Tunable notch response for ultra wide-band bandpass filter

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.

High frequency rejection using L shaped defected microstrip structure in ultra wideband bandpass filter

A novel ultra-wideband (UWB) bandpass filter (BPF) structure is presented. The presented structure consists of two quarter-wavelength coupled-line series in the centre position and two quarter-wavelength shorted coupled-line shunts on both sides. The new UWB structure shows the multiple-mode resonant characteristic and two shunt shorted coupled-lines can provide two transmission zeros on both sides of the passband. As a validation, a microstrip UWB BPF was designed and fabricated. Sharp and deep rejection is achieved on both the lower and the upper stopband. In addition, a notched band is designed at 8.0 GHz for a rejecting satellite communication signal. The measurement results agree well with the full-wave EM simulated responses.

An ultra-wideband (UWB) bandpass filter (BPF) with two cascaded cross-shaped resonators is proposed and implemented. As the starting work of this letter, a cross-shaped resonator with wide passband is introduced. With the use of even- and odd-mode approach, this initial resonator is characterized and designed to build up a UWB BPF. And then, a cascaded UWB BPF is fabricated to satisfy Federal Communications Commission indoor mask.

A compact ultra-wideband (UWB) bandpass filter (BPF) with three transmission zeros in the notched-band is presented in this paper. A dual coupled microstrip/coplanar waveguide (CPW) structure with slotlines on the bottom are used. The notched-band is generated by a pair of small U-shaped slot-line on the bottom layer and a hollow microstrip resonator on the top layer, and three transmission zeros are achieved at frequency 5.85GHz, 5.9GHz, 5.95GHz without extra circuit size. The UWB bandpass filter (BPF) has been designed, fabricated and measured. The measured results agree with the simulated result closely.

In this paper an ultra wideband microstrip Bandpass filter is proposed using stepped impedance resonators (SIR) and defected ground structures (DGS). This band-pass filter is designed to operate within the Ultra Wide Band frequency range from 4.0 GHz to 11.0 GHz with 7.0 GHZ bandwidth and centre frequency at 7.5 GHz. This prototype filter is designed on RT/Duroid 5880 substrate of thickness 0.787mm with dielectric constant 2.2. The filter is simulated and optimized using Zealand IE3D simulation software v14.0. The passband of the filter has five transmission poles. Insertion loss within the passband is better than -1.5dB and the return loss is kept less than -20dB and a total fractional bandwidth of 93.33% is obtained. The prototype built can be used in UWB communications or localization systems.

A novel ultra-wideband (UWB) bandpass filter (BPF) with dual notched bands using the hybrid microstrip and coplanar waveguide (CPW) structure is proposed, to prevent interference problems between the UWB radio system and existing radio systems. A multiple-mode resonator on a CPW is formed to allocate its first three resonant modes around the lower-end, centre and upper-end of the 3.1 to 10.6 GHz UWB passband. Its two sides are fed by two microstrip-to-CPW transitions with enhanced frequency-dispersive coupling degree. The dual narrow notched bands are introduced by embedding a open stub in the CPW line and etching two U-shaped slots on the ground plane to form defected ground structures (DGSs) in each side of the microstrip structure. Then, dual-band rejected filtering properties in the C-band (3.7–4.2 GHz) and WLAN (5.15–5.825 GHz) are achieved. The UWB bandpass filter with notched bands has been carried out by designs and related simulations to demonstrate the notch-band-included and upper-stopband-improved performances.

In this paper, a multiple-mode resonator (MMR) using localized substrate integrated artificial dielectric (L-SIAD) is proposed to construct a compact ultra-wideband (UWB) bandpass filter (BPF). Due to the electromagnetic bandgap (EBG) property of L-SIAD, this MMR provides a broad upper stopband for the BPF. Meanwhile, broadside coupled-lines are used to provide tight coupling and sharp skirt for the BPF by the coupling transmission zero. Finally, such a UWB BPF is designed and fabricated. The measured results demonstrated that this filter has broad upper stopband, sharp rejection skirt, and low insertion loss in passband with flat group delay.

This paper presents a ultra-wideband (UWB) bandpass filter (BPF) with one controllable notch band. The proposed BPF covers a bandpass frequency area from 3.1 to 10.6 GHz. Which is consists of a main transmission line with characteristic impedance 50 Ohms, and five loaded short-/open-circuit microstrip lines. Hereinto, one shorted-circuit stub is used to achieve low frequency stopband and cut-off frequency stopband, and other four open-circuit stubs are utilized to realize the target notch band and to optimize high frequency stopband performance. To obtain a certain notch-band bandwidth, two stubs working for notch band are designed with adjusted gap distance to couple with each other. Based on theoretical analysis, simulation by HFSS tool and optimization, an UWB BPF with one notch band bandwidth from about 4.94 to 6.38 GHz with -10 dB is established to cover bandpass domain from 3.1 to 10.6 GHz. Analysis and simulation data are in good agreement, the design method is verified well..

A compact ultra-wideband (UWB) bandpass filter (BPF) is implemented with stepped impedance resonators (SIR) and T-shaped line. Fractional bandwidth (FBW) of the UWB BPF can be adjusted properly by changing the impedance ratio of the SIR. A transmission zero is created by the central open stub of the T-shaped line to suppress the second harmonic of the filter. In addition, the filter size is further reduced by introducing T-shaped transmission line. The resulting UWB filter indicates a FBW of 108% with three transmission zeros at 2.3, 11.1 and 13.4 GHz. Good agreement can be observed between simulated and measured responses.

A compact ultra-wideband (UWB) band-pass filter (BPF) with band-notch function is presented in this paper. In the proposed structure defected ground structure (DGS) and four short-circuited bent stubs are used in order to improve the performance of the filter and reduce the size of the filter simultaneously. The upper stop-band with more than 15dB attenuation level extends to 20 GHz. Moreover, a meander-line embedded open-circuited (EOC) stub inside a slot on the main resonator is employed in order to create a narrow band-notch function at WLAN frequencies. The measurement results for the fabricated UWB BPF are in good agreement with simulation predictions and reveals that it satisfies well the demands of the Federal Communications Committee (FCC) with a band-notch function at 5.5 GHz.

This letter presents an on-chip ultra-wideband (UWB) bandpass filter (BPF) in 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> SiGe BiCMOS Process. The proposed UWB BPF is constituted by cascaded quasi-elliptic response high-pass filter (HPF) and low-pass filter (LPF). A series <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> circuit is introduced in the classical fifth-order lumped-element HPF, so that a transmission zero (TZ) is generated to form quasi-elliptic response. The microstrip line LPF with two series of open stubs can generate another two TZs, which also result in quasi-elliptic response. Step-to-step design procedure is given to guide the UWB BPF design. The measured result shows that the fabricated UWB BPF covers the frequency range of 10 – 50 GHz with the in-band return loss better than 13.5 dB, and the minimum in-band insertion loss is 1.99 dB. The core size of fabricated UWB BPF is 382 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times 428\,\,\mu \text{m}$ </tex-math></inline-formula> excluding testing pads.

In this paper, a novel synthesis theory is proposed to design ultra-wideband (UWB) bandpass filters using 3λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> /4 (λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> is the wavelength at central frequency of the filter) parallel-coupled line resonators. By using the first two resonant modes of the 3λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> /4 parallel-coupled line resonators, this kind of UWB BPF can achieve a wide bandwidth larger than 100%. In order to alleviate the requirement on fabrication precision, aperture-enhanced coupled lines are introduced in the filter. A three-degree UWB filter with a midband frequency of 6.85GHz is synthesized, simulated and fabricated. Measured results indicate that the filter is low loss in the passband, and the attenuations in the lower and upper stopbands satisfy the indoor limit issued by the Federal Communications Commission (FCC).

A novel ultra-wideband (UWB) bandpass filter is proposed on an aperture-backed microstrip line. With an aperture on the ground, a non-uniform resonator is constructed with the first three resonant modes occurring within the UWB band while the parallel coupling between resonator and feeders is largely enhanced. The designed filter exhibits good UWB passband behaviour with insertion loss <1.0 dB and group delay variation <0.25 ns.

An ultra-wideband (UWB) bandpass filter based on transversal signal-interaction concepts is proposed. By cascading a planar Marchand balun and two transmission lines with different electrical lengths, a new UWB bandpass filter (fractional bandwidth 86-111.5%) with two transmission zeros close to the passband is realised. Good agreement is observed between the simulated and measured results.