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In this article, a low loss and compact microstrip ultra-wideband bandpass filter (UWB-BPF) with a narrow-notched band is recommended for suitable applications in ultra-wideband wireless communication systems. The design methodology is presented to develop the microstrip structure of the UWB-BPF pursued by a single notched band (NB) in the passband of the UWB filter. An array of I-shaped defected ground structures and L-shaped defected microstrip structures based lowpass filters is cascaded with a shorted stub based highpass filter to achieve a UWB-BPF response. The two identically folded open stubs are loaded to obtain the narrow NB. The center frequency of the UWB-BPF without the NB is 3.5 GHz, and the stopband is suppressed up to 14.5 GHz. The fractional bandwidth achieved is 160%, with a circuit area of 0.11 ${\rm{\lambda }}_{\rm{g}}^{\rm{2}}$ λ g 2 . Furthermore, the single NB is attained at 5.7 GHz to reject interferences of signal from the 5G network with an attenuation level of 59 dB. The electromagnetic simulated and experimental responses of the designed structures demonstrate a well-matched behavior among them. The NB at 5.7 GHz in the UWB-BPF passband region suppresses the signal interference from the 5G network (5500 MHz), WLAN (5900 MHz), and WiMAX (5800 MHz). [ABSTRACT FROM AUTHOR]

This research presents an innovative dual-band microstrip patch antenna design enhanced with defected ground structures (DGS) and barium strontium titanate (BST) thin film, tailored for wireless local area network (WLAN) and WiMax applications. The first design phase involved the development of an microstrip patch antenna (MPA) using an flame retardant (FR4) substrate with a permittivity (er1) of 4.3 and a thickness of 1.524 mm, enhanced with DGS. This configuration achieved a single-band resonance at 4.1 GHz, with a bandwidth of 0.82 GHz and a return loss (S11) of -32 dB. The second phase involved the integration of a BST thin film, with a high permittivity(er2) of 250 and a thickness of 0.1 mm, into the DGS-enhanced microstrip patch antenna (MPA). This modification led to a transformation in the antenna's performance, enabling dual-band operation at resonance frequencies of 2.8 GHz and 5.8 GHz. Further, there was a corresponding substantial increase in bandwidth to 1.34 GHz and 1.25 GHz, respectively, an improvement in S11 values to -16.3 dB and -21.4 dB. Moreover, and antenna's size of 14×10×1.524 mm³. The study underscores the critical role of innovative material use and design optimization in advancing antenna technology, offering significant enhancements in bandwidth, and miniaturization, for wireless communication systems. [ABSTRACT FROM AUTHOR]

Recently, skyrmions are constructed in the system of localized spoof surface plasmons (LSSPs), showing topological robustness and near‐equidistant multi‐resonant response. Guided wave excitation of the LSSP skyrmions plays an elementary role in large‐scale planar integration and construction of complex networks. However, it is not investigated. In this study, the LSSP skyrmions are excited by guided waves supported by two kinds of widely used transmission lines, microstrip line and coplanar waveguide. Space‐coiling meta‐structures with different shapes that support LSSP skyrmions are etched on the ground planes as defected ground structures (DGSs). All structures including resonator, transmission line, input and output ports are in one plane. The structures are fabricated on printed circuit boards (PCBs) and the near‐equidistant multi‐resonant spectra of the LSSP skyrmions are measured. Moreover, to reduce the material loss, the structure is made on MgB2 superconducting film, and the quality factor (Q‐factor) is increased by seven times compared to the corresponding mode on PCB. This study paves the way for the massive planar integration of the LSSP skyrmions and the construction of complex networks with the LSSP skyrmions, and provides an idea for developing metasurfaces with low material loss in the microwave and terahertz bands. [ABSTRACT FROM AUTHOR]

A novel miniature wideband rectangular ring antenna is proposed for 4.6–6.2 GHz which is compatible with IoT applications. The wideband response of the proposed antenna is achieved by a partial ground and stair step structure. Because modifying the width and etching the ground plane does not improve the impedance matching over a large bandwidth, a triangular shape DGS is inserted in the partial ground plane to increase the antenna bandwidth with enhanced return loss. The wideband features of the antenna were explored here by incorporating different DGS shapes such as triangles, rectangle, pentagon, circle, and oval in the partial ground. The results have been successfully verified through measurement. The simulated fractional bandwidth is greater than 29% at 4.6–6.2 GHz whereas the measured fractional bandwidth is 27.6% at 4.75–6.2 GHz. In both cases, the maximum return loss is greater than 55 dB. The gain of the antenna is greater than 2.6 dB with good efficiency and nearly omnidirectional radiation pattern in shape. Due to its compact size and outstanding performance, the suggested stair step-shaped rectangular ring antenna could be a promising choice for IoT and wireless applications. [ABSTRACT FROM AUTHOR]

This article presents a miniaturized filtering power divider with low‐pass behavior and a wide attenuation band. The proposed FPD has an operating frequency (fo) of 1.52 GHz with a relative stopband rejection of 165% and an electrical circuit size of (0.25λg × 0.14λg). The microstrip structure responsible for low‐pass filter response is modeled using two rectangular‐shaped open resonators (ORs) loaded with multiple sections of the interdigital capacitor. The low‐pass filter operates at a cut‐off frequency of 1.56 GHz and passband insertion loss of 0.35 dB. The output ports are connected with a 100 Ω isolation resistor to obtain good isolation in the passband. The two dissimilar defected ground structures are introduced in the ground plane for achieving circuit miniaturization and wide harmonic suppression up to 15 GHz. The electromagnetic simulated results of both the low‐pass filter and FPD show a well‐matched behavior with the experimental ones. The proposed FPD is suitable for GPS applications. [ABSTRACT FROM AUTHOR]

The paper presents the design and analysis of a corona-shaped fractal antenna with a defected ground structure (DGS) for wireless applications. The fractal concept with an inverse patch medium DGS (IPM-DGS) technique is proposed and applied to achieve multi-band frequencies with a high efficiency. The same structure on the top face of the antenna is used as the ground face in an inverse medium. Resulting in the same corona fractal structure as the DGS. The overall dimension of the antenna is 55mm x 55mm (0.48λ × 0.48λ at the lowest resonant frequency) and is designed on a felt substrate to operate at 2.62 GHz, 3.02 GHz, 3.35 GHz, 3.5 GHz, and 3.62 GHz. The maximum gains of 4.06 dBi and 5.13 dBi with efficiencies of 82% and 80 % are observed at 2.62 GHz and 3.02 GHz, respectively, making the proposed antenna potentially suitable for wearable WBAN/WLAN applications. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a novel four-band diplexer using defected ground structures with compact size, low insertion loss and high isolation is presented. To begin with, there are 16 defected ground stepped impedance resonators (DSIRs) controlling four passbands characteristics. Every four DSIRs can generate one passband. Then, four different DSIRs use the same feeding line. According to the group delay, we can determine the relative physical position of the first resonator. For the demonstration, a four-band diplexer operating at 2.45/4.2 and 3.5/5.2 GHz with the fractional bandwidths of 10, 7, 6.2 and 5% is designed and fabricated. Finally, measured results agree well with simulated results. [ABSTRACT FROM AUTHOR]

A wideband common-mode (CM) suppression reconfigurable filter is proposed for high-speed all-pass differential circuits. The filter adopts three varactor-loaded compact defected ground structures (DGSs) to achieve continuous reconfigurability in its operation frequency with a large CM suppression dynamic range in the bandwidth. The varactors play an important role in widening the accessible instantaneous bandwidth and miniaturizing the structure. The three DGS cells with a total area of 15 mm × 10 mm are implemented symmetrically under the differential lines, to obtain reconfigurable CM bandstop characteristics which can be continuously adjusted from 1.8 to 8.1 GHz. A coupled LC resonator equivalent model is developed to represent and analyze the proposed filter, which explains its operation principle and assists in accelerating the reconfiguration design method. A good agreement between full-wave simulations and measured results is demonstrated, which validates the proposed design.

In this brief, we realize a simultaneous wireless power and information transfer (WPIT) system using co-existing coupled defected ground structure (DGS) resonators. First, co-existing DGS resonators are utilized in the design of simultaneous band stop filter (BSF) responses. Then, coupling two sets of co-existing DGS-BSFs achieves simultaneous WPIT. The DGS resonators have spiral elliptical-shape and share the same ground plane. The coupling characteristics are studied to improve the kQ-product of power carrier and reduce the cross-coupling with the Information carrier. A prototype is fabricated having a size 30 mm $\times15$ mm for both transmitter (TX) and receiver (RX). The separation between TX and RX is 15 mm. At this separation, the measured efficiencies are 71% and 66% at 49.6 MHz and 149 MHz, respectively, and the isolation between the power channel TX and the information channel RX is 39 dB at 49.6 MHz. [ABSTRACT FROM AUTHOR]

A compact, low-cost microstrip bandpass filter (BPF) with low insertion loss and wide attenuation band is presented in this article. The proposed structure consists of multiple interdigital capacitor sections and a T-shaped stub which is connected to the ground using via. The wide stopband response is achieved by the inclusion of defected ground structures (DGS). Addition of these defected ground structures also reduces the circuit size. The designed BPF of centre frequency 0.9 GHz is fabricated, measured, and its lumped equivalent circuit is also obtained. A good agreement is found among IE3D simulated results, circuit simulated results, and the measured results. The obtained results for the proposed bandpass filter (BPF) are −3 dB fractional bandwidth (FBW) of 63% and minimum insertion loss of 0.59 dB. The relative stop band (RSB) rejection is found up to 177% and the normalized circuit size (NCS) is found 0.012 λ g 2 . This proposed filter can be used for GSM and other microwave circuitry in wireless communication system. [ABSTRACT FROM AUTHOR]

A two‐port planar dual circularly polarised microstrip patch antenna is presented. The designed antenna has two groups of patches, each for transmission and reception. In one such group, only the central patch with truncated opposite corners is probe‐fed whereas the surrounding patches act as parasitic patches for bandwidth and gain enhancement. A defected ground structure (DGS) consisting 4 units of complementary square spiral resonators is used to enhance the port‐to‐port isolation as well as the axial ratio (AR) bandwidth. Based on the measured data of the fabricated prototype, the antenna is seen to have an impedance bandwidth of 900 MHz with the centre frequency of f0=6.40GHz. Moreover, the AR bandwidth is measured to be 600 MHz at fAR=6.36GHz, whereas the peak gain within this band is found to be ranging from 6.8 to 7.9 dBic. It is also noted that the AR bandwidth lies entirely within the impedance bandwidth and the cross‐polarisation discrimination is 20 dB in the boresight direction. [ABSTRACT FROM AUTHOR]

In this paper, new designs of optically transparent wearable antennas have been presented. The explored antennas have the excellent features of high flexibility, small size, low specific absorption rate (SAR) and high optical transparency. The proposed antennas are realised by utilising highly flexible, optically transparent and low‐cost materials. For achieving compactness in antenna dimension and for improved transparency, square‐ring‐shaped radiator is used in the antenna design. To improve the efficiency and gain of the square‐ring patch antennas, a new technique is proposed in this paper. The proposed technique utilises a strip line that connects the middle of the two opposite sides of the ring. Full ground plane is used in antenna design to reduce the back radiation. However, full ground plane reduces optical transparency. To elevate optical transparency without affecting antenna's back radiation significantly, a new technique of defected ground structure is investigated in this study. With this defected ground structure, the optical transparency is improved by about 6% without significantly compromising the SAR. The compatibility of the proposed antennas for wearable applications are investigated by examining the performances on flat and bent phantoms. Moreover, the robustness of the antennas are studied by subjecting the prototypes to multiple bending operations. [ABSTRACT FROM AUTHOR]

In 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. [ABSTRACT FROM AUTHOR]

In this work, a compact two-element triple-band multiple-input multiple-output (MIMO) antenna loaded with reflective type metasurface (MS) for enhancing the gain, isolation and impedance bandwidth (IBW) is presented. The two-element radiator antenna consists of a microstrip feed line on the upper side of the substrate and defected ground structure (DGS) on the backside on which multiple slots are etched for obtaining triple-band antenna performance. Due to DGS loading, the entire dimensions of the single radiator antenna are reduced to 22 × 22 × 1.6 mm3 with smaller electrical dimensions of 0.17λ0 × 0.17λ0 × 0.012λ0 at the first resonating frequency. The proposed two-port MIMO antenna with MS operates at 2.36–2.50, 3.43–3.50 and 5.15–5.88 GHz with percentage bandwidths of 5.76, 2.02 and 13.22% for the three operating bands. Due to MS loading, a gain improvement of 5.49, 4.57 and 0.80 dBi is noticed with a maximum gain of 3.98, 5.25 and 2.66 dBi is obtained at the three operating frequencies of 2.46, 3.51 and 5.32 GHz, respectively. The intended antenna is appropriate for working in IEEE 802.11 b/g/n (2.4–2.484 GHz) WLAN, IEEE 802.11 a/h/j (5.15–5.825 GHz) WLAN, and IEEE 802.16e (3.4–3.5 GHz) WiMAX wireless applications. [ABSTRACT FROM AUTHOR]

This study reports, for the first time, the use of coupled‐line‐based impedance matching in wireless power transfer (WPT) system. The transmitter and receiver of the WPT system are realised by microstrip feed line and symmetric coupled line at the top plane. The ground plane is realised with triangular‐shaped defect along with the excitation slot mounted by an external capacitor. The defect in the ground plane and the external capacitor regulate the resonant frequency and also enable miniaturisation of the WPT system. The design is augmented with a systematic analytical approach for impedance matching and a simplified design procedure for the WPT system. A novel equivalent circuit model consisting of parallel LC network and coupled lines is also developed for the evaluation of the proposed WPT system design technique. A prototype of the system operating at 300 MHz developed on Rogers RO4350B substrate achieves a peak efficiency of 80% at a transmission distance of 17 mm. An excellent agreement between the measured and the electromagnetic simulated results is a testament of the robustness of the proposed design technique. Furthermore, evaluation of the commonly used WPT‐related figure of merit shows significant enhancement when compared to the existing state of the art. [ABSTRACT FROM AUTHOR]

In this research, the return path discontinuity (RPD), located under the power amplifier (PA) substrate, of X‐band transceiver module (Base), mounted on a four‐layer printed circuit board (PCB), is investigated to improve the signal integrity by reducing the difference in the reference potential. This study is performed by initially employing the wirebond method, through the assessment of both numbers and sizes of bondwires by advanced design system (ADS). Six bondwires of 25 µm are added, producing an improvement of 6.82 dB for the reflection coefficient and 1.19 dB for the isolation and insertion loss. For further improvement, spiral shape defected ground structure (DGS) is implemented in the inner ground layer (layer 2) without using bond wires. The DGS simulation results illustrate an improvement of 3 dB for S11 and 0.6 dB for S12. To improve the electromagnetic compatibility (EMC), the authors propose combination and integration of both wirebond and DGS methods, called wirebond–DGS method, which results in an improvement of 11.86 dB for S11, 1.34 dB for S12 and S21, and 12.03 dB for S22. Finally, the wirebond–DGS RF module was fabricated and the measurement results exhibit an improvement of 8.07 dB for S11 and 9.39 dB for S22 in comparison with the fabricated Base module. In addition, 0.53 dB improvement for both S12 and S21 is also achieved. [ABSTRACT FROM AUTHOR]

A size‐reduced spiral DGS on double‐layered substrates with supplementary dielectric slabs is proposed. Because the attached additional substrates with a higher dielectric constant can increase effective dielectric constant faced on the DGS pattern in a ground plane, the spiral DGS pattern can be designed with a smaller size. In addition, impedance and linewidth of microstrip line on the proposed structure can maintain the same characteristics thanks to ground isolation. Simple equivalent circuit and its characterization are provided for double‐layered spiral DGS designs. The proposed spiral DGS is implemented based on the equivalent circuit model, and its miniaturization of 50% is verified with good agreements. [ABSTRACT FROM AUTHOR]

In this study, a novel high-isolation wideband divider based on multi-layer elliptical defected ground structure coupler is presented along with its analytical theory and design procedure. The proposed divider could be conveniently applied for high- power applications with less loss for the absence of isolation resistors. The simulation results show that in 3.1–10.6 GHz, the return loss S(11) and S(22) are −4 dB within 4–9 GHz, and the amplitude and phase difference between port 2 and port 3 is

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]

This study presents a new slitted electromagnetic bandgap (EBG) structure to filter undesired wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) bands in the ultra‐wideband (UWB) spectrum. A simple UWB antenna which consists of a microstrip tapered feed line, a circular patch and a defected ground structure is used as a reference antenna. The antenna is then integrated with a slitted EBG structure near the feed line to notch two interfering bands. The created notched bands by the EBG structure can be independently controlled. Owing to structural symmetry of the proposed antenna, the size can be reduced by approximately half to form a miniaturised antenna. The miniaturised antenna has the same full‐size antenna characteristics with little change in the notched bands specifications. Frequency domain measurement results show that the full‐size and miniaturised antennas have a flat transfer function, and a group delay variation of about 0.5 ns in the entire UWB band except for the notched bands. [ABSTRACT FROM AUTHOR]

This Letter presents a balanced‐to‐single‐ended (BS) crossover for dual‐band applications by using two rings included of composite right‐ and left‐handed (CRLH) transmission lines (TLs) with controllable frequency ratio feature. Two dumbbell defected ground structures (DGSs) are employed through balanced TLs to suppress out‐of‐band common‐mode. Theoretical analysis expresses that the frequency ratio can be controlled by suitable selecting of the element values and the number of designing cells of the CRLH TLs. Furthermore, desired impedances and electrical lengths of DGSs are obtained at the frequency of common‐mode rejection by using even‐ and odd‐mode analyses. To validate the proposed structure, a dual‐band BS crossover operating at 1.8 and 4.2 GHz is fabricated. Measurement results show that the fabricated proposed structure has good performance at the designed frequency bands. [ABSTRACT FROM AUTHOR]

In this study, a novel high-isolation wideband divider based on multi-layer elliptical defected ground structure coupler is presented along with its analytical theory and design procedure. The proposed divider could be conveniently applied for high- power applications with less loss for the absence of isolation resistors. The simulation results show that in 3.1–10.6 GHz, the return loss S11 and S22 are <−15 dB, the overall isolation S23 is <−20 dB and the best part achieves−50 dB. Insertion loss S21 and S31 are both >−4 dB within 4–9 GHz, and the amplitude and phase difference between port 2 and port 3 is <1 dB and 2°, respectively. [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]

A new design of single‐ended‐to‐balanced (SETB) filtering power divider (FPD) with wideband common‐mode (CM) suppression is presented. To effectively realise high suppression of CM noise, a hybrid structure constructed by both the double‐side parallel‐strip line (DSPSL) and a half‐mode defected ground structure (HMDGS) serving as the mid‐inserted conductor plane are adopted. Besides, due to the effect of HMDGS, the rejection of second harmonics for the differential‐mode (DM) transmission is also improved. Meanwhile, by employing two pairs of dual‐mode resonators symmetrically coupled with a stepped‐impedance input feed line and adding a DSPSL stub, wideband‐filtering performance with high selectivity is achieved. For validation, a prototype of the proposed SETB‐FPD centred at 5.9 GHz with a 3‐dB fractional bandwidth (FBW) of 27% is designed, fabricated and measured. Results indicate that the proposed SETB FPD exhibits good performances of high selectivity, wide upper stop band, good isolation between two balanced output ports and 30‐dB suppression of CM noise over the DM pass band. [ABSTRACT FROM AUTHOR]

In this paper, a novel compact T-shape defected ground structure (DGS) is proposed in order to reduce the mutual coupling between elements in a microstrip antenna array structure. The proposed DGS has considerable advantages compared to an H-shaped DGS. As is known, DGS insertion is a common problem in microstrip antenna array structures. However, the proposed T-shaped structure is more compact so it could be suitable for a compact microstrip array antenna. The T-shaped DGS is about 24% more compact than the H-shaped one. However, the most important novelty of our work is reducing mutual coupling both in the E-plane and the H-plane, which previously was discussed just in the E-plane. Finally, we have considered the disturbing effect of mutual coupling on the side lobe level (SLL) of unequally spaced arrays; using these results, a T-shaped DGS has been implemented in an 8-element unequally spaced array antenna in order to reduce its SLL. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, impedance transformers and branch line hybrids are selected to demonstrate the impact of defected ground structures on the operational bandwidth of microwave circuits. Three different branch line hybrids are studied with simulations and laboratory measurements, these are; a standard branch line hybrid, one using tapered lines and another one using both tapered lines and DGS. Based on these results, an optimum design in terms of location, size and number of DGS was proposed to achieve the widest operational bandwidth. Simulation and measured results demonstrate that correct usage of DGS and tapered lines can enhance the bandwidth of a narrowband microwave circuit. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:311-316, 2016. [ABSTRACT FROM AUTHOR]

This study presents a novel dual-band antenna design methodology utilising a dual-frequency impedance transformer with defected ground structure (DGS). The proposed dual-frequency DGS impedance transformer generates a second resonant frequency from a conventional single-band antenna, resulting dual-band operation. Simulation studies illustrate that the adopted design achieves versatile configurations for arbitrary operating frequencies and diverse input impedance ranges in planar antenna structures. To experimentally verify the proposed design methodology, a dual-frequency DGS impedance transformer was implemented for a 2.4 GHz monopole antenna to obtain a 900/2400 MHz dual-band antenna. Measurement shows that the 10 dB return loss bandwidth in 900 MHz band is 34.4 MHz, whereas that in 2400 MHz band is wider than 530 MHz. Typical monopole radiation patterns are observed at both operating bands.

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]

A compact ultra-wideband (UWB) bandpass filter (BPF) is proposed based on end coupled microstrip transmission line, defected ground structure and defected microstrip structure. The experimental filter shows a fractional bandwidth of 110% at a centre frequency, with two observable transmission zeros (attenuation poles) at 2.1 and 11.7 GHz. Measured results exhibit an UWB passband from 3.02 to 10.6 GHz with mid-band insertion loss of 1.8 dB and group delay variation

This letter presents a new design for wireless power transfer (WPT) applications using two coupled bandstop filters (BSF). The stopband is created by etching a defected structure on the ground plane, and the power is transferred through electromagnetic (EM) resonant coupling when the two BSFs are coupled back to back. An equivalent circuit model of the proposed WPT system is extracted. Verification of the proposed design is performed through a good agreement between the EM simulation, circuit simulation, and measurement results. The proposed system achieves a measured WPT efficiency of 68.5% at a transmission distance of 50 mm using a compact size ( $40\times 40$ mm ^{2}) . This results in a figure of merit of the proposed system to be 0.856 and the ratio of transmission distance/lateral size is 1.25 that is the highest among the WPT systems proposed so far using planar structures. [ABSTRACT FROM PUBLISHER]

A microstrip meander line with a single H-shaped Defected Ground Structure (HDGS) is employed to design a novel compact lowpass filter with sharp roll off and wide stop band. Two parametric studies were conducted to analyze the sensitivity of the HDGS position and the size effects on the filter response. The design is fabricated to have a 6 GHz cutoff frequency using Rogers TMM 10i substrate, with an area of 7.6 x 6 mm². The measured results are in a good agreement with simulation prediction. [ABSTRACT FROM AUTHOR]