Stepped Impedance Resonators Research Articles

Compact Wideband BPF With Wide Stopband Using Substrate Integrated Defected Ground Structure

In this letter, a compact wideband bandpass filter (BPF) with a wide stopband is proposed based on the substrate integrated defected ground structure (SIDGS) and folded stepped-impedance resonator (FSIR). Such a SIDGS resonator can not only allocate a specific resonance with compact size but also introduce the different harmonic positions compared with a traditional microstrip line resonator. Meanwhile, due to the discrepant harmonic positions of proposed SIDGS and FSIR, a wide stopband response can be achieved using a compact stacked-coupled scheme. To verify the mechanism, a miniaturized wideband BPF operating at 1.69 GHz (i.e., f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) is implemented and fabricated. A measured wide stopband up to 11.8 f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> with a 20-dB rejection level is achieved.

Miniaturized DGS based multi‐band pass filters for satellite applications

This paper presents three types of novel miniaturized single, double and triple band filters using DGS based modified stepped impedance resonator. The modified resonator is linked with square resonators resting on the ground plane. Three types of filters have been proposed with zero rejection, single rejection and double rejection bands. These filters are derived from one another. Hence, there exists some similarity in the filter geometries. However, all the proposed filters are distinct in its design and performance. The double rejection bands are created using half wavelength resonators to reject two different frequency bands. The single rejection band is obtained using F-shaped strip and zero rejection band is obtained using meander etched DGS structure. The proposed triple band-band pass filter (TB-BPF), double band-band pass filter (DB-BPF) and single band-band pass filter (SB-BPF) are simulated and tested with its equivalent prototype. The proposed Type I TB-BPF produces tremendous bandwidth ranges from 2.2 to 4.2 GHz, 4.4 to 7.2 GHz and 8 to 12.8 GHz, Type II DB-BPF operates in two bands such as 2.8–7.9 GHz and 8.2–12.6 GHz and Type III SB-BPF has single pass band from 2.7 to 4.5 GHz. The overall dimension of the filter is achieved to be 0.4 λg × 0.37 λg. Also the measured results are almost matching with simulated results.

A compact UWB antenna with dynamically switchable band-notched characteristic using broadband rectenna and DC-DC booster

AbstractIn this article, a dynamically switchable ultra-wideband (UWB) planar monopole antenna employing defected ground structure (DGS) with a folded stepped impedance resonator (SIR) that can operate as either a UWB mode or the single band-notched mode is introduced. The UWB monopole antenna contains a novel whirligig-shaped radiating patch and a chambered conductor as a partial ground plane. The switchable UWB antenna uses one PIN diode as switching elements in the DGS-SIR structure without any biasing network. When the state of diode is OFF, the planar monopole antenna changes to the UWB mode, and when the diode is turned ON, a frequency notch is created at 5–6 GHz. The state of diode is set to the “ON” state dynamically in the presence of a 5–6 GHz RF signal that is detected by using a wireless power management unit (PMU) that contains a broadband rectenna and a DC-DC passive booster. The rectenna consists of a novel cypress-shaped monopole antenna as a signal receiving part and two sub-rectifiers which are connected to a 3 dB branch-line coupler with a grounded isolation port. The antenna switches from UWB to single band-notched when an RF input signal (≥8.5 dBm) in the 5.25 GHz is sensed by the RF PMU with a conversion efficiency of 26% and DC output voltage of 0.36 V, and it fades immediately in real time when the external RF signal is eliminated. In the three-tone signals, the efficiency and input signal improvements are about 10% and −5.5 dBm in the low-power levels, especially, and so develop and enhance the performance of the dynamic reconfigurability.

Stopband Characteristics Improvement of Waveguide Planar E-plane Filters

The development results of new waveguide planar filters with high selectivity are presented in this article. New bandpass filters (BPF) based on folded metal structures have poles of attenuation characteristics near the filter passband and they are focused on selectivity improvement. Filters are designed in a fully symmetrical topology, which improves performance reproducibility, manufacturability, and reduces manufacturing cost. The proposed BPFs on metal-dielectric structures are based on stepped impedance resonators (SIR) with preservation of the “in-line” topology. They allow us to expand the stopband to the boundaries of the waveguide operating passband and significantly increase the insertion loss level in comparison with the original filters based on homogeneous resonators. In this case, the typical filter linear dimension reduction is about of 30%. Also we show, that the proposed filters form the attenuation characteristic pole far from the filter passband, which makes it possible to achieve a high rejection level with a small number of resonators. The measured characteristics of the filter prototypes are in good agreement with simulation results.

A new compact microstrip dual bandpass filter using stepped impedance and λ /2 bended resonators

In this paper, a compact dual-band bandpass filter (DB-BPF) is implemented by using a pair of coupled stepped impedance resonators (SIRs) and a pair of λ/2 bended resonators for the modern wireless communication systems such as WiMAX and WLAN (3.4 and 5.4-GHz). The physical layout is presented and explained the establishment of an LC equivalent circuit. Moreover, the second passband of the proposed dual-band bandpass filter can be independently controlled by inserting the open-circuited stubs at the end of the λ/2 bended resonators without increasing the circuit size. Simulation results show that the second passband can be ranged from 5.6 to 4.8-GHz with the bandwidth of 400 ± 96-MHz, whereas the first passband is fixed with the bandwidth of 280 ± 8.5-MHz. The measured results exhibit the insertion losses (S21) lower than 1.2 and 1.4 dB, and the return losses (S11) of −23 and −32 dB at the first and second passbands, respectively, which show a good agreement with simulation results. The dual-band microstrip filter is fabricated on RT/Rogers 4003 substrate with a compact size of 0.24λg × 0.25λg.

Mathematical Quad Cross-Stub Stepped Impedance Resonator Application

This simulation study involved the use of a QC-SSIR (quad cross-tub stepped impedance resonator) to examine the behavior and performance of the MW-BPF (multi-wideband band pass filter). To evaluate the performance of the proposed model, it was compared to the case of the conventional resonator. In the results, MW-BPF was found o exhibit a superior performance in terms of the ease of fabrication, good transmission coefficients, and a wider fractional bandwidth. For the filter structure analysis, this study incorporated the ABCD matrix, with the design of the MW-BPF also based on the FR4 microstrip. The experimental conditions and parameters were set in such a way that for the substrate, tan = 0.0265, thickness = 1.6 mm, and r = 4.4, and thickness h = 1.6 mm. at 2.58GHz, 1.71 GHz, and 0.81 GHz, the proposed QC-SSIR-based MW-BPF achieved transmission coefficients/fractional bandwidths of 1.93dB/13.9%, 1.49dB/18.7%, and 0.60dB/49.3%, respectively. Relative to the filter size reduction, the FQC-SSIR (folded quad cross-tub impedance resonator) was incorporated. The resultant observations indicated a possibility of BPF size reduction up to 46%. Also, the proposed framework was found to yield (at 2.62, 1.80, and 0.82 GHz) 1.76dB/12.5%, 1.21dB/17.7%, and 0.57dB/49.6% transmission coefficient/fractional bandwidths, respectively. It is also worth indicating that the filter employed LTE2600, WCDMA1800, and GSM800.

Highly compact quad‐band bandpass filter with flexibly controllable passbands

This letter reports a highly compact microstrip quad-band bandpass filter based on two folded λ/4 stepped impedance resonators and three folded dual-mode short stub-loaded resonators. The two stepped impedance resonators not only form the first passband but also serve as the feed structure and provide the source-load coupling path for the three higher passbands created by the short stub-loaded resonators. Thus, a compact size can be obtained, and three pairs of transmission zeros can be realised near the three higher passbands to improve the frequency selectivity. It has been shown that the centre frequencies and bandwidths of the four passbands can be controlled independently. A microstrip quad-band bandpass filter centred at 1.1/2.05/3/3.55 GHz is implemented and tested achieving an extremely small size of 0.07λg × 0.14λg, where λg is the guided wavelength at 1.1 GHz. This presents one of the smallest quad-band bandpass filter ever demonstrated in the literature.

A novel printed monopole antenna with folded-line SIR loading

A novel printed monopole antenna with simple, low-profile and convenient design is presented in this paper. The antenna composes of a printed monopole antenna and a folded-line stepped impedance resonator (SIR) loaded on the bottom of the substrate. The resonant frequency is decreased by the coupling between the folded-line SIR as the near-field resonant parasitic (NFRP) element and radiation patch of the monopole antenna. The stronger the coupling, the lower the frequency. At the same time, the introduction of the NFRP element does not require an additional circuit for impedance matching, a novel the printed monopole antenna can be achieved. After analyzing the principle of the proposed antenna, a sample antenna has been manufactured and measured to prove the estimated performance of the proposed antenna. The measured results of the proposed antenna are consistent with the simulation, which shows that the design method in this paper is accurate and effective.

Design and fabrication of a microstrip lowpass filter with wide tuning range as harmonic suppression with application in Wilkinson power divider

In this article, a tunable lowpass filter (LPF) with a hexagonal stepped impedance resonator and multi open stubs is designed. The − 3 dB cut-off frequency for the proposed LPF is 2.2 GHz. Insertion loss (IL) and return loss (RL) in the passband zone are 0.3 dB and 15 dB, respectively. The frequency response slope (roll-off rate) for the proposed LPF is very sharp and equal to 142.4 dB/GHz. The tuning range of − 3 dB cut-off frequency for the presented LPF is very wide and equal to 2.7 GHz [from 0.5 to 3.2 GHz (84.3%)]. To achieve the desired structure and harmonics suppression, a conventional power divider was designed initially, then the transmission lines (with length of λ/4) were replaced with two LPFs. The isolation, IL, and input RL for the proposed modified Wilkinson power divider are better than 20.1 dB, 3.1 dB and 21.2 dB, respectively, at operating frequency of 1.8 GHz (GSM band). The proposed modified Wilkinson power divider eliminates the 2nd–11th harmonics with high levels of attenuation. The feature selective validation method depicts that the simulation and measurement results for the proposed LPF are in good agreement with each other.

Design of New Compact Multi-Layer Quint-Band Bandpass Filter

In this paper, we propose the new compact multilayer quint-passband bandpass filter. The multilayer substrate technique is used for further miniaturizing the circuit size. The filter has quint passband at 1.8, 2.5, 3.3, 3.8 and 4.5 GHz. Coupled resonators such as the stepped impedance resonators (SIRs), stub-loaded uniform impedance resonators (UIRs), and quarter-wavelength uniform impedance resonators are applied to produce the quint-passband of the filter simultaneously. The stub-loaded uniform impedance resonators and stepped impedance resonators can easily obtain a filter with closed passbands. Using a multilayer substrate technique, the filter can provide multipath propagation to improve the frequency response and achieve a compact circuit size. The proposed quint-passband bandpass filter shows a simple configuration, a practical design method, and a small circuit size.

3-D Single- and Dual-Polarized Frequency-Selective Rasorbers With Wide Absorption Bands Based on Stepped Impedance Resonator

A 3-D frequency-selective rasorbers (FSR) with wide absorption bands at both sides of the transmission window based on stepped impedance resonator (SIR) is presented and investigated in this article. The proposed FSR features thin thickness, wide absorption bands and lumped-element-free characteristics. The transmission channel is constructed from a parallel waveguide based on SIR to provide the transmission path and reduce the thickness of the whole structure. The absorption channel is filled with magnetic absorber to provide a wide absorption band, while meander-line in shunt connection with the absorber is used to avoid lumped components and to obtain a low insertion loss at the passband. The detailed design concept and analysis are illustrated and the fundamental operating principle of the FSR is demonstrated with the help of an equivalent circuit model (ECM). A design example is provided and it exhibits a passband at 7.1 GHz with a transmission bandwidth of 22.6% for less than 3 dB insertion loss and fractional bandwidth of 128.0% with reflectivity less than −10 dB. Moreover, one dual-polarized FSR is also designed and analyzed to generalize the design strategy. Both single- and dual-polarized prototypes are designed, fabricated, and measured to verify the design concept. Good agreement can be observed between the simulated and measured results.

Design of a Microwave Lowpass – Bandpass Filter using Deep Learning and Artificial Intelligence

In this paper, a lowpass – bandpass dual band microwave filter is designed by using deep learning and artificial intelligence. The designed filter has compact size and desirable pass bands. In the proposed filter, the resonators with Z-shaped and T-shaped lines are used to design the low pass channel, while coupling lines, stepped impedance resonators and open ended stubs are utilized to design the bandpass channel. Artificial neural network (ANN) and deep learning (DL) technique has been utilized to extract the proposed filter transfer function, so the values of the transmission zeros can be located in the desired frequency. This technique can also be used for the other electrical devices. The lowpass channel cut off frequency is 1 GHz, with better than 0.2 dB insertion loss. Also, the bandpass channel main frequency is designed at 2.4 GHz with 0.5 dB insertion loss in the passband.

Synthesis and Design of Highly Selective Multi-Mode Dual-Band Bandstop Filter

This paper presents the synthesis and design of the multi-mode dual-band bandstop filter (MM-DBBSF). A highly selective multi-mode dual-band bandstop response is obtained using a quarter wavelength coupled line structure. It has been shown that by increasing the coupled line's order, the selectivity and the transmission zeros are increased in the desired stopband. Moreover, a step impedance resonator (SIR) is used between two coupled lines to achieve more transmission poles for better out of band selectivity. The paper show a detailed theoretical synthesis of the coupled line and SIR structure. In order to validate the theoretical model, ideal and microstrip topologies are designed and simulated. Furthermore, a high-frequency substrate is used to fabricate four prototypes. The simulated and measured results show good concurrence.

Compact Wideband Dual-Band SIW Bandpass Filters

A novel method to design compact wideband dual-band substrate integrated waveguide (SIW) bandpass filters (BPF) is proposed in this paper. By loading a novel beeline compact microstrip resonant cells (BCMRCs) with band-gap characteristics on top layer of SIW, two wide passbands separated by a stopband are generated. In order to enable the filter to have lower reflection coefficients in the two passbands, we use a tapered gradient line embedded with rectangular slots and loaded open stubs as the transition structure from microstrip line to SIW. The wideband dual-band BPF (DBBPF) is fabricated. The lower-band and upper-band fractional 3-dB bandwidths are 58.2% and 22.6%, while the measured minimum insertion losses (ILs) are 0.7 and 0.92 dB, respectively. The stepped-impedance openloop ring resonator (SIOLRR) is introduced in order to improve the selectivity of the filter. The wideband DBBPF with SIOLRR is studied, simulated and measured. Two transmission zeros are generated in the stop band between the two passbands. Good agreement between simulated and measured results can be obtained.

Design of Dualband Bandpass High-Temperature Superconducting Filter With Group Delay Equalization

A novel dualband high-temperature superconducting (HTS) bandpass filter is proposed with group delay equalization for 5G emergency communication receivers with N41 and N79 bands in this paper. The dual-folded stub-loaded stepped impedance resonator (DSLSIR) is applied to realize dualband performance. The proposed DSLSIR has miniaturized circuit size and more design freedom to independently adjust the two designed center frequencies, comparing with other reported DSLSIRs. Two cross-coupling transmission lines are added at the top and bottom parts of the cascaded sixth-order filter with DSLSIRs to flatten the group delay of the passband at both bands. A dualband bandpass HTS filter etched on the YBCO superconducting material is fabricated to verify the proposed design method. The measurement is actualized at the temperature of 77 K to make YBCO microstrip lines perform superconducting features. The results show that the first center frequency is 2.595 GHz with 6.2% bandwidth for N41 band and 0.3 dB insertion loss while the second center frequency is 4.85 GHz with 2% bandwidth for N79 band and 0.4 dB insertion loss. Meanwhile, the group delays at the N41 and N79 bands keep 2 ns fluctuations in the 60% passband. The agreement between the measured and simulated results indicates that the proposed dualband bandpass HTS filter with low insertion loss, sharp roll-off skirt and flat group delay is a promising candidate for emergency communication receiver.

High Selectivity Single Wideband and Quad-Band HTS Filters Using Novel Quad-Mode Resonators With Self-Coupled Structure

This paper presents improved quad-mode resonators based on the open/short-end load of the center stub, which introduces the self-coupled structure. Compared with the traditional stub-loaded stepped impedance resonator (SLSIR), the proposed quad-mode resonators can significantly reduce the circuit size and further increase the design freedom. First of all, a comprehensive theoretical analysis is performed to infer the resonant characteristics of the proposed resonator. Then, two design prototypes based on different center loads of the resonator were demonstrated to verify the feasibility of the design method. First, a prototype of a wideband high temperature superconducting (HTS) filter with an FBW of 89% is proposed, whose center frequency (CF) can be flexibly controlled. Next, a quad-band HTS filter using different central stub load is proposed, which centered at 1.20, 2.52, 3.51, 4.44 GHz with the 3-dB FBW of 4.8%, 3.96%, 3.97% and 2.2%, respectively. The internal and external coupling mechanisms are also carefully studied to meet the specified requirements. The two prototypes proposed in this paper both have the advantages of compact size, ultra-low insertion loss and steep suppressed skirts. In addition, the measured results are in good agreement with the EM full-wave simulated results.

AN ANALYSIS OF HIGH SELECTIVITY AND HARMONIC SUPPRESSION BASED ON STEPPED-IMPEDANCE RESONATOR STRUCTURE FOR DUAL-MODE DIPLEXER

AN ANALYSIS OF HIGH SELECTIVITY AND HARMONIC SUPPRESSION BASED ON STEPPED-IMPEDANCE RESONATOR STRUCTURE FOR DUAL-MODE DIPLEXER

A 3.9GHz/63.6% FBW Multi-Mode Filtering Power Divider Using Self-Packaged SISL

In this brief, a self-packaged substrate integrated suspended line filtering power divider with wideband and high frequency selectivity by using coupled-line termination added multi-mode resonator has been developed, and has been demonstrated by experiment. Three transmission zeros have been realized due to the coupled-line termination loaded stepped impedance resonator and multi-mode resonator, which improve the frequency selectivity and out-of-band suppression importantly. The wideband filtering power divider has a measured center frequency of 3.9GHz, a fractional bandwidth of 63.6%, an insertion loss of 0.74dB, an in-band isolation (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">23</sub> ) of no less than 18.3dB, and an out-of-band rejection of more than 40dB.

Parametric and Structural-Parametric Synthesis of Nonuniform Transmission Line Resonators

This article discusses methods of parametric and structural-parametric synthesis of resonators, which contain transmission line segments of the same length. These methods allow optimizing resonators of various configurations with different segments number $N$ and characteristic impedances $Z_{0i}$ . We will call optimal resonators if they have a minimum ratio $m = Z_{\mathrm {0max}}/Z_{\mathrm {0min}}$ at given ratio between the critical frequencies (poles and zeros of the input impedance). The input impedances of the resonators under consideration at the Richards’ frequency variable $S$ are described by the reactance functions of $N$ degree: $Z^{N}(S)$ . The parametric synthesis refers to stepped impedance resonators (SIRs). The structural-parametric synthesis refers to resonators of a more general form, which contain open- and short-circuited stubs. The methods are based on two states established in this paper: the order of the reactance function $Z^{N}(S)$ should be the minimum possible ( $N = N_{\mathrm {min}}$ ) to implement the required ratio between certain critical frequencies; the characteristic impedances of the composite sections $Z_{0i}$ take only two values $Z_{\mathrm {0min}}$ or $Z_{\mathrm {0max}}$ . These methods were used to synthesize different resonators useful for practical application. With the help of the structural-parametric synthesis, the resonators of a more complex configuration are synthesized, which significantly exceed SIRs. The results of the measurements and simulation are presented.

Planar Diplexer Design Using an Energetic Coupling Approach

This paper presents a simple procedure to design planar diplexers making use of an energetic coupling approach. The targeted diplexer uses a stepped impedance resonator (SIR) to generate two resonant frequencies at the desired pass bands. The energetic coupling theory is employed to obtain appropriate coupling factors between the SIR and the diplexer outputs. In order to validate the proposed design method two diplexers satisfying the GSM and WLAN application frequencies have been fabricated and characterized. One prototype has been implemented in microstrip technology, while for the fabrication of the other one a low-cost 3D printing multilayer process has been used. In both cases measurements are in good agreement with simulated responses.