcavity are used to produce electrical coupling, and the cross coupling is realized by the microstrip transmission line above the SIW cavity. The coupling strength is mainly controlled by the width and height of the slot. The length of the open-ended microstrip line controls the sign of the cross coupling. The cross coupling with different signs are used in the filter to produce a pair of transmission zeros (TZs) at both sides of the passband. In order to prove the validity, a fourth-order SIW quasi-elliptic filter with TZsat both sides of the passband is fabricated in a two-layer printed circuit board. The measured insertion loss at a center frequency of 3.7 GHz is 1.1 dB. The return loss within the passband is below −18 dB with a fractional bandwidth of 16%. The measured results are in good agreement with the simulated results. [ABSTRACT FROM PUBLISHER]

A synthesis method for an even-order Chebyshev bandpass filter of a substrate-integrated waveguide (SIW) is proposed in this paper. The transformation of a Chebyshev polynomial is studied and applied to achieve an equal source and load termination for an even-order filtering response. This transformed Chebyshev polynomial is used to design a millimeter-wave (mmW) SIW bandpass filter through electric coupling of SIW resonators or cavities. The cascaded resonators are formed by properly etching the slots on the top metal plane of a single SIW cavity, and these slots create electric coupling as desired in a filter design. The proposed synthesis procedure of coupled-resonator bandpass filter with an even-order Chebyshev response is given and discussed here in detail. The theoretical and extracted external quality factor ( QE ) and coupling coefficient ( $K$ ) are utilized to determine the filter circuit dimensions. Two fourth-order bandpass filters are designed at 140 GHz under a Chebyshev response using magnetic coupling and electric coupling as design examples. These two filters are used to prove the correctness of the proposed synthesis method as well as the advantages of electric coupling in mmW. In order to prove the validity, the previously proposed fourth-order filter using electric coupling is fabricated. The filter is fabricated in a single substrate layer using a low-temperature cofired ceramic technology and measured in a frequency band around 140 GHz. The measured results are in good agreement with simulated results. [ABSTRACT FROM AUTHOR]

Millimeter-wave (mmW) bandpass filter using substrate integrated waveguide (SIW) is proposed in this paper. The propagation constants of three different types of electromagnetic bandgap (EBG) units are discussed and compared with their passbands and stopbands performance. The slotted-SIW unit shows a very good lower stopband and upper stopband performance. The mmW bandpass filter with three cascaded uniform slotted-SIW-based EBG units is constructed and designed at 40 GHz. The extracted coupling coefficient ( K ) and quality factor ( Q ) are used to determine the filter circuit dimensions. To prove the validity, the previous proposed structure is fabricated in a single circuit layer using low-temperature co-fired ceramic technology and measured at 40 GHz, respectively. The measured results are in good agreement with simulated results in such frequency and the measured insertion losses at 40 GHz is 1.42 dB, respectively. [ABSTRACT FROM AUTHOR]

Millimeter-wave (mmW) bandpass filters (BPFs) using substrate integrated waveguide (SIW) are proposed in this paper. The propagation constants of two different types of electromagnetic bandgap (EBG) units are discussed and compared for their passbands and stopbands performance. In among, the slotted-SIW unit shows a very good lower and upper-stopband performance. The mmW BPF with three cascaded uniform slotted-SIW-based EBG units is constructed and designed at 40-GHz. This EBG filter exhibits good out-of-band performance. To further improve the in-band performance, a third-order mmW BPF with nonuniformly cascaded slotted-SIW unit is designed at 140 GHz. The filter is investigated with the theory of electric coupling mechanism. The extracted coupling coefficient (K) and quality factor (Q) are used to determine the filter circuit dimensions. To prove the validity, the two proposed structures are fabricated in a single-circuit layer using low temperature co-fired ceramic technology and measured at 40 and 140 GHz, respectively. The measured results are in good agreement with the simulated results in such high frequency. The measured insertion losses at 40 GHz and 140 GHz are 0.72 and 1.913 dB, respectively. [ABSTRACT FROM AUTHOR]

In this article, a class of wideband bandpass filters (BPFs) using triple-mode coaxial resonators has been introduced. Each triple-mode resonator is utilized with TM010 mode, TE− mode, and TE+ mode orthogonal to each other. Two L-shaped feeding probes and a loading disk are adopted to implement the miniaturization of these wideband BPFs. To observe the degree of miniaturization, we set a design specification of the same fractional bandwidth (FBW) of 40% at the same central frequency of 2.5 GHz. After employing the L-shaped feeding probes and loading disk, the efficient circuit size without cavity thickness is reduced by 80% compared with the triple-mode wideband filter without L-shaped feeding probes and loading disk. In contrast, the unloaded quality factors are slightly changed. In addition, another advantage of this work is that the upper stopband is extended to $2.5f_{0}$. Three experimental wideband BPFs in the large, medium, and small sizes are designed, manufactured, and tested for demonstration. Good agreements are obtained between simulation and experiment. [ABSTRACT FROM AUTHOR]

This paper proposes a triple-mode dielectric-loaded cylindrical cavity diplexer by using a novel packaging technique for long term evolution (LTE) base station applications. Four metal cavities, loaded by a triple-mode dielectric resonator (DR), are designed to resonate at two different frequencies for the diplexer operation. In this context, three resonant modes of a single cavity are classified as a TM mode and a pair of hybrid degenerate modes (HE modes). The two degenerate modes in the same cavity are properly excited by employing an off-centered DR instead of a traditional corner-cut structure as a perturbation element. Finally, such a diplexer is designed and fabricated, and good agreement between measurement and simulation is achieved. [ABSTRACT FROM AUTHOR]