Performance Of Bandpass Filter Research Articles

Incremental use of FFT as a solution for low BT-product reverberation time measurements

The limitations in performance of band-pass filters to accurately process rapid decaying signals in lower frequency bands is an obstacle for some measurements within building acoustics. For instance, it would be beneficial to be able to accurately measure reverberation times down to the 20 Hz one-third octave band for impact sound in timber buildings. Here, it is tested whether calculations with FFT with small incremental steps may be a way to achieve discrete frequency time signals with faster performance than traditional band-pass filters. The tests show that incremental FFT gives accurate estimations of the reverberation time corresponding down to 0.1 s at 20 Hz with a spectral resolution of 2 Hz. Using the one-third octave limits it is possible to form approximate one-third octave band results. It is seen that accurate estimations of reverberation time are achievable for BT⩾0.5 (T=0.1 seconds for the 20 Hz one-third octave band) and possibly even lower, if the dynamic range in the interrupted noise signal is sufficient. The higher one-third octave results show to work as well. A disadvantage with the method is that during short reverberation times (0.1 s) there is a severe spectral leakage to the side bands. Also, the method requires higher dynamic range decay signals compared to band-pass filtered signals. If a one-third octave resolution is requested, a dynamic range of 50 dB or greater is preferable. With a coarse resolution of e.g., 10 Hz and having no averaging into one-third octave bands, it is possible to measure short reverberation times (0.1 s) with signals having close to the same dynamic range used in classical band-pass filtered reverberation time measurements.

A 10.23–15.7-GHz Varactor-Tuned Microstrip Bandpass Filter With Highly Flexible Reconfigurability

This article demonstrates a 10.23–15.7-GHz varactor-tuned microstrip bandpass filter (BPF) with fully controllable center frequency, bandwidth, and transmission zeros. The concept of cascading a tunable low-pass unit together with a tunable high-pass unit is adopted to achieve the reconfigurable BPF. A comprehensive loss analysis is carried out to determine the preferable circuit topologies for low-pass filter (LPF) and high-pass filter (HPF), respectively. This not only overcomes the limitation of low quality factor of varactor at high frequency, but also contributes to a highly flexible reconfigurability of the BPF. A reconfigurable LPF using defected ground structure (DGS) and a quasi-elliptic HPF using microstrip technology are then proposed to demonstrate the improved BPF performance at high frequency. The measured results show that the designed BPF is capable of operating in five working modes, with a center frequency tuning range from 10.23 to 15.7 GHz and a fractional bandwidth (FBW) tuning range from 32.48% to 95.76%. The minimum in-band insertion loss reaches 2.55 dB. A steep cutoff characteristic and ultrawide stopband with high rejection level are successfully achieved and are well preserved during the whole tuning process, demonstrating the superiority of the designed BPF.

Design of 4 × 4 and 8 × 8 Filtering Butler Matrices Utilizing Combined 90° and 180° Couplers

In this article, a novel design approach for designing 4×4 and 8×8 filtering Butler matrices is proposed. The matrices, composed of combined 90° couplers and 180° filtering couplers as well as phase shifters, provide incremental phase shifts and a bandpass filter performance. The detailed design process and synthesis method for the Butler matrices are presented. A three-layer symmetrical stripline structure is used to realize the Butler matrix, allowing a fully planar structure without interlayer connections. For experimental verification, two prototype 4×4 and 8×8 filtering Butler matrices, operating at the center frequency of 2.4 GHz with a bandpass response, are devised, manufactured, and tested. The test results match well with the simulation ones. Based on the measurements, array factors have been calculated, which further indicate the acceptance of the measured results.

3D conformal bandpass millimeter-wave frequency selective surface with improved fields of view

Conventional planar frequency selective surfaces (FSSs) are characterized in the far-field region and they are sensitive to the incidence angle of impinging waves. In this paper, a spherical dome FSS is presented, aiming to provide improved angular stable bandpass filtering performance as compared to its planar counterpart when the FSS is placed in the near-field region of an antenna source. A comparison between the conformal FSS and a finite planar FSS is presented through simulations at the frequency range between 26 to 40 GHz in order to demonstrate the advantages of utilizing the conformal FSS in the near-field. The conformal FSS is 3D printed and copper electroplated, which leads to a low-cost and lightweight bandpass filter array. Placing it in the near-field region of a primary antenna can be used as radomes to realize compact high-performance mm-wave systems. The comparison between simulated and measured conformal FSS results is in good agreement. The challenges that arise when designing, manufacturing, and measuring this type of structure are reported and guidelines to overcome these are presented.

A Miniaturized Ka-Band Bandpass Filter Using Folded Hybrid Resonators Based on Monolithic Microwave Integrated Circuit Technology

A miniaturized Ka-band bandpass filter (BPF) is presented by using monolithic microwave integrated circuit (MMIC) technology in this brief. Aiming at low cost and high integration, small die area of MMIC BPFs is significantly required for RF front-end modules.However, the filtering performance of BPFs is negatively correlated to its miniaturization. To this end, the folded hybrid resonator is investigated in this brief, which is composed of a quasi-lumped capacitor and a distributed microstrip line. To realize miniaturization, two metal layers of GaAs process are fully utilized. For low loss, the distributed inductor is designed on the top thick layer, while the quasi-lumped capacitor is on the lower metal layer of high sheet resistance. To reduce the unwanted mutual coupling between adjacent quasi-lumped capacitors, shielding structures are added into BPFs, resulting in a 5-dB and 12-dB enhancement to the lower and upper stopbands, respectively. Based on the mixed electric-magnetic coupling topology, a second-order MMIC bandpass filter is designed and fabricated by using GaAs process. Small die area, low loss, high selectivity, and wide stopband are simultaneously obtained, indicating a promising application of the proposed miniaturized MMIC bandpass filters.

QZSS L1 Bandwidth Frequency Filter Design for QZSS Receiver

We present the design of bandpass filter on the frequency of the QZSS satellite, by providing bandwidth at the cut-off frequency equally to the bandwidth of the QZSS L1 with selecting the response characteristic on Butterworth maximally flat amplitude. Bandpass filter design using frequency of the QZSS L1 with bandwidth is 24MHz. The design procedure involves two steps, the first step is to find the required order of the filter, which we use 3rd order, and the second step is to find the scale factor that must be applied to the normalized parameter values. The Band-Pass Butterworth filler is a combination between low pass and high pass. For the Butterworth filter, the value of a resistor that has been used are 50Ω. Then go to find the capacitor and inductor and by using PSpice as the tools for the simulation. The results of the output of bandpass filter at -3dB was between 1563 and 1587MHz. And was bandwidth around 24MHz. The combination of the lowpass filter and high pass filter is to perform as the bandpass filter. Therefore, there are two combinations also in designing bandpass filter. The aim of this combination is to have an influence on the performance of bandpass filter. As a conclusion, this designed filter on the frequency of QZSS L1 is to be useful by using bandpass filter.

High performance bandpass filters using printed circuit board packaging technique

In this paper, two compact filters with high selectivity and wideband harmonic suppression are proposed, which use printed circuit board packaging technique. The filters are designed based on the complementary split-ring resonators (CSRRs) and short-circuit centered stepped impedance resonator (SCSIR). High selectivity and wideband harmonic suppression are achieved by controlling the transmission zeros. The center frequency and transmission zeros near the passband can be controlled independently by adjusting the parameters of the CSRR and the SCSIR, respectively. Two bandpass filters are designed with the typical coupling matrix theory. The measured insertion loss is within 2 dB for the two bandpass filters. The transition band from the cut-off frequency to 40 dB attenuation is only 0.12 GHz.

An Active Bandpass Filter for LTE/WLAN Applications Using Robust Active Inductors in Gallium Nitride

This brief demonstrates the performance of the first active bandpass filter to implement an active inductor in gallium nitride (GaN) technology. Fabrication of the filter and inductor was done using a 0.5 μm pHEMT GaN process with the system implemented on one 2 mm by 2 mm die. The tuning range of the active filter was measured to be 749 MHz at a centre frequency of 3.39 GHz with separate amplitude and quality factor tuning. An amplitude range for S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> was measured to be from -12.2 dB to 13.7 dB within the operating frequency range. Taking advantage of the active inductor's negative impedance the filter was able to produce a quality factor of 138. On-chip, the active inductor occupies an area of 350 μm by 175 μm compared to approximately 350 μm by 350 μm for their passive counterparts of similar inductance (a 50% decrease in size). The filter was designed for LTE/WLAN applications to demonstrate the capabilities of the active inductor.

Effect of the defected microstrip structure shapes on the performance of dual-band bandpass filter for wireless communications

Due to the progression growth of multiservice wireless communication systems in a single device, multiband bandpass filter has attract a great attention to the end user. Therefore, multiband bandpass filter is a crucial component in the multiband transceivers systems which can support multiple services in one device. This paper presents a design of dual-band bandpass filter at 2.4 GHz and 3.5 GHz for WLAN and WiMAX applications. Firstly, the wideband bandpass filter is designed at a center frequency of 3 GHz based on quarter-wavelength short circuited stub. Three types of defected microstrip structure (DMS) are implemented to produce a wide notch band, which are T-inversed shape, C-shape, and U- Shape. Based on the performance comparisons, U-shaped DMS is selected to be integrated with the bandpass filter. The designed filter achieved two passbands centered at 2.51 GHz and 3.59 GHz with 3 dB bandwidth of 15.94 % and 15.86 %. The proposed design is very useful for wireless communication systems and its applications such as WLAN and WiMAX

A Broadband Filter Transmitarray Based on Quasi-Yagi Antenna Element

A transmitarray (TA) antenna operating at X-band with band-pass filtering performance is presented. The proposed antenna is composed of a wideband TA and a filter feed antenna. Two quasi-Yagi antennas are connected as the unit cell of the proposed TA, leading to high transmission efficiency over a broadband range. By simply changing the length of the transmission lines, 360° phase shift is obtained. To verify this idea, a design with 16×26-unit cells is simulated and optimized, showing that approximately 14.5% 1-dB and 24.6% 3-dB gain bandwidths are achieved, respectively, with the peak gain of 23.1 dBi. Moreover, by employing the bandpass filter feed antenna, good bandpass filtering property is achieved, showing that the upper and lower out-of-band suppression in the 0.3GHz range can reach 27.3dB and 24.2dB, respectively, with the passband range from 9.6GHz to 11.9GHz.

Waveguide bandpass filter with multiple transmission zeros

ABSTRACTThis paper presents a lightweight waveguide bandpass filter using planar structure insert, which can control the location of transmission zero and center frequency independently. The proposed planar insert consists of three concentric circular complementary split-ring resonators. The structure resonates at a particular frequency and produces two transmission zeros above and below the passband, thus improving the stopband performance of conventional complementary split-ring resonator-loaded waveguide bandpass filter. To demonstrate this, a second-order bandpass filter has been designed. It has been shown that by varying the split gap dimensions of upper and lower circular complementary split-ring resonators, the transmission zeros can be independently controlled.

New method of analysis and design of frequency and bandwidth reconfigurable active filter

A new method of analysis and design of reconfigurable active bandpass filter is proposed. The proposed method involves matrix manipulation for equating passive inverter impedances with those of active inverter (both input and output impedances). Designing of active filter involves the designing of active inverter and active resonator. The filter performance is analysed in frequency range 500 MHz to 1.5 GHz. The narrow band filter is switched between two bands with varying fractional bandwidth and centre frequency. The physical implementation comprise elements employing ATF 21186 FET on RT Duroid 5880 substrate with dielectric constant 2.2 and thickness 0.127 mm. Active resonator comprises of an active capacitor and a passive inductor. The active inverter along with active resonator employed in active filter circuit provides reconfigurability in frequency (≈200 MHz) as well as in bandwidth with the variation in gain of approximately 8-10 dB. The electrical performance of active band pass filter shows good agreement with the measured response. To best of my knowledge first time integration of active inverter and active capacitor is done. Intergration of such kind allows for frequency as well as bandwidth tuning. The electrical performance of active band pass filter shows slight deviation from with the measured response.

Codesigned Wideband High-Efficiency Filtering SIW Slot Antenna with High Selectivity and Flat Gain Response

A substrate integrated waveguide (SIW) slot antenna with wideband bandpass filtering performance is proposed in this journal. It consists of a SIW cavity, a transverse slot, three metal posts, and a SMA connector. Three metal posts split the SIW cavity into two TE110-mode resonators. A long nonresonant transverse slot is utilized to realize a half TE110-mode resonator and generate radiation simultaneously so as to reduce the size and release the use of extra radiator. Three in-band resonance poles and a radiation null at both out-of-bands are obtained. A prototype is fabricated and measured. Measured results demonstrate the proposed antenna is with a center frequency of 4.26 GHz, a fractional bandwidth of 9.1%, a high efficiency of 93%, and flat gain response and good skirt selectivity of 270 dB/GHz and 330 dB/GHz for the lower and upper out-of-band, respectively.

On-chip self-calibration system for CMOS active inductor band pass filter

A calibration system aiming for automatically correcting the effect of process variation on performance of on-chip Active Inductor Band Pass Filter (AIBPF) is presented. The benefit of using active inductors to build on-chip band pass filter is less chip area consumption and the tunability of center frequency compared to designs employing passive inductors. However, the fatal drawback of active inductor is performance degradation caused by process variation generated during chip fabrication. The proposed calibration system has the ability to detect process variation and adjust the AIBPF center frequency back to the designed 5.2 GHz by compensating the bias voltage. Simulation results show this calibration system can significantly improve the yield of circuits employing AIBPFs.

Codesigned High-Efficiency Single-Layered Substrate Integrated Waveguide Filtering Antenna With a Controllable Radiation Null

This letter proposes a codesigned substrate integrated waveguide (SIW) filtering slot antenna with a controllable radiation null in gain response. The antenna is composed of a single-layered SIW cavity, four metalized posts, a transverse slot, and a vertical SMA connector. Four metalized posts are introduced to split the cavity into two TE 110-mode resonators. The transverse slot is utilized not only to generate radiation, but also to further split one TE110-mode resonator into two half-mode resonators. The bandpass filtering performance is achieved by the couplings between three resonators and the slot. One radiation null has been introduced for selectivity enhancement, and it will occur at the frequency where the slot is placed at about quarter-wavelength from the shorted wall of the cavity. So by changing the position of the slot, frequency of radiation null can be easily controlled, even from one side to another side of the passband. For demonstration, one antenna with a lower out-of-band radiation null and another one with an upper out-of-band radiation null have been designed, fabricated, and measured. Experimental results show that the antennas have the merits of high efficiency, high selectivity, and easily controllable radiation null.

Enhancement of 5 GHz on-chip bandpass filter performance by using CMOS-MEMS inductors

We propose the use of microelectromechanical system (MEMS) inductors to enhance the performance of a 5-GHz on-chip bandpass filter. The proposed filter is implemented using the TSMC 0.18 μm one-poly six-metal (1P6M) CMOS process. For reducing substrate loss to improve filter performance, the silicon substrate underlying the filter’s MEMS inductors is removed using the Chip Implementation Center micromachining postprocess. Compared to conventional on-chip CMOS inductors on-silicon substrate, the simulation results obtained using the CMOS-MEMS inductors showed a quality factor improvement of 264.3% at 5.5 GHz. The measured insertion loss of the proposed filter with the CMOS-MEMS inductors is 3.2 dB at 4.7 GHz, and the ripple is 0.6 dB in the passband. The − 3-dB bandwidth ranges from 4.2 to 5.8 GHz. The attenuation is better than − 22 dB for frequencies ranging from 1 to 3.8 GHz and − 25 dB from 6.9 to 10 GHz in the stopband. The shape factor of the filter is 1.97:1 at an attenuation of 25/3 dB. The chip area is very small, and the optimal chip size is 1.3 × 0.75 mm2. The proposed filter could be integrated directly with the silicon base process, namely, CMOS and BiCMOS, for 5-GHz band wireless front-end applications.

Notice of Retraction: Experimental Validation of a 3D FSS Designed by Periodic Conductive Fibers Part-1: Band-Pass Filter Characteristic

This study covers the design, manufacturing, and experimental electrical tests for a novel three-dimensional (3-D) band-pass frequency selective surfaces (FSS) containing continuous and discontinuous conductive fibers. The proposed FSS is designed based on 3-D numerical simulations to operate in the frequency range 8–12 GHz with resonant frequency at around 9.5 GHz. An equivalent circuit model of the proposed FSS is constructed to predict and understand the electrical behavior of the structure. Moreover, the experimental result of a fabricated prototype is obtained to demonstrate the validity of both the simulation results and the equivalent circuit model prediction. Furthermore, a quasi-isotropic multilayer FSS having fibers with different orientations is considered to provide a band-pass filter performance under various incident angles for both transverse electric (TE) and transverse magnetic (TM) polarizations.

Design and Performance of a High- $Q$ Narrow Bandwidth Bandpass Filter in Empty Substrate Integrated Coaxial Line at $K_{u}$ -Band

This letter presents the design and performance of a planar narrow bandwidth bandpass filter with high quality factor. The structure is composed of an empty substrate integrated coaxial line with the center conductor suspended in air. The component dimensions have been calculated by means of classical microwave filter design theory. The filter has been manufactured using standard printed circuit board fabrication processes. A measured insertion loss of 1.59 dB, 2.93% fractional bandwidth, and a $Q$ -factor of 1505 have been obtained at 15 GHz. A $Q$ -factor comparison with other substrate and empty substrate integrated technologies shows the advantages of the solution considered in this letter. The proposed filter proves to be suitable for the implementation of integrated microwave or millimeter-wave subsystems with severe restrictions, i.e., low in-band losses, very narrow bandpass responses, low frequency dispersion, high out-of-band rejection, and low manufacturing cost.

A novel compact and high performance bandpass filter based on SIW and CMRC technique

Based on the substrate integrated waveguide (SIW) and compact microstrip resonant cell (CMRC) technique, a compact and high performance planar bandpass filter (BPF) is proposed in this paper. The SIW cavity, which has the advantages of high quality and low insertion loss, provides a highpass characteristic. The CMRC structure etched on the top metal plane of the SIW cavity behaves as a lowpass filter, and it can also effectively reduce the dimension of the filter. In order to improve the out-of-band rejection and sharpen skirt selectivity, the open circuit lines at the input and output ports of the filter are introduced. Moreover, the bandwidth and center frequency of the proposed filter can be flexibly tuned by adjusting the cutoff frequencies of the SIW and CMRC separately. As a verification, a representative BPF having a center frequency of 4.54GHz and a 3dB bandwidth of 1.39GHz is designed, fabricated, and experimentally evaluated. The simulated and measured results are in good agreement.

Free-standing double-layer terahertz band-pass filters fabricated by femtosecond laser micro-machining.

We report on the fabrication and transmission properties of free-standing single-layer and double-layer THz bandpass filters. These filters are fabricated on aluminum foils using femtosecond laser micro-machining. The aluminum foils are periodically patterned with cross apertures with a total area of 1.75×1.75 cm2, also known as frequency-selective surfaces. Their terahertz transmission properties were simulated using the FDTD method and measured using a time-domain terahertz spectroscopy system. The simulation results agree with the measurements results very well. The performance of single-layer bandpass filters is as good as the commercial equivalents on the market. The double-layer filters show extraordinary transmission peaks with changing spacing between the two layers. We show the contour map of the electric field distribution across the apertures, and ascribe the new transmission peaks to the interference and coupling of surface plasmon polaritons between the two layers.