U-shaped Defected Ground Structure Research Articles

Differential Negative Group Delay Circuit Topology with Reverse Nested Double U-shaped Defected Ground Structure

Differential Negative Group Delay Circuit Topology with Reverse Nested Double U-shaped Defected Ground Structure

Design of Compact Monopole Antenna with U-Shaped Defected Ground Structure (DGS) for UWB Application

This paper described the design of a compact printed monopole antenna with U-shaped Defected Ground Structure (DGS) for ultrawideband (UWB) application. The implementation of DGS facilitates in reduction of size and increases in antenna performance. The DGS and antenna design parameters are simulated using CST Microwave Studio 2020, and the measurement is carried out using R&S Vector Network Analyzer (VNA). The optimized design of the proposed UWB antenna with U-shaped DGS presented smaller in size (23.88mm x 29.10mm x 0.813mm) with a reduction of 32% compared to the conventional design, which fabricated on Rogers RO4003C substrate with a relative permittivity, εr = 3.38. Simulation results show that the proposed antenna provided a very wide range of frequency (3.2 - 20GHz), 144.8% of BW. The simulated and measurement results show good agreement.

Implementation of defected ground structure for microstrip filtenna design

A microstrip patch filtenna inspired by defected ground structure (DGS) is presented in this article. It uses modified split ring resonator and capacitance loaded strip as a radiating element. The presented structure is incorporated with a pair of double U-shaped DGS (DU-DGS) to obtain filtering characteristics. The width of DU-DGS plays a vital role in selecting attenuation poles of the filter as well as for the filtenna circuit. The separation distance between the DU-DGS also affects the resonant frequency of the structure. Both radiation and filtration can be performed through a single structure, otherwise known as filtenna. The physical size of the proposed filtenna in terms of guided wavelength is 2.465λg × 1.160λg × 0.116λg at 10.8 GHz, and is comparatively less to others reported, so is considered as a superior feature. The presented filtenna possesses impedance bandwidth of 700 and 1800 MHz at 10.8 and 16.6 GHz, which covers standards of X- and Ku-band, respectively. So, this can be referred to as dual band filtenna. The radiation pattern shows omnidirectionality in both E and H planes at resonance.

A Simple WiMAX and RFID Band-Notched UWB Bandpass Filter and Its Susceptibility Study

An ultra-wideband (UWB) bandpass filter (BPF) with a fractional bandwidth (FBW) of about 110%, transmission zero at the high-frequency edge, and band notches at the worldwide interoperability for microwave access (WiMAX) and radio frequency identification (RFID) band is presented in this paper. The filter is based on single short-circuited stub, U-shaped defected ground structure (DGS) array, two U-shaped resonators and two stepped impedance resonators (SIRs). The filter is compact and exhibits a selective filtering characteristic equivalent to a three-pole Chebyshev filter. The design procedure has been described and verified by full-wave electromagnetic (EM) simulation and measurement. The proposed filter has low insertion loss, sharp rejection, and excellent in and out band performance. Due to its applications in WiMAX and RFID systems, the filter may be subjected to high EM radiation from the antenna and nearby sources. Therefore, susceptibility study of such a filter is very important. Hence, the susceptibility study of the band-notched UWB BPF has been carried out by subjecting the structure to an interference source.

CPW based Band Pass Filter Using DGS for ISM Band Applications

The design and simulation of coplanar waveguide (CPW) bandpass filter (BPF) has been described in this paper. It mainly focuses on Defected Ground Structure (DGS), where U-shaped DGS with open stub in transmission line has been introduced. By etching the DGS pattern in ground and transmission will change the distribution of inductance and capacitance to produce filtering effect. This paper also discusses about the influence of geometrical parameter l for the improvement in the frequency response of bandpass filter. As increasing the dimension of the geometric parameter l shift the center frequency to the higher frequencies. This filter offers a bandwidth of 1.65 GHz with passband ranging from 2.1 GHz to 3.75 GHz with a stopband rejection is about -28 dB.

Study of compact microstrip lowpass filter with improved performance using defected ground structure

A compact lowpass filter (LPF) with wide stopband which uses four non-uniform cascaded defected ground structure (DGS) units along with a 50 Ω microstrip line is reported in this article. Each DGS unit, which consists of a combination of three isosceles U-shaped DGSs is analyzed in terms of an equivalent RLC circuit model. Every DGS of the DGS unit along with microstrip line provides one attenuation pole. It is found through performance comparison of the proposed U-shaped DGS with dumbbell- and fork-shaped DGSs that the proposed U-shaped DGS is compact and provides higher quality factor. Further, the modeling of the proposed LPF is carried out using equivalent RLC circuit model. The results obtained through numerical and circuit simulations are compared. The proposed LPF has size of 14.44 mm × 3.4 mm, 3-dB cut-off frequency of 14.2 GHz, and greater than 40 dB and 22 dB stopband rejection up to 21.8 GHz and 30 GHz respectively. The proposed LPF is fabricated and experimentally tested. The experimental results are nearly in agreement with corresponding numerical/circuit simulation results.

Design and Fabrication of a Novel Quadruple-Band Monopole Antenna Using a U-DGS and Open-Loop-Ring Resonators

In this Article, a novel quadruple-band microstrip patch antenna is proposed for the systems operating at quad-band applications. The antenna structure is composed of modified rectangular patch antenna with a U-shaped defected ground structure (DGS) unit and two parasitic elements (open-loop-ring resonators) to serve as a coupling-bridge. The proposed antenna with a total size of 31×33 mm2 is fabricated and tested. The measured result indicates that the designed antenna has impedance bandwidths for 10 dB return loss reach about 180 MHz (4.4–4.58 GHz), 200 MHz (5.4–5.6 GHz), 1100 MHz (7.2–8.3 GHz), and 700 MHz (9.6–10.3 GHz), which meet the requirements of the wireless local area network (WLAN), worldwide interoperability for microwave access (WiMAX), C and X bands applications. Good agreement is obtained between measurement and simulation results.

Compact Balanced Dual-Band Bandpass Filter Based on Modified Coupled-Embedded Resonators

A new compact balanced dual-band bandpass filter based on coupled-embedded resonators with modified ground plane is presented in this work. Common-mode is rejected within the two differential passbands by symmetrically introducing four coupled U-shaped defected ground structures below the resonators. Common-mode rejection is significantly improved when compared with the standard (solid ground plane) filter with similar geometry thanks to the introduction of four extra transmission zeros. Due to the symmetry, the differential mode is not significantly affected by the presence of the U-shaped resonators. Circuit-model data, full-wave simulations and measurements are provided to verify the benefits of the proposed dual-band filter.

Miniaturized lowpass filter with ultra-wide stopband using dual-plane defected structures

A miniaturized lowpss filter (LPF) with ultra-wide stopband is proposed by using the complementary rectangle split ring defected microstrip structure (CRSR-DMS) and the quad U-shaped defected ground structure (QU-DGS). The presented CRSR-DMS can provide a sharp rejection rate and two obvious attenuation poles while the QU-DGS can produce four independently controlled transmission zeros. Based on the characteristics of the defected structures, the proposed LPF is constructed by using four cascaded CRSR-DMS units and four cascaded QU-DGS units. The measurement result of the designed filter with 3 dB cut-off frequency at 2.0 GHz shows that the obtained 20 dB rejection band ranges from 2.12 GHz to more than 20 GHz within a small circuit area of 0.73λg * 0.13λg, λg being the guided wavelength at 2.12 GHz.

A simple transformation of improved WLAN band pass to low pass filter using defected ground structure (DGS), defected microstrip structure (DMS) and multilayer-technique

A novel transformation of band pass- to low pass filter is introduced in this paper. First a compact microstrip band pass filter designed, optimized and realized by combining a simple multilayer method with magnetically coupled microstrip U-shaped DGS resonators is proposed. The DGS- and DMS-techniques demonstrated the ability to suppress the undesired harmonic response. The proposed band pass filter is transformed to a new structure with low pass characteristics using a simple strip connection between the neighboring microstrip resonators. The designed compact filters have low insertion loss, sharp transition regions due to the presence of two-transmission zeros at both edges of the pass bands. The measured resonance frequency, bandwidth and insertion loss are 3.4 GHz, 40%, and 0.5 dB respectively. The compact transformed low pass filter offers a wide stop band with a rejection higher than 20 dB up to more than 10 GHz. The undesired harmonic has been successfully suppressed. The simulated and measured results show good agreement and validate the proposed approach.

A NOVEL MINIATURIZED DUAL-BAND BANDSTOP FILTER USING DUAL-PLANE DEFECTED STRUCTURES

A novel miniaturized dual-band bandstop fllter (DBBSF) is proposed by using the T-shaped defected microstrip structures (DMSs) and the U-shaped defected ground structures (DGSs) in this paper. The layout of the dual-band bandstop resonator (DBBSR) is presented at flrst. The dual stopbands of the DBBSR can be separately controlled since the mutual coupling of the defected structures is negligible. The working principles of the T-shaped DMS and U-shaped DGS are then provided and their design process is summarized. On the basis of the DBBSR, the design methodology of the compact DBBSF is proposed before its design procedures are presented. Following the design procedures, a second-order and third- order DBBSFs with Butterworth frequency response are designed, simulated and fabricated. The equivalent circuit models of the designed fllters are also developed. Full-wave simulation results of the fabricated DBBSFs are in good agreement with the circuit simulation and measurement results, validating our proposed design methodology.

Develop Dual-Mode DGS Bandpass Filters Using High Quality Factor Aluminum Oxide Ceramic Substrates

Aluminum Oxide microwave dielectric ceramics exhibit good microwave dielectric characteristics and suitable be used in the microwave devices. In this letter, using screen-printing technique and Ag/Pd paste, a novel dual-mode 2.4 GHz microstrip bandpass filter with U-shaped defected ground structure is screen printed on the Aluminum Oxide (Al2O3, relative dielectric constant=9.8) microwave dielectric ceramic substrate. In addition, a pair of input/output microstrip lines are designed to be 50 Ω and coupled to a λ/4×λ/4 square loop resonator. And in the ground plane, a U-shaped defected ground structure is used toλ excite the degenerate modes, which can be considered as a perturbation element to control the odd-mode frequency and -3 dB bandwidth of the bandpass filter. Finally, the coupling effects between these degenerate modes are presented and detailed investigated.

NEW U-SHAPED DGS BANDSTOP FILTERS

In this paper, new microstrip bandstop fllters with single band, dual-band and tri-band by using U-shaped defected ground structures are presented without the assistance of coupled lines or certain resonators, and the application of DGS is developed. The proposed bandstop fllters have good performances of low loss, multi- band operation, transmission zeros which improve the fllter frequency selectivity, and miniaturization because of the cascade of DGS and minimum defected patterns which reduce the circuit size. The new designs are demonstrated by measurement.

STUDY OF AN EXTREMELY WIDEBAND MONOPOLE ANTENNA WITH TRIPLE BAND-NOTCHED CHARACTERSISTICS

Three notched bands are generated, at selected frequen- cies, in an extremely wideband base antenna to support multiple com- munication systems while avoiding inference from other existing nar- rowband systems. The design of a fully printed extremely wideband antenna and creating triple band-notched functions are addressed in this paper. Measurements demonstrate that the proposed printed base antenna has an extremely wide 2:1 VSWR bandwidth from 0.72GHz, to 25GHz with a ratio bandwidth of 34:1. The antenna has a simple structure and can be fabricated at low cost for multi-band and wide- band wireless communication devices. Besides, this paper presents a technique to form three notched bands within the operating frequency range of the base antenna. By introducing a half-wavelength U-shaped defected ground structure (DGS) and a pair of quarter-wavelength open arc-shaped slots to the radiating patch, three notched bands are created to prevent interference from WLAN (2.4{2.484GHz and 5.15{ 5.85GHz) systems and downlinks of X-band satellite communication (7.25{7.75GHz) systems.

ANALYSIS OF A SMALL UWB FILTER WITH NOTCH AND IMPROVED STOPBAND

A microstrip based Ultra-Wideband (UWB) Bandpass Filter (BPF) with a notch at WLAN and simultaneously improved stopband till 18GHz is proposed. Meander shaped Defected Ground Structures (DGS) are used to implement the notch within the passband and two double U-shaped DGS structures present under the input and output feeding lines are used to attain the suppressed stopband. An equivalent circuit model of the proposed UWB fllter structure is presented in the manuscript. Experimental results are in good agreement with the simulated data.

Mutual coupling suppression in microstrip array using defected ground structure

A defected ground structure (DGS) is used to suppress mutual coupling between elements in a microstrip array and eliminate the scan blindness in an infinite phased array. Two kinds of DGSs, namely back-to-back U-shaped and dumbbell-shaped DGSs, are analysed and compared. The analysis indicates that the back-to-back U-shaped DGS is better at suppressing propagation of surface waves in microstrip substrate. A two-element microstrip array with back-to-back U-shaped DGS is designed and the array characteristics against different element distances are studied. The results show that the degree of the mutual coupling suppression is increased when the element distance is reduced. However, compared with the traditional array, a higher gain and lower side lobes are obtained when a larger element spacing is selected. The scan blindness of an infinite microstrip phased array in E-plane is studied by simulation, and the calculation demonstrates that the scan blindness can be eliminated by applying a back-to-back U-shaped DGS to the infinite phased array.

A NOVEL G-SHAPED SLOT ULTRA-WIDEBAND BANDPASS FILTER WITH NARROW NOTCHED BAND

A novel G-shaped slot ultra-wideband (UWB) bandpass fllter with a very narrow notched band is proposed. The basic ultra- wideband fllter is short-circuited stub bandpass fllter consisting of shunted ‚=4 short-circuited stubs and ‚=4 connecting lines. To avoid the interferences such as WLAN signals. The G-shaped slot embedded in the stub fllter is used to obtain the notched band inside the UWB passband. Additional U-shaped defected ground structures are adopted to improve the out-band suppression. Measured results show that the proposed fllter has an ultra-wide bandwidth from 3.1GHz to 10.6GHz, and the insertion loss is less than 1dB. Speciflcally, the fabricated fllter possesses a 10dB notched fractional bandwidth (FBW) of 2.36% at the notched center frequency of 5.8GHz. It also achieves a stop band with 20dB attenuation.

A compact U‐shaped defected ground structure microstrip low‐pass filter with wideband rejection

AbstractA compact triple U‐shaped slots etched on the microstrip ground are used to implement a novel low‐pass filter.A rectangular open stub and a radius stub are used to produce transmission zeros and thus result in wide stopband. Good low‐pass performance and wide stopband characteristics can be achieved by this new structure. One prototype is fabricated to demonstrate the validity of the design strategies. The simulated and measured results indicate that the insertion loss is less than 0.25 dB and the return loss is less than −16.7 dB in the whole passband. In addition, significant improvement on rejection band can be observed; the stopband bandwidth better than −25 dB is about 105% (from 2.6 to 8.4 GHz). © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 497–499, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24960

Compact band‐notched ultra‐wideband antenna using defected ground structure

AbstractA compact printed monopole ultra‐wideband (UWB) antenna with the band‐notched function is proposed. The antenna consists of a fan‐shaped metal patch and a trapeziform ground with a 50 Ω tapered coplanar waveguide (CPW) transmission line. By simply adjusting the length of the U‐shaped defected ground structure (DGS) in the ground plane, the band‐rejected filtering properties for the WLAN band is achieved. The proposed antenna is successfully simulated, designed, and measured, which shows an ultra‐wide matched impedance band from 3 to 15 GHz for VSWR ≤2 with a stop‐band of 5–6 GHz. The stable radiation patterns are also obtained. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 286–289, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24946

Compact Pentagon Ultra-Wideband Bandpass Filter with Good Out-of-Band Performance

A novel compact pentagon ultra-wideband band-pass filter with spurious suppression over a very wide band is proposed. The filter is based on a circuit model using hybrid bended pentagon microstrip and five quarter-wavelength short-circuited stubs, and using double reverse U-shaped defected ground structure (DRU-DGS) provides attenuation pole to suppress the second spurious harmonic. The design was successfully realized in theory and verified by full-wave EM simulation of the full layout and the experiment. The proposed filter had a good performance, including an ultra-wideband bandpass (3.1–10.6 GHz), low insertion loss, sharp rejection, and a flat group delay of about 0.10 ns over the most center band. The filter also demonstrated an UWB reject band from 12 GHz to more than 20 GHz at –20 dB.