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A bandwidth-tunable balanced filter (BTBF) is proposed, which utilizes the quarter-wavelength coupled lines with multi-point loaded varactors and half-wavelength transmission lines. The varactor-loaded coupled lines combined with the pair of the half-wavelength transmission lines provide the basic wideband differential-mode (DM) passband and common-mode (CM) suppression, and the loaded varactors can tune the lower edge, the upper edge and the impedance matching (IM) of the passband. Thus, tunable bandwidth with almost constant center frequency can be achieved by controlling the bridged varactor Cv1 and the series varactors Cv2 and Cv3. Compared to the state-of-the-art designs, the proposed design offers significant advantages of broad tuning range of DM bandwidth, wide minimum DM bandwidth, low insertion loss, and simple structure. For demonstration, a prototype is designed with the DM bandwidth tuning range of 24.7%, the minimum DM fractional bandwidth (FBW) of 46.5%, the maximum insertion loss inside the IM bandwidth of 2.3 dB. [ABSTRACT FROM AUTHOR]

A new design approach to achieve compact size and high common‐mode (CM) suppression of balanced filters is proposed with two back‐to‐back microstrip semi‐circular patch resonators. In feeding structures, metalized via holes are adopted to vertically feed patches by differential pairs. Then, TM11 mode is excited and TM31 mode can be rejected, resulting in wideband differential‐mode (DM) harmonic rejection. Besides, with a slotline etched in the common ground plane, desired coupling strength can be achieved for a target bandwidth. Meanwhile, by virtue of the stacked structure, source‐load coupling can be easily introduced to generate transmission zeros close to the passband. With theory guidance, two balanced filter prototypes centered at 2.4 GHz are designed. Simulation and measurement results both indicate that proposed balanced filters exhibit high DM and CM performances as well as a compact size about 0.26λg × 0.53λg. [ABSTRACT FROM AUTHOR]

The enhancement of horizontal boundaries of potential field sources is of great significance for the study of geological structures. Most of the existing filters for horizontal edges enhancement are presented based on the derivatives of potential field data, but these filters often show some shortcomings, for example, the output edges are divergent, strong and weak anomalies cannot be balanced, or some extra false edges appear in the results. In this paper, the edges enhancement filter MMA based on mathematical morphology is first defined by the combination of the basic operators of mathematical morphology. In order to make the filter have the ability to balance different amplitude anomalies, MMAZ and MMAT are proposed, and both of them can be used to delineate the horizontal edges of the field sources by their maxima. The experimental results of synthetic data show that MMAZ and MMAT have good equalization and anti-noise performances. Compared with several traditional filters, the horizontal edges of geological bodies obtained by these two filters are clearer and more convergent, and there are no extra edges in the output results for the complex situations that positive and negative anomalies exist simultaneously. Finally, the two new equalization filters are applied to gravity anomaly data in a potash mine area in Vientiane basin of Laos and the aeromagnetic anomaly of a metal mine in northwest China, the obtained positions of the structures are more accurate and clearer, which further illustrates the effectiveness of the two filtering techniques. [ABSTRACT FROM AUTHOR]

Quasi‐reflectionless balanced bandpass filters (BPFs) using absorption network for common‐mode (CM) rejection and stopband extension are proposed and demonstrated. First, a quasi‐reflectionless balanced BPF is constructed by using absorption network and a uniform impedance resonator (UIR), where absorption network consists of lossy stubs loaded at both the input/output port and the ends of the coupling line (CLs). Owning to the resonating of absorption network, a three‐pole balanced BPF with CM and differential‐mode (DM) reflectionless performance are realized. Meanwhile, harmonic of DM is suppressed by exploring the loading position of the resistor. Second, to improve the selectivity of the filter, two open stubs are symmetrically loaded to the center of the UIR, a five‐pole quasi‐reflectionless balanced BPF with two transmission zeros are presented. Both proposed quasi‐reflectionless balanced BPFs are fabricated and measured. The measured results are in good agreement with the simulated ones, verifying the proposed design concept. [ABSTRACT FROM AUTHOR]

A differential magnetic field probe based on a balanced filter is proposed to improve electric field suppression. The probe comprises a rectangular metal loop for detection and a balanced filter transmission. Three 1/4λ stepped impedance transmission lines are designed between the detective part and balanced filter for impedance matching. The balanced filter can suppress the common mode signals generated by a normal electric field but has little influence on the differential signals detected by a tangential magnetic field thus, the electric field suppression of the magnetic probe can be enhanced. The measurement results show that the working frequency of the proposed magnetic probe ranges from 10 to 20 GHz, and the electric field suppression ratio is over 35 dB from 10 to 15 GHz. [ABSTRACT FROM AUTHOR]

A class of balanced dual-band bandpass filters (BPFs) with planar transversal-signal-interference coupled-line sections is reported. In their building balanced dual-band BPF stage under differential-mode excitation, a second-order quasi-elliptic-type dual-band bandpass filtering transfer function is obtained. Specifically, from the transversal interaction among their two open-ended and virtually-short-ended half-wavelength coupled-line paths, sharp-rejection differential-mode dual passbands with several out-of-band transmission zeros at both sides are realized. To attain high common-mode suppression levels within the differential-mode passbands, two open-ended line segments are connected at the symmetry plane of the devised balanced dual-band BPF stage. Moreover, higher-order schemes based on in-series-cascaded multi-stage designs to further increase differential-mode selectivity and in-band common-mode rejection are illustrated. The operational principles and parametric-analysis design rules of the engineered transversal-coupled-line-based balanced dual-band BPF approach are detailed. Additionally, for a rigorous interpretation of their zero/pole characteristics, a digital-modeling framework is applied to them to connect RF balanced filters with their discrete-time versions. For practical-validation purposes, a microstrip prototype of two-stage/fourth-order balanced dual-band BPF is built and tested. It exhibits measured differential-mode dual passbands with center frequencies of 1.464 GHz and 2.294 GHz, 3-dB fractional bandwidths of 8.74% and 9.68%, and in-band common-mode rejection levels above 23.16 dB and 31.36 dB, respectively. [ABSTRACT FROM AUTHOR]

This brief reports on the RF design and practical development of a non-reciprocal balanced bandpass filter (BPF) that exhibits a highly-selective quasi-elliptic response in the forward direction of propagation that is shaped by four transmission poles and two transmission zeros (TZs). By modulating some of the filter’s resonators with phase-progressed AC signals, a non-reciprocal response is obtained in the differential mode. Its common-mode is also highly suppressed due to the incorporation of a balanced network that results in two additional TZs and resistive loss that are unique to the common-mode. The filter order can be increased by cascading additional resonators. For validation purposes, a microstrip prototype centered at 725 MHz was designed, manufactured, and measured. It showed a high isolation in the differential-mode reverse transmission of up to 62.1 dB. Moreover, the common-mode was suppressed by over 45 dB in a bandwidth greater than one octave. [ABSTRACT FROM AUTHOR]

A supercompact balanced wideband bandpass filter (BPF) based on capacitor-loaded one-eighth wavelength three-line coupled structure is proposed. Multiple differential-mode (DM) transmission poles, DM transmission zeros, and common-mode (CM) transmission zeros can be obtained and controlled by loading multiple capacitors on the three-line coupled structure, which makes the filter achieve wideband DM filtering response and CM suppression. Compared with the state-of-the-art balanced wideband BPFs, the proposed design has the advantages of compact size and simple structure. A prototype centered at 0.66 GHz with the 3-dB fractional bandwidth of 43.8% is demonstrated, which exhibits the supercompact size of $0.003~\lambda ^{2}_{g}$ ($\lambda _{g}$ is the guided wavelength at the center frequency) and the minimum insertion loss of 0.43 dB. [ABSTRACT FROM AUTHOR]

In this brief, for the first time, we propose common-mode (CM) and differential-mode (DM) reflectionless balanced bandpass filters (BPFs) using half-wavelength ring resonator. By loading absorptive stubs at input/output ports and the ends of the coupled-lines (CLs), the BPFs can realize input-/two-port wideband CM and DM reflectionless performance from dc, as well as wide filtering band and all-stop CM suppression. As for the input-reflectionless type, two extra transmission zeros (TZs) can be obtained by loading $\lambda /2$ stubs between the CLs. Besides, the impedances of the CLs can determine the CM suppression level, and the absorption performance can be independently adjusted. The operational foundations and explicit equations are discussed and derived. Good agreements between the simulated and measured results verify the design theory. [ABSTRACT FROM AUTHOR]

Balanced dielectric resonator (DR) filters with multiple reconfigurable passbands are proposed in this article. Based on the field distributions of two pairs of orthogonal degenerate modes, quad-mode differential-mode (DM) operations are achieved by the specific probe feeding structure. More importantly, the four modes are flexibly controlled by different inserted screws and the detailed principle is illustrated for reconfiguration. For demonstration, a dual-band balanced filter with independently frequency-tunable passbands and a quad-band one with selectable number of passbands are fabricated and measured. Good agreement between the simulated and measured results is observed. The exhibited low DM loss, high common-mode (CM) rejection, and independent tuning abilities verify the proposed method in miniaturized reconfigurable filter designs. [ABSTRACT FROM AUTHOR]

In this paper, a balanced tri‐band band‐pass filter (BPF) with the third independently tunable passband and the other two fixed ones based on a novel multi‐stub loaded resonator (MSLR) is presented. Due to the symmetrical circuit structure, the even‐and odd‐mode methods are applied to analyze the differential‐mode (DM) and the common‐mode equivalent circuits of the proposed resonator, and the correspondingly resonant characteristics can be obtained. With the approximate design of the MSLR, the first three DM resonant frequencies are employed to form the three DM passbands. Then, the external coupling structure can be controlled by coupled lines to meet the required specifications. Furthermore, the frequency tuning of the third DM passband can be realized by adjusting the varactors loaded at the end of the resonators. Finally, the source and load coupling is introduced to improve the frequency selectivity. For verification, a balanced tri‐band BPF with the tunable third DM passband was designed, manufactured and tested. The fabricated filter has central frequencies of the first two fixed bands located at 2.4 and 2.95 GHz, the third one tuning from 4.17 to 4.41 GHz, and the correspondingly fractional bandwidths (FBWs) are 12.3%, 3.5% and 1.9% ± 0.89%. The experimental results are in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

This paper presents a balanced fifth-order Substrate Integrated Waveguide (SIW) band-pass filter operating at 39 GHz. The filter uses the balanced nature of the SIW resonators and the odd-mode property of the TE102 mode. Five rectangular resonators have been used to develop a fifth-order band-pass filter and the couplings between them with the external quality factors have been determined. The filter yields a good response in the KA band of the electromagnetic spectrum. It has a smaller footprint and operates at a higher frequency range compared to other filters with the same technology. The Common-Mode (CM) signal has been effectively suppressed to more than -30 dBs throughout the considered range. The return loss of - 30 dBs and an insertion loss of -4 dBs for the Differential-Mode (DM) operation are achieved at the operating frequency of 39 GHz. The half-mode operation of the filter has been also implemented and the results have proven to be satisfactory. [ABSTRACT FROM AUTHOR]

Two different types of three pairs of coupled lines (TPCL) structures with bandpass and all-stop filtering (ASF) characteristics, respectively, are proposed and analyzed through impedance matrix deduction and input admittance calculation. Combined with the stepped-impedance stubs, high-selectivity single-ended and balanced filters using TPCL structures have been presented. Five transmission poles (TPs) within the passband and six deep transmission zeros (TZs) from 0 to $2f_{0}$ ($f_{0}$ : passband center frequency) can be realized in both of single-ended and balanced filters. For demonstration, two sharp roll-off single-ended and balanced filter prototypes with good in-band characteristics (insertion losses and return losses) and high common-mode suppression are designed, whose measured 3-dB fractional bandwidths are of 35% and 34.4% (differential mode), respectively. Good agreement between the simulations and measurements validates the design concept.

A compact dual-band balanced bandpass filter with high frequency selectivity and adjustable passband based on the perturbed circular substrate integrated waveguide cavity is firstly proposed in this paper. Two pairs of metallic vias are located at 45°direction of cavities to separate a pair of degenerate modes (TM110 modes) to achieve the differential-mode (DM) dual-band response. Moreover, the perturbation vias can also be used to control the center frequency of the second DM passband while the first one still stays unaffected. The introduction of source-load coupling makes the filter exhibit excellent selectivity. And four controllable transmission zeros appear near two DM passbands. Finally, good common-mode suppression has been got owing to the proposed balanced structure. The measured results are in accordance with the simulated ones well. [ABSTRACT FROM AUTHOR]

This paper reports on high-order balanced bandpass filters (BPFs) that are continuously tunable in terms of frequency and bandwidth and can be intrinsically switched-off. They use a hybrid integration scheme based on two different types of capacitively loaded resonators—ceramic coaxial and microstrip—that reduce the filter size, enhance its out-of-band selectivity and common-mode suppression, and allow for multiple levels of transfer function tuning. High selectivity is obtained in the differential mode due to the high number of poles and transmission zeros present. The common mode is highly suppressed through the introduction of additional transmission zeros and resistively loaded resonators. Furthermore, the use of ceramic coaxial resonators results in supplementary transmission zeros that are used to lower the out-of-band transmission in the differential mode. Multiple levels of tuning are obtained by reconfiguring only the frequency of the BPF's resonators. For experimental validation, a tunable mixed-technology microstrip prototype was manufactured and measured at S-band. It exhibited frequency tuning between 2.22 and 2.94 GHz, bandwidth tuning between 104 and 268 MHz, and an intrinsically switched-off mode with isolation >50 dB in the differential mode. For all states, the common mode was suppressed by at least 35 dB at the center frequency and within a wide range. [ABSTRACT FROM AUTHOR]

In this paper, a novel dual-wideband balanced bandpass filter (BPF) based on branch-line structure is proposed. For analysis, the equivalent circuits of differential-mode (DM) and common-mode (CM) of the filter are built based on the even- and odd-mode method. With a proper synthesis design of DM bisection, dual passbands with a multi-order filtering response can be obtained. Additionally, three open-circuited stubs are centrally loaded on the CM bisection and six controllable transmission zeros are therefore generated. Thus, two stopbands are formed and then a favorable CM suppression within DM passbands is obtained. For demonstration, a third-order dual-wideband balanced BPF is designed with two passbands operating at 2.54 and 4.62 GHz. Good agreement between the simulated results and measured results is obtained, which verifies the validity of the proposed design method.

In this article, a compact triple‐mode balanced passband filter with intrinsic common‐mode (CM) suppression is designed by using a single isosceles right triangle perturbed half‐mode substrate integrated waveguide (HMSIW) cavity. The perturbation metallic vias are introduced to tune the first three resonant modes of HMSIW cavity to form a passband. Furthermore, the planar differential microstrip‐pin feed structure is designed to excite the perturbed substrate integrated waveguide cavity. Under CM operation, when the substrate's height is less than λg/4, the space between perfect electric conductor and perfect magnetic conductor cannot transmit electromagnetic wave, so CM noise can effectively cut off at the planar differential feed structure in a wide frequency range. Finally, a prototyped prototype at 4.5 GHz is designed and fabricated, and measured results show good agreement with simulated ones. [ABSTRACT FROM AUTHOR]

A balanced substrate integrated waveguide (SIW) filter is proposed by etching transverse slots on the top surface. The SIW structures between each two adjacent slots are resonators operating at TE20δ mode for differential-mode (DM) operation and at TE10δ and TE30δ modes for common-mode (CM) operation. The proposed TE20δ-mode resonator is much shorter than the traditional TE201-mode resonator, which causes the whole design to be compact and low loss. Furthermore, the strong electric coupling formed by slots make it have wider bandwidth when compared with the state-of-the-arts. A prototype is designed at 3.5 GHz with the size of 1.2λd × 0.83λd (λd is the wavelength in dielectric at the center frequency), the minimum insertion loss of 0.91 dB, the 3-dB fractional bandwidth (FBW) of 16%, and the FBW for 20 dB CM suppression of 79%.

This article presents a balanced tri‐band superconducting band‐pass filter (BPF) with controllable center frequencies (CFs) and fractional bandwidths (FBWs) using novel double square ring loaded resonators (DSRLRs). Due to the symmetrical structure of the proposed DSRLR, the differential mode (DM), and common mode (CM) equivalent circuits of the resonator are analyzed by using even‐ and odd‐mode methods, and the resonant characteristics can also be obtained. With the proper design of the proposed DSRLR, the first three DM resonant frequencies are utilized to construct the three DM passbands, and their CFs can be adjusted by changing the lengths of the corresponding stubs. Then, the internal coupling between resonators can be controlled independently by the additional capacitive loading microstrip and the interdigital coupling structure. In addition, the so‐called frequency dispersion technique is used to enhance CM suppression in the proposed balanced tri‐band BPF by loading additional multiple stubs on the symmetry plane. Consequently, the proposed tri‐band BPF can realize controllable CFs and FBWs with broadband CM suppression. Prototype balanced filters with CFs of 1.7/2.45/3.4 GHz and FBWs of 2.9%/3.2%/1.8% were designed, manufactured, and measured for verification. The experimental results agree well with the simulated ones. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this letter, a compact dual-band dual-mode substrate integrated waveguide (SIW) balanced band-pass filter (BPF) with intrinsic common-mode (CM) suppression is designed by using a single perturbed SIW circular cavity. The vias and slot perturbations are introduced to tune the resonant modes TE010, TE110 (a pair of degenerate modes), and TE210 of a circular cavity. Thus, they can be used to form two differential-mode (DM) passbands with independently adjustable center frequencies and bandwidths. The SIW can be seen as a natural balun with intrinsic CM suppression. Furthermore, the planar differential excitation structure is designed to excite the perturbed SIW cavity. The CM noise cannot excite SIW cavity due to the characteristics of hybrid electromagnetic boundary. Finally, a compact dual-band dual-mode SIW balanced BPF at 8 and 10 GHz is designed and fabricated, and the measured results show good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

This paper presents a novel planar balanced bandpass filter (BPF) with wideband common mode (CM) noise suppression and in‐band CM noise absorption using coupled lines (CLs) with short‐circuited stubs to realize high selectivity and wideband differential mode (DM) filtering performance. Two one‐quarter wavelength stubs loaded with grounded resistors are introduced to realize wideband CM noise suppression. Thus, CM noise can be suppressed under a certain level at all frequencies. Four resistors are used to achieve CM noise absorption by dissipating the CM noise into heat, which can avoid the noise being reflected to the communication system and realize a wide absorption bandwidth with 90% absorption efficiency. For demonstration, an absorptive balanced BPF operating at 3.5 GHz with wide 3‐dB fractional bandwidth (FBW) of 79.43% is fabricated and experimentally validated. It is worth noted that the absorptive balanced BPF can realize broadband CM noise suppression from 0 to 8 GHz, and the CM noise is well absorbed more than 10 dB from 2.41 to 4.63 GHz. Besides, wideband CM noise absorption with 90% efficiency from 2.51 to 4.60 GHz is realized, which indicates potential applications in improving the performance of the balanced radio frequency (RF) circuits. Good agreements between the simulated and measured results are observed. [ABSTRACT FROM AUTHOR]

In this brief, a novel multi-mode square ring loaded resonator (SRLR) is presented, and a tri-band balanced bandpass filter (BPF) with good performances is developed. The multi-mode SRLR consists of a ring resonator and six open stubs, and its resonant characteristics is obtained by the odd/even-mode method. Compared with conventional SRLR, the symmetrical SRLR has more degree of freedom in controlling the resonance modes. Thus, a wide upper DM stopband can be achieved by choosing proper electrical lengths of open stubs. Moreover, frequency dispersion technique is used to enhance common-mode (CM) suppression in the proposed balanced tri-band BPF. By loading a cross-shaped stub and open-loop stub to the center of the first and second order SRLR respectively, five CM transmission zeros (TZs) are produced. Therefore, a wideband CM suppression can be achieved with the DM response almost intact. To verify this design method, a tri-band balanced filter operating at 2.4, 3.5 and 5.2 GHz has been designed, simulated and fabricated. Measured results exhibit good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Chongqing University of Posts & Telecommunications (Natural Science Edition) is the property of Chongqing University of Posts & Telecommunications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the terminated coupled-line pairs, this article reports a novel design method to synthesize a common-mode (CM) reflectionless all-stop filter with differential mode (DM) bandpass characteristic for balanced radio-frequency (RF) transmitter. With the adoption of symmetric property, the equivalent circuit models for both DM and CM are developed for the design purpose. The main contribution of this article is the development of a systematic impedance matching method to CM noise. Compared with conventional approach like adjusting the transmission zeros, the CM noise power would be dissipated on the terminators (resistors) rather than reflected. For practical validation, two butterworth microstrip prototypes (2nd-order/ 4th-order) were manufactured and measured in the 0–5.0 GHz range. It would be found that the measured CM absorption rate is over 88% from 0 to 5 GHz for both samples. Besides, the DM center frequency locates at 1.0 GHz with the measured 3-dB fractional bandwidth of 56% and 65%, respectively. To author's best knowledge, this work is the first RF balanced bandpass filter that is capable of absorbing the CM noise at all frequencies. [ABSTRACT FROM AUTHOR]

A class of coupled-multiline quasi-elliptic-type balanced diplexer device with closely spaced channels and its balanced coupling-routing-diagram formalism to simultaneously model its differential- and common-mode operation are reported. It employs third-order combline-type bandpass filters (BPFs) in its filtering channels, whose resonating lines are connected at one of their extremes to the symmetry plane of the balanced-circuit structure (i.e., virtual grounds for the differential mode), along with a multiextracted-pole/coupled-multiline dual-band BPF junction and single-band BPF output cells. In differential-mode operation, the dual-band BPF junction adds one in-band pole to each diplexer channel and three transmission zeros (TZs) to both channels, whereas the single-band BPF output cells incorporate one in-band pole and two TZs in their corresponding channels. In this manner, increased-selectivity differential-mode BPF transfer functions for the diplexer channels when compared to those of its third-order combline-type BPFs are obtained. Grounded resistors are connected at the symmetry plane of the balanced diplexer for all the resonating lines of the combline-type BPFs, which become detuned with regard to the poles associated with the dual-band BPF junction and the single-band BPF output cells under common-mode excitation. This allows for high common-mode suppression levels in wide spectral ranges to be realized for both channels while maintaining the same TZs as in differential-mode operation. For practical-validation purposes, a 1.6-GHz/1.8-GHz microstrip prototype is manufactured and tested. [ABSTRACT FROM AUTHOR]

In this letter, compact-balanced bandpass filter (BPF) and filtering crossover are proposed with intrinsic common-mode (CM) suppression by using a single-layered substrate-integrated waveguide (SIW) cavity. The SIW cavity with low profile is TEn0m mode resonator, which has only one nonzero electric field component. Hence, it is also a natural frequency selection device of the differential signal. Meanwhile, the CM signal cannot excite the cavity due to the characteristics of perfect electric conductor (PEC) and perfect magnetic conductor (PMC). For the design of the balanced SIW BPF, the differential-mode (DM) equivalent half circuit is a single-ended SIW filter with height halved. Furthermore, the microstrip differential transition structure is designed to excite the SIW cavity and has little conversion between DM and CM. On this basis, a compact SIW-balanced filtering crossover is proposed using the degenerate modes TE102 and TE201. Finally, compact third-order SIW-balanced BPF and filtering crossover are designed and fabricated, and the measured results show good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

In this article, the co-design of novel self-packaged balanced bandpass filters (BPFs) integrated with the functionality of impedance transformation is presented for the first time. The proposed design is based on a modified branch-line structure, which is composed of two different branch lines and two identical coupled-line sections. Analysis results show that the considered filters can not only achieve Chebyshev equal-ripple responses with impedance transformation properties for the differential mode (DM) but also can efficiently improve the bandwidth of the common-mode (CM) rejection with resorting to this modified branch-line structure. Furthermore, according to the specified equal-ripple fractional bandwidth (FBW), in-band return loss (RL) level, and impedance transformation ratio ${m}$ , the DM frequency response can be directly determined. Two design prototypes, the second-order balanced BPF with a 50–75- $\Omega $ ($m= 1.5$) impedance transformation and the third-order one with a 50–200- $\Omega $ ($m= 4$) impedance transformation, are implemented in self-packaged forms by using the multilayer liquid crystal polymer (LCP)-bonded printed circuit board (PCB) technology. Theoretical, simulated, and measured results are recorded in good agreement, well verifying the design concept. [ABSTRACT FROM AUTHOR]

In this work, a new balanced band pass filter and its design procedure are proposed. The filter is based on a novel resonator, named LTLC resonator, which consists of two inductors (L), two Transmission Lines (TLs) and one capacitor (Cs). The resonators are designed by using its equivalent circuits and its design equations which are presented in this work. The filter exhibits central frequency at f0d = 0.988 GHz, Fractional Band Width (FBW) of 10.1%, Common Mode Rejection Ratio (CMRR) better than 51 dB at the center frequency, Common Mode (CM) rejection better than −40 dB from 0.5 GHz to 3.3f0d and better than −30 dB from 0.5 GHz to 4f0d. This paper includes analysis, design methodology and experiments. [ABSTRACT FROM AUTHOR]

In this paper, a newly shunted-line stepped-impedance resonator (SLSIR) is studied and applied to realize high-order balanced filter design for radio astronomy application. The proposed SLSIR not only has more flexible control of the internal coupling between adjacent units but also provides more design freedom for the cascade connection of high-order filter. Then, the operating theory of three kinds of electrically, magnetically, and electromagnetically coupled SLSIR pairs has been discussed and utilized to high-performance filter design. Hence, fourth-order balanced filter using electromagnetically coupled SLSIR pairs is investigated and designed, which exhibits an excellent filtering performance under differential-mode (DM) operation as well as a high common-mode (CM) suppression level. In addition, the production mechanism of DM transmission zero is modeled and analyzed. Based on the analysis above, two dissimilar types of coupled SLSIR pairs with the same fundamental frequency but different harmonics are adopted to design an eighth-order balanced filter. Finally, the high-order balanced filter is fabricated on 0.5-mm-thick MgO wafer with double-sided YBCO thin films. Measured results show that the eighth-order balanced filter operates at 2.53 GHz with the corresponding in-band insertion loss of 0.1 dB. Results well verify the proposed structure with high selectivity, low insertion loss, and wide stopband performances. [ABSTRACT FROM AUTHOR]

This paper reports on design of novel balanced bandpass filters (BPFs) using quarter-wavelength stub resonators. For the design purposes, differential-mode (DM) and common-mode (CM) half-equivalent circuits are established and analyzed carefully. In this paper, CM noise is introduced into the filter and dissipated on the resistors on periodic bands. First, a balanced BPF topology based on conventional quarter-wavelength stub filter is presented. By symmetrically introducing series matching resistors to the ground at the center of the stub, CM noise can be rejected either reflectively or reflectionlessly without affecting DM performance. The harmonic property of stubs provides periodic CM suppressing response as long as the resistor has no serious parasitic reactance. By doing so, CM noise can be suppressed under a certain level at all frequencies. However, the harmonic property also leads to some spurious passbands. This defect can be avoided by an improved filter topology with two additional capacitors. To reserve the CM feature, the corresponding DM and CM half equivalent circuits are developed as well. The proposed layouts are fabricated on a two-layer printed circuit board. The resulting experimental circuits exhibit the expected electrical performance, forming balanced BPFs with CM noise suppression level over 12 dB at all frequencies, and show an agreement with the simulated results. [ABSTRACT FROM AUTHOR]

This paper presents a new miniaturized ultra-wideband (UWB) multilayer balanced bandpass filter (BPF) using the liquid-crystal polymer technology. The design is based on the use of two baluns and uses the transversal signal-interference concept for the realization of differential-mode (DM) passband and common-mode (CM) stopband. The broadside coupled stripline structure is adopted in this paper to realize UWB performances and pure TEM mode. The fabricated prototype is self-packaged, light in weight, and cost effective with a small footprint. The demonstrated balanced BPF achieves the excellent DM and CM responses within the entire bandwidth, centered at 6.85 GHz. The simulation and measurement results show good agreement. [ABSTRACT FROM AUTHOR]

This paper presents a novel balanced filter with enhanced stopband by using discriminating coupling. The proposed design utilizes third-order quarter-wavelength coupled resonators to obtain the filtering responses. Discriminating coupling is applied between feedline and resonator. The circuit is theoretically analyzed and implemented for demonstration. The operating frequency is located at 2.4 GHz and the common-mode rejection is larger than 20 dB up to 9 GHz (3.75f0). Due to discriminating coupling, the differential mode out-of-band rejection is larger than 20 dB up to 18 GHz (7.5f0), which shows wide stopband. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method for designing a dual-channel balanced filter and a dual-channel balun filter based on the quad-mode dielectric resonator (DR) for the first time. By sharing one common quad-mode DR, two balanced filters or two balun filters are integrated as one single-cavity configuration, featuring compact size and high integration. A cylindrical DR with two short ends is investigated to construct the quad-mode DR. By properly arranging input and output feeding probes, two modes of the DR are only excited by the feeding probes of one channel and the other two modes are excited by that of the other channel. Accordingly, signals cannot be transmitted between the two channels, resulting in high isolation. Moreover, the required out-of-phase characteristics of the balanced and balun filters can be obtained by the inherent electromagnetic field properties of the DR without adding additional circuits, featuring a simple structure. For demonstration, a dual-channel balanced filter and a dual-channel balun filter are designed and fabricated, showing excellent balanced or balun filter performance of each channel as well as high isolation between the two channels. As compared to the other reported DR balanced and balun filters, the proposed designs exhibit a significant size reduction, which are attractive in wireless systems. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Posts & Telecommunications (Natural Science Edition) is the property of Chongqing University of Posts & Telecommunications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, two high selectivity balanced filters with multiple transmission zeros using ring resonators are proposed. Four, and six transmission zeros are easily realized to improve the differential mode passband selectivity and common mode suppression. Over five octaves common mode suppression can be realized by the bandstop performance of the coupled lines and stubs. Two balanced filters with 3-dB bandwidths of 23.6 and 23.5% are designed and measured. Good agreement can be found between the theoretical and measured results. [ABSTRACT FROM AUTHOR]

Two novel high selectivity wideband balanced filters based on open/shorted stubs with multiple transmission zeros are proposed in this brief. Two and four transmission zeros near each passband for the differential mode (DM) can be easily achieved for two balanced filters. In addition, the common mode can be suppressed with three and five transmission zeros with an insertion loss greater than 15 dB/20 dB over a wide frequency band. Two prototypes with 3-dB fractional bandwidths of 67.6% and 37.8% for the DM with an insertion loss greater than 15 dB (7.0–12.7 GHz) are designed and fabricated. A good agreement can be observed between the measured results and the theoretical expectations. [ABSTRACT FROM PUBLISHER]

A class of balanced dual-band planar diplexer with frequency-contiguous channels for the differential mode and high common-mode rejection is presented. It exploits double-stub-loaded filtering cells with resistors connected at the symmetry plane of the overall diplexer. In this manner, a sharp-rejection dual-band operation for each diplexer channel with transmission zeroes (TZs) at both sides of the differential-mode dual passbands is obtained. In addition, broadened common-mode suppression and low common-mode in-band input power reflection can be realized. The theoretical foundations and design guidelines for the devised dual-band differential-mode diplexer are provided. Moreover, for practical-validation purposes, a microstrip prototype with imbricated 1.51-GHz/2.41-GHz and 1.92-GHz/2.85-GHz lower and upper dual-band channels is manufactured and tested. [ABSTRACT FROM AUTHOR]

This letter demonstrates a design of a compact balanced bandpass filter (BPF) with stopband extension and common-mode (CM) suppression using asymmetric stepped-impedance resonator (SIR) pairs and a spoof surface plasmon polariton (SPP) feeding structure. The configuration of balanced SIR pairs is analyzed theoretically to obtain a wide stopband response and intrinsic CM suppression within differential-mode passband. Moreover, a novel SPP feeding structure is adopted as a low-pass filter and impedance matching section for enhancing filter transmission responses. Finally, a balanced BPF operating at 0.85 GHz with the SPP feeding structure is designed and fabricated to verify the design method. [ABSTRACT FROM AUTHOR]

In this paper we prove the existence of a completion of a T0–pre-uniform space (X,U), with the property that each Cauchy filter in (X,U) contains a weakly round filter.

Two ultra-wideband balanced bandpass filters based on transversal signal-interference concepts are proposed in this paper. By employing the two structures: microstrip/slotline transition, and quarter-wavelength shorted coupler lines, 180° phase shift can be easily implemented for each design. In addition, due to the different transmission paths, wideband common mode rejection and differential mode transmission bandwidth can be achieved. Two balanced filters centered at 3 GHz are calculated, fabricated and measured successfully. For the differential mode, the 3-dB fractional bandwidths are 102% from 1.47 GHz to 4.53 GHz and 103% from 1.52 GHz to 4.61 GHz, respectively, and the return loss are both greater than 20 dB. For the common mode, signals are suppressed below -20 dB and -15 dB over the whole frequency band. [ABSTRACT FROM AUTHOR]

Two novel high selectivity balanced filters based on transversal signal-interaction concepts with wideband common mode suppression are proposed in this paper. Four and six transmission zeros near each passband are realized to improve the selectivity for the differential mode. In addition, the common mode can be suppressed with insertion loss greater than 15 dB over a wide frequency band. Two prototypes ( Ɛr = 2.65, h = 0.5 mm, tan δ = 0.003) with 3-dB fractional bandwidths of 31.3% and 32% for the differential mode with upper stopband greater than 18 dB are designed and fabricated. Good agreements can be observed between measured results and theoretical expectations. [ABSTRACT FROM AUTHOR]

In this paper, a class of balanced wideband and dual-band bandpass filters (BPFs) is proposed and designed on a hybrid multimode resonator. This resonator is composed of two distinctive kinds of transmission lines, i.e., microstrip line and slotline, so it is called a hybrid resonator. On one hand, the resonator itself has the common-mode (CM) rejection as an inherent property by virtue of the hybrid structure; on the other hand, the microstrip/slotline transitions for feeding are avoided because normal microstrip feeding schemes are valid via microstrip lines inside this resonator. As such, the proposed hybrid resonator is largely different from those in the existing balanced BPFs with intrinsic CM rejection. In the traditional one, the resonator is formed by a slotline and it is connected with microstrip/slotline transitions for differential-mode (DM) transmission and CM rejection. What is more valuable, the hybrid resonator can be easily constructed by replacing a portion of then microstrip line in the traditional microstrip resonator with the slotline. Thus, the diversity of the balanced wideband BPFs with intrinsic CM rejection can be extremely enhanced and the balanced dual-mode dual-band BPF can be successfully designed. Two different balanced BPFs under wideband and dual-band operations are finally designed and fabricated to support our theory. [ABSTRACT FROM PUBLISHER]

This letter presents the coupling matrix design of differential/balanced RF filters. They exhibit: i) a highly suppressed common mode that is obtained by multiple transmission zeros and resistively loaded poles and ii) a differential mode that exhibits a quasi-elliptic-type transfer function that can be tuned in frequency and bandwidth (BW) and can be intrinsically switched-off. The filter’s reconfiguration properties are attained by only tuning the resonant frequencies of its constituent resonators. Thus, it exhibits less in-band insertion loss than tunable differential architectures in which tuning of couplings is required. For practical validation purposes, a microstrip prototype was manufactured and measured in the 1.4–1.9-GHz range with the following characteristics. Differential mode: center-frequency tuning between 1.36 and 1.9 GHz (1.4:1), BW tuning between 43 and 270 MHz (6.3:1), and an intrinsically switched-off mode with isolation (IS) > 22 dB. Common mode: 70%, 40-dB suppression BW and IS > 60 dB at the center frequency for all tunable states. [ABSTRACT FROM AUTHOR]