Slots or defects integrated on the ground plane of microwave planar circuits are referred to as Defected Ground Structure. DGS is adopted as an emerging technique for improving the various parameters of microwave circuits, that is, narrow bandwidth, cross-polarization, low gain, and so forth. This paper presents an introduction and evolution of DGS and how DGS is different from former technologies: PBG and EBG. A basic concept behind the DGS technology and several theoretical techniques for analysing the Defected Ground Structure are discussed. Several applications of DGS in the field of filters, planar waveguides, amplifiers, and antennas are presented.

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Defected Ground Structure: Fundamentals, Analysis, and Applications in Modern Wireless Trends

A compact filtering antenna is designed for the modern wireless communication systems in this letter. First, a two-pole Butterworth bandpass filter is designed. Then, by substituting the second port and resonator with fan-shaped patch antenna (traditional antenna) with defected ground structure (DGS), a filtering antenna is formed. Compared to the traditional antenna, the filtering antenna obtains the flatter gain response within the passband, good selectivity at the passband edge, and the wider bandwidth. Measured results show that the filtering antenna can operate at 2.4 GHz and has a 460-MHz bandwidth and a 2.3-dBi peak gain within the passband. Moreover, a radiation zero occurs at 3 GHz.

A Compact Filtering Antenna With Flat Gain Response Within the Passband

In this study, a novel design of circularly polarized antenna based on Koch fractal geometry is presented and experimentally investigated. Circular polarization and size reduction are achieved by placing two asymmetric Koch fractal geometries on x- and y-planes of the single-probe-feed square radiator. Further, to tune resonant frequency around the 911-MHz, four arrow-shaped slots are inserted in diagonal axes of the square radiator. It is perceived that compact size of the antenna can be achieved by increasing the overall size of the arrow-shaped slots and indentation angles of Koch fractal geometry. The antenna is fabricated on FR4 substrate with a size of $54 \times 54 \times 1.6\,\text{mm}^3$ ( $0.162 \lambda_{0}\times 0.162 \lambda_{0}\times 0.0048 \lambda_{0}$ at 900 MHz) and tested to validate the proposed design. The 3-dB axial-ratio bandwidth and impedance bandwidth of the proposed antenna design are found to be 8 MHz (907.0–915 MHz) and 37.0 MHz (891.0–928.0 MHz), respectively. The measured results confirm that the proposed design covers US radio-frequency identification (RFID) band (902–928 MHz) and can be used for RFID short-range reading applications.

Design of Koch Fractal Circularly Polarized Antenna for Handheld UHF RFID Reader Applications

A structure of a compact ultra-wideband monopole antenna has been presented. The antenna consists of a microstrip-fed rectangle radiator as well as a ground plane with a rectangle slit and an L-shaped stub. The critical factor in achieving a small size is a careful design procedure involving numerical optimisation of all geometry parameters of the antenna aiming at explicit size reduction while maintaining acceptable electrical performance. The final design exhibits dimensions of only 9.45 × 18.5 mm and a footprint of 175 mm
 2
. Experimental validation and comparisons with competitive designs are also provided.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2015.4432

Compact UWB monopole antenna for internet of things applications

A novel coplanar waveguide-fed transparent antenna for ultrawideband applications with enhanced bandwidth is presented. In this design, different techniques have been used to broaden the bandwidth. The rectangular radiator of the antenna is equipped by the staircase technique to increase the overlapped resonant frequencies. Moreover, two major and minor symmetrical rectangular stubs are mounted on top of the quarter-circle slot ground by using a dual axis to significantly increase the bandwidth between 3.15 and 32 GHz for VSWR <; 2. AghT-8 transparent thin film is used in the design of the proposed antenna to obtain a very compact size and lightweight structure.

CPW-Fed Transparent Antenna for Extended Ultrawideband Applications

A novel coplanar waveguide (CPW)-fed compact ultrawideband (UWB) microstrip antenna is proposed for ultrawideband applications. The proposed antenna posseses a method to minimize the monopole antenna by loading of inverted L-strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with overall size of $25 \times 25 \times 1.6\ {\hbox{mm}}^3$ achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6-13.04 GHz (10.44 GHz).

A CPW-Fed Compact UWB Microstrip Antenna

A microstrip-fed wideband antenna with defected ground structure is proposed for WLAN and WiMAX band applications. The proposed antenna uses an annular ring radiator which is encircled by a rhombus shaped strip and the defected ground plane. The ground plane is cambered shaped and cut out by rectangular-shape slot and thus forms a defected ground structure. The parametric study is carried out to study the effects of varying dimensions on the antenna performance. To validate simulation results of the design a prototype is fabricated on the commercially available FR4 material. Measured results shows a good agreement with the simulated results. It is found that the antenna shows wide bandwidth of 86.71% (2.4–6.0 GHz) which covers entire WLAN and WiMAX bands. Thus the proposed antenna is well suitable for WLAN/WiMAX applications.

A wideband antenna with defected ground plane for WLAN/WiMAX applications

A novel single-feed arrowhead-shape slotted microstrip antenna for circular polarization (CP) is proposed. To achieve CP radiation and antenna size reduction, an arrowhead-shaped slot is embedded in the first quadrant along the diagonal axes of a square patch. Thus, the structure is asymmetric, and good-quality CP performance can be achieved by adjusting the size of the slot. The antenna is simulated and practically fabricated. Measured results confirm the validity of this design and show a good agreement with simulated results. The antenna generates CP radiation at 911 MHz with an overall size of 87 × 87 × 4.572 mm 3. The fabricated antenna shows an impedance bandwidth of 35.0 MHz (888.0-923.0 MHz) with 8.0 MHz (908.0-916.0 MHz) 3-dB axial-ratio bandwidth (ARBW).

Circularly Polarized Arrowhead-Shape Slotted Microstrip Antenna

A novel dual-band asymmetric slit with defected ground structure microstrip antenna for circular polarization (CP) operation is proposed. In which, the lower resonant band is excited by cutting asymmetric slit on square microstrip antenna, and a new concept of defected ground with truncated corners structure is used to excite upper resonant band. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. Antenna is compact in size and shows a good quality of polarization at both resonant bands. Antenna shows the bandwidth of 7.5% (2.30–2.48 GHz) and 2.94% (3.80–3.9 GHz) at lower and upper bands, respectively. The antenna also shows 40 and 11 MHz, 3-dB axial ratio bandwidth at lower and upper bands, respectively. The return loss and radiation pattern of the proposed antenna remain consistent for both resonant bands. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1198–1201, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27547

A novel dual‐band asymmetric slit with defected ground structure microstrip antenna for Circular Polarization operation

A novel CPW-fed hexagonal-shape monopole-like ultrawideband (UWB) antenna is proposed for UWB applications. The proposed antenna posses a method to minimize the monopole antenna by using a hexagonal shape over the conventional monopole patch antenna to lower the height of the antenna. The ground is vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with very compact overall size of 25 × 23 × 1.6 mm3 achieves good impedance matching, stable radiation patterns, and constant group delay over an operating bandwidth of 2.71–12.61 GHz (9.9 GHz). © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2582–2587, 2013

Binod Kr Kanaujia

Papers

A CPW-Fed Compact UWB Microstrip Antenna

A wideband antenna with defected ground plane for WLAN/WiMAX applications

Circularly Polarized Arrowhead-Shape Slotted Microstrip Antenna

A novel dual‐band asymmetric slit with defected ground structure microstrip antenna for Circular Polarization operation

A CPW‐fed hexagonal‐shape monopole‐like UWB antenna