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This work presents a novel microstrip dual-band bandpass filter (BPF) using meandros spirals and patch cells, which is proposed for the first time by this work. It occupies a very compact size of 0.0017 λg2. The proposed filter is designed to operate at Fo1=0.85 GHz and Fo2=1.85 GHz for GSM-850/GSM-1900 applications. In addition to the small size, it has several advantages in terms of wide fractional bandwidths (FBW), low insertion losses and high return losses at both channels. The simulated insertion losses at the lower and upper passbands are 0.05 dB and 0.1 dB, respectively. Another advantage of the proposed BPF of this work is the attenuated harmonics, where it is able to suppress 1st, 2nd, 3rd and 4th harmonics (4.11 Fo1) with -20 dB maximum harmonic level.

In this article, a novel compact microstrip dual-narrowband bandpass filter (DNBPF) is presented with wide and high rejection levels in the stopbands. The location of each passband is independently controllable/tunable/selectable. The filter structure is made up of three-coupled-asymmetrical transmission lines, open-ended stubs and direct-transmission lines. Employing these lines can generate two narrowband passband filters. By combining these passband filters, the proposed DNBPF is configured. The proposed DNBPF is investigated. The center frequency of the first and second passband are 5.745 and 6.489 GHz, respectively. Also, the proposed DNBPF presents the fractional 3-dB bandwidth of the first and second passband 3.66 and 2.33%, respectively. It has the flattest group delay variations in comparison with previously published papers due to the design freedom. |S12|< -30 dB is from 10.1 to 19.25 GHz in the last stopband. The occupied area of the proposed DNBPF is 0.225 λ g × 0.11 λ g , where λ g is the guided wavelength at the first center frequency. [ABSTRACT FROM AUTHOR]

This letter presents a non‐reciprocal diplexer with integrated functions of a conventional bandpass diplexer and two isolators. This is achieved by spatio‐temporally modulating the resonator frequencies in a coupled‐resonator diplexer. Due to the high channel‐to‐channel isolation, the diplexer channels can be independently modulated without affecting each other. A microstrip diplexer example is demonstrated with good agreement between the measurement and the simulation. The fabricated diplexer has two non‐reciprocal bandpass channels at 829 and 997 MHz, with a minimal insertion loss of 4.9 and 6.1 dB, and a 20‐dB isolation bandwidth of 38 and 37 MHz, respectively. To the best of the authors' knowledge, this is the first time that a non‐reciprocal diplexer has been presented. [ABSTRACT FROM AUTHOR]

This paper presents a new design of a super compact Ultra wideband (UWB) band-pass filter (BPF) with rejection of X-band satellite applications. For covering the UWB bandpass, the proposed filter is realized using hybrid technique which is achieved by using a Microstrip-Coplanar waveguide-Microstrip transition. The basic structure consists of a modified microstrip in the top layer and CPW in the bottom layer. Later, open-circuited stubs are embedded in the top to implement in-band transmission zeros (TZ) so as to circumvent interference. The simulated results show that the UWB bandpass filter has a high adaptation (S11 ≤ −18 dB) and insertion loss better than 0.4 dB at the passband. The impedance bandwidths are about 114% (3–11 GHz) with upper stopband extends to more than 14 GHz with a depth of greater than 38 dB. In addition, the UWB BPF shows a flat group delay performance with a variation of about 0.15 ns over the entire bandwidth. A prototype of the filter is fabricated and tested. Good agreement is achieved between measurement and simulation. The proposed UWB BPF is compact in size with overall dimensions of 14 by 9.2 mm2. Consequently, the obtained results prove that the presented filter is suitable for UWB wireless devices.

In this paper a microstrip bandpass filter using cascading technique is presented. The 3 dB passband of this filter extends from 2 GHz to 3.8 GHz. The return loss for this range is below -10 dB. The filter has a fractional bandwidth of 62.06% subject to design frequency of 2.9 GHz for WIFI and WiMAX applications in the range of 2 GHz to 3.8 GHz. The measured results show good agreement with the simulations. The filter is designed on FR4 substrate. The proposed filter has a compact size of λg × 0.3λg, where λg is the guided wavelength at a frequency of 3 GHz. [ABSTRACT FROM AUTHOR]

In this article, a new compact microstrip dual-narrowband bandpass filter is introduced with wide and strong rejection level in the first and last stopband. The location of the second passbands is controllable by a resonator without changing the center frequency of the first passband. The filter structure consists of coupled and stepped transmission lines and radial stubs. Also, fractional 3 dB bandwidth of the first and second passband are 2.35 and 1.62%. The last stopband of the proposed filter is wide. The overall size of the proposed filter is , where is the guided wavelength at the first center frequency. [ABSTRACT FROM AUTHOR]

In conventional multiplexer designs that use a direct-feed filter in each channel selection, matching circuits are typically crucial for achieving low loading effects between channel circuits. However, existing matching designs are often complex, and time-consuming optimizations are required when the number of multiplexer channels exceeds three. This paper proposes and verifies two four- and one five-channel multiplexers with simple and effective matching designs. [ABSTRACT FROM PUBLISHER]

In the design of bandpass filters, the use ofλ/2 stubs of shunt configuration had been mostly unacceptable due to their effect of narrow stopband bandwidths in the ensuing filters. The design of bandpass filter presented in this article introduces 360° series transmission line segments to increase the stopband bandwidths to an acceptable level without affecting the wide passband. This designed filter has low insertion loss of less than –1.98 dB and a fractional bandwidth of 50% at 6 GHz mid-band frequency. A sharp rejection in the stopband is observed. To further widen the bandwidth of stopbands, a series capacitor and a shunt stub are used. The transmission line model of the filter is in good agreement with measured results. The filter is planar and is fabricated on FR-4 substrate which makes it cost-effective and easy to fabricate. [ABSTRACT FROM AUTHOR]

In this paper, design and simulation of broadband parallel-coupled microstrip bandpass filters used for modern wireless communication technology (Military & Industrial System such as Low Noise Block ( ) in Television Satellite) are presented, Four designs of filters at 10GHz center frequency are proposed. The first design is parallel coupled microstrip filter, which modify by bending some of microstrip conductors in specific angle( ) as shown in the second design to modify the characteristics and results. In this paper, design and simulation of broadband parallel-coupled microstrip bandpass filters used for modern wireless communication technology (Military and Industrial System such as Low Noise Block ( ) in Television Satellite) are presented, Four designs of filters at 10GHz center frequency are proposed. The first design is parallel coupled microstrip filter, which modify by bending some of microstrip conductors in specific angle as shown in the second design to modify the characteristics and results. The third design is U-shape parallel coupled filter which modify by bending its stripes with the same angle as above as shown in the fourth design to obtain the best characteristics and results. All filters are simulated by using CAD (Microwave office 2000 version 3.22) and implemented on the Roger RT-duroid 6006, PTFE ceramic substrate with Dielectric constant, loss tangent and substrate height.

In this present work a novel concept for designing of tunable bandpass filter has been introduced with the help of end coupled microstrip transmission line, defected ground structure (DGS) and defected microstrip structure (DMS). Utilizing this concept, one bandpass filter of 8 GHz center frequency with 30 % fractional bandwidth (FBW) at −3 dB has been implemented for the applications of X-band communication systems. The structure has been simulated with Method of Moment (MoM) based IE3D EM simulator and Measured with Agilent make vector network analyzer of model N5230A. Finally, the simulated result and measurement result provides good agreement between them. [ABSTRACT FROM AUTHOR]

A novel compact parallel-coupled line bandpass filter (BPF) with complementary split ring resonators (CSRRs) is presented in this letter.The proposed BPF, with a combination of CSRRs and parallel-coupled lines, has the advantages of compact size and simpler design procedure compared with conventional CRSS BPFs. The prototype filter achieves the measured insertion loss of 1.4 dB at 3.6 GHz. The implementing area is 0.35 λg × 0.14 λg, where λg is the guided wavelength at the resonant frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:506-509, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27373 [ABSTRACT FROM AUTHOR]

Triple band microstrip tri-section bandpass filter using stepped impedance resonators (SIRs) is designed, simulated, built, and measured using hair pin structure. The complete design procedure is given from analytical stage to implementation stage with details. The coupling between SIRs is investigated for the first time in detail by studying their effect on the filter characteristics including bandwidth, and attenuation to optimize the filter perfomance. The simulation of the filter is performed using method of moment based 2.5D planar electromagnetic simulator. The filter is then implemented on RO4003 material and measured. The simulation, and measured results are compared and found to be very close. The effect of coupling on the filter performance is then investigated using electromagnetic simulator . It is shown that the coupling effect between SIRs can be used as a design knob to obtain a bandpass filter with a better performance for the desired frequency band using the proposed filter topology. The results of this work can used in wireless communication systems where multiple frequency bands are needed. [ABSTRACT FROM AUTHOR]

A microstrip filter based on a single-ring bandpass section integrated with a band-trimming section incorporating two cascaded rings was demonstrated featuring enhanced sideband suppression. The stop-band for the input bandpass section could be selectively eliminated via the proposed band-tailoring section without causing any excessive loss, thereby improving the overall transmission of the device with regard to higher suppression, sharper roll-off, and narrower bandwidth. For the completed device with the center frequency at 4 GHz, the suppression ratio was increased by -8 dB, the 3-dB bandwidth was reduced from 98 MHz to 48 MHz with negligible excessive loss, and the filter quality factor was elevated by about 105%. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2866–2869, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23795 [ABSTRACT FROM AUTHOR]

A generic microstrip structure is used for the design of all-type broadband filters, based on the analogy between wave and transmission line theories. A Matlab-based lumped (LC) and scattered (microstrip line) filter design tool is developed for the automation of the filter design. Sample lowpass, highpass, bandpass, and bandstop filters are designed and their operational characteristics are validated via in-house prepared FDTD-based virtual microstrip circuit simulator. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2390–2393, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21975 [ABSTRACT FROM AUTHOR]

This study proposes a filter with four switching modes (dual-band lowpass-bandpass filter mode, lowpass filter (LPF) mode, bandpass filter (BPF) mode, and both-bands-turned-off mode). In the dual-band lowpass-bandpass mode, the measured lowpass channel in-band insertion loss and cutoff frequency were less than 0.37 dB, and approximately 1.5 GHz, respectively; the measured center frequency, measured minimal insertion loss, and 3 dB fractional bandwidth of the bandpass response were approximately 2.4 GHz, 3.3 dB, and 9%, respectively. The measured suppression levels of the turned-off lowpass band and bandpass band responses were better than 26 and 33 dB, respectively. [ABSTRACT FROM PUBLISHER]

The matching circuit design of a lowpass-bandpass diplexer may be a challenge in conventional designs because a wideband (from zero frequency to approximately the cutoff frequency of the lowpass filter) open condition is required to achieve in bandpass channel circuit. This paper proposes a new lowpass-bandpass diplexer that involves using a simple matching design that can easily meet the required matching condition in each channel circuit. The measured results are in good agreement with the simulated responses. For the lowpass channel, the measured in-band insertion loss and cutoff frequency are less than 0.25 dB and approximately 1.5 GHz, respectively. For the bandpass channel, the measured minimal insertion loss, center frequency, and 3 dB fractional bandwidth are approximately 2.42 dB, 2.4 GHz, and 7.6%, respectively. The measured isolation between the two operating bands is better than 35 dB. [ABSTRACT FROM PUBLISHER]

Differentially driven devices represent a highly promising research field for radio frequency (RF), microwave (MW), and millimeter-wave (mmWave) designers and engineers. Designs employing differential signals are essential elements in low-noise fourth-generation (4G) and fifth-generation (5G) communications. Apart from the conventional planar MW components, differential–fed balanced microstrip filters, as promising alternatives, have several advantages, including high common-mode rejection, low unwanted radiation levels, high noise immunity, and wideband harmonic suppression. In this paper, a comprehensive and in-depth review of the existing research on differential-fed microstrip filter designs are presented and discussed with a focus on recent advances in this research and the challenges facing the researchers. A comparison between different design techniques is presented and discussed in detail to provide the researchers with the advantages and disadvantages of each technique that could be of interest to a specific application. Challenges and future developments of balanced microstrip bandpass filters (BPFs) are also presented in this paper. Balanced filters surveyed include recent single-, dual-, tri-, and wide-band BPFs, which employ different design techniques and accomplish different performances for current and future wireless applications. [ABSTRACT FROM AUTHOR]