U-shaped Patch Research Articles

Tunable terahertz metamaterials based on electrically controlled piezoelectric actuators

A new concept of tunable terahertz metamaterial with electrically controlled characteristics is suggested. Two versions of creating tunable metamaterials using piezoelectric cantilevers as controllable elements are designed. Configurations of tunable metamaterials designed as planar metal-dielectric structures of arrays of U-shaped resonators and square metal patches with piezoelectric actuators are proposed.

A Wideband Monopole Antenna Using Parasitic Elements

A novel wide band U-shaped monopole antenna with two C-shaped parasitic elements, suitable for WLAN and WiMAX operations, is pretented experimentally and numerically. The wide-band characteristics are obtained by using the U-shaped patch and the two C-shaped parasitic elements along the CPW signal strip. And the simulated wide antenna yields a 10dB impedance bandwidth range from 2.51GHz to 6.0GHz. The antenna is as small as 20×30×1.6mm3. The investigated antennas have been successfully designed, simulated, showing good impedance bandwidth and omni-directional radiation patterns.

Planar compact inverted U-shaped patch antenna with high-gain operation for Wi-Fi access point

A planar compact inverted U-shaped patch antenna with high-gain operation for Wi-Fi system has been proposed and investigated.It provides relatively wider impedance bandwidth of 162 MHz covering the 2.45 GHz band (2400–2484 MHz). The proposed planar compact patch antenna also provides the directional radiation patterns with maximum peak antenna gain and efficiency of 7.5 dBi and 87% across the operating band, respectively. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:567–569, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25788

A Compact Filtering Microstrip Antenna With Quasi-Elliptic Broadside Antenna Gain Response

Design, fabrication, and measurement of a compact filtering microstrip antenna with second-order quasi-elliptic broadside antenna gain response are presented. A U-shape radiating patch is excited by a T-shape resonator through an inset coupling structure. The U-shape patch acts as a radiator as well as the last stage of the filter, and the inset coupling structure can be treated as the admittance inverter in filter design. The design procedure follows the circuit approach-synthesis of bandpass filters. The broadside gain of the filtering antenna has two poles in passband and two broadside radiation nulls (zeros) at the band edges for improving selectivity. Compared to the conventional inset-fed microstrip antenna, with a little extra circuit area, the proposed filtering antenna has a flatter passband response, better frequency skirt selectivity, and almost twice wider bandwidth. The measurement result shows a good agreement with the simulations.

Compact U-array MIMO antenna designs using IWO algorithm

In this article, design of a novel compact four-channel multiple input multiple output (MIMO) antenna is described. The antenna is composed of four U-shaped patch elements and operates at 5.8 GHz. The single U-shaped patch antenna, to operate at this frequency, is designed using the Invasive Weed optimization algorithm. This algorithm is then applied to design two and four-channel MIMO antenna arrays for high degree of isolation. To measure the array performance under MIMO signaling conditions, a multiport metric is used to characterize the compact array rather than the scattering matrix characterization. The measurement and simulation results of reflection coefficient, mutual coupling, and radiation pattern are presented and discussed. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.

Arterial Switch Operation With a Single Coronary Artery: The Autograft Concept

A single coronary artery, especially if associated with anterior looping, remains a risk factor when performing an arterial switch operation for transposition of the great arteries. In such a situation, to avoid the risk of overstretching, we used a modification of the aortic autograft concept to transfer the single coronary artery, resulting in a tension-free relocation.

Totally Laparoscopic Combined Freehand Ileocystoplasty and Malone Procedures

Cecostomy performed together with open enterocystoplasty can allow continent bowel evacuation in children with neurogenic dysfunction. We present the first report on a combined approach to fecal and urinary incontinence in children with myelomeningocele that was performed exclusively by freehand laparoscopy. We treated six dysrhaphic patients for total urinary and fecal incontinence by laparoscopy. Through five ports, a selected segment of ileum was isolated with cautery. A single-layer intestinal anastomosis, fashioning of the U-shaped patch, and anastomosis to the opened bladder dome were all done by endocorporeal freehand suturing. The tip of the appendix was simply brought to the skin via a trocar site. The procedures took 5 to 8.5 hours. Patients remained hospitalized for 5 to 16 days (median 5 days). At 13 to 16 months' follow-up, all patients remain continent of urine, and nearly perfect fecal continence has resulted on antegrade enema. Leak from the ileal anastomosis in one patient resolved rapidly with conservative management. One short retrocecal appendix later developed stenosis and was replaced by a tubed cecal flap. Apart from its cosmetic advantage, this procedure is notable for addressing all evacuation problems at one session. Our suturing time seems reasonable compared with open sutured precedents. Use of a gastrointestinal stapling device for anastomosis would have significantly increased the cost while not necessarily guaranteeing against complications. We present this laparoscopic combination as an effective alternative to its open counterpart.

Design of multiple U‐shaped slot microstrip patch antenna for 5‐GHz band WLANs

AbstractIn this study, a multiple U‐shaped slot microstrip patch antenna for application in the 5‐GHz band is designed and fabricated. To obtain sufficient bandwidth in the operating band, foam is inserted between the substrate and ground plane, a coaxial probe source is used, and the position of the probe shift is adjusted from the center to the left. The measured result (5.02–5.955 GHz) of the fabricated antenna satisfies the conditions of VSWR < 2.0 in 5‐GHz band (5.15–5.35 GHz, 5.47–5.725 GHz, and 5.725–5.825 GHz): gain of 3.88–9.28 dBi and broad radiation pattern. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 486–488, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20510

Design of multiple U‐shaped slot microstrip patch antenna in Hiper‐LAN band

AbstractIn this paper, a multiple U‐shaped slot antenna is described, designed, fabricated, and measured for Hiper‐LAN. The design is based on a U‐shaped slot and two inverted U‐shaped slots. To obtain sufficient bandwidth, a foam layer is inserted between the ground plane and substrate. A measured impedance bandwidth approximately 400 MHz or about 7.6% (VSWR ≤ 1.5) referenced to the center frequency is obtained. The gain is measured at 5.43–4.45 dBi. The experimental far‐field patterns are shown to be broad across the pass band, with the 3‐dB beam width in azimuth and elevation at 58.17° and 66.57°, respectively. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 368–370, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11384

An inverted u-shaped patch antenna for compact operation

By using a novel inverted U-shaped radiating patch in place of the conventional planar patch, compact operation of air-substrate patch antennas is presented. The inverted U-shaped patch is formed by adding two downward rims at the two radiating edges of a planar rectangular or square patch. And owing to the added rims, the excited patch's surface current paths are lengthened, which effectively lowers the antenna's resonant frequency and results in large antenna size reduction (>50%). The proposed compact design has been successfully applied to air-substrate patch antennas fed by an aperture-coupled feed. In addition to large size reduction obtained, the proposed antenna with an air-substrate thickness about 5% the wavelength of the center operating frequency can have an impedance bandwidth (10-dB return loss) greater than 9%, a peak antenna gain of about 6.4 dBi, and good broadside radiation patterns with cross-polarization levels better than 20 dB in principal planes.

A quarter-wave U-shaped patch antenna with two unequal arms for wideband and dual-frequency operation

A wideband and dual-frequency quarter-wave U-shaped patch antenna with two unequal arms on FR4 substrate is presented. The U-shaped patch antenna is fed electromagnetically by another coaxially-fed patch on the same layer, which operates at a higher frequency band. In this paper, we first proposed a new technique to obtain two closely staggered resonant modes to achieve a wide impedance bandwidth using two unequal arms of the U-shaped patch for the lower band. For the substrate thickness = 5, 7.5 and 11 mm, the measured bandwidths of the antennas operating around at 900 MHz are 7%, 10%, and 18%, respectively. Then, we modify the coaxially-fed patch so that both bands are wide in bandwidth. The resulting antenna operating at 900 and 1800-MHz bands with the substrate thickness 11 mm has a measured impedance bandwidth of 13.3% and 20 respectively. This thickness corresponds to 0.033 free-space wavelength at 900 MHz. The far-field radiation patterns are stable in the two operating bands. The proposed antenna is simple in structure compared with the regular stacked or coplanar parasitic patch antennas. It is highly suitable for indoor mobile communications.

Pancreaticojejunostomy with invagination of spatulated pancreatic stump into a jejunal pouch

Background: Pancreaticoenteric anastomosis after pancreatic resection is of major concern as anastomotic leak continues to be common. There is no unanimity for the preferred technique and overall incidence of pancreatic leak is reported to be 2% to 14%. Methods: A new safe method of anastomosing pancreatic stump to a jejunal pouch is described. A 15-cm length of the jejunal end is detubularized and reconfigurated into a U-shaped patch. The pancreatic stump is mobilized for about 3 cm and the duct is spatulated posteriorly and anastomosed to a cut in convex margins of the patch. This is converted into a pouch invaginating the spatulated pancreaticojejunal anastomosis. Results: Eleven cases of periampullary malignancy after pancreaticoduodenectomy have been operated on with no pancreatic leak. Conclusions: Even a bulky pancreas can be invaginated into the pouch. The resulting anastomosis is completely intraluminal. Spatulated mucosa to mucosa anastomosis should reduce the chances of late stenosis.

Evolving experience with continent urinary diversion using the Indiana pouch.

The Indiana continent urinary reservoir procedure for urinary diversion was performed in 46 patients. After the first 8 cases several modifications were made to the Indiana pouch. These modifications include complete detubularization of the colonic segment, construction of the pouch augmented with a U-shaped patch of ileum and, more recently, the use of stapled plication. The mean postoperative follow-up period was 46 mo (range 4.5-74.1 mo). There was 1 perioperative death and this case was excluded from the follow-up study. Late complications related to the urinary reservoir occurred in 12 (26.7%) of the 45 patients. Stone formation was observed in 5 patients. Out of 45 patients, 42 achieved complete urinary continence while 2 suffered mild nocturnal incontinence and 1 had significant leakage. Three had unilateral hydronephrosis due to ureteroanastomotic stricture. Reservoirgraphy demonstrated no reflux into the upper urinary tract in all of the follow-up cases. Loopography of the efferent limb showed that a staple-plicated ileum functions better than a suture-plicated one in terms of reliability of the continence mechanism and ease of catheterization. The Indiana pouch should be considered for any patient requiring cutaneous urinary diversion because it is technically easy to perform and it has a low revision and high continence rate.

Sinus venosus type of atrial septal defect with partial anomalous pulmonary venous return

This report describes our method of repairing the sinus venosus type of atrial septal defects. The superior vena cava is compartmentatlized by means of a single double-armed suture. Caval catheters are used as temporary internal shunts, and a vertical U-shaped patch is incorporated into the atriotomy suture line. The experiences with 27 cases are presented.