Compact Ultra-wideband Bandpass Filter Research Articles

A compact modified U-shaped UWB bandpass filter

ABSTRACTA compact ultra wideband bandpass filter (BPF) with sharp rejection and wide upper stopband is proposed in this letter. The proposed bandpass filter is constructed using modified U‐shaped multimode resonator (MMR). The U‐shaped MMR is loaded with two open stubs on the symmetrical locations. This proposed resonator has five resonant modes, out of which two are odd modes and the remaining are even modes. These modes are present in the UWB band and are used to realize the wideband passband of the filter. By optimizing the dimensions of the stubs, the five resonant modes of the resonator can be brought into the desired passband. This bandpass filter with fractional bandwidth better than 110% is simulated, fabricated, and measured. The measured impedance bandwidth of filter is from 3.75 to 13.75 GHz with an insertion loss of 2 dB and return loss better than 11 dB. The simulated and measured results show a good agreement. The group delay variation is less than 0.25 ns. A wide stopband bandwidth with 16 dB attenuation is up to 19 GHz is obtained in the proposed filter. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2172–2175, 2015

Design of Compact UWB Bandpass Filter with Improved Out-of-band Performance Using Distributed CRLH Transmission Lines

This study presents an Ultra-Wideband (UWB) filter with improved out-of-band performance. The proposed filter adopts novel Composite Right/Left-Handed (CRLH) Transmission Lines (TLs), which are modeled with distributed elements instead of lumped elements. A unit cell of the CRLH TLs is theoretically analyzed to derive the design formulas. The analyzing results confirm that the proposed structures are CRLH TLs. A novel UWB bandpass filter with improved out-of-band performance is designed and fabricated using the induced formulas. The measurement results show that the fabricated UWB bandpass filter has an insertion loss of less than 2.8 dB, a bandwidth of 2.8-10.4 GHz and a rejection of more than 18 dB from 11.6 to 23.4 GHz.

A novel compact ultra-wideband (UWB) bandpass filter with triple-notched bands

A novel compact microstrip ultra-wideband (UWB) bandpass filter with three sharply notched bands and good selectivity is presented in this letter. Triple-notched bands filtering effects are achieved by adding open-circuited stubs and introducing asymmetric dual-line coupling structure to the feed lines, providing a high degree of adjusting freedom and not increasing the filter size. The frequencies of the notched bands and the upper stopband transmission zero can be independently controlled by adjusting the structural parameters of feed lines. Finally, a microstrip UWB filter with triple-notched bands is simulated and fabricated with good agreement.

Super compact UWB BPF with one narrow notched band and wide stopband

A super compact ultrawideband (UWB) bandpass filter (BPF) with one narrow notched band and wide stopband is presented. The basic UWB BPF contains four folded shunt quarter-wavelength short-circuited stubs separated by a three-line coupled structure with length of λg0/4. A coupled folded quarter-wavelength resonator and three semicircle defected ground structures are used to achieve one desired notched band and good stopband characteristic, respectively. The predicted results on S-parameters are compared with measured ones and good agreement is achieved. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:763–765, 2015

High selectivity UWB bandpass filter with a wide notched-band

This article presents a compact ultrawideband (UWB) bandpass filter (BPF) with sharp selectivity, wide notched-band, wide out-of-band rejection, and approximately flat group delay. The proposed filter structure is composed of a U-shaped open-circuited line that is interdigitally coupled to the input/output feed-lines using high impedance lines. The structure generates multiple resonant modes across the UWB span between 3.1 and 10.6 GHz, however, high coupling between the feed-lines and the U-shaped structure transforms the discrete resonant modes into an UWB BPF. Coupling is enhanced by inserting dielectric slots in the ground-plane immediately under the coupling-lines. A wide notched-band is implemented by introducing asymmetry in the coupled lines. This was achieved by making one of the coupling lines longer by folding it and extending the line to partially couple with U-shaped structure. The length of the extended coupled line and the position of the folded section determine the center frequency of the notch-band and its 3-dB bandwidth. The notch was designed to be centered at 5.5 GHz with appropriate 3-dB bandwidth to blocking interference from WLAN signals. The selectivity of the filter was enhanced by loading the U-shaped structure with a T-shaped open-circuited stub to generate two additional resonant modes in the filter's passband and two transmission zeros that were strategically located at the upper and lower cut-off frequencies of the filter. The design was fabricated and its performance verified. The proposed filter has dimensions of 9.4 × 9.9 mm2.

A Novel Compact UWB Bandpass Filter with Quad-Notched Bands Based on S-SCRLHs Resonator

AbstractA novel compact ultra-wideband (UWB) bandpass filter (BPF) with a quad band-notched function using S-SCRLHs (splitted simplified composite right/left-handed) resonator is presented. The S-SCRLHs resonator, which exhibits quadruple resonance, is realized by coupling double S-SCRLH resonator. The S-SCRLHs resonator is integrated into a conventional UWB BPF. The notched frequencies can be adjusted according to specification by altering the S-SCRLHs resonator. Band-rejected filtering properties around the C-band satellite communication band, 5.2 GHz WLAN band and the X-band satellite communication band are generated. The notching frequencies are located at 4.2/5.2/6.3/7.8 GHz. Both simulated and measured results are provided with good agreement. Compared with other BPFs, the proposed BPF has the advantages of compact size, multi-stopband and good selectivity.

Design of a compact dual‐band‐notch ultra‐wideband bandpass filter based on wave cancellation method

In this study, a compact ultra-wideband (UWB) bandpass filter (BPF) with sharp roll-off, improved out-of-band performance and dual-band-notch operation is presented and its design procedure is discussed. In the proposed structure, in order to reject the unwanted harmonic pass bands, a pair of modified cross-shaped coupled lines (CCLs) is implemented along the ports of the filter. Moreover, a pair of half-circle-shaped stubs and a stepped-impedance stub are loaded on the main resonator in order to obtain additional transmission zeros (TZs) which are controllable separately. Implementation of the CCLs and the stub loaded resonator (SLR) reduce the total size of the presented microstrip BPF. Besides, by extending and folding the upper coupled line of each CCLs and also through an open stub which is protruded inside a slot on the main resonator, dual-band-notch operation is added to the performance of the presented filter. The fabricated prototype has a small size and is capable to cover frequency band of 2.8–10.69 GHz with two band-notch functions at 4.9–5.4 and 7.83–8.25 GHz which suppresses the interference between UWB spectrum with wireless local area network (WLAN) and satellite communication frequency bands, respectively. The proposed filter has a compact size while showing good return loss and insertion loss characteristic in the frequency band of interest.

Compact UWB BPF using slotted resonator with an independently controllable notched band

In this paper, a novel compact ultra-wideband (UWB) bandpass filter (BPF) without and with one sharply notched band is presented. The UWB bandpass characteristic is achieved using slotted resonators (SR) and a notch is obtained by spiral defected ground structure (SDGS) without any change in SR structure. Center frequency of the notched band can be easily changed (from 5 to 9 GHz) by tuning the dimensions of SDGS. To verify the feasibility of the proposed filter, two UWB BPFs, one without the notched band and the other with a notched band, at 8.0 GHz are developed and fabricated, there by suppressing the spurious satellite-communication signal within passband. Measured results of two fabricated filters have the advantages of wide −3 dB bandwidth from 3.1 to 10.6 GHz (which satisfies the requirements of US Federal Communication Commission -specified UWB limits), compact size, low insertion loss (<0.6 dB), and a wide upper stopband with high attenuation (−20 to −50 dB).

Modelling and validation of a simple and compact wide upper stop band ultra‐wideband bandpass filter

A compact ultra-wideband (UWB) bandpass filter (BPF) is proposed based on end coupled microstrip transmission line, defected ground structure and defected microstrip structure. The experimental filter shows a fractional bandwidth of 110% at a centre frequency, with two observable transmission zeros (attenuation poles) at 2.1 and 11.7 GHz. Measured results exhibit an UWB passband from 3.02 to 10.6 GHz with mid-band insertion loss of 1.8 dB and group delay variation <0.45 ns. The BPF achieves a wide stopband with < −18 dB attenuation up to 20 GHz.

Ultra‐wideband bandpass filter using multi‐stub‐loaded ring resonator

A compact ultra-wideband (UWB) bandpass filter (BPF) using a multi-stub-loaded ring resonator is presented. The resonant frequencies of the proposed resonator can be tuned freely by changing the lengths of the corresponding stubs. By utilising the proposed multimode resonator, four resonant frequencies are evenly allocated in the UWB range and two transmission zeros are introduced at the lower and upper stopbands. Parallel-coupled feedlines with defected ground structures were utilised to provide sufficient external coupling. To validate the design theory, an UWB BPF operating in the frequency range from 3.1 to 10.6 GHz was designed, analysed and fabricated. Measurements showed good agreement with simulations.

Compact ultrawideband bandpass filter with triple notched‐bands and sharp transmission zeros based on CSRR, DGS, AND FMRR configurations

ABSTRACTThe folded multiple‐mode resonators (FMMR) with complementary split ring resonator (CSRR), and defected ground structures (DGS) are introduced for notched‐band ultrawideband (UWB) bandpass filter design in this article. Using the CSRR, FMRR, notched wide‐band responses can exist in the UWB passband for blocking the interference. Adjusting the size factor of CSRR, the wide tuning ranges of notch frequencies included the desired frequencies of 5.2/5.8 GHz are achieved. The lower insertion loss (0.31 dB), higher rejection level (−50 dB), wider bandwidth (FBW 75%), and wider stopband (extended to 2.01 f0 below −20 dB rejection level) of UWB band at the central frequency f0 = 4.58 GHz are obtained. Second, design a CSRR, DGS, FMRR, triple notched‐band UWB filter with the wider bandwidth (2.51 to 8.03 GHz, FBW = 124%), lower insertion loss (0.36 dB), and sharp transmission zeros (−49.77/−48.40 dB) of UWB band at central frequency f0 = 4.43 GHz are presented. Using the CSRR and interdigital couple, three notch responses can exist in the UWB passband for blocking the interference signals. Adjusting the size factor of CSRR and interdigital couple, the wide tuning ranges of notched‐band included the desired frequencies of 4.80/5.20/6.38 GHz are achieved. The wide tuning ranges of three notched‐band cover from 4.2 to 6.6 GHz. The design procedure related to the geometry is proposed. It is a simple way to control the notch responses. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2324–2330, 2014

Design of Compact UWB Bandpass Filter with Sharp Rejection Characteristics

This study presents an Ultra-Wideband (UWB) filter with sharp rejection characteristics at the upper Wireless Local Area Network (WLAN) band. The filter adopts the modified Composite Right/Left-Handed (CRLH) Transmission Lines (TLs), the unit cell of which is theoretically analyzed to derive the design formulas. Subsequently, a UWB bandpass filter is designed using these formulas. The measurement results show that the fabricated UWB bandpass filter has an insertion loss of less than 1.1 dB, bandwidth of 3.1~4.9 GHz and a rejection of more than 50 dB at 5.8 GHz.

A compact ultra wideband bandpass filter using arrow coupled lines with defected ground structure

A new ultra wideband bandpass filter (UWB-BPF) using arrow coupled lines and U-slot defected ground structures (U-DGS) is proposed. The input and output feeding lines are connected to the coupled lines placed on the conductor side of the substrate while the U-slot DGS was etched from the ground side below. The effect of U-DGS slot dimensions on the operating bandpass of the filter was studied. The filter was simulated using both IE3D and HFSS simulators. The simulation results are in good agreement with the realized filter. The filter operating passband extended over the UWB frequency 3.0–9.5GHz while the group delay variation in the passband is in the range of 0.5°.

Compact UWB Bandpass Filter With Dual Notched Bands Using Defected Ground Structures

This letter proposes a novel ultra-wideband (UWB) bandpass filter (BPF) with dual notched bands using triangular defected ground structures (DGS). Two symmetrical dumbbell-shaped interdigital capacitors are formed to improve the BPF's performance. Three pairs of tapered defected ground structures are studied and adopted to suppress the spurious passband by assigning their transmission zeros towards the out of band signal. A small UWB BPF is obtained by combining these two structures. One of the arms in coupled-line sections is extended and folded to create a notched band at 5.3 GHz, and a meander line slot is developed to create another notched band at 7.8 GHz. Simulated and measured results are in good agreement indicating that the proposed BPF has a passband from 2.8 to 11.0 GHz and a wide stopband bandwidth with 20 dB attenuation up to 30.0 GHz.

Compact dual‐notched balanced UWB BPF with folded triple‐mode slotline resonator

A compact dual-notched balanced ultra-wideband (UWB) bandpass filter (BPF) is designed by using the folded triple-mode slotline resonators and differential microstrip–slotline transitions. Two differential-mode transmission zeros near the passband edges are created to improve the selectivity, due to a cross-coupling between two microstrip open stubs beyond the cross-junction position as well as between the input and output. Good matching in the whole passband can be achieved by properly choosing the width of the microstrip open stubs. The inverse QWRs coupling stepped-impedance microstrip stub loaded in the 50 Ω microstrip feedlines can generate multiple transmission zeros to suppress the common-mode resonance and realise dual-notched bands in the UWB passband. Good agreement can be obtained between the measured results and simulated ones.

Compact ultra-wideband bandpass filter with variable notch characteristics based on transversal signal-interaction concepts

A novel technique is presented to design highly compact microstrip ultra-wideband UWB bandpass filters that exhibit high selectivity quasi-elliptical response. The design is based on transversal signal-interaction concepts that enable the inclusion of single or dual notch-bands within the filter's passband to eliminate interference from other services that coexist within the UWB spectrum. The filter configuration comprises of two transmission paths which include folded T-shaped stepped impedance resonators SIRs that are capacitively coupled with the input/output lines to enable signal transmission. It is shown that by combining the filters of different passband centre frequencies an UWB filter can be realised with either a single- or dual-notch function. The theoretical performance of the filter is corroborated via measurements to confirm that the proposed filter exhibits UWB passband of 123% for a 3 dB fractional bandwidth, a flat group-delay with maximum variation of less than 0.3 ns, passband insertion loss less than 0.94 dB, high selectivity, a sharp rejection notch-band with attenuation of -23 dB, and a good overall out-of-band performance. Furthermore, the filter occupies a significantly small area of 94 mm2 compared with its classical counterparts. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:549-559, 2014.

Compact UWB bandpass filter with triple notched bands using parallel U‐shaped defected microstrip structure

A novel compact ultra-wideband (UWB) bandpass filter (BPF) with triple sharply notched bands and good selectivity is proposed using a parallel U-shaped defected microstrip structure (UDMS). The initial UWB BPF comprises interdigital coupled lines and an E-shaped multiple-mode resonator to achieve two transmission zeros on both sides of the passband, thus improving skirt selectivity. Then, three parallel UDMSs are introduced, which have the properties of achieving the triple band-notched characteristics and providing a high degree of adjusting freedom. To validate the design theory, a microstrip UWB BPF with three notched bands centred at 5.2, 5.8 and 8.0 GHz, respectively, is designed and fabricated. Both the simulation and the experimental results are provided which have good agreement.

Design of compact ultrawideband bandpass filter with notch band

ABSTRACTA novel ultrawideband (UWB) bandpass filter (BPF) with triple notched bands is presented. By embedding a modified H‐shaped resonator with an additional outer line into a conventional UWB BPF, band‐rejected filtering properties around the 3.5‐GHz WiMAX band, the 5.2/5.8‐GHz WLAN band, and the X‐band satellite communication band are generated. The notched frequencies can be adjusted according to specification by altering the modified H‐shaped resonator. Sharp rejections occur at 3.6, 5.3, 7.7, and 7.95 GHz. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:323–326, 2014

Compact Microstrip UWB Bandpass Filter With Dual Notched Bands Using E-Shaped Resonator

A new microstrip ultra-wideband (UWB) bandpass filter (BPF) with two sharp notches using E-shaped resonator is proposed in this letter. The circuit topology and its corresponding electrical parameters of the initial microstrip UWB BPF are achieved by a variation of genetic algorithm (GA). Then, the resonance properties of the E-shaped resonator are studied. Results reveal that the multiple-mode property of the E-shaped resonator can be utilized in the UWB BPF design to achieve dual band-notched performance. To validate the design concept, a microstrip UWB BPF with two notched bands respectively centered at frequencies of 5.9 GHz and 8.0 GHz is designed and fabricated. Both simulation and experimental results are provided with good agreement.

Compact UWB BPF using coupled‐line triple‐mode resonator

A novel and compact microstrip ultra-wideband (UWB) bandpass filter (BPF) based on a triple-mode resonator is designed, fabricated and measured. The proposed resonator is composed of a coupled line with a half-pass characteristic, which is connected directly with each other at one end and is short-circuited to the grounding plane at the other end. A simple structure and design approach to the proposed filter is provided and demonstrated. To implement the design on a microstrip, the directly tapped-transition input/output ports are used to excite the coupled-line multi-mode resonator. The measured results are in good agreement with the electromagnetic simulated results. The proposed filter shows a 3 dB fractional bandwidth of 117.3% at the central frequency (f c) with a return loss of better than 12 dB and an insertion loss of < 0.5 dB within the passband response.