This paper focuses on a tutorial overview of defected ground structure (DGS). The basic conceptions and transmission characteristics of DGS are introduced and the equivalent circuit models of varieties of DGS units are also presented. Finally, the main applications of DGS in microwave technology field are summarized and the evolution trend of DGS is given.

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An Overview on Defected Ground Structure

A broadband inverted E-H shaped microstrip patch antenna is proposed and experimentally investigated. The antenna employs novel E-H shaped patch with L-probe feed technique. Prototype of the proposed antenna has been fabricated and measured for electromagnetic analysis including the impedance bandwidth, radiation pattern, and antenna gain. The designed antenna has a dimension of 80mm by 50mm, leading to broad bandwidths covering 1.76GHz to 2.38GHz. Stable radiation patterns across the operating bandwidth are observed. In addition, a parametric study is conducted to facilitate the design and optimization process.

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Broadband E-h Shaped Microstrip Patch Antenna for Wireless Systems

Split Ring Resonators (SRR) and Complementary Split Ring Resonators (CSRR) are widely used to design metamaterial structures. These structures when excited by suitable electromagnetic fields have resonance behavior and show unusual properties such as negative permeability and permittivity near the resonance frequency region. In this paper, CSRRs are used to design a bandpass waveguide filter in the X-band. The circuit model of these elements in the waveguide is similar to parallel L and C components that are placed in parallel form in a transmission line. Resonance frequency and bandwidth of LC resonance circuit are adjusted by proper choice of the CSRR geometrical dimensions. Then, to design the miniaturized filter these structures are combined with proper admittance inverter. The admittance inverter is designed such that its electric length is very smaller than the conventional λ/4 transmission line. As a result, a filter is compacted about 66% in comparison to the λ/4 transmission line as admittance inverter. Simulation results by Ansoft HFSS (Based on the Finite Element Method) confirm the results of filter circuit model. 108 Bahrami, Hakkak, and Pirhadi

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Analysis and Design of Highly Compact Bandpass Waveguide Filter Using Complementary Split Ring Resonators(CSRR)

A new high gain wideband L-probe fed inverted EE-H shaped slotted (LEE-H) microstrip patch antenna is presented in this paper. The design adopts contemporary techniques; L-probe feeding, inverted patch structure with air-fllled dielectric, and EE-H shaped patch. The integration of these techniques leads to a new patch antenna with a low proflle as well as useful operational features, as the broadband and high gain. The measured result showed satisfactory performance with achievable impedance bandwidth of 21.15% at 10dB return loss (VSWR • 2) and a maximum gain of 9.5dBi. The antenna exhibits stable radiation pattern in the entire operating band.

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Design Analysis of High Gain Wideband L-Probe Fed Microstrip Patch Antenna

In this communication, a novel broadband dual circularly polarized (CP) antenna is presented. This antenna consists of an U-shaped slot to achieve broadband CP radiation and two 50- $\Omega $ microstrip-fed ports to realize both right-hand circular polarization and left-hand circular polarization at the same frequency band. The axial ratio bandwidth (ARBW) is greatly broadened by moving the feeding ports to upper portion of the U-shaped slot. To verify this design, the proposed antenna is fabricated and measured. The measured −10 dB reflection coefficient bandwidth is about 114.4% (1.80–6.61 GHz) and the 3-dB ARBW is approximately 110.5% (1.83–6.35 GHz). The isolation between two ports is better than 14.8 dB within the ARBW.

A Design of U-Shaped Slot Antenna With Broadband Dual Circularly Polarized Radiation

A novel dual-band bandpass filter with meander-loop resonator and complement split-ring resonator (CSRR) defected ground structure (DGS) is proposed in this letter. Microstrip meanderloop resonator and CSRR DGS are operated for respective passbands. Several finite attenuation poles in stopbands are realized to improve the selectivity of the proposed bandpass filter and isolation between the two passbands. Compact size, dual band and high selectivity characteristics are realized by this type of filter structure. The filter is evaluated by experiment and simulation with very good agreement.

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Design of Novel Dual-Band Bandpass Filter with Microstrip Meander-Loop Resonator and CSRR DGS

A novel design of dual circularly polarized antenna is proposed. By etching cross slots on the patch, circular polarization (CP) is achieved. The patch is fed by two L-strips which provide wide impedance bandwidth and high isolation level. Polarization diversity between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) is provided by switching the two ports and both LHCP and RHCP signals can be received simultaneously. The experimental results show that the 3 dB axial ratio CP bandwidth of the proposed design is increased two times, as compared to a referential CP antenna fed by L-strip. The details of experimental results for the proposed design are presented and discussed.

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Gao-Lei Wu

Papers

Design of Novel Dual-Band Bandpass Filter with Microstrip Meander-Loop Resonator and CSRR DGS

A novel design of dual circularly polarized antenna fed by l-strip