Dumbbell-shaped Defected Ground Structure Research Articles

Development of a New Equivalent Circuit of DGS with Ideal Transformer

In this paper, a new equivalent circuit of a rectangular dumbbell‐shaped defected ground structure (DGS) with an ideal transformer is proposed. The proposed circuit incorporates a parallel resistor in the DGS gap, enabling the extraction of the coupling coefficient of DGS occurring in the narrow line gaps. Both circuit simulations and measurements demonstrate excellent agreement, confirming excellent performance compared to the measured results. Unlike the conventional equivalent circuit, which consists only of the lumped element, this one has an accuracy of only DGS units. In the proposed circuit, an ideal transformer has higher accuracy for the DGS in parallel with a resistor. We observed that increasing the resistance of the parallel resistor on the DGS unit leads to a decrease in the coupling coefficient and, conversely, decreasing the resistance prompts an increase in the coupling coefficient. The goal of this study is to develop a new equivalent circuit for a DGS unit with the ideal transformer, especially to find the coupling coefficient that occurred in the DGS gap. Here, we analyzed that the structure of the DGS unit had a gap, and the coupling coefficient must be built into any value. To demonstrate the effectiveness of the proposed circuit, DGS was used to design and conduct fabrication and measurement. The advantages of the proposed circuit analysis of the DGS behavior can be used to develop the attenuation pole as a one‐pole low‐pass filter, paving the way for future applications and developments in microwave and RF circuit design.

High isolation of SPDT PIN diode switch using switchable dumbbell-shaped DGS in millimeter wave 28 GHz band

This paper proposes a high isolation of single pole double throw (SPDT) PIN diode switch using switchable dumbbell-shaped defected ground structure (DGS). The proposed SPDT switch was designed for radio frequency (RF) front-end transceiver of antenna array multiple input multiple output (MIMO) in millimeter wave 28 GHz band. The switchable dumbbell-shaped DGS can be switched between allpass and bandstop responses where the bandstop response of the DGS can be utilized as a high isolation in the SPDT PIN diode switch circuit. A simple mathematical analysis is explained in this paper for the bandstop and allpass responses of the switchable dumbbell-shaped DGS. The propose SPDT switch was designed based on Roger RT/Duroid 5880 with 0.254 mm thickness and relative dielectric constant of 2.2. The simulated result showed that the proposed SPDT PIN diode switch produced an isolation of 36.36 dB at 27.3 GHz (center of 28 GHz band), which was 63% higher than the conventional SPDT design.

Revolutionary Triangular Patch Antenna with Dumbbell-Shaped Defected Ground Structure for 5G at 3.7 GHz: A Disruptive Design Innovation

This research proposes the use of a triangularshaped printed antenna operating at 3.7 GHz as a Defected Ground Structure (DGS) for a 5G communication system. The design of triangular antenna is incorporates with a printed Dumbbell shaped DGS structure in order to reduce the cost of antenna fabrication. The aim is to improve service performance, effectiveness, and quality of 5G communication systems. The proposed antenna has been analyzed and found to have return losses of -28.73 dB at the resonant frequency of 3.73 GHz, and an antenna gain of 3.23 dB. The DGS design is expected to increase the performance and this antenna be a choice for 5G communication systems.

Broadband Bandpass Filter for UWB Networks with Multiple In-Band Transmission Zeros

Proposed in this manuscript is a broadband bandpass filter (BPF) with dual in-band transmission zeros (TZs) and elongated stopband for application in ultra-wideband (UWB) networks. The basic structure is developed on the principle of broadside coupling of microstrip-to-coplanar waveguide (CPW). Semi-elliptical microstrips on the top are arranged in back-to-back manner and coupled to the open circuited CPW in the ground. The basic BPF is of 3rd order with good insertion/return loss. To this basic BPF structure multiple defected ground structures (DGS) in the shape of complimentary split ring resonator (CSRR) are appended to place dual Tzs within the passband and later dumbbell-shaped DGS are engraved in the CPW to widen the stopband. Also, an approximate equivalent lumped element circuit model is developed and its frequency characteristics matched against full-wave EM simulation. The proposed dual notched BPF is finally fabricated and is found to occupy a compact area of 13.6 × 6.75 mm2.

Novel Wilkinson Power Divider with an Isolation Resistor on a Defected Ground Structure with Improved Isolation

A modified Wilkinson Power Divider is proposed in this paper that utilizes defected ground structure (DGS) in parallel with an isolation resistor. The proposed DGS section is incorporated between the output ports, and the isolation resistor is soldered in parallel with the DGS in the ground plane, instead of on the top plane as in a conventional Wilkinson power divider, to achieve improved or preferable isolation. The proposed design is comprised of two pairs of microstrip transmission lines with equal impedances and varied electrical lengths. The parameters of the main circuit and the DGS section are acquired separately. The parameters of the proposed main circuit are derived by applying conjugate matching theory. Dumbbell-shaped DGS is introduced in the ground plane between the output ports, which acts as a parallel resonator, yielding an attenuation pole at the resonant frequency that contributes to improved isolation. By applying the previous well-known circuit theory, the lumped elements of the equivalent circuit of the DGS were achieved. The physical dimensions of the equivalent circuit for the DGS section were obtained by three-dimensional EM simulation. The measured results show improved isolation, return loss and better bandwidth as compared with other similar works. Furthermore, the proposed circuits designed at resonating frequencies of 3 and 2 GHz presented comparatively good return losses, S11 of about −25.54 and −31.24 dB, respectively, and achieved improved isolations, S32 between the output ports, in an order of about −40.83 and −36.05 dB, respectively, which is rather exceptional and desirable.

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.

Characterization of electrolyte content in urine samples through a differential microfluidic sensor based on dumbbell-shaped defected ground structures

AbstractIn this paper, a differential microfluidic sensor and comparator based on a pair of microstrip lines loaded with dumbbell-shaped defected ground structure resonators is applied to the characterization of electrolyte concentration in samples of horse urine. Since variations in the total electrolyte content in urine may be indicative of certain pathologies, the interest is to use the device as a comparator, in order to determine changes in the electrolyte concentration as compared to a reference level. To validate the approach, we have made differential measurements of a set of urine samples with different electrolyte concentrations (which have been previously obtained by means of electrochemical methods). The obtained results correlate with the nominal electrolyte concentrations of the samples, thereby pointing out the potential of the approach as a low-cost pre-screening method (or complementary diagnosis system) to detect potential pathologies or diseases in horses and other animals.

Research of Dumbbell Shaped DGS to Enhance The Bandwidth and Multiple Band Applications

A monopole microstrip rectangular patch with dumbbell shape slotted on ground for multiple band, enhance the bandwidth. The proposed antenna is fabricated on FR 4 epoxy material with electrical permittivity of 4.4 and magnetic permeability 1.The dimensions of proposed antenna are 70 x 50 x 1.6 mm3 and the dumbbell shape is slotted on ground of substrate which resonates at four different frequencies 5.9 GHz, 7 GHz, 8.7 GHz and 9.7 GHz. The proposed antenna has bandwidths of 200 MHz 300 MHz, 300 MHz, 300 MHz at four resonant frequencies The proposed antenna covers 4/8 GHz C band, 8/12 GHz X band and used in radar, satellite communications. The reflection coefficient (S11), radiation characteristics, peak gain and VSWR of designed antenna are described

Design and Analysis of Inset Fed Wide-Band Rectenna with Defected Ground Structure

The design proposed and fabricated in this paper is a slotted wide-band rectenna with the inclusion of Defected Ground Structure (DGS) which can harvest RF energy in the frequency range of 5.336–6.194[Formula: see text]GHz with a center frequency of 5.8[Formula: see text]GHz. For the development of antenna, FR4 substrate having a dielectric permittivity of 4.3 has been adopted. Two parallel slots on the patch are incorporated on either side of the feed line to obtain the wide-band structure. Dumbbell-shaped DGS is also incorporated exactly underneath the feed line to increase the gain of the antenna. HSMS-285C Schottky diode has been used for the implementation of the rectifier circuit and a Greinacher voltage doubler has been chosen. ADS design software has been used for rectifier simulation and CST has been used for the designing of the antenna. Current behavior on the patch can be investigated to explore the wide-band mechanism. The antenna operates in the frequency range of 5.336–6.194[Formula: see text]GHz and with VSWR less than 2, which corresponds to 16.07% impedance bandwidth. The antenna achieves a gain of 6.189[Formula: see text]dB and a directivity of 8.776[Formula: see text]dBi. The conversion efficiency of the rectifier was optimized to 75% at 5.8[Formula: see text]GHz. The proposed design gave an output of 3.2[Formula: see text]V which can be used under numerous energy harvesting and wireless power transmission applications.

A Compact Lowpass Filter Using Interdigital Line Resonator with Wide Stopband

A compact (0.14 λg × 0.18 λg), low-cost microstrip lowpass filter of 2 GHz cut-off frequency is presented in this paper. The proposed filter structure is designed using interdigital line resonator (ILR) which makes it compact in size. The inclusion of dumbbell-shaped defected ground structures with the ILR structure offers excellent harmonic suppression and broader attenuation band up to 20 GHz, i.e. stopband rejection is almost 164%. The insertion loss of the filter is lower than 0.3 dB. A modification in J-inverter topology is further proposed to demonstrate the coupling behaviour of the presented ILR unit. The lumped equivalent circuit of the designed ILR-based lowpass filter is derived and simulated. Finally, the proposed microstrip filter is fabricated and measured. A good agreement is found among EM-simulated results, circuit-simulated results and the measured results. Such low-loss, high-performance lowpass filter can be used in surface ship radar and satellite communications.

Miniaturized half‐mode SIW band‐pass filter design integrating dumbbell DGS cells

AbstractThis paper presents the numerical and experimental results of a miniaturized half‐mode substrate integrated waveguide HMSIW C‐band pass filter with defected ground structure DGS, using two slots and dumbbell shape defected ground structure. These two slots which are etched on the upper plane of the SIW cavity are used to constitute a multiple‐mode resonator, and the dumbbell‐shape fractal DGS etched on the bottom plane can considerably enhance the filter's performances. The manufactured band‐pass filter in half mode based on SIW technology has a size nearly half of that of a normal filter. The measurements results obtained by CST in C‐band show that the manufactured filter has a large transmitted bandwidth of about 1.53 GHz from 5.97 to 7.5 GHz. The higher measured insertion is about −2.6 dB and the lower return loss measured is about −34 dB. The size of filter design achieved is 7.48 × 38.12 mm2 which make it the more compact in comparison with some published works at the C‐band frequency.

Flexible Design Method for Microstrip Bandstop, Highpass, and Bandpass Filters Using Similar Defected Ground Structures

It is well known that the typical low-pass characteristics can be obtained by a cascaded structure of alternating high- and low-impedance transmission-line (TL) segments. On the contrary, this paper focus on modifying this stepped impedance TLs to obtain the bandstop, highpass, and bandpass responses. A basic structure consisting of dumbbell-shaped defected ground structures (DGSs), complementary split ring resonators (CSRRs) DGSs and interdigitated coupling structures is proposed, which can simultaneously satisfy the design of different types of filters. Then, open stubs and short stubs are appropriately selected and achieve the necessary flexibility among the conversions of different frequency responses. Furthermore, different units are ingeniously embedded into the stepped impedance TLs to obtain good performances and small dimensions. By employing the extracted parameters and equivalent circuits, different types of frequency responses are well explained. Finally, the proposed filters are fabricated and measured, the measured results show a great agreement with simulated results.

Dual-band UWB bandpass filter with triangular DB-DGS for WLAN applications in DSRC band

A dual-band Ultra-wideband (UWB) bandpass microstrip filter with triangular dumbbell shaped defected ground structure (DB-DGS) for wireless local area network applications in DSRC band is proposed in this article. The proposed dual-band filter has center frequencies at 2.67 GHz and 4.68 GHz, return loss obtained is −33.40 dB and −16.55 dB respectively, wide bandwidth of 1.21 GHz (26%), pass band between 2.14 GHz and 6.44 GHz and high gain of 10.30 dB which makes it suitable for modern applications in dedicated short range communication operating in 5.8 GHz band. To further validate the design concept, a microstrip UWB filter is designed, fabricated and tested. Comparison is made among circular, square and triangular dumbbell shaped DGS on the basis of scattering parameters and bandwidth, in which triangular shaped DB-DGS outperforms the other two. Further, parametric analysis of triangular DB-DGS has been performed and comparison is made with filters of similar nature. Experimental results are in good agreement with simulations. The fabricated filter is compact in size, has low insertion loss, exhibits high selectivity and demonstrates excellent out of-band performance.

A compact planar ultra-wideband bandpass filter with multiple resonant and defected ground structure

A compact bandpass filter with dumbbell shape Defected Ground Structure (DGS) operating on ultra wide pass band (UWB – 3.1 to 10.6GHz) is proposed. It is based on hybrid microstrip coplanar waveguide (dual sided metal) structure. A Multiple Resonant Structure (MRS) is constructed using coplanar waveguide (CPW) planar transmission line. The MRS makes the resonance using quarter wavelength and half wavelength open-ended CPW. The equispaced three resonances at lower (3.1GHz), center (6.85GHz) and higher edge (10.6GHz) of the whole Ultra Wide Band is achieved using CPW MRS. To make the band as flat as possible, two more resonances are introduced using quarter wavelength microstrip patches on top of the commonly shared substrate, so the proposed filter becomes a five pole bandpass filter. A dumbbell shaped defected ground structure on either side of CPW MRS improves the return loss almost less than 20dB over the whole UWB passband. The simulated results of proposed filter show good transmission response within passband and good rejection in out of the band. The simulated and measured results are very close to each other which proves the efficacy of proposed design.

Design and realization of microstrip filters with new defected ground structure (DGS)

In this paper, various microstrip filters, such as bandpass (narrow/wideband) filters, dual band bandpass filter and lowpass filters, are designed with new metal strips loaded defected ground structure (DGS). In this proposed DGS, metal strips are introduced in connecting slot of dumbbell shaped DGS (DB-DGS). This new DGS is an improved version of conventional (dumbbell-shaped) DGS with enhanced characteristics of filters. With this new metal strip loaded DB-DGS, a bandpass (narrow-band/wide-band) filters, dual-band bandpass filter and lowpass filters, are designed with improved characteristics. The entire proposed filters are designed and fabricated with the same substrate area using 50Ω, λg/4 microstrip line which is very compact to conventional microstrip filters. For validation of proposed designs, all fabricated filters are measured in Rohde and Schwarz Vector Network Analyzer 1127.8500 and also compared with circuit simulated results. All the simulations are carried out in HFSS V10 and ADS2006A.

Design and characterization of an efficient multi-layered circularly polarized microstrip antenna

A novel asymmetric “+” shaped fractal slotted circularly polarized microstrip antenna with a Yagi–Uda structure is proposed. Four asymmetric plus shape slots are embedded symmetrically in the center of all four quadrants of a square patch. To suppress undesirable higher modes, dumbbell-shaped defected ground structure (DGS) is introduced at the ground layer of the antenna. We introduce a method to compensate the reduction in gain occurring due to the presence of DGS, without changing in the overall size of the antenna. A 3 dB axial ratio bandwidth of 4 MHz at center frequency of 862 MHz, 10 dB impedance bandwidth of 13.20 MHz and a gain of 4.25 dB is achieved with the proposed antenna. A laboratory prototype of the proposed antenna is made to cross-verify the simulation results. Very good agreements between the two are obtained. The proposed antenna may prove useful for International Mobile Telecommunication application for designing high-gain arrays.

A NOVEL DUMBBELL-SHAPED DEFECTED GROUND STRUCTURE WITH EMBEDDED CAPACITOR AND ITS APPLICATION IN LOW-PASS FILTER DESIGN

A novel dumbbell-shaped defected ground structure (DB-DGS) with embedded capacitor is presented in this paper. Compared with conventional DB-DGS structure, the proposed DB-DGS exhibits many attractive characteristics including double resonance, high Q value and compact size. The equivalent lumped circuit model for the novel DGS is developed, and its parameters are extracted. Based on this new DB-DGS, a low-pass filter (LPF) using the novel DB-DGS has been constructed, which provides a more steep rejection property, a wider stopband and compact size. The proposed structure is experimentally verified through the demonstration of a low-pass filter design.

A Novel Compact Microstrip Lowpass Filter with Sharp Transition and Improved Stopband

A novel compact microstrip lowpass filter (LPF) is proposed in this paper, which consists of the complementary rectangle split ring defected microstrip structure (CRSR-DMS), open stubs, spurline and the dumbbell-shaped defected ground structure (DGS). Due to the unique response of the presented CRSR-DMS, a low passband insertion loss and a sharp transition of the proposed LPF was achieved. Meanwhile, an improved stopband was obtained by properly adjusting the working frequencies of open stubs, a third-order LPF using spurline and dumbbell-shaped DGS. The measured result of the designed LPF shows that attenuation rate reaches 159 dB/GHz and a wide stopband is obtained from 4.07 GHz to more than 15 GHz. DOI: http://dx.doi.org/10.11591/telkomnika.v13i1.6760 Full Text: PDF

An Equivalent Circuit Model for a Dumbbell-Shaped DGS Microstrip Line

This paper presents an equivalent circuit model for a dumbbell-shaped defected ground structure (DGS) in a microstrip line. The effects of equivalent circuit elements of a dumbbell-shaped DGS and their magnetic coupling to the host transmission line are modeled as a simple lumped-element circuit. In addition, simple approximate expressions to determine the main circuit parameters for this model are presented. The transfer characteristic calculated by the proposed circuit model is compared with the results of EM simulation and measurement.

A modeling method for dumbbell‐shaped DGS and its parameter extraction

ABSTRACTThis article presents an equivalent circuit model for a dumbbell‐shaped defected ground structure (DGS) in a microstrip line. The effects of equivalent circuit elements of a dumbbell‐shaped DGS and their magnetic coupling to the host transmission line are modeled as a simple lumped‐element circuit. By adding a virtual capacitor on the narrow etched gap, the values of inductance and capacitance of the dumbbell‐shaped DGS in the ground plane were extracted. Also, other main circuit parameters of the proposed circuit model were extracted using EM simulation result. This article provides one approach for understanding the operating principle of the DGS structures. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2910–2913, 2014