Search

Abstract In multistage decimation filters some stages operate at the low sampling rate, thus reducing the required number of additions per output sample (APOS). State‐of‐the‐art methods for the design of these filters usually consider only two stages. In addition, these methods do not optimize the number of APOS explicitly. This Letter proposes a framework for the design of multistage decimation filters with minimum number of APOS. To accomplish this task, the structures which contain maximum number of stages allowed by specified decimation factor are optimized. As a case study, multistage filters whose stages are cascaded‐integrator‐comb filters are considered. It is illustrated by several examples that the proposed optimum filters ensure smaller number of APOS and higher folding‐band attenuation than those obtained by recent methods for multistage filter design.

Abstract The present work focuses on the state‐of‐charge (SOC) estimation of a lithium‐ion battery in terms of a second‐order extended Kalman filter (EKF). First, an equivalent circuit model is introduced to describe the performance of lithium‐ion batteries. The model parameters are then identified through hybrid pulse power characterization experiments conducted over a wide range of temperatures (−10 to 55°C). A two‐dimensional mathematical relationship is established with respect to the SOC and temperature based on a dual‐fifth polynomial expression. The main effects and sensitivities of the SOC and temperature on the parameters are analysed according to the principle of variance analysis and partial derivatives. An estimation algorithm is developed, which combines the two‐dimensional parameter model and second‐order EKF. Finally, the proposed approach is validated compared to other estimation schemes through discharge experiments under extreme temperatures and dynamic loading profiles, which yields experimental results that estimate the SOC with an absolute error of less than 4.5% under harsh conditions. This not only demonstrates that it can characterize dependency of the model parameters on the operating conditions and address the uncertainty of model parameters, but also verifies the advantage of present method at low temperatures especially at sub‐zero temperatures.

Abstract In this letter, a novel eighth‐mode ridged substrate integrated waveguide (EMRSIW) is proposed by bisecting the RSIW resonator along the virtual magnetic walls. The EMRSIW shows a size of nearly one‐eighth of a conventional RSIW resonator and a significant size reduction compared to the conventional eighth‐mode SIW resonator. A prototype of a third‐order bandpass filter with transmission zeros has been designed and tested.

Abstract In this letter, a novel wideband bandstop filter with controllable equal‐ripple response is newly presented. The proposed topology consists of two cascaded transmission lines and three open‐circuited stubs, where, one two‐section OS is shunted between two transmission lines, two three‐section OSs are shunted at two output ports, respectively. By using the proposed design approach, both passband and stopband provide controllable equal‐ripple responses independently, where there are five transmission zeros and six reflection zeros in a single period of frequency domain. For demonstration, an experimental BSF centered at 2 GHz with 20‐dB FBW 129.5% and 30‐dB stopband rejection is designed and fabricated. The simulations and measurements agree with the design theory very well.

Abstract A low‐loss Ka‐band coupled‐resonator bandpass filter based on the printed ridge gap waveguide (PRGW) technology is presented for millimetre‐wave communication applications. The PRGW is employed to allow electromagnetic‐wave propagation in the air gap in order to avoid dielectric loss and improve transmission performance which is suitable for millimetre‐wave applications. The bandpass filter is implemented with two transmission zeros which are easily obtained by adjusting the stub length of two T‐shape stub‐loaded resonators (SLR). From its simulation frequency response, the filter has an insertion loss of 0.8 dB, a return loss less than −20 dB during the passband and high selectivity in cut‐off frequency. The prototype of the proposed filter is fabricated and tested and a good agreement can be observed between the measured and simulated results.

Abstract Cross‐coupled microwave filter with flexible topology is an essential component in a modern communication system. Among the various filter networks, the use of an extended box section can effectively reduce the difficulty of filter design, but the synthesis approach for this popular structure is not well developed. This paper presents the synthesis method based on the folded coupling matrix to derive the extended box sections. At the same time, an eighth‐degree filter with extended sixth‐degree box sections is synthesized to demonstrate the correctness of the approach. Finally, the new approach's feature to derive advanced circuits such as peculiar quintets is discussed, indicating that it has certain universality.

Abstract Two dual‐mode filters implemented by folded substrate integrated waveguide (FSIW) are proposed here. The high order modes (TE103 and TE301) in the FSIW cavity are employed to realize the function of filters. The non‐resonating node TE202 mode is employed in the first filter to realize the transmission zero below the passband. A metal pin and an L‐shaped slot are used in another dual‐mode filter to restrict the parasitic mode, TE202 mode. The proposed FSIW dual‐mode filters with simple structures exhibit compact size and good frequency selectivity. As per knowledge, it is the first time that the quarter mode FSIW (QMFSIW) cavities are utilized to design the multimode filters. The measured results agree well with the simulated ones, which validates the feasibility of the compact dual‐mode filters based on the technology of double‐layered FSIW.

Abstract The letter presents a triple‐mode short‐circuited circular patch resonator for bandpass filter (BPF) design. The resonator employs the TM010 mode as its dominant mode, the resonant frequency of which is lower than that of the TM110 mode. In addition, four radial slots are etched on the patch to extend the current paths of the TM110 and TM210 modes, shifting down the resonant frequencies of the two modes. The adjacent triple modes can be used to design wideband BPF. Meanwhile, the centre frequency (CF) and bandwidth (BW) can be tuned by the length of the slots. Furthermore, the short‐circuited vias are arranged in a circle providing a tuneable parameter to control the CF and BW as well. According to the symmetry of the geometry, the resonator can be bisected to realise half‐mode resonance. Two cascaded half‐mode semi‐circular patch resonators are applied to design BPF with high selectivity. BPFs using the circular patch resonator and the semi‐circular patch resonator are designed and measured for demonstration.

Abstract This letter reports an accurate and rigorous design method for a distributed‐element reflectionless bandpass filter capable of producing a reflectionless response at two ports simultaneously. The design method relies on novel transmission‐line reflectionless filter prototypes. This work presents a stub‐based reflectionless filter prototype and its design formulas in terms of a target transmission response. It also provides a stub‐less coupled‐line reflectionless filter prototype equivalent to the stub‐based prototype in case where stubs are not feasible. A second‐order bandpass filter has been designed and fabricated to verify the design method. Reasonable agreement between the measured performance and the simulated one has been obtained, confirming that the proposed design is valid.

Abstract In this correspondence, high‐precision computer numerical control milling is utilised to demonstrate a doubly loaded iris, cross‐coupled waveguide bandpass filter for inline operation within the W‐band. This sixth‐order filter is designed in a stacked H‐plane configuration and utilises both E‐plane and H‐plane doubly loaded irises to maintain the flow of a TE102‐mode electromagnetic field. In this configuration, a high rejection level is maintained outside of the passband while a good unloaded quality factor is obtained through the support of larger resonator dimensions. The filter is designed for approximately 2% fractional bandwidth centred at 97.5 GHz and has been fabricated as three brass components. Measurements of the filter agree very well with the simulated results and demonstrate a spurious‐free design over the full W‐band.

Abstract In this letter, a novel frequency‐reconfigurable substrate integrated waveguide (SIW) bandpass filter (BPF) based on gravity field is proposed. By inverting the proposed filter, the liquid metal would flow into or out of the non‐metallic via‐holes under the influence of gravity, so that the filter centre frequency can be switched from 1.76 GHz (4.54%) in state 1 to 2.02 GHz (5.94%) in state 2, and the insertion losses are maintained at 2.6 dB and 2.4 dB, respectively.