A 60-GHz compact dual-mode on-chip bandpass filter (BPF) is presented using gallium arsenide (GaAs) technology. To demonstrate the working mechanism of the proposed BPF, an LC equivalent circuit ...model is conceived and analyzed for further investigation of the transmission poles and zeros. Finally, a prototype of the BPF is fabricated and tested to validate the proposed idea, whose simulated and measured results are in good agreement. The measurements show that it has a center frequency of 58.7 GHz with a bandwidth of 18.4%, and the minimum insertion loss within the passband is 2.42 dB. The chip size, excluding the feedings, is about 0.158 mm <inline-formula> <tex-math notation="LaTeX">\times0.344 </tex-math></inline-formula> mm.
A novel on-chip dual-mode resonator (OCDMR) is proposed for the design of millimeter-wave (mm-wave) bandpass filters (BPFs). The proposed OCDMR consists of a stub-loaded metallic line and two ...identical open-end lines, which are extended and bent in opposite directions for coupling to the input and output ports. The two resonant frequencies of OCDMR can be independently adjusted by changing geometric parameters. To clarify the working mechanism of OCDMR, an LC equivalent circuit is constructed to imitate the resonant characteristics of OCDMR, which is calculated and analyzed in detail. Then, using the proposed OCDMRs, three different on-chip mm-wave BPFs with multiple transmission zeros (TZs) are designed and fabricated using 0.13-<inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>m SiGe BiCMOS technology. Good agreement between simulations and measurements validates the feasibility of OCDMR for applications in the on-chip mm-wave BPFs.
This article presents a new decoupling and matching network (DMN) design for symmetric, single- and dual-band two-element antenna arrays. The DMNs use parallel-line-based coupling elements. The ...decoupling between the output ports of the proposed DMN and the reflection coefficients at these ports is obtained using the scattering parameters of the coupled antenna array and those of the DMN. These are clearly expressed as functions of the DMN's design parameters. These design parameters are determined using a simple numerical method to provide high inter-element isolation and good impedance matching for the array. To verify the proposed synthesis procedure, three DMN example designs are considered. These include one for a single-band array and two for dual-band arrays having different frequency ratios. Prototypes of these antennas along with their DMNs were designed, fabricated, and experimentally characterized. In each case, a good agreement between the measured and theoretical results is achieved. Simulation and measurement results show that the proposed DMN design and its associated synthesis procedure can be employed to significantly improve the interelement isolation of single- and dual-band, two-element arrays in various scenarios.
In this paper, a dual-band metamaterial absorber in the terahertz frequencies is proposed and its refractive index sensing characteristics is analyzed. The metamaterial structure is designed using a ...square metal ring with four T-shaped strips loaded outside of the ring, where the metal periodic array is on top of a silicon wafer backed with a metal ground plane. The resonant frequencies of the absorber are at 0.89 and 1.36 THz, whose absorption rates are both over 99% under normal TE and TM polarized incidences. The full widths at half maximum of them are 4.4 and 11.2 GHz, respectively, resulting in high quality factors (
-factors) for these two frequency bands. The absorption rate of the absorber remains stable as the incident and polarized angles are changed. Several proposed metamaterial absorbers are experimentally fabricated and electron beam lithography (EBL) technology is employed. Good measurement results of the dual-band absorption performance are obtained using a terahertz time-domain spectroscopy system based on photoconductive antennas. Furthermore, the metamaterial absorber also shows sensing properties for analytes with different refractive indices or thicknesses. This work provides a new choice for the design of high-
dual-band terahertz metamaterial absorbers and their application to refractive index sensing.
A compact dual-band bandpass filter (BPF) based on parallel coupled lines and shorted stubs has been presented in this Letter. The transmission and reflection coefficients of the proposed dual-band ...BPF are straightforwardly derived via the input impedances using odd- and even-mode analysis methods. Four transmission poles in the two passbands and nine deep transmission zeros (TZs) in the stopband can be realised. The centre frequencies and bandwidths of the two passbands can be tuned by controlling the impedance parameters of the coupled lines and shorted stubs. For demonstration, a prototype example of this dual-band BPF with a small size is experimentally characterised. The measured results show that it has high-frequency selectivity with multiple TZs at the stopband.
A gallium arsenide (GaAs)-based millimeter-wave broadband bandpass filter (BPF) is proposed based on slotted half-mode substrate integrated waveguide (HMSIW) spoof surface plasmon polaritons (SSPPs). ...The center frequency and bandwidth of this SSPP-based on-chip BPF can be easily controlled by tuning the geometry dimensions of the SSPP unit cell, which is attributed to its unique dispersion characteristics. For demonstration, a prototype of the proposed BPF is fabricated and experimentally characterized, with good agreement between the simulated and measured results. Due to the ability of the strong electric field confinement, the proposed on-chip SSPP structure has lower coupling feature with closely-spaced transmission line circuits than its counterpart traditional HMSIW structure.
A compact fifth-order wideband bandpass filter (BPF) using simple coupled lines with sharp rolloff skirts is proposed in this letter. Five transmission poles within the passband and eight deep ...transmission zeros from 0 to <inline-formula> <tex-math notation="LaTeX">2\!f_{0} </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">f_{0} </tex-math></inline-formula> denotes the center frequency of the passband) can be realized through input impedance calculations. For demonstration, a wideband BPF prototype centered at 2.05 GHz with high-stopband rejection is designed and fabricated, whose measured 3-dB fractional bandwidth is of 60% (1.44-2.66 GHz). Good agreement between the simulations and measurements validates the design idea.
A class of millimeter-wave E-plane waveguide bandpass filters (BPFs) based on spoof surface plasmon polaritons (SSPPs) have been presented in this article. Three kinds of SSPPs, with different ...patterns coated on the dielectric substrate, are inserted into the E-plane of WR-10 standard rectangular waveguide for the design of BPFs. To clarify the filtering characteristics of the proposed BPFs, the dispersive properties of different SSPP unit cells are investigated and discussed. The electromagnetic simulation results demonstrate that the bandwidths and center frequencies of the proposed E-plane waveguide BPFs can be flexibly adjusted by controlling the asymptotic frequencies of SSPP unit cells. For verifying the design feasibility, these three E-plane waveguide BPFs are fabricated and measured. Good agreement between measurements and simulations indicates that the proposed idea will be a good candidate for the BPF design with low insertion loss and flexible adjustment of center frequency and bandwidth.
We numerically demonstrate a tunable dual-band terahertz metamaterial absorber (MA) with near-unity absorption using single-layer square graphene ring structure with T-shaped graphene strips. By ...periodically loading four T-shaped graphene strips to the square graphene ring periodic array without additionally increasing the size of MA device, the pre-existing resonant frequency will have a red shift and simultaneously a new resonance will be generated at higher frequency for achieving a dual-band MA. The two absorption peaks can be tuned to the resonant frequencies of interest by varying the parameters of the square graphene ring and T-shaped graphene strips. The operating frequency of the absorption spectrum can be also manipulated by adjusting the chemical potential of graphene, without changing their geometric parameters. Additionally, numerical results show that the proposed MA possesses polarization-independent and incident-angle-insensitive properties. To further extend the proposed structure's application with more absorption peaks, a tri-band MA is investigated through adding four more T-shaped graphene strips based on the dual-band absorber configuration. Therefore, our research work will be a good candidate for the design of various graphene-based tunable multi-band absorbers at different frequency regions with potential applications in optoelectronic devices and systems.
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