Showing papers on "Stopband published in 2020"
TL;DR: In this article, a dual-polarized millimeter-wave (mm-wave) patch antenna with bandpass filtering response is proposed, which consists of a differential-fed cross-shaped driven patch and four stacked parasitic patches.
Abstract: This article presents a novel dual-polarized millimeter-wave (mm-Wave) patch antenna with bandpass filtering response. The proposed antenna consists of a differential-fed cross-shaped driven patch and four stacked parasitic patches. The combination of the stacked patches and the driven patch can be equivalent to a bandstop filtering circuit for generating a radiation null at the upper band edge. Besides, four additional shorted patches are added beside the cross-shaped driven patch to introduce another radiation null at the lower band edge. Moreover, by embedding a cross-shaped strip between these four stacked patches, the third radiation null is generated to further suppress the upper stopband. As a result, a quasi-elliptic bandpass response is realized without requiring extra filtering circuit. For demonstration, a prototype was fabricated with standard PCB process and measured. The prototype operates in the 5G band (24.25–29.5 GHz) and it has an impedance bandwidth of 20%. The out-of-band gain drops over 15 dB at 23 and 32.5 GHz, respectively, which exhibits high selectivity. These merits make the proposed antenna a good element candidate for the 5G mm-Wave massive MIMO applications to reduce the requirements of the filters in the mm-Wave RF front ends.
88 citations
TL;DR: In this paper, the authors investigated the feasibility of designing a high gain on-chip antenna on silicon technology for subterahertz applications over a wide-frequency range, which achieved high gain by exciting the antenna using an aperture fed mechanism to couple electromagnetics energy from a metal slot line, which is sandwiched between the silicon and polycarbonate substrates, to a 15-element array comprising circular and rectangular radiation patches fabricated on the top surface of the poly carbonate layer.
Abstract: This letter investigates the feasibility of designing a high gain on-chip antenna on silicon technology for subterahertz applications over a wide-frequency range. High gain is achieved by exciting the antenna using an aperture fed mechanism to couple electromagnetics energy from a metal slot line, which is sandwiched between the silicon and polycarbonate substrates, to a 15-element array comprising circular and rectangular radiation patches fabricated on the top surface of the polycarbonate layer. An open ended microstrip line, which is orthogonal to the metal slot-line, is implemented on the underside of the silicon substrate. When the open ended microstrip line is excited it couples the signal to the metal slot-line which is subsequently coupled and radiated by the patch array. Measured results show the proposed on-chip antenna exhibits a reflection coefficient of less than −10 dB across 0.290–0.316 THz with a highest gain and radiation efficiency of 11.71 dBi and 70.8%, respectively, occurred at 0.3 THz. The antenna has a narrow stopband between 0.292 and 0.294 THz. The physical size of the presented subterahertz on-chip antenna is 20 × 3.5 × 0.126 mm3.
67 citations
TL;DR: This brief proposes the design and measurement of tunable, highly selective and wide-stopband microwave filters using substrate integrated waveguide (SIW) technology, and a prototype is fabricated on RT/duroid 5870 substrate and measured.
Abstract: This brief propose the design and measurement of tunable, highly selective and wide-stopband microwave filters using substrate integrated waveguide (SIW) technology. A two pole filter is designed using optimized cavity parameters. Two higher order (4-pole) filters are designed by connecting two cavities vertically and horizontally through coupling slots. In this way, four poles are achieved in two cavities, in which the proposed filter produces $2\times \text{N}$ poles in N cavities. A varactor diode is employed in both configurations to make the filters tunable. The proposed filters have wide upper stopband performance [20 dB up to $4.8f_{1}$ (Filter 1) and 20 dB up to $4.2f_{1}$ (Filter 2)], lower insertion losses [0.2-1.1 dB (Filter 1) and 0.2-1.5 dB (Filter 2)] and good tunability ranges [2.7–3.4 GHz (Filter 1) and 3.1–3.9 GHz (Filter 2)]. In order to validate the proposed design, a prototype is fabricated on RT/duroid 5870 substrate and measured. The simulated results accord closely with the measured results.
55 citations
TL;DR: In this paper, a two-dimensional solid structure with embedded inertial amplification mechanisms that shows an ultrawide stop band (band gap) at low frequencies was designed and the compliant hinge connections were designed to achieve the maximum possible stop band width.
54 citations
TL;DR: In this article, a mass-beam resonator was used to obtain a specific and low-frequency stopband for a sandwich-like plate with a fixed cantilever beam and mass block.
52 citations
TL;DR: A high-isolation and wide-stopband diplexer with controllable transmission zero nearby the passband, is implemented using substrate integrated waveguide elements and good agreement between simulation and measurement can be observed.
Abstract: In this brief, a high-isolation and wide-stopband diplexer with controllable transmission zero (TZ) nearby the passband, is implemented using substrate integrated waveguide elements. The TZ is generated by the mixed electric and magnetic coupling scheme of $ {TE}_{ {101}}$ mode. It can be flexibly controlled by changing the length of rectangular apertures while keeping good wide-stopband performance unchanged. An ${X}$ -band diplexer with lower and upper channels centered at 9.5 GHz and 10.5 GHz was designed, fabricated, and measured to verify the proposed concept. Good agreement between simulation and measurement can be observed. The designed diplexer exhibits a high isolation level larger than 45 dB over the whole band and a wide stopband up to 20 GHz.
44 citations
TL;DR: In this article, the authors presented the first demonstration of distributed and symmetrical all-band quasi-absorptive filters that can be designed to arbitrarily high orders and showed simultaneous input and output absorption across both the passband and the stopband.
Abstract: In this article, we present the first demonstration of distributed and symmetrical all-band quasi-absorptive filters that can be designed to arbitrarily high orders. The proposed quasi-absorptive filter consists of a bandpass section (reflective-type coupled-line filter) and absorptive sections (a matched resistor in series with a shorted quarter-wavelength transmission line). Through a detailed analysis, we show that the absorptive sections not only eliminate out-of-band reflections but also determine the passband bandwidth (BW). As such, the bandpass section mainly determines the out-of-band roll-off and the order of the filter can be arbitrarily increased without affecting the filter BW by cascading more bandpass sections. A set of 2.45-GHz one-, two-, and three-pole quasi-absorptive microstrip bandpass filters are designed and measured. The filters show simultaneous input and output absorption across both the passband and the stopband. Measurement results agree very well with the simulation and validate the proposed design concept.
43 citations
TL;DR: In this article, a simple dual-polarized antenna with filtering responses and enhanced bandwidth is proposed for base station applications, which concludes three parts: dipole elements, baluns, and a ground plane.
Abstract: In this article, a simple dual-polarized antenna with filtering responses and enhanced bandwidth is proposed for base station applications. The antenna concludes three parts: dipole elements, baluns, and a ground plane, which is the same as that of a widely used traditional base-station cross-dipole antenna. By employing only two parasitic elements without using very complicated circuits, the proposed dual-polarized antenna achieves not only filtering response but also widened bandwidth. Each parasitic element produces one transmission zero at higher frequency for the polarization it is associated with, while the other parasitic element produces another transmission zero at lower frequency band for the perpendicular polarization. The two introduced radiation nulls near the passband edge are also controllable. The working mechanism for achieving filtering responses is given. To demonstrate the idea, a simple dual-polarized filtering base-station antenna element is fabricated. The proposed antenna obtains 63% (1.68–3.23 GHz) impendence bandwidth with voltage standing wave ratio (VSWR) less than 1.5. The antenna also features good isolation of more than 32 dB and stable beamwidth variation of less than ±5°. The measured gain within working band is around 8.5 dBi, while the radiation suppression level in stopband is 13 dB.
42 citations
TL;DR: In this article, a mixed quarter and one-eighth modes substrate integrated waveguide (SIW) bandpass filter (BPF) is proposed to provide wide stopband response and high selectivity characteristics by using different SIW cavities.
Abstract: This letter presents the design of mixed quarter- and one-eighth modes substrate integrated waveguide (SIW) bandpass filter (BPF). The transmission zeros (TZs) of the proposed SIW BPF can provide wide stopband response and high selectivity characteristics by using different mode SIW cavities. For validation, two- and three-stage SIW BPFs with Chebyshev response were designed at a center frequency ( $f_{0}$ ) of 8 GHz. The measured results are consistent with the simulations. For two-stage BPF, the insertion loss smaller than 0.9 dB is measured within the passband of 0.65 GHz (7.75–8.4 GHz). The return loss higher than 19.7 dB is measured within the same passband. The spurious is produced at around 18 GHz ( $ ). The stopbands are attenuated more than 17.31 dB from the dc to 5.68 GHz ( $0.71f_{0}$ ) and from 9.28 GHz ( $1.16f_{0}$ ) to 16.67 GHz ( $2.08f_{0}$ ). The TZs are produced at 10 GHz and around 18 GHz due to a small cross-coupling between source/load and the interaction of the higher resonant modes of cavities, respectively. For three-stage BPF, the $\vert S_{21}\vert $ and $\vert S_{11}\vert $ smaller than −1.3 dB and −18 dB are measured within the passband of 7.57–8.45 GHz fractional bandwidth (FBW = 11%), respectively. The TZs are produced at 1.102, 1.9, and $2.39f_{0}$ and provide higher selectivity and attenuation compared to two-stage BPF.
41 citations
TL;DR: In this article, a fully metallic glide-symmetric waveguide filter with transmission in $Ka$ -band and attenuation at its second harmonic is proposed, which can be easily integrated with an antenna.
Abstract: A fully metallic glide-symmetric waveguide filter with transmission in $Ka$ -band and attenuation at its second harmonic is proposed. The filter is low-loss and cost-effective for high frequencies, and it can be easily integrated with an antenna. Glide symmetry and the possibility of breaking this symmetry provide an additional degree of freedom for passband and stopband control. A new kind of 2-D glide symmetry, referred to as braided glide symmetry, is presented, showing an increased attenuation per unit cell.
41 citations
TL;DR: In this article, the dispersion characteristics of a glide-symmetric holey periodic surface are investigated, with special emphasis on a detailed study of its stopbands, and an extensive parametric study is carried out, rigorously establishing a set of critical criteria for the use of such a periodic surface as an electromagnetic bandgap structure in gap waveguide technology.
Abstract: The dispersion characteristics of a glide-symmetric holey periodic surface are investigated, with special emphasis on a detailed study of its stopbands. The unit cell is modeled as a multiport network associated with multiple modes at each of the lattice boundaries. Enforcing the periodic conditions, the real and imaginary parts of the wavenumbers of the Floquet modes are calculated through an eigenproblem posed in terms of the generalized multimodal transfer matrix, which is computed from the scattering parameters obtained with a full-wave simulator. This procedure allows us to take into account the higher order modal couplings between adjacent unit cells that are crucial for accurate dispersion analysis. The resulting simulation-assisted approach provides both a convenient computational tool and a very fruitful physical insight that reveals the existence of complex modes, the convergence of opposite-parity modes, and the anisotropy in both passband and stopband. This approach enables a precise calculation of the attenuation constant, which is not possible with conventional techniques as the eigenmode solvers of commercial software. Based on this approach, an extensive parametric study is carried out, rigorously establishing a set of critical criteria for the use of such a periodic surface as an electromagnetic bandgap structure in gap waveguide technology. Moreover, the analysis of the directional properties of the structure is applied to further suppress the leakage.
TL;DR: A novel perfect edge reflector is proposed with elimination of longitudinal spurious ripples in the design of the SH0 plate acoustic wave (PAW) resonators, applicable to the ultra-wideband filters and next-generation tunable filters.
Abstract: This study lays a foundation for the design of the SH0 plate acoustic wave (PAW) resonators based on LiNbO3 plate, and are applicable to the ultra-wideband filters and next-generation tunable filters. The coupling coefficient ( $k^{2}$ ) of SH0 mode is optimized to as high as 55% and wideband spurious are well controlled by analyzing the propagation characteristics of plate modes in LiNbO3. The SH0 mode is demonstrated to be slowly dispersive and features the superiority of interdigital transducer (IDT)—defining frequency over most other plate modes. On the device level, the transducer types and electrode materials are investigated and compared. In addition, for edge-reflected SH0 resonators, stopband dispersion analysis is provided and the longitudinal ripples are suppressed. For edge-reflected SH0 resonators, a novel perfect edge reflector is proposed with elimination of longitudinal spurious ripples.
TL;DR: A realization method of wide-stopband substrate-integrated waveguide (SIW) diplexers and dual-band bandpass filters (BPFs) with widely realizable frequency ratios is presented using modified intrinsic modes suppression technique.
Abstract: A realization method of wide-stopband substrate-integrated waveguide (SIW) diplexers and dual-band bandpass filters (BPFs) with widely realizable frequency ratios is presented using modified intrinsic modes suppression technique. Design procedures of dual-band and wide-stopband characteristics for different frequency ratios are systematically summarized by sufficiently using the limited design degrees of freedom. The mixed dual- and single-mode cavities and the offset external coupling slots could help to flexibly control the dual-band frequencies and bandwidths. Meanwhile, the internal coupling windows could produce predictable wide-stopband performance when properly arranged at the positions of weakest electric fields of specific unwanted spurious modes determined by the frequency distributions for the required frequency ratio. Two SIW diplexers and an SIW dual-band BPF with frequency ratios of 1.225, 1.5, and 1.425 are synthesized and designed for demonstration, extending the stopband up to $1.79{f} _{0}$ with better than 24 dB rejection level, $2.05{f} _{0}$ and $2.34{f} _{0}$ with better than 20 dB rejection level, respectively.
TL;DR: In this article, a single-layer Goubau line leaky-wave antenna is proposed to achieve both high-scanning rate and wide scanning angle range, which leads to performance enhancement in both scanning rate and angle range.
Abstract: A glide-symmetry Goubau line leaky-wave antenna for achieving both high scanning rate and wide scanning angle range is introduced. The novelty of the design is its combination of glide symmetry and a single-layer Goubau line. This combination leads to performance enhancement in both scanning rate and scanning angle range. Utilizing a corrugated Goubau line in a glide-symmetry fashion closes its stopband at the cutoff frequency while slowing down its group velocity. As the dispersion around the closed stopband is shifted to the fast-wave region by periodic profile modulation, the space harmonics exhibit high-scanning-rate radiation. In conjunction with this, the single-layer nature of the Goubau line allows the beam to scan from nearly endfire to backfire directions, leading to a wide scanning angle range. Numerical examples and experimental validation are provided to validate the proposed design. These show that the proposed antenna exhibits dual-band operation, where one band scans 152° within 2.2 GHz (corresponding to scanning rate of 69°/GHz) with 67% efficiency, while the second band scans 145° within 0.7 GHz (corresponding to scanning rate of 207°/GHz) with 26% efficiency. A tradeoff between scanning rate and efficiency always exists in high-scanning-rate leaky-wave antennas. One is able to freely choose the preferred scanning rate in this single antenna. A comparison with other related works shows that the proposed antenna exhibits the best performance.
TL;DR: A novel ultra-wide stopband compact microstrip bandpass filter (BPF) with low insertion loss and compact size is presented based on two five-stage stepped impedance resonators which are capacitively coupled to each other’s.
Abstract: In this brief, we present a novel ultra-wide stopband compact microstrip bandpass filter (BPF) with low insertion loss and compact size. The proposed filter is designed based on two five-stage stepped impedance resonators (SIRs) which are capacitively coupled to each other’s. The five-stage SIRs can be used to have miniaturized size as well as suppression of harmonics. In this BPF, by increasing stages of SIRs, multiple transmission zeros are generated. Therefore, a compact BPF with a ultra-wide stopband could be achieved. The bandpass region of the proposed filter is extended from 3.58 GHz up to 10.31 GHz with insertion loss lower than 0.42 dB. The rejection level is better than −26 dB from 11.25 GHz up to 30 GHz and better than −17.5 dB up to 100 GHz. The center frequency of the proposed BPF is located at 6.95 GHz with −3 dB fractional bandwidth (FBW) of 97%. The dimension of the fabricated filter is $0.128\,\,{\lambda }_{\textbf {g}}{\times }{0.378}\,\,{\lambda }_{\textbf {g}}$ . The simulation results are verified by fabrication and measurement up to 30 GHz that there is a good agreement between them.
TL;DR: In this article, two novel classes of high-selectivity input-reflectionless bandpass filters (BPFs) with narrow and wide-band characteristics and out-of-band transmission zero (TZs) are presented.
Abstract: Two novel classes of high-selectivity input-reflectionless bandpass filters (BPFs) with narrow- and wide-band characteristics and out-of-band transmission zeros (TZs) are presented. These input-reflectionless BPFs, which are based on a complementary-duplexer approach, respectively, exploit intercoupled short-/open-ended dual- behavior resonators (DBRs) and coupled line/T-stub two-path transversal filtering stages in their main BPF channel. Their absorptive auxiliary channel is made up of a resistively terminated dual-band bipath transversal filtering cell, whose dual passbands are allocated in the stopband regions of the main BPF channel. Thus, the RF-input-signal energy that is not transmitted by the main channel in its attenuated bands is dissipated by the loading resistor of the auxiliary one. Hence, input-reflectionless properties are attained in the whole BPF architecture. The theoretical design principles of the conceived narrow- and wideband input-reflectionless BPF approaches are described. Furthermore, their experimental usefulness is verified through the development and characterization of two microstrip sharp-rejection BPF prototypes centered at 2 GHz.
TL;DR: This paper presents a straightforward design procedure to achieve some of the best performance of this class of microstrip filters, composed of three different polygonal-shaped resonators, two of which are responsible for stopband improvement and one of which is designed to enhance the selectivity of the filter.
Abstract: This paper presents a very efficient design procedure for a high-performance microstrip lowpass filter (LPF). Unlike many other sophisticated design methodologies of microstrip LPFs, which contain complicated configurations or even over-engineering in some cases, this paper presents a straightforward design procedure to achieve some of the best performance of this class of microstrip filters. The proposed filter is composed of three different polygonal-shaped resonators, two of which are responsible for stopband improvement, and the third resonator is designed to enhance the selectivity of the filter. A holistic performance assessment of the proposed filter is presented using a Figure of Merit (FOM) and compared with some of the best filters from the same class, highlighting the superiority of the proposed design. A prototype of the proposed filter was fabricated and tested, showing a 3-dB cut-off frequency (fc) at 1.27 GHz, having an ultrawide stopband with a suppression level of 25 dB, extending from 1.6 to 25 GHz. The return loss and the insertion loss of the passband are better than 20 dB and 0.25 dB, respectively. The fabricated filter has a high FOM of 76331, and its lateral size is 22.07 mm × 7.57 mm.
TL;DR: In this article, the influence of boundary conditions on the stop band effect in finite locally resonant metamaterial beams is investigated numerically, and three solutions are analyzed to reduce the effect of the edge modes: (i) varying the tuned frequency, (ii) the number or (iii) the positions of the individual tuned vibration absorbers added to the host structure.
TL;DR: A modified multi-spurious modes suppression technique is proposed to realize wide-stopband substrate-integrated waveguide (SIW) bandpass filters (BPFs), which is to set the external ports and internal coupling windows to the positions of weakest electric fields of specific spurious modes.
Abstract: A modified multi-spurious modes suppression technique is proposed to realize wide-stopband substrate-integrated waveguide (SIW) bandpass filters (BPFs), which is to set the external ports and internal coupling windows to the positions of weakest electric fields of specific spurious modes. To extend the stopband as wide as possible with the limited design degrees of freedom, different feeding and coupling positions are fully exploited to reject unwanted modes in specific cavities. By suppressing the out-of-band spurious peaks as much as possible and removing the first unsuppressed spurious resonance to the farthest position, the widest stopband can be achieved intrinsically. A second- and a third-order SIW BPFs are synthesized, designed, fabricated, and tested as demonstrations, realizing the stopbands of $2.51{f} _{0}$ and $3.85{f} _{0}$ with the rejection level better than 25 dB and 20 dB, respectively.
TL;DR: In this paper, a narrowband dual-band bandpass filter with independently tunable passbands is presented through a systematic design approach and a size-efficient coupling system is proposed with the capability of being integrated with additional resonators without increasing the size of the circuit.
Abstract: A narrowband dual-band bandpass filter (BPF) with independently tunable passbands is presented through a systematic design approach A size-efficient coupling system is proposed with the capability of being integrated with additional resonators without increasing the size of the circuit Two flag-shaped resonators along with two stepped-impedance resonators are integrated with the coupling system to firstly enhance the quality response of the filter, and secondly to add an independent adjustability feature to the filter The dual passband of the filter is centered at 442 GHz and 72 GHz, respectively, with narrow passbands of 212% and 115% The lower and upper passbands can be swept independently over 600 MHz and 1000 MHz by changing only one parameter of the filter without any destructive effects on the frequency response According to United States frequency allocations, the first passband is convenient for mobile communications and the second passband can be used for satellite communications The filter has very good in- and out-of-band performance with very small passband insertion losses of 05 dB and 086 dB as well as a relatively strong stopband attenuation of 30 dB and 25 dB, respectively, for the case of lower and upper bands To verify the proposed approach, a prototype of the filter is fabricated and measured showing a good agreement between numerically calculated and measured results
TL;DR: This article presents the ultraminiaturized wideband quasi-Chebyshev and -elliptic low-pass power dividers (PDs) with an impedance-transforming function using integrated passive device (IPD) technology, occupying only the sizes of $1.1\times1.2$ and 2 and
Abstract: This article presents the ultraminiaturized wideband quasi-Chebyshev and -elliptic low-pass power dividers (PDs) with an impedance-transforming function using integrated passive device (IPD) technology, occupying only the sizes of $1.1\times1.2$ mm2 and $1.1\times1.6$ mm2, respectively. The generalized quasi-Chebyshev low-pass matching network with the detailed design procedure is utilized to construct the circuit schematic of the proposed wideband PD. In order to further improve stopband rejection, a quasi-elliptic network is introduced, resulting in an extra transmission zero (TZ). For demonstration, the quasi-Chebyshev and -elliptic PDs based on IPD technology are designed, manufactured, and measured, respectively. Measurements indicate that the quasi-elliptic PD with TZ shows good electrical responses, including lower than 1.08-dB insertion loss, all better than 15-dB return loss and isolation from 2.49 to 5.0 GHz.
TL;DR: An all-in-one leaky wave antenna design, which features high scanning rate, continuous scanning capability across the broadside, 45° linear polarization or circularly polarization, single-layer configuration, and single-side radiation is proposed.
Abstract: A class of 45° linearly polarized and circular polarized high scanning rate leaky wave antennas are proposed in this paper, which is based on slow-wave substrate integrated waveguide structure. High scanning rate leaky wave antennas have recently become attractive for imaging applications and automotive radar. These applications also require a continuous scanning range without an open stopband, as seen at broadside for ordinary leaky wave antennas. Furthermore, both 45° linearly polarization and circularly polarization are required in practical applications. In this paper, we propose an all-in-one leaky wave antenna design, which features high scanning rate, continuous scanning capability across the broadside, 45° linear polarization or circularly polarization, single-layer configuration, and single-side radiation. Two design examples are provided to illustrate the proposed principle. Both simulation and experimental validation are given.
TL;DR: A planar 2 × 2 filtering patch antenna array with high selectivity and wide stopband is investigated for marine communications, and a larger 4 × 4 filtering array is designed by just using a traditional four-way power dividing network.
Abstract: A planar 2 × 2 filtering patch antenna array with high selectivity and wide stopband is investigated for marine communications. The 2 × 2 patch array is composed of a driven patch and four identical parasitic patches placed nearby. A forked-microstrip-line-coupled rectangular slot is used to excite the driven patch, while the neighboring parasitic patches are capacitively coupled by the driven patch. Owing to the hybrid feeding effect of the forked feed line, a radiation null can be generated at the lower band-edge. Simultaneously, another radiation null can be generated at the upper band-edge owing to the radiation cancellation effect between the driven patch and the parasitic patches. Consequently, no power dividing feeding network is required for the 2 × 2 array, and the quasi-elliptic bandpass filtering response is achieved without utilizing any complex filtering/non-filtering circuits. In addition, the proposed filtering array exhibits a wide stopband capable of suppressing the second-harmonic radiation effectively. Based on this 2 × 2 array, a larger 4 × 4 filtering array is further designed by just using a traditional four-way power dividing network. For validation, both of the 2 × 2 and 4 × 4 filtering patch arrays operating at 5.25 GHz are fabricated and tested. The measured results show that the two patch arrays have comparable impedance bandwidths of about 4.4%. The in-band peak gains are given by 11.1 and 15.5 dBi respectively, which are suitable for the long-distance shore-to-ship communications.
TL;DR: In this article, a microstrip dual-band bandpass filter (DBBPF) based on an octagonal loop resonator (OLR), tapered resonators and open bended stubs (OBSs) is designed and analyzed.
Abstract: Abstract In this paper, a microstrip dual-band bandpass filter (DBBPF) based on an octagonal loop resonator (OLR), tapered resonators and open bended stubs (OBSs) is designed and analysed. The proposed structure produces two passbands with the centre frequencies of 3.65 and 5.67 GHz. The marked advantages of the proposed filter are as follows: Two centre frequencies can be individually tuned. The bandwidth of the upper passband can also be controlled. Furthermore, the DBBPF benefits from an ultra-wide upper stopband from 5.9 up to 21 GHz with an attenuation level of higher than 20 dB and a small size of 0.21 λg × 0.26 λg, where λg is the guided wavelength at 3.65 GHz. The designed filter is horizontally and vertically symmetrical leading to a reciprocal S matrix. Other remarkable specifications of the proposed filter are the insertion loss < 0.62 dB, the return loss > 20.2 dB and sharp response. To provide an analytical description, the LC equivalent circuits of initial and main resonators are presented. Acceptable similarity between simulated and measured results verifies the design process.
TL;DR: This work proposes a novel objective (normalized error fitness) function and a robust hybrid algorithm for the effective searching of the optimal filter coefficients for providing excellent sharp edge frequency response during the filtering action.
Abstract: The filter is an important building block of modern communication and electronic systems. Based on well-defined bandwidth, it extracts the desired portion of the spectrum when the raw input signal is applied. Efficacy of filtering depends on the preciseness of bandwidth to avoid co-channel interference and signal loss. In addition, it must provide higher stopband attenuation and passband attenuation very close to unity with a tolerable quantity of pass/stop band ripple. Design/implementation of sharp edge modern FIR filter is structured as a multi-objective, constrained, complex, and highly nonlinear (hence multimodal) error minimization challenge. Hence, this work proposes a novel objective (normalized error fitness) function and a robust hybrid algorithm for the effective searching of the optimal filter coefficients for providing excellent sharp edge frequency response during the filtering action. Most popular particle swarm optimization (PSO) and differential evolution (DE) algorithm are effectively combined together to frame the proposed hybrid DE-PSO algorithm for enhancing the exploration and exploitation abilities of it. The proposed hybrid algorithm is validated using twelve different benchmark functions. Through simulations, the qualitative performance of the proposed approach is compared with the conventional PSO, DE, real-coded genetic algorithm and the Parks–McClellan method.
TL;DR: TwoDual-band bandpass filters (BPFs) and a dual-band filtering power divider (FPD) are proposed and fabricated based on the aforementioned hybrid microstrip/DGS cells, and measured and simulated results are in a fairly-close agreement.
Abstract: In this paper, two types (i.e., type-A and type-B) of hybrid microstrip/defected ground structure (DGS) cells are proposed for passive circuit implementation with ultra-wide stopband. Both cells consist of the stepped-impedance DGS and embedded folded slotline on the ground, which could obtain the dual-resonances. In type-A cell, a microstrip T-stub on the top side is introduced, which can not only allocate a strong coupling to the DGS with slotline on the bottom side, but also act as the input/output port. To finely adjust the dual-resonances of the type-B cell, a grounded microstrip patch is used. Meanwhile, such compact cells could feature an ultra-wide upper stopband, due to their own slow-wave effect. Based on the aforementioned hybrid microstrip/DGS cells, two dual-band bandpass filters (BPFs) and a dual-band filtering power divider (FPD) are proposed and fabricated. Measured and simulated results are in a fairly-close agreement. Both dual-band BPFs exhibit the ultra-wide upper stopband, which extends up to 40 GHz with a high rejection level about 30 dB. Besides, the dual-band FPD has merits of more than 18.7 dB of in-band isolation and 28 dB stopband rejection levels up to 40 GHz.
TL;DR: In this article, a dual-polarized filtering antenna without using extra parasitic element or filtering circuit is proposed, which consists of two pairs of dipole arms and baluns, which introduce two radiation nulls in the upper stopband and another radiation null is generated by the radiation cancellation between the dipoles and the baluns.
Abstract: A dual-polarized filtering antenna without using extra parasitic element or filtering circuit is proposed. The proposed antenna consists of two pairs of dipole arms and baluns. The balun feeding scheme is used to form two half-wavelength resonators, which introduce two radiation nulls in the upper stopband. Meanwhile, in the lower stopband, another radiation null is generated by the radiation cancellation between the dipoles and the baluns. As a result, a bandpass filtering response is realized owing to these three radiation nulls. For demonstration, a prototype is fabricated and measured. The prototype has an impedance bandwidth of 50% (return loss >15 dB within the band 1.65−2.75 GHz). The average measured gain is 8.1 dBi. Within the lower stopband of 0−1.25 GHz, the out-of-band suppression level is more than 30 dB. Furthermore, the suppression level is over 16 dB in the upper stopband of 3.3−5 GHz. Such features make the proposed antenna suitable for multiband array applications to reduce the mutual coupling between elements operating at adjacent frequencies.
TL;DR: In this article, the integration of frequency selective surfaces (FSSs) with retroreflectors for the realization of chipless wireless indoor localization tag landmarks is presented, where the high radar cross section (RCS) of a trihedral corner reflector is signed with an FSS-based stopband filter, so that the backscattered power from several corner reflectors can be distinguished by a mobile reader according to the frequency response of the FSS.
Abstract: This letter presents the integration of frequency selective surfaces (FSSs) with retroreflectors for the realization of chipless wireless indoor localization tag landmarks. As an example, the high radar cross section (RCS) of a trihedral corner reflector is signed with an FSS-based stopband filter, so that the backscattered power from several corner reflectors can be distinguished by a mobile reader according to the frequency response of the FSS. Measurement results with a 3 × 3 × 3 cm3 trihedral corner reflector and a stopband FSS in a Rogers RT/Duroid 5880 high-frequency laminate at 90 GHz shows an RCS above $-$ 25 dBsqm for 90° coverage in the TM plane. Due to the high RCS, measurements at distances up to 4 m with a standard 25 dBi gain horn antenna and a vector network analyzer as a reader are shown. These preliminary results show the potential of the concept for applications such as indoor localization with sub-mm accuracy, where high bandwidths, but only a low number of bits, are needed for the identification of the tag landmarks.
TL;DR: In this paper, a compact microstrip lowpass filter with sharp selectivity and wide stopband was proposed, which is based on dualplane dual-plane DGS and achieved a 3dB cutoff frequency of 2.11 GHz with high relative stopband bandwidth of 159.2% within the rejection level of 18dB.
Abstract: A compact microstrip lowpass filter with sharp selectivity and wide stopband designed on the basis of dual-plane, is presented. Initially, a basic one pole defected ground structure (DGS) filter is modified so as to achieve sharp selectivity as well as compact size. The modified DGS reduces the circuit size of the filter by 68.8%. To suppress the higher order harmonics, mirrored symmetrical uniform impedance stubs are designed in the top surface of the substrate, thereby wide stopband up to 20 GHz is achieved. The stopband suppression level of the filter is improved by incorporating a spurline resonator which acts as a defected microstrip structure (DMS) in the top microstrip line. The designed filter has 3 dB cutoff frequency of 2.11 GHz with high relative stopband bandwidth of 159.2% within the rejection level of 18 dB. The wide passband frequency range of the proposed filter covers the GSM, GPS, Wi-Fi communications and various L-band applications such as aircraft surveillance etc.
TL;DR: A compact lowpass filter (LPF) with wide stopband, very sharp roll-off response and wide tuning range is presented for microwave diode detector applications, employing two hexagonal-shaped resonators and multiple open-end stubs as suppression cells.
Abstract: In this brief, a compact lowpass filter (LPF) with wide stopband, very sharp roll-off response and wide tuning range is presented for microwave diode detector applications. It employs two hexagonal-shaped resonators and multiple open-end stubs as suppression cells. The results of the proposed hexagonal-shaped resonator and LC circuits are in good agreement. The 3 dB cut-off frequency for the proposed LPF is 2.2 GHz and the roll-off-rate (ROR) parameter for the proposed LPF is very sharp and equal to 308.6 dB/GHz. Furthermore, insertion loss (IL) and return loss (RL) in the passband region are better than 0.3 dB and 18 dB, respectively. Moreover, the stopband is wide, ranging from 2.34 to 18 GHz, with a 22 dB rejection level. The tuning range of 3 dB cut-off frequency is also wide, equal 0.48 to 1.7 GHz (71%). As an application demonstrator, an envelope detector was designed and fabricated. The proposed detector (with LPF) highly suppresses any harmonics of the fundamental frequency. The proposed LPF and microwave detector is designed, simulated, fabricated and measured. The results of simulation and measurement are in good agreement.