Jawad K. Ali

A new miniaturized fractal bandpass filter based on dual-mode microstrip square ring resonator

A novel fractal dual-mode microstrip bandpass filter design has been introduced in an attempt to produce filters with highly miniaturized size for modern wireless applications. The filter structure has been generated based on the 3rd iteration Minkowski-like pre-fractal geometry, using the conventional dual-mode square ring resonator as the initiator in the fractal generation process. The space-filling property, self-similarity and the diagonal symmetry of the structures corresponding to the successive iteration levels of this fractal geometry have found to produce reduced size filter structures with accepted performance. The bandpass filter structure produced by the 3rd iteration of this fractal geometry can be considered as a novel design with adequate performance. This design structure possesses a size reduction of about 72% compared with the conventional dualmode square ring resonator operating at the same frequency and using the same substrate material. In addition, the new design technique seems reliable, since it provides the filter designers with more degree of freedom and further size reduction as compared with those reported in the literatures.

A new microstrip-fed printed slot antenna based on Moore space-filling geometry

In this paper, a new design of miniature, multiband slot antenna is presented. The slot structure of the proposed antenna is based on the 3rd iteration of the Moore space-filling geometry, which is a closed variant of the conventional Hilbert space-filling curve. The slot structure is constructed on the ground plane side of a dielectric substrate. The slot antenna is fed by a 50 Ω microstrip line, printed on the reverse side of the substrate. The proposed antenna possesses a miniature size with a slot side length of about half the guided wavelength. Furthermore, the antenna performance curves show that it offers a multiband behaviour with enhanced bandwidths, as compared with those offered by antenna structures based on other spacefilling geometries. Expressions have been presented to correlate antenna slot parameters with the first resonant frequency, and among the subsequent resonant frequencies as well.

New Microstrip Bandpass Filter Designs Based on Stepped Impedance Hilbert Fractal Resonators

ABSTRACT The proposed microstrip bandpass filters in this paper have compact sizes and narrow band responses which are the requirements of modern wireless communication circuits. These filters are constructed from dual-edge coupled resonators; each resonator is based on applying step impedance resonator generator on first and second iteration of Hilbert fractal resonators on each segment of each iteration level. They have been designed for the industrial, scientific, and medical band (ISM) band applications at a centre frequency of 2.4 GHz using a substrate with a dielectric coefficient of 9.6 and thickness of 0.508 mm. The performance of bandpass filters has been analysed using a method of moments (MoM) based on software package, Microwave Office 2009, from Advanced Wave Research Inc., which is widely adopted in microwave research and industry. Simulation responses show that these filters possess good frequency response characteristics with second harmonics suppression. Moreover, these filters showed noticeable miniaturization which is an important feature for many communication applications. The simulated and measured results are in good agreement.

A new miniature Peano fractal-based bandpass filter design with 2nd harmonic suppression

A new compact microstrip bandpass filter design is presented in this paper as a candidate for use in modern wireless communication systems. The proposed filter structure is composed of two fractal-based microstrip resonators. The structure of each resonator is in the form of the 3rd iteration Peano fractal curve. The resulting filter structure based on these resonators, shows a considerable size reduction compared with the other microstrip bandpass filters based on other space-filling geometries designed at the same frequency. A second bandpass filter design based on the same resonator but with a tuning stub has been also presented, in an attempt to provide practically useful means to tune the filter to the specified performance with a considerable tuning range. The performance of the resulting filter structures has been evaluated using a method of moments (MoM) based electromagnetic simulator IE3D, from Zeland Software Inc. Results show that the proposed filter structures possess good return loss and transmission responses besides the size reduction gained, making them suitable for use in a wide variety of wireless communication applications. Furthermore, performance responses show that the second filter, based on Peano shaped resonator with stub, has less tendency to support the 2nd harmonic.

Miniaturised microstrip bandpass filters based on Moore fractal geometry

This paper presents new microstrip bandpass filter design topologies that consist of dual edge-coupled resonators constructed in the form of Moore fractal geometries of second and third iteration levels. The space-filling property for proposed fractal filters has found to produce reduced size shapes in accordance with sequential iteration levels. These filters have been prepared for ISM band applications at a centre frequency of 2.4 GHz using a substrate with a dielectric coefficient of 10.8, dielectric thickness of 1.27 mm and metallisation thickness of 35 µm. The output responses of each fractal bandpass filter have been determined by a full-wave-based electromagnetic simulator Sonnet software package. Simulated and experimental results are approximately compatible with each other. These responses clarify that these fractal filters have good transmission and return loss characteristics with blocked higher harmonics in out-of-band regions.

A new design of dual band microstrip bandpass filter based on Peano fractal geometry: Design and simulation results

The proposed filter design topology is based on dual coupled resonators constructed in the form of Peano fractal geometry. A dual-band microstrip bandpass filter with a quasi-elliptic response has been designed for first time based on 1st iteration Peano fractal geometry at resonant frequencies of 2.25 GHz and 4.825 GHz using a substrate of a relative dielectric constant of 10.8 and thickness of 1.27 mm. The performance of the bandpass filter structure has been analyzed using a method of moments (MoM) based software package, Microwave Office 2009, from Advanced Wave Research Inc. Results show that this filter possesses good frequency response characteristics in addition to dual bands gained which can be used for modern communication applications.

New Dual Band Dual-Mode Microstrip Patch Bandpass Filter Designs Based on Sierpinski Fractal Geometry

Dual band dual mode chebychev micro strip band pass filter designs are introduced for first time in this paper. The proposed filter designs are based on the use of dual mode square slotted patch micro strip resonator. These filter structures are fractally generated using Sierpinski fractal curve geometry applied to the conventional square micro strip patch from 1st to 2nd iteration levels where the first band designed at fundamental frequencies (5.475, 5.45 and 5.4) GHz for each iteration while the second band( 8.925, 9.15, 9.05) GHz for each iteration. These filters have been designed using a substrate with a dielectric constant of 10.8 and thickness of 1.27mm. The performance of filter structures, based on resonators has been evaluated using a full-wave based electromagnetic simulator Sonnet software package. Performance simulation results show that these filter structures are compact in addition to good frequency responses and narrow bands gained.

A compact Peano-type fractal based printed slot antenna for dual-band wireless applications

This paper presents the design of a new Co-Planar Waveguide (CPW) fed dual band printed slot antenna with enhanced bandwidths for use in wireless applications. The fractal based slot structure of the proposed antenna is in the form of Peano fractal curve of the second iteration as being applied to the two sides of a rectangular slot. The proposed antenna is to be etched using a substrate with relative permittivity of 4.4 and thickness of 1.6 mm. The resulting antenna has overall dimensions of 36 mm × 45 mm which is suitable for mobile terminal applications. Modeling and performance evaluation of the proposed antenna have been carried out using the CST Microwave Studio. Simulation results shows that the proposed antenna offers dual -10 dB impedance bandwidths of more than 1.2 GHz and 1.4 GHz for the lower and the upper bands respectively with corresponding average gains of about 2.5 dBi and 4 dBi throughout these bands. The first resonant band, centered at 2.50 GHz, extends from 1.91 to 3.11 GHz. This band covers the 2.4 GHz WLAN band (2.4-2.483 GHz) and the 2.5 GHz mobile WiMAX operating band (2.5-2.7 GHz), while the second resonant band, centered at 5.20 GHz; extends from 4.51 to 5.91 GHz. This band covers the U-NII mid-band (5.47-5.725 GHz) and U-NII high-band (5.725-5.875 GHz). Besides the compact size, the antenna offers reasonable radiation characteristics with omnidirectional radiation patterns in the two bands.

A miniature fractal-based dual-mode dual-band microstrip bandpass filter design

In this paper, a fractal-based complementary split-ring resonator (CSRR) has been introduced as a defected ground structure (DGS) in the ground plane of a dual-mode microstrip bandpass filter to produce a new compact filter with dual-band response. The conventional double square ring resonator structure is modified such that its inner ring is made with a fractal shape instead of a square. Measured and simulation results show that the resulting filter offers a dual passband response; the higher passband is attributed to the dual-mode microstrip ring structure, whereas the lower passband is as a result of the embedded CSRR DGS structure. In addition, the results show that the position of the lower passband could be varied, to a certain extent, without affecting the position of the higher passband by applying higher fractal iteration levels to the inner split ring. These features, together with the compact size the proposed filter offers, make it suitable for use in a wide variety of dual-band communication applications. Measured results, carried out on filter prototypes, have been found in agreement with those theoretically predicted.

Wide Bandpass and Narrow Bandstop Microstrip Filters based on Hilbert fractal geometry: design and simulation results.

This paper presents new Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) incorporating two microstrip resonators, each resonator is based on 2nd iteration of Hilbert fractal geometry. The type of filter as pass or reject band has been adjusted by coupling gap parameter (d) between Hilbert resonators using a substrate with a dielectric constant of 10.8 and a thickness of 1.27 mm. Numerical simulation results as well as a parametric study of d parameter on filter type and frequency responses are presented and studied. WBPF has designed at resonant frequencies of 2 and 2.2 GHz with a bandwidth of 0.52 GHz, −28 dB return loss and −0.125 dB insertion loss while NBSF has designed for electrical specifications of 2.37 GHz center frequency, 20 MHz rejection bandwidth, −0.1873 dB return loss and 13.746 dB insertion loss. The proposed technique offers a new alternative to construct low-cost high-performance filter devices, suitable for a wide range of wireless communication systems.