Defected Ground Structure Cell Research Articles

Size Reduction and Harmonics Suppression in Microwave Power Dividers

In this paper, several types of microstrip power divider are studied and compared in terms of harmonics suppression and size reductions. The importance of this research lies in the fact that power dividers are critical components in various communication systems, and their performance directly affects the overall system efficiency. The conventional structure of the power divider has an acceptable performance at operating frequency in terms of excellent output ports isolation, low insertion loss, and high return loss, but occupies large size and passes unwanted signals at higher frequencies along with desired signal without any suppression. Harmonics are popular distortion and has different distortion impacts in many different facilities. Recently, several techniques are introduced to overcome these drawbacks. Applied open stubs, applied resonators, lumped reactive components such as capacitors and inductors, coupled lines, defected ground structure (DGS), and electronic band gaps are common methods, which are widely used to overcome these drawbacks. Finally, the study results show that the resonator-based power dividers and coupled-line-based power dividers have good performances in terms of size reduction and harmonic suppression but increase insertion loss parameter. Furthermore, the lumped reactive component-based power dividers and applied DGS and electromagnetic bandgap cells suppress unwanted harmonics, but they need extra process to fabrication, which is undesirable. Moreover, the open-stub-based power dividers have moderate performance with simple structure, but size reduction and harmonics suppression are not so superior in this method.

CSRR-DGS Bandpass Filter Based on Half Mode Substrate Integrated Waveguide for X-Band Applications

In this paper, a half mode substrate integrated waveguide (HMSIW) bandpass filter using defected ground structure cells (DGS) is proposed. By using the periodic square CSRR resonant properties of DGS according to design requirement, an X-band band-pass filter is designed and analyzed to meet compact size, low insertion loss, and high rejection. The simulation results obtained by CST in X-band show that the proposed filter is characterized by a large transmitted bandwidth of about 1.38 GHz from 13.03 to 14.41 GHz. The higher simulated insertion loss is about −2.6 dB and the lower return loss is about −34 dB. The proposed filter size is 9.50 × 38.00 mm2 which make it a compact component. The structure is optimized using CST simulator. For the proposal validation, the simulation results is compared by HFSS. The simulation results are in good agreement for the two simulator.

Frequency-reconfigurable wideband bandstop filter using varactor-based dual-slotted defected ground structure

A reconfigurable bandstop microstrip line filter with wide continuously adjustable stopband is proposed in this letter. Dumbbell-shaped defected ground structure cells based on dual coupling slots are used to reduce the complexity of the filter and simplify the equivalent circuit modeling. Three varactors crossing the center coupling slots are utilized together with isolating capacitors to obtain the reconfigurability, of which the frequency range can be adjusted from 1.8 to 8.0 GHz. An equivalent-circuit model using coupled LC resonators is developed to firstly attain physical understanding of the filter’s working principle and secondly to assist the filter design. Three pairs of perpendicular stubs are introduced onto the microstrip line to improve the transmission and maintain signal integrity in the passband. The filter has been fabricated and experimentally characterized, with the good agreement observed between simulation and measurement validating the concept.

Substrate Integrated Waveguide Based Bandpass Filter with Defected Ground Structure for FMCW Radar Application

Aims : Substrate Integrated Waveguide (SIW) based bandpass filter is presented in this paper. Objectives: In the proposed design, bandpass response is achieved by combining SIW structure with elliptic shaped Defected Ground Structure (DGS) cells. Methods : Simulation of the proposed structure is carried out using commercial software Ansoft High Frequency Structure Simulator (HFSS), which is a three-dimensional frequency domain electromagnetic solver based on the Finite Element Method (FEM). Analysis of three different types of DGS cells including rectangular, circular and elliptical has been carried out. Moreover, Frequency tuning is also carried out by changing the dimension of DGS. Result : Proposed filter is fabricated on the dielectric material RT duroid 5880 with the dielectric constant ɛεr=2.2, dissipation factor tanδ=4 x 10-4 and height h= 0.508 mm. The measured return loss of 25.71 dB and insertion loss of 1.24 dB with 3 dB Fractional Bandwidth (FBW) of 4.8% at the center frequency of 7 GHz. Conclusion : Good agreements are observed between the experimental results and the simulations.

CIRCULAR DEFECTED GROUND MICROSTRIP BAND-REJECT FILTER DESIGN FOR RADAR COMMUNICATION

In this paper, a novel narrow band microstrip band-reject filter is designed using three circular shape defected ground structure (DGS). Three circular shape defected ground structure are linked by a path in the ground plane where etching process is applied. The path length of middle DGS cell is 8 mm and the path length of corner DGS cell is 11 mm whereas the path width of all three DGS cell is 0.6 mm and the radius of circular shape defected ground structure is 2.1 mm. The mid-stop band frequency of the designed filter is 1.61 GHz which is applicable for the satellite and radar communication for the purpose of S-Band. The stop bandwidth of proposed filter is 1 GHz to 2.2 GHz which is useful for narrowband communication. The proposed filter has minimum return loss of 0.11 dB and maximum insertion loss of 60 dB at mid stop-band frequency 1.61 GHz. IE3D 14.1 EM simulation tool is applied for finding out the desired outcome. The proposed microstrip band stop filter has a coverage area of (35.1 mm× 14.4 mm) 505.44 mm2 for the top layer and (16.6 mm× 19 mm) 315.4 mm2 for the ground layer which is more compact as compared to other existing band stop filter designs.

Design of Integrated Millimeter Wave Microstrip Pseudo-Interdigital Band pass Filter Using 0.18μm CMOS Technology

High selectivity design of an improved on-chip band pass filter for 60 GHz millimeter-wave applications using0.18 μm CMOS technology is presented. A new type of miniaturized microstrip bandpass filters with pseudo- interdigital structure without via holes grounded resonators is described. A very compact filter of this type, having a size less than quarter-wavelength by quarter-wavelength at a mid-band frequency of 60 GHz was designed. The adoption of a pseudo- interdigital BPF and utilization of two transmissions zero permits a compact size and high selectivity for the BPF. Besides, two defected ground structure cells are etched under the coupled lines to improve the filter insertion loss. The proposed BPF has the center frequency of 60 GHz, insertion loss of -3.6. dB, a 3dB band width of 8 GHz, and core size 200×500 μm2 with total chip size 500×300 μm2 (including bonding pads

Lowpass Filter with Hilbert Curve Ring and Sierpinski Carpet DGS

Good performance and compact size are the paramaters which are vital when desiging a filter. One of the creteria of good performance is selectivity. This research, conducted by Hilbert Curve Ring and Siepinski Carpet, is used as defected ground structure to overcome filter selectivity. By using three cascadeds Hilbert Curve Ring defected ground structure cells and three steps Sierpinski carpet, a lowpass filter is designed and fabricated. The measurement result for lowpass filterwith Hilbert Curve Ring defected ground structure has sharper selectivity with the cut off frequency at 2.173 GHz and the insertion loss value is 2.135 dB. While the measurement result for three steps Sierpinski carpet has the cut off frequency at 1.728 GHz and the insertion loss value is 0.682 dB.

Design of a wideband common-mode filter using approximate closed-loop pattern of compact C-shaped defected ground structure

A compact common-mode filter is proposed to suppress common-mode noise for application of high-speed differential signal traces. The filter adopts one big C-shaped defected ground structure (DGS) cell in the left of ground plane and two small C-shaped DGS cells with opposite direction in the right of ground plane. Because these DGS cells have different dimensions, the filter has three adjacent equivalent resonant points, which can suppress wideband common-mode noise effectively. The left C-shaped DGS and its adjacent C-shaped DGS cell form an approximate closed structure, which can efficiently reduce the influence of the mutual capacitance. The filter provides a common-mode suppression from 3.6 GHz to 14.4 GHz over 15 dB while it has a small size of 10 mm10 mm. The fractional bandwidth of the filter is 120%, and the differential signals still keep good signal integrity. The experimental results are in good agreement with the simulated results.

Compact Size On-Chip 60 GHz H-Shaped Resonator BPF

In this letter, we propose a compact size, small insertion loss 60 GHz on-chip H-shaped resonator bandpass filter (BPF) using 0.18 $\mu\text{m}$ standard CMOS technology. The BPF Size is miniaturized by loading the H-shaped resonator with metal-insulator-metal capacitors at its ends. Besides, two defected ground structure cells are etched under the coupled lines to improve the filter insertion loss. Furthermore, selectivity is enhanced by loading the center of the H-shaped resonator with two unsymmetrical meander line stubs generating two transmission zeroes at 50 and 70 GHz. The fabricated BPF chip size is $240 \times 650 \mu\text{m}^{2}$ . The measured insertion loss and fractional bandwidth are 2.5 dB at 60 GHz and 21%, respectively.

Parasitic effect compensation of defected ground structure and its application to design of bandpass filter

This study demonstrates the parasitic effect observed in the passband of a bandpass filter (BPF) using a defected ground structure (DGS). This parasitic effect has been compensated by employing step discontinuity in the microstrip feed line. By implementing this technique, the performance of a pseudocombline BPF of 5 GHz operating frequency and a fractional bandwidth of around 15% together with a DGS cell is improved. The filter provides less than −1 dB insertion loss in the operating frequency and a stop band attenuation of about −20 dB on average. When the final BPF structure is simulated, fabricated, and measured, good agreement is observed between the simulated and measured results. The BPF proposed is applicable in the wireless LAN and RADAR systems.

X‐band substrate integrated waveguide bandpass filter using novel defected ground structure cell

ABSTRACTIn this letter, an X‐band wide stopband bandpass filter is presented, which combines substrate integrated waveguide with defected ground structure (DGS) cells. Three DGS cells, including a pair of face to face modified dumbbells embedded with E‐shape slots, are adopted to achieve bandpass performance. The wide stopband is implemented by loading low pass filter, which is designed using stepped impedance open stubs, at the input/output ports. To validate the methodology, a filter with center frequency of 8.55 GHz is designed and measured, and the measured results are in good agreement with simulated ones. The designed filter has an insertion loss of 1.45 dB, a return loss of 18.8 dB in passband, and a wide upper stopband of more than 30‐dB suppression up to 45 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1156–1160, 2015

A broad stopband common-mode suppression defected ground structure filter with complementary structure

A low-cost defected ground structure (DGS) wideband stopband filter adopting complementary structure is proposed, which is designed for common-mode noise suppression in high-speed differential signals. The filter is etched below the low cost FR4 printed circuit board. To avoid stimulating the common-mode noise, the DGS cells on ground planes are kept symmetrical to the central line of the two differential signal lines. Both sides of the filter adopt a symmetric cup-shape DGS structure and the middle of the filter adopts a symmetric umbrella-type structure. All of the DGS structures are complementary, which makes the filter compact and miniaturized. What is more, because the spaces among the three DGS are closer, there exist the mutual inductances among them, which are utilized to achieve a wide stopband filter. The simulated result demonstrates the proposed filter has a wideband bandwidth of 6.8 GHz over 20 dB. In order to analyze the effect of compact structure of the filter, a filter having the same DGS patterns but large spaces among them is compared with it. The simulated result demonstrates that the stopband bandwidth of the compared filter has a wideband bandwidth of 4.4 GHz over 20 dB, of which the bandwidth is about 2.4 GHz less than that of the proposed filter. It is obvious that there exists a mutual inductance in the compact DGS structure common-mode filter, which plays an important role in broadening the bandwidth of the proposed filter. In order to facilitate analysis, an equivalent model of LC circuit is also given. The equivalent parameters of LC can be deduced from the definition of 3 dB cut-off frequency and resonant frequency, of which the values can be obtained by the HFSS simulation. The simulated and measured results show that the differential signal under the DGS filter is nearly intact, and the common-mode noise can be reduced over 20 dB from 4.6 GHz to 11.4 GHz and over 15 dB from 4.3 GHz to 12 GHz, while the area of the filter is only 10 mm by 10 mm. Compared with the periodic DGS at the same suppression depth of common-mode noise over 20 dB, the method has the advantages that surface area is reduced to no more than 30%, and the stopband width is increased by over 50%.

Design of Ultra Wideband Bandpass Dual Band FilterUsing Defected Ground Structures

This paper presents a novel approach for designing compact and ultra wideband filter with independently controlled central frequencies. The structure consists of a microstrip line and two defected ground structure cells that are imbedded together. Each of the cells results in respective passband, outer cell for the first passband and inner one for the second passband. By changing dimensions of the resonators the central frequency of two passbands can be independently regulated in a wide range. Several attenuation polls in the stopband are realized that improve the isolation between two passbands. A 1.8GHz, 3.3GHz dual band filter is designed and simulated with fractional bandwidth of 43% and 15%.

CHARACTERIZATION OF COMPACT V-BAND GAAS CMRC FILTER USING SLOW WAVE CPW TRANSMISSION LINES TECHNOLOGY

This work presents a compact, high performance GaAs V-band bandpass fllter (BPF) using a slow-wave coplanar waveguide transmission line (S-CPW TLine) and a CMRC (compact microstrip resonant cell). The slow-wave CPW Tlines have potential for the use in miniaturized low loss compact passive devices in the millimeter-wave frequency band. Owing to strong slow-wave efiect, the longitudinal length of the S-CPW is shorter than that of a classical microstrip based on the same technology. The S-CPW TLines in the designed fllter were realized with a reconflgurable defected ground structure (DGS). Adding the conventional inductively coupled resonator CMRC BPF allows the resonator to be miniaturized by the exploitation of the transversal dimensions of the CPW, while maintaining its performance as measured by insertion and return losses. However, the DGS cell allows reconflguration of the structure from a low-band to a high-band BPF. The design of the fllters with the DGS using fllters that are designed for V-band applications is explained.

Design of a Compact Ka-band Balanced Mixer Based on a Novel Wide-band Equivalent Circuit of the Schottky Diode

A compact Ka-band balanced mixer based on a novel Schottky diode model is presented in this paper. According to its physical structure, a novel 3D electromagnetic model of the Schottky diode is proposed. Meanwhile, a wide-band equivalent circuit is built, which takes all high frequency effects existing in the diode into account. All the parasitic reactances are extracted from the electromagnetic model-based S-parameters up to 110 GHz. Based on the proposed equivalent circuit, a Ka-band balanced mixer is designed and optimized, where bandpass filters with open stubs and a lowpass filter based on defected ground structure cells are used. The measured results show that the conversion loss is below 9 dB from 30 GHz to 40 GHz with the minimum of 6.7 dB at 35 GHz. The normalized size of the mixer is only 3.3λ g × 3.3λ g , whereλ g is the wavelength at 35 GHz.

Design of Novel 4-GHz Bandpass Filter Using a Combination of Defected Ground Structure Resonators and Admittance J-Inverter

A wideband quasi-elliptical bandpass filter with enhanced reject-band performance is presented. The proposed bandpass filter utilizes a new asymmetric defected ground structure (DGS) under a pair of end-coupled microstrip line. The DGS consists of two square headed slots connected transversely with a rectangular slot. The DGS-microstrip resonator provides band-accept filtering characteristics. To be equivalent to the circuit DGS is demonstrated. The presented equivalent circuit shows both resonant and anti-resonant properties. The equivalent circuit parameters are extracted using the modeling method of proposed DGS. A better selectivity in lower transition band in comparison to upper transition band is observed in the frequency response. To improve the roll-off in upper transition band, a pole is created by putting an additional DGS unit under the same microstrip line. The combined structure shows bandpass characteristics with deep and wide stopband on both sides of the passband. The bandwidth and centre frequency of the filter is controlled by the dimensions of both DGS cells. The article presents some promising patents on Defected Ground Structure Resonators and Admittance J-Inverter.

Performance Enhancement Of Microstrip Hairpin Band Pass FilterUsing Dumbbell DGS and Split Ring Resonator DGS

 Abstract—In this paper, five pole chebyshev microstrip band pass filter is designed using hairpin resonators. A dumbbell shaped defected ground structure and square split ring resonator DGS are presented to suppress the second and third order harmonics of bandpass filter. Dumbell and square split ring resonator defected ground structure cells are etched under feed lines for improving stop band rejection without affecting the centre frequency and insertion loss of basic filter. For effective suppression of higher order harmonics open stubs are also used at the input and output feed lines. A five pole chebyshev microstrip band pass filter is designed with 700 MHz bandwidth at the centre frequency of 2.5 GHz. Band pass filter is simulated using ADS 2009 software. The simulated results of conventional band pass filter, dumbbell DGS bandpass filter and SRR DGS bandpass filter are compared and tabulated. Compared to dumbbell DGS bandpass filter, SRR DGS bandpass filter has improved suppression at second harmonic frequency.

Reconfigurable defected ground structure cell using PIN diodes on Coplanar Waveguide technology

AbstractThis article addresses a novel reconfigurable defected ground structure resonator fabricated on Coplanar Waveguide (CPW) technology. The resonator is endowed with an original design that enables the generation of multiple transmission zeros at arbitrary frequencies. The chosen design is indeed based on a slot defect created on the lateral ground planes of the CPW with the double advantage to allow a simple reconfiguration, by means of surface mounted (or fabricated) components, and a compact solution, by exploiting the transversal dimension of the CPW. Three different states of the diodes configuration are investigated, where in each state multiple transmission zeros are produced in the frequency range from 1 GHz to 11 GHz. Slotline design equations are used to identify the resonant frequencies of the transmission zeros and validated using the magnetic field distribution inside the slot. In this work, the reconfigurability is first proven by means of open and short circuits in specific locations and then replaced by PIN diodes. Simulated and measured results are in good agreement. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 766–770, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25003

A NEW DEFECTED GROUND STRUCTURE AND ITS APPLICATION FOR MINIATURIZED SWITCHABLE ANTENNA

A new defected ground structure (DGS) is flrstly proposed in this paper, which has better slow-wave efiect than that of cross or dumbbell one. Using the model of transmission line, its equivalent parameters are extracted. With good omni-directional properties, the proposed DGS is then used in the design of a proximity coupled antenna for its miniaturization. The size of the developed antenna is about 68% smaller than that of the conventional one. Further, two artiflcial cells are added on the feed line to reduce the protrudent stub length from 26.9mm to 18.94mm. With the utility of the DGS and artiflcial cells, the size of proximity coupled antenna is reduced signiflcantly. By introducing a PIN diode at the end of feed line, the antenna is switchable in both x- and y-direction linear polarizations. Such miniaturization in antenna size has little negative efiect on its cross polarization, with both simulated and experimental results presented for comparison.

An improved asymmetric defected ground structure cell and its application to lowpass filter

AbstractAn improved asymmetric defected ground structure cell is presented and analyzed. Based on this structure, a microstrip lowpass filter with low passband loss and high stopband suppression is designed and fabricated. Measured passband losses are below 1 dB, and a sharp slop is obtained at passband frequency fringe. The suppression is no <30 dB in stopband from 2.98 to 10 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2933–2935, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24778