Md. Nurunnabi Mollah

Demonstration on performance characteristics of microstrip low-pass filter for various substrates employing Tschebycheff distribution

In modern microwave design sector, Electromagnetic Band Gap (EBG) structures which is a unique innovation by virtue of their high potency and low complexity in designing with integrated circuits. This article examines the relationship between operating performance of different substrates and Tschebycheff polynomial distribution. A number of methods, method of moments (MOM) for numerical analysis and Tschebycheff polynomial distribution for designing the traditional circular pattern on ground plane are used. In like manner, the parametric comparison has been demonstrated in view of the selectivity, 20-dB insertion loss bandwidth (20-dB IL BW) and 10-dB return loss bandwidth (10-dB RL BW). The consequence of that is, two substrates FR4 and RT/Duroid 5870 prevail with good matching upto 70 dB, negligible ripple less than 0.7 dB in the passband and wider, deeper stopband performance upto 6-7.5 GHz. Improving compactness of the circuit with high efficiency, this complication is solved by Tschebycheff polynomial distribution.

A new approach to design microstrip low pass filter using novel defected ground structure

A microstrip transmission line on a Binomial distributed hybrid defected ground structures (DGS) with interleaving photonic bandgap structures (PBGS) are proposed. Four different approaches are utilized to realize the better performance of the low pass filter (LPF). In all these cases, the length, width or both is made non-uniform in accordance with the co-efficient of Binomial distribution. It can be seen that, by applying Binomial distribution on DGS and interleaving PBGS the performance of LPFs are significantly improved.

Uniform high-Q factored 3:9 annular ring resonator in coupled-line bandpass filter: Design and applications

To enhance the efficacy of antennas, filters and microwave circuits, EBG structures have been developed into most notable framework considering their unique electromagnetic and sophisticated properties. This article investigates the relationship between the aspect ratio of annular ring and performance of the coupled-line filter. A number of methods, uniform distribution of ring patterns with constant filling factor 0.35 and lumped circuit model, method of moments for numerical analysis are used. Originally, the parametric comparison has been demonstrated reviewing the selectivity, 3-dB cut-off frequency and Q factor. Consequently, not only a very sharp selectivity of 56.67 dB/GHz with narrow bandwidth, low insertion loss in the passband but also wide stopband up to 13GHz with Q factor of 118 with 0.69% deviation are achieved. This structure should ease the task of designers of designing a compact matching network for the microwave receiver with high Q factor and sharp selectivity.

Chebyshev type-I low pass filter using annular ring resonator: A comparative performance analysis for different substrates

In this letter, compact microstrip Chebyshev function low pass filters (LPFs) with sharp roll-off based on annular ring resonators (ARRs) on various substrates and its design theory are demonstrated. To fabricate ARRs, Chebyshev type - I function with fixed side lobe level (SLL) and method of moments (MOM) for numerical analysis are applied. The ARRs inscribed on the ground plane, behave as shunt connected capacitances with low radiation, nevertheless the 50 Ω transmission line on the upper plane provide the total transmission to realize the Chebyshev function response. Consequently, RT/Duroid 5880 prevails with low insertion loss (<0.6 dB), wide stopband, very sharp roll-off (>90 dB/GHz) and isolation up to 70 dB in the stopband. The frequency responses of the device from the two different softwares are in good agreement with the known theoretical data.

Low-Profile Impedance Matched Wideband Double Inverted-F Antenna for WiMAX/Wi-Fi Operations in a Laptop Computer

In this paper a wire type low-profile impedance matched wideband double inverted-F (DIFA) antenna for WiMAX/Wi-Fi operations in a laptop computer is presented by means of numerical simulations. The antenna has a compact size of 9×20 mm2 and provides a wider bandwidth of 2.5 GHz (5050~7550 MHz) which fully covers the 5.5 GHz operating band. Moreover it has very high peak gain of 7.0 dBi with less than 1.5 dBi gain variation within the 5.5 GHz operating band. In application of matching network, the input impedance of the antenna well matched to the antenna feeding, also improvement in return loss and voltage standing wave ratio (VSWR) is achieved. In addition the antenna has good return loss and radiation characteristics.

A quasi-elliptic low pass filter based on complementary split ring resonator with sharp selectivity and wide stopband

This Paper illustrates the low pass filter (LPF) topology based on complementary split ring resonator (CSRR) with added slot. The introduction of a slot structure in the CSRR can not only reduce the group velocity of the transmission but also decrease the inductive reactance which results in compactness of the device by providing the transmission zero after resonance. Therefore, quasi-elliptic function and extension of the rejection band has been established. In other words, this LPF exhibits significant improvement on rejection bandwidth, selectivity and return loss (RL) in the passband. Besides, with electrical length for the ring is o.11Xg (single cell), the device characterizes by pointing out the capability of the approach with rejection levels of 13-dB over 50% of the stopband and selectivity of about 142 dB/GHz. The group delay is within 0.20 ns over 75% of frequency of interest. Well agreement between theoretical and simulated data are accomplished.

Chebyshev quarter wavelength wideband bandstop filter based on dumbbell annular ring resonator

In this letter, a novel seventh order equal ripple wideband bandstop filter (BSF) is proposed and demonstrated. This device is based on dumbbell annular ring (DAR) resonators which introduces additional magnetic coupling with quarter wavelength open circuited stubs in the conventional 50-Ω transmission line. However, introducing this DAR resonators (DARRs) generate multiple transmission zeros which is responsible for wider stop band and can be determined from the S-plane. Moreover, the proposed BSF has selectivity up to 170 dB/GHz, rejection level is better than 50-dB, suppress reflection up to 12-dB in the pass band and fractional bandwidth 113.1%. Besides, the group delay is within 3 ns over the 80% of the stop band. The simulated frequency performances of the device from two different softwares are in well agreement with the theoretical data.

A novel quasi-lumped UWB high pass filter with multiple transmission zeros

In this letter, a compact sixth order microstrip Chebyshev short circuited stubs high pass filter (HPF) via hole grounding is proposed. It is fundamentally based on quasi-lumped short circuited stubs of an optimum commensurate line band pass filter, which widen the bandwidth of the device. Furthermore, the resonant frequency and return loss performance can be improved by multiple transmission zeros, generated because of via hole grounding. Moreover, the proposed high pass filter (HPF) has wide bandwidth up to 10 GHz which satisfies the UWB spectrum, rejection level is better than 18-dB with multiple deep transmission zeros. Besides, the group delay is 1.5 ns over the 97% of the passband. Moreover, the simulated frequency responses under different via hole dimension from two softwares are in good agreement with the theoretical response.

Offset EBGS against tapered EBGS: Substantial reduction of microstrip stopband filter in size

A technique of reducing the size of the tapered EBGS assisted microstrip T-line is proposed. After that, offset EBGS has been proposed for getting improved performance over tapered EBGS. This technique also eliminates the limitation of having larger size of the mother EBGS while using tapered EBGS. Offsetting EBGS includes effective use of number of EBGS at the beneath of T-line, substantially reduced size of the T-line, and improved performance with a controllability.

Ballistic Performance Study of Nanowire FET: Effect of Channel Materials and Phonon Scattering

The ballistic performance of Si and Ge nanowire (NW) is compared in this study. Current–voltage characteristic is obtained by self-consistently solving the nonequilibrium Green’s function (NEGF) transport equation with Poisson’s equation. The result is obtained at ⟨001⟩ channel orientation. Simulation result shows Ge NW gives higher ON-state current than Si NW, when OFF-state current is made equal by gate metal work function engineering. However, at subthreshold region, performance of NW FET for both material is almost identical. The intravalley and intervalley electron–phonon scattering effect is also calculated using the deformation potential theory and the self-consistent Born approximation. It is found that electron–phonon scattering effect is more pronounced at ON-state of Si NW FET. The ballistic current decreases with the decrease in diameter of the Si NW FET due to electron–phonon scattering.