Ground Strip Research Articles

Compact coplanar waveguide-fed monopole antenna with a folded ground strip for 5-GHz wireless applications

The design of a compact coplanar waveguide-fed monopole antenna partially surrounded and coupled by a folded ground strip is presented. By properly tuning the gap between the monopole antenna and the ground strip, it is able to operate in the 5-GHz band for wireless application. From the experimental results, a resonant mode excited at around 5.5 GHz is observed with 10-dB bandwidth measured from 4.88 to 6.3 GHz. Good radiation patterns with near omnidirectional pattern in the azimuth plane are also observed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26330

Discussion of ‘The Highland Boundary Fault and the Highland Border Complex’ by B. J. Bluck, Scottish Journal of Geology , 46 , 113–124

P.W. Geoff Tanner writes: In this paper, Bluck has failed to provide a balanced and accurate assessment of the progress that has been made over many years to find a robust, modern geological interpretation of the Highland Border. This is no trivial matter, for the rocks exposed in this narrow strip of ground retain many of the clues to understanding the causes, and subsequent development, of the Caledonian c . 470 Ma Grampian Event, and the role played by the Highland Boundary Fault in continental-scale plate-tectonic reconstructions (Strachan & Dewey 2003; Tanner 2008). The Highland Boundary Fault is considered by Bluck to define the contact between the Southern Highland Group (Dalradian) and the ‘Highland Border Complex’. However, at outcrop this boundary is variously seen as a fault (North Esk), a lithological transition (Keltie Water), or the sole of an ophiolite (Innellan), and there is no evidence of a major, through-going fault between Arran and Stonehaven, as conventionally depicted (Tanner 2008). Conflicting interpretations of Highland Border geology have generated two diametrically opposed models, essentially summarized below, variations notwithstanding, as A & B. In model A (Curry et al . 1984; Bluck 1985), the rocks between uncontested Southern Highland Group (Dalradian) to the NW and the unconformable Old Red Sandstone to the south, were assigned to the ‘Highland Border Complex’ (HBC). The latter was once ‘considerably separated’ from the Dalradian block, and acquired a northerly dip and younging direction before the two were amalgamated, following the Grampian Event, by movement on the Highland Boundary Fault. In model B (Tanner & Sutherland 2007), the HBC was divided into two parts: the Trossachs Group (now the youngest part of the Dalradian Supergroup), and an overlying, allochthonous unit, the Highland Border Ophiolite (HBO). The main differences between the two models are: all of the …

Novel Microstrip Periodic Structure and Its Application to Microwave Filter Design

This letter proposes a new type of microstrip slow-wave structure. The proposed structure has the signal strips and the inserted ground strips periodically loaded in the internal part of the conventional microstrip line. The proposed microstrip line has not only the same outline contour but also a lower phase velocity compared to the conventional one, especially for the thick substrate. In addition, the slow-wave factor and the characteristic impedance are easily varied by adjusting the structural parameters. A third-order Chebyshev filter with a passband ripple of 0.05 dB and a bandwidth of 10% was designed and fabricated using the proposed microstrip line. The simulated and measured results agree well with each other.

Highly Miniaturized On-Chip 180° Hybrid Employing Periodic Ground Strip Structure for Application to Silicon RFIC

A highly miniaturized on-chip 180° hybrid employing periodic ground strip structure (PGSS) was realized on a silicon radio frequency integrated circuit. The PGSS was placed at the interface between SiO2 film and silicon substrate, and it was electrically connected to top-side ground planes through the contacts. Owing to the short wavelength characteristic of the transmission line employing the PGSS, the on-chip 180° hybrid was highly miniaturized. Concretely, the on-chip 180° hybrid exhibited good radio frequency performances from 37 GHz to 55 GHz, and it was 0.325 mm2, which is 19.3% of a conventional 180° hybrid. The miniaturization technique proposed in this work can be also used in other fields including compound semiconducting devices, such as high electron mobility transistors, diamond field effect transistors, and light emitting diodes.

Broadband CPW-Fed Circularly Polarized Square Slot Antenna With Three Inverted-L-Shape Grounded Strips

A new form CPW-fed broadband circularly polarized square slot antenna (CPSSA) with three inverted-L-shape grounded strips around the corners of the slot is proposed and fabricated. In comparison to the previous CPSSA structures, the axial-ratio (AR) bandwidth of the antenna is increased, which is two times wider than the previous proposed design. By embedding the L-shape strip to the ground plane and using the vertical stub to the feed line, very good axial-ratio bandwidth is obtained. The measured impedance bandwidth and AR of the realized CPSS antenna with optimized parameters is from 2 to 7 GHz (3.5:1, 110%) for VSWR ≤ 2 and 2-5 GHz (2.5:1; 85%) for AR ≤ 3 dB respectively. Throughout this letter, the improvement process of the AR and S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> properties is completely presented and discussed.

A CPW-Fed Broadband Circularly Polarized Regular-Hexagonal Slot Antenna With L-Shape Monopole

A regular-hexagonal structure of wide-slot antenna for broadband circular polarization (CP) based on coplanar waveguide (CPW) feed is presented. By protruding into the slot an L-shape monopole patch, and featuring two inverted-L grounded strips around two opposite sides of the slot, wide impedance bandwidth and wide axial-ratio (AR) bandwidth can be obtained simultaneously. By notching a rectangle in the ground conductor near the feed line, the antenna performance is further improved. The proposed antenna can provide an impedance bandwidth ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> <; -10 dB) of 86% and a 3-dB AR bandwidth of 50%, respectively.

Compact circularly-polarised slot antenna for UWB applications

A simple compact broadband circularly-polarised square slot antenna (CPSSA) fed by a coplanar waveguide is presented. A CP bandwidth larger than 38.2% can be attained simply by embedding two inverted-L grounded strips around two opposite corners whereas the impedance bandwidth can be greatly improved through the tuning stubs. The designed CPSSA antenna is 25×25×0.8 mm3, which is 56% smaller than previous CPSSA structures operating over the frequency band between 2.9 and 11.2 GHz for VSWR<2.

Wideband waveguide to microstrip probe transition with LTCC technology

A novel broadband waveguide to microstrip probe transition based on low-temperature co-fired ceramic (LTCC) technology is presented and experimentally verified for the first time. To improve the bandwidth and impedance matching, a multilayer step-shape matching structure beneath the probe is buried in the LTCC substrate, which is implemented by installing conducting ground strips on different substrate layers connected by the staggered via side walls. A waveguide to microstrip probe transition is fabricated to verify the design with compact size. Measured results show good agreement with simulated results.

Parameter Extraction and Optimal Design of Spiral Inductor Using Evolution Strategy and Sensitivity

For precise electromagnetic (EM) field simulation of the spiral inductor, electric conductivity of the inductor substrate is determined by evolution strategy to match the Taiwan Semiconductor Manufacturing Company (TSMC) process. Based on this parameter, patterned ground shield (PGS) of an on-chip spiral inductor is designed using deterministic optimization method. The design parameters are lengths and widths of ground strips and widths of slots. For sensitivity analysis, approximate adjoint variable method is used. Significant increase in <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> -factor is observed in final design while reduction of inductance is minimal. Spiral inductor with optimized PGS is used in input matching circuit of 2.45-GHz low noise amplifier (LNA), which shows improved noise figure characteristics compared to non-PGS case.

A Slow-Wave Microstrip Line With a High-Q and a High Dielectric Constant for Millimeter-Wave CMOS Application

A slow-wave microstrip line (S-MSL) designed in 0.13 μm CMOS technology with a high-Q and a high dielectric constant is proposed in this letter. Grounded metal strips with two metal layers are located in zigzags in order to prevent penetration of the electric field into the silicon substrate. These metal strips equate the potentials of the ground planes and thus eliminate the parasitic coupled slotline mode without requiring additional air-bridges. Also, locating the ground planes in the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layers instead of on the top metal reduces the size of the gap between the signal line and ground planes relative to the conventional structure. This allows relaxation of the metal density rule of the CMOS processes. Measured results for the proposed S-MSL show that the relative permittivity is 25 and the quality factor ranges from 18 to 37.7 between 20 and 60 GHz. The wavelength of the measured 253 μm S-MSL is 4/λ at 60 GHz.

Broadband CPW-Fed Circularly Polarized Square Slot Antenna With Lightening-Shaped Feedline and Inverted-L Grounded Strips

A novel design is described for a circularly polarized square slot antenna (CPSSA). Circular polarization (CP) operations can be attained using a lightening-shaped feedline protruded from the signal line of the feeding coplanar waveguide (CPW). The CP bandwidth can be significantly enhanced by implanting a pair of inverted-L grounded strips into the slot and adjusting the dimensions of the lightening-shaped feedline, whereas the impedance bandwidth can be greatly enlarged through tuning embedded vertical and horizontal stubs. The designed antenna was measured to exhibit a CP bandwidth of as high as 48.8%.

Small Printed Monopole Antenna for Wireless USB Applications

This paper presents a small printed monopole antenna of size 10 × 29 × 0.8 mm3. The proposed antenna consists of a rectangular radiating patch on one side and a rectangular ground metal with an inverted L-shaped ground strip on the other side. With this simple structure, the proposed antenna provides an impedance bandwidth ranging from 3.05 to 5.82 GHz, which covers the wireless USB (WUSB) operation band of 3.1–4.85 GHz. Good radiation performance and low gain variation are also obtained using the proposed antenna. Equipping with the advantages of dimension and performance, the proposed antenna appears as a promising candidate for USB dongle application. The detail of the proposed antenna design and experimental results obtained thereafter are presented and discussed in this article.

A Superconducting Microstrip Ultra-Wideband (UWB) Bandpass Filter at VHF-Band

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A compact superconducting ultra-wideband filter with a passband from 125 to 260 MHz is demonstrated. The filter consists of ten shunt short-circuited stubs separated by connecting lines. The short-circuited stubs are grounded via a grounding strip that is attached to the box wall by a number of SiAl bonding wires. The filter is realized on two 2 in <formula formulatype="inline"> <tex Notation="TeX">${\rm YBCO/LaAlO}_{3}$</tex></formula> substrates, which are connected by two bonding wires. The measured results demonstrate an insertion loss of less than 0.08 dB and a return loss of better than 21 dB without tuning. Furthermore, the experimental results of the filter are in good agreement with the simulated ones. </para>

Compact CPW‐fed tri‐band monopole antenna for PCS and 2.4/5GHz WLAN applications

AbstractA compact tri‐band monopole antenna with coplanar waveguide (CPW)‐fed structure is presented for applications in PCS and 2.4/5 GHz WLAN systems. By using a spiral strip and a meandered strip closed to an inverted‐L ground strip, the proposed antenna with a compact size of 30 × 30 × 1.6 mm3 including the ground can not only meet the impedance bandwidth requirements for PCS band (1.85–1.99 GHz) and WLAN bands (2.4–2.484 GHz and 5.15–5.825 GHz), but also can provides good radiation characteristics and antenna gains for the operating bands, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2495–2498, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24593

Fabrication-Tolerant Microstrip Quarter-Wave Stepped-Impedance Resonator Filter

The etching error causes serious frequency drift of a microstrip stepped-impedance resonator (SIR). This paper proposes a novel microstrip quarter-wave SIR structure, which is insensitive to fabrication tolerances. Inserting several ground strips in the low-impedance section of the resonator keeps the impedance ratio almost constant in spite of inaccurate fabrication. As an additional benefit, the resonator size would be miniaturized because the characteristic impedance of the microstrip line in the low-impedance section is mainly controlled by the signal strips and the inserted ground strips in a coplanar manner. The concepts and characteristics of this modified resonator structure are discussed in detail. The filters constructed by the conventional microstrip SIR were also designed and fabricated at the same frequency band to compare with the proposed ones. Measured results show that each proposed filter has compact size, wide stopband, and high tolerance to fabrication errors. Two four-pole cross-coupled filters were designed and fabricated to demonstrate the feasibility.

Currents in buried grounding strips connected to communication tower legs during lightning strikes

During a lightning strike to communication tower stroke currents are shared by the tower and by the shields of the cables along the tower. The currents in the tower proceed towards the grounding system (possibly a combination of counterpoises or ring conductors or ground rods or grounding grids) connected to tower legs' foundation. In this paper, lightning strike to communication tower on mount Gaisberg in Austria is considered and measured currents at the tower top and those shared by an instrumented grounding strip connected to one of the tower leg's are presented. The measured currents at different locations on the 70-m long ground strip are compared with the predictions of a frequency dependant lossy transmission line (TL) model and reasonably good agreement was found. From this validation it is claimed that the TL models are appropriate for lightning transient analysis of grounding systems.

Role of snow in the hydrology of a High Arctic riparian wetland

Riparian wetlands are narrow strips of saturated and vegetated ground forming critical links between dry ground and waterways. The hydrology of a riparian wetland situated within a polar oasis landscape near Eastwind Lake, Ellesmere Island, Nunavut (80°80′N, 85°35′W) was investigated in 2006 using a combination of fieldwork and modelling. Supplemental information from 2005 was also employed. This study showed that deep snow in the nearby stream channel does not promote a period of extended over-bank flooding but instead initially serves as a dam blocking most streamwater from entering and flooding the wetland. It was not until the snow dam melts and disintegrates in response to favourable weather conditions that the wetland becomes flooded and fully recharged. This was a delay of three weeks from the previous year. For the remainder of the 2006 growing season, contributions of meltwater from late-lying snow beds located within and adjacent to the stream channel and near the headwaters were essential for maintaining saturated conditions in the wetland.

Effects of conventional and grass-feeding systems on the nutrient composition of beef1

The objectives of this study were to determine the nutrient composition of grass-fed beef in the United States for inclusion in the USDA National Nutrient Database for Standard Reference, and to compare the fatty acid composition of grass-fed and conventionally fed (control) beef. Ground beef (GB) and strip steaks (SS) were collected on 3 separate occasions from 15 grass-fed beef producers that represented 13 different states, whereas control beef samples were collected from 3 regions (Ohio, South Dakota, and Texas) of the United States on 3 separate occasions. Concentrations of minerals, choline, vitamin B(12), and thiamine were determined for grass-fed beef samples. Grass-fed GB samples had less Mg, P, and K (P < 0.05), and more Na, Zn, and vitamin B(12) (P < 0.05) than SS samples. Fat color, marbling, and pH were assessed for grass-fed and control SS. Subjective evaluation of the SS indicated that grass-fed beef had fat that was more yellow in color than control beef. Percentages of total fat, total cholesterol, and fatty acids along with trans fatty acids and CLA were determined for grass-fed and control SS and GB. Grass-fed SS had less total fat than control SS (P = 0.001), but both grass-fed and control SS were considered lean, because their total fat content was 4.3% or less. For both GB and SS, grass-fed beef had significantly less (P = 0.001 and P = 0.023, respectively) content of MUFA and a greater content of SFA, n-3 fatty acids, CLA, and trans-vaccenic acid than did the control samples. Concentrations of PUFA, trans fatty acids, n-6 fatty acids, and cholesterol did not differ between grass-fed and control ground beef. Trans-vaccenic acid (trans-11 18:1) made up the greatest concentration of the total trans fats in grass-fed beef, whereas CLA accounted for approximately 15% of the total trans fats. Although the fatty acid composition of grass-fed and conventionally fed beef was different, conclusions on the possible effects of these differences on human health cannot be made without further investigation.

Circularly Polarized Square Slot Antenna With a Pair of Inverted-L Grounded Strips

This paper presents a new wideband circularly polarized square slot antenna (CPSSA) with a coplanar waveguide (CPW) feed. The proposed antenna features two inverted-L grounded strips around two opposite corners of the slot and a widened tuning stub protruded into the slot from the signal strip of the CPW. Broadside circular-polarization (CP) radiation can be easily obtained using a simple design procedure. For the optimized antenna prototype, the measured bandwidth with an axial ratio (AR) of less than 3 dB is larger than 25% and the measured VSWR les 2 impedance bandwidth is as large as 52%.

On the modeling of sound propagation over multi-impedance discontinuities using a semiempirical diffraction formulation

Several approximate extensions of the semi-empirical De Jong model [De Jong et al., J. Sound and Vib. 86, 23–46 (1983)] are considered for the prediction of sound propagation over multiple impedance discontinuities. A limitation in the original formulation of the De Jong model is highlighted and a modified form that overcomes this limitation is derived based on reciprocity. This leads to the development of a model for multiple impedance discontinuities that can be used for the investigation of sound-wave propagation above a mixed, striped soft ground that is created by either porous absorbent strips, embedded grooves, or wells with different depths. The accuracy of the model is validated against the boundary element method. It is then used to evaluate the importance of the imaginary part of the admittance of the ground strips on sound attenuation along welled surface. It is shown that the attenuation performance of a surface with multiple impedance discontinuities is high when the imaginary part of the average admittance is large and negative (with an −iωt convention), but the magnitudes of the attenuation peaks are also substantially affected by diffraction from the impedance discontinuities.