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A double‐layered DGS transmission line is proposed with a smaller DGS size and less radiation loss. Changing the air boundary to a dielectric boundary reduces the effective electric length at the DGS aperture area. An equivalent circuit model is introduced to analyze the DGS transmission line and the resonator circuit designs. Due to the increase in the effective dielectric constant, the proposed structure can be realized with less sensitivity to metallic environments. From the experimental results, the proposed double‐layered DGS can achieve a reduction of 90.1% in size and insensitivity at up to 5 mm of separation from the DGS aperture to the metallic plate. [ABSTRACT FROM AUTHOR]

We report a high performance linear phase low pass filter (LPF) designed for partial response (PR) modulations. For the implementation, we adopted microstrip technology and a variant of the standard stepped-impedance technique. Defected ground structures (DGS) are used for increasing the characteristic impedance of transmission lines. Experimental results prove that the proposed filter can successfully modulate a non-return-to-zero (NRZ) signal into a five levels PR one. [ABSTRACT FROM AUTHOR]

ABSTRACT This article proposes the novel design of a coplanar waveguide fed (CPW-Fed) monopole ultra wideband (UWB) semifractal antenna with dual band-notched specification and circular polarization (CP) attributes at ITU-R (7.725-8.5 GHz). The semifractal patch of antenna is composed of unitcell which unitcell patterns form branchs of tree. The fractal geometry in radiator leads to have an effective impedance matching over the UWB spectrum. The Dual-band filtering property can be adjusted finely by embedding a pair of L-strips length inside the slotted conductor-backed-plane (SCBP) and mirrored defected ground structure (MDGS). Beside that, the length and position of L-strips have great role in achieving CP in ITU-R band. The actual size of the miniature and fabricated antenna is limited to 15 × 15 × 1 mm3 and it operates across 2.2-12.52 GHz for S11<−10dB, except the bandwidths of 3.1-3.6 for WiMAX and 5-6 GHz for WLAN. The antenna has CP bandwidth from 7.5 to 8.5 GHz for axial ratio less than 3 dB. The antenna's parameters were investigated to fully understand their affects. Main parameters achieved from this analysis enabled the optimization of the antenna's entire performances. The prototype was fabricated, to validate the performance of antenna, through simulations and measurements. The measured results certify the antenna radiates omnidirectionally and has a large impedance bandwidth, dual-band rejection and CP property. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2483-2487, 2015 [ABSTRACT FROM AUTHOR]

In this article, a compact butler matrix for wireless communications is designed and implemented at 2.4 GHz using defected ground structures (DGS).The butler matrix consists of a 3-dB coupler, crossover (0-dB coupler), and phase shifter. The 3-dB coupler and crossover are compacted using T-model of transmission line and DGS. The size of proposed butler matrix is about 35% of a conventional matrix. To verify simulation results, designed matrix has been implanted and measured. Fortunately, there is very good agreement between simulation results and measured results. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2294–2298, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25474 [ABSTRACT FROM AUTHOR]

In this paper, a DPDT (Double-Pole Double-Throw) switch with defected ground structure (DGS) is newly proposed for transceiver systems. A biased varactor diode is introduced to control the on/off operation of the proposed switch. In order to confirm the validity of the switch, we design and implement the switch at the 2.45-GHz frequency. It is designed specifically for antenna-diversity switching for WLAN applications. The experimental results show very low insertion loss, excellent power handling, and high isolation performances. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1127–1130, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21561 [ABSTRACT FROM AUTHOR]

A novel band-stop filter using Gosper fractal-shaped defected ground structures has been designed and manufactured. The improvement in the filter selectivity has been achieved by introducing a multiresonance fractal-shaped defect leading to a higher filter order, simultaneously maintaining its compact size. The experimental results prove the validity of proposed solution and its utility in novel miniaturized and severe requirement filter applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 227–229, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24869 [ABSTRACT FROM AUTHOR]