Traditional Patch Research Articles

A novel reconfigurable microstrip patch antenna with frequency and polarization diversities

A single-fed microstrip patch antenna with frequency and polarization diversities is presented in this article. The proposed antenna consists of a square patch fed along its diagonal line with four parasitic stubs added around its four sides connected by four PIN diodes. The center of edges of two stubs far away from the feed point is connected to ground via another two diodes, while those of the other two stubs are connected to ground via capacitors. By turning these diodes on and off, the antenna has five different operating states. It is capable of switching between right hand circular polarization and left hand circular polarization in the frequency band (2.422–2.448 GHz), and also can operate at two frequency bands with horizontal and vertical polarization or vertical and horizontal polarization, respectively. In addition, it can radiate 45° linear polarization as a traditional patch antenna fed along its diagonal line. The measured results verify the reconfigurable characteristics of the antenna and demonstrate that it is a good candidate for wireless communication applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1494–1500, 2015

Miniaturized bent slotted patch antenna over a reactive impedance surface substrate

A reactive impedance surface (RIS) based miniaturized bent slotted patch antenna is proposed and investigated for S-band applications around 2.39 GHz. Bent slots in the patch reduce the patch antenna size by increasing current path on the patch. Further a RIS substrate with cross-shaped patch elements printed over a grounded dielectric is optimized and investigated for antenna miniaturization. The proposed bent slotted patch antenna over RIS substrate is 38.75% miniaturized with respect to traditional patch antenna at a fixed operating frequency. The proposed antenna reveals an overall volume of 0.280λ0 × 0.280λ0 × 0.036λ0on a low-cost FR4 substrate at 2.39 GHz for S-band applications. The proposed antenna is fabricated and measured for its return loss. The measured results are in good agreement with simulated one.

Planar Patch Clamp System Capable of Recording Mechanosensitive Activity of Ion Channels

Response to mechanical stimuli, which includes proper development of biological tissues and organs, is essential to the cell. Mechanosensitive ion channels are the basic elements among mechanosensing molecules and complexes. Although the traditional patch clamp technique using glass micropipettes is still widely used for electrophysiology, it is difficult to control the mechanical stimulus to ion channels in this system. Here we developed a novel patch clamp system with a planar stretchable electrode to record mechanosensitive responses of ion channels. Planar electrodes of 100 μm thickness were fabricated using silicone resin. Next, we prepared HEK293 cells transfected with the stretch-activated KCa (SAKCA) channel, which is mechanosensitive, for planar patch clamp recordings. Using our planar patch clamp system, a gigaohm seal was achieved with a maximum seal resistance of 10 GΩ. The success rate of gigaohm seal formation was 37%. Then we recorded single channel currents with a slope conductance of 285.4 pS, which is parallel to the known SAKCA current. Using scanning electron microscope, we confirmed elongation of the aperture by 37.7% when 50% stretch was applied to the planar electrode. It is expected that a controllable and sufficient stretch stimulus can be applied to the cellular membrane using our newly developed planar patch clamp system.

Low-RCS, High-Gain, and Wideband Mushroom Antenna

In this letter, a high-gain and wideband mushroom antenna with wideband low radar cross section (RCS) is presented. The mushroom structure is resonant at the antenna operating frequency, and the in-band RCS can be reduced significantly. The bandstop frequency selective surface (FSS) designed at the operating frequency of the antenna is used to replace the metallic ground of the antenna so that the out-of-band RCS of the proposed antenna can be reduced while maintaining the high gain. Furthermore, square metallic patches printed periodically below the cells of the FSS are utilized to add a new zero-degree reflection phase in the desired frequency range to enhance the bandwidth of RCS reduction. As a result, a wideband RCS reduction can be achieved both in and out of antenna operating frequency band. The results show that the RCS of the proposed antenna is dramatically reduced over a wide frequency range, compared to the traditional patch antenna.

A Miniaturized Patch Antenna by Using a CSRR Loading Plane

This paper presents a design methodology for the implementation of a miniaturized square patch antenna and its circuit model for 5.15 GHz ISM band. The miniaturization is achieved by employing concentric complementary split ring resonator (CSRR) structures in between the patch and ground plane. The results are compared with the traditional square patch antenna in terms of area, bandwidth, and efficiency. The area is reduced with a ratio of 1/4 with respect to the traditional patch. The miniaturized square patch antenna has an efficiency, bandwidth, and reflection coefficient of 78%, 0.4%, and −16 dB, respectively. The measurement and circuit modeling results show a good agreement with the full-wave electromagnetic simulations.

Impact of the coupling effect and the configuration on a compact rectenna array

This paper proposes an experimental study of the coupling effect of a rectenna array. The rectifying antenna consists of a compact and efficient rectifying circuit in a series topology, coupled with a small metamaterial-inspired antenna. The measurements are investigated in the X plane on the rectenna array's behavior, with series and parallel DC- combining configuration of two and three spaced rectennas from 3 cm to 10 cm. This study shows that the maximum efficiency is reached for the series configuration, with a resistive load of 10 kQ. The optimal distance is not significant for series or parallel configuration. Then, a comparison between a rectenna array with non-optimal mutual coupling and a more traditional patch rectenna is performed. Finally, a practical application is tested to demonstrate the effectiveness of such small rectenna array.

Broadband Unit-Cell Design for Highly Anisotropic Impedance Surfaces

A unit-cell design for highly anisotropic impedance surfaces is simulated and experimentally demonstrated. The unit cell consists of a grounded dielectric substrate with a metal patch and plated metal via. The design has a ring of metal removed from the patch so that the resonant effect of the via is reduced. The reduced resonance prevents backward-wave modes which are difficult to excite experimentally. On grounded dielectric substrates, the transverse-magnetic mode is fundamental and the transverse-electric (TE) mode is bound above a cutoff frequency. It is shown that highly anisotropic surface impedance can only be achieved below the TE cutoff frequency. The proposed unit cell is constructed using printed-circuit-board fabrication technology, and the result is a unit cell that obtains highly anisotropic impedance over a broader frequency range than traditional patch or mushroom unit cells.

A Low-RCS and High-Gain Partially Reflecting Surface Antenna

We propose a novel design to reduce the radar cross section (RCS) and enhance the gain of a patch antenna by using partially reflecting surface (PRS). The PRS consists of two layers of metallic patterns on both sides of a dielectric slab. The metallic pattern on the bottom side is utilized to construct Fabry-Perot resonance cavity with ground plane of a patch antenna, while it is designed to absorb most of the incident wave on the top side. The PRS can enable the patch antenna to simultaneously achieve high gain and low RCS. Measurement results show that the antenna gain is enhanced by about 6.5 dB at 11.5 GHz, and its RCS is dramatically reduced in a broad frequency range from 6 to 14 GHz, compared with the traditional patch antenna without the PRS.

Bandwidth and Gain Enhancement of Patch Antenna with Stacked Parasitic Strips Based on LTCC Technology

A compact patch antenna with stacked parasitic strips (SPSs) based on low temperature cofired ceramic (LTCC) technology is presented. By adding three pairs of SPSs above the traditional patch antenna, multiple resonant modes are excited to broaden the bandwidth. At the same time, the SPSs act as directors to guide the antenna radiation toward broadside direction to enhance the gain. The measured results show that the prototype antenna achieves an impedance bandwidth of 16% forS11<-10 dB (32.1–37.9 GHz) and a maximum gain of about 8 dBi at 35 GHz. Furthermore, the radiation patterns and gain are relatively stable within the operating bandwidth. The total volume of the antenna is only 8 × 8 × 1.1 mm3.

Dynamic clamp in cardiac and neuronal systems using RTXI.

The injection of computer-simulated conductances through the dynamic clamp technique has allowed researchers to probe the intercellular and intracellular dynamics of cardiac and neuronal systems with great precision. By coupling computational models to biological systems, dynamic clamp has become a proven tool in electrophysiology with many applications, such as generating hybrid networks in neurons or simulating channelopathies in cardiomyocytes. While its applications are broad, the approach is straightforward: synthesizing traditional patch clamp, computational modeling, and closed-loop feedback control to simulate a cellular conductance. Here, we present two example applications: artificial blocking of the inward rectifier potassium current in a cardiomyocyte and coupling of a biological neuron to a virtual neuron through a virtual synapse. The design and implementation of the necessary software to administer these dynamic clamp experiments can be difficult. In this chapter, we provide an overview of designing and implementing a dynamic clamp experiment using the Real-Time eXperiment Interface (RTXI), an open-source software system tailored for real-time biological experiments. We present two ways to achieve this using RTXI's modular format, through the creation of a custom user-made module and through existing modules found in RTXI's online library.

A Continuously Tunable Miniaturized Patch Antenna

A tunable miniaturized patch antenna is introduced. Miniaturization is achieved by placing a layer of complementary split-ring resonators horizontally between the radiating patch and the ground plane. Tuning is implemented by detouring the current flow on the additional layer through a lumped capacitor or varactor, thereby shifting the resonant frequency. The result is a miniaturized antenna that is compact, easily fabricated, and tunable across a useful band. A measured prototype demonstrates a tuning range of 2-2.45 GHz while maintaining an area no larger than 1/9 of a traditional patch antenna.

Regeneration result of excavator-mounted rototiller in direct seeding of Scots pine on forestry-drained peatland

The need to regenerate peatland forests is expected to increase in the near future in Finland due to harvest of large amounts of peatlands drained during the 1950s and 1960s. In anticipation of this, a new type of excavator-mounted rototiller for soil scarification in peatlands has been developed in Finland to improve the moisture conditions of the seedbed by mixing the ground vegetation, raw humus layer, and peat. The regeneration result of the new rototiller was compared with traditional patch scarification (i.e. scalping) in direct seeding of Scots pine in three forestry-drained peatland sites in eastern Finland. After two growing seasons, rototilling offered no advantage over scalping in terms of the number of established seedlings, probability of empty patches, or seedling height. Seedling establishment was on average higher on scalping (10%) than on rototilling (8%). The main problem in rototilling may have been the loose and porous structure of the seedbed resulting in drought and frost damages.

Laparoscopic repair of perforated peptic ulcer: Patch versus simple closure

BackgroundLaparoscopic correction of perforated peptic ulcer (PPU) has become an accepted way of management. Patch omentoplasty stayed for decades the main method of repair. The goal of the present study was to evaluate whether laparoscopic simple repair of PPU is as safe as patch omentoplasty. MethodsSince June 2005, 179 consecutive patients of PPU were treated by laparoscopic repair at our centers. We conducted a retrospective chart review in December 2012. Group I (patch group) included patients who were treated with standard patch omentoplasty. Group II (non-patch group) included patients who received simple repair without patch. ResultsFrom June 2007 to Dec. 2012, 179 consecutive patients of PPU who were treated by laparoscopic repair at our centers were enrolled in this multi-center retrospective study. 108 patients belong to patch group. While 71 patients were treated with laparoscopic simple repair. Operative time was significantly shorter in group II (non patch) (p = 0.01). No patient was converted to laparotomy. There was no difference in age, gender, ASA score, surgical risk (Boey's) score, and incidence of co-morbidities. Both groups were comparable in terms of hospital stay, time to resume oral intake, postoperative complications and surgical outcomes. ConclusionLaparoscopic simple repair of PPU is a safe procedure compared with the traditional patch omentoplasty in presence of certain selection criteria.

Miniaturized Circularly Polarized Microstrip RFID Antenna Using Fractal Metamaterial

A novel miniaturized circularly polarized (CP) microstrip antenna that can handle UHF band (920&#x2013;925&#x2009;MHz, corresponding to the assigned band for RFID in China) has been designed, fabricated, and measured in this paper. The miniaturization of antenna is achieved by a special cross-shaped fractal metamaterial structure that is inserted between the patch and ground plane. The measured results show that the antenna possesses an impedance bandwidth of 8.7&#x25; with VSWR <svg style="vertical-align:-0.96915pt;width:14.825px;" id="M1" height="11.225" version="1.1" viewBox="0 0 14.825 11.225" width="14.825" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,9.95)"><path id="x2A7D" d="M531 103l-474 214v50l474 215v-56l-416 -184l416 -183v-56zM531 -71l-474 214v56l474 -214v-56z" /></g> </svg> 1.5&#x2009;:&#x2009;1 and 3-dB axial bandwidth of 3.8&#x25;. Furthermore, the proposed antenna has 10.2&#x25; size reduction compared with traditional patch antenna. The tested results are in good agreement with that of the simulations.

Individual‐based approach to the detection of disturbance history through spatial scales in a natural beech‐dominated forest

AbstractQuestionWe connected tree‐census and dendrochronological research data (74.2 ha) in order to answer the following questions: How do we apply an individual‐based approach, which allows us to abandon the traditional patch model, in the research of disturbance history through spatial scales? What is the disturbance history of the natural forest? How do we understand the influence of the Kyrill storm, which affected the reserve on 18 January 2007? How does the disturbance history in dendrochronological records correspond to real disturbances?LocationŽofínský Prales (48 °40′ N, 14 °42′ E, 735–830 m a.s.l., granite, Czech Republic)MethodsRepeated tree‐censuses (&gt;20 000 trees) were carried out in 1975, 1997 and 2008. These surveys served as the basis of dendrochronological research, during which 3 020 trees were sampled. A boundary line (BL) approach and geostatistical techniques were used to detect disturbance intensity and its spatial pattern.ResultsThe mean disturbance rate was 11.0% canopy loss per decade (maximum 33.7%) in the core zone. Bordering forests were directly affected by humans after 1800. A maximum of nine disturbance events were recorded per tree, but there were also 3% of non‐suppressed trees without records of disturbance events. The Kyrill storm represented a singular event in the forest history from the point of view of its exceptional spatial pattern (ranges up to 320.0 m), but not from the perspective of disturbance intensity. The relationship between disturbance intensity (y) and the range of spatial autocorrelation (x) can be explained by the equation y = 10.6863 + 0.0783*x (R2 = 0.546, P = 0.009). The spatial variability of releases ≥50% of BL corresponds to real disturbance events, while the insertion of weak releases led to the overestimation of range. The frequency of releases was affected by a decrease in air pollution at the beginning of the 1990s.ConclusionsEffects of small‐scale disturbances predominate in forest dynamics. Disturbance intensity was often not directly in accordance with the range of spatial autocorrelation. The ecological role of disturbance is therefore biased if disturbance intensity is used as the sole criterion. The results suggest the importance of historical and geographical contingency in ecosystem development.

Miniaturization of Patch Antennas Using a Metamaterial-Inspired Technique

A new design methodology for producing highly miniaturized patch antennas is introduced. The methodology uses complementary split-ring resonators placed horizontally between the patch and the ground plane. By optimizing the geometry of the split rings, sub-wavelength resonance of the patch antenna can be achieved with a good impedance match and radiation characteristics comparable to those of a traditional patch antenna on a finite ground plane. Construction of the optimized antenna is straightforward, requiring only the sandwiching of two etched circuit boards. High levels of miniaturization are demonstrated through simulations and experiments, with reductions of a factor of more than four in transverse dimension achieved for a circular patch resonant at 2.45 GHz. Although miniaturization is accompanied by a decrease in antenna radiation efficiency and a loss of fractional bandwidth, antenna performance remains acceptable even for a 1/16 reduction in patch area.

An Omnidirectional Wrappable Compact Patch Antenna for Wireless Endoscope Applications

An inductively loaded compact patch antenna for a radiation frequency of 433 MHz is designed taking into consideration a human-body model and fabricated on a flexible liquid crystalline polymer (LCP) substrate, which is subsequently wrapped into a cylindrical shape to achieve a monopole-like omnidirectional radiation pattern for wireless endoscope applications. The wrapped patch antenna has a stretched length of 31 mm (0.07λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ), and its cylindrical form has a diameter of 10 mm and a width of 18.5 mm, whose dimensions are designed to be comparable to those of a commercially available capsule endoscope. Compared to a traditional patch antenna with the same radiation frequency, an 86% length reduction is achieved. Omnidirectionality is desired to increase the space coverage in communication between the randomly moving capsule inside and the receiver outside the body. The enclosed cylindrical cavity, surrounded by the ground plane of the patch, provides an electromagnetic interference (EMI) protected room that is useful for the placement of other electronic components. Multiple inductive notches on a patch designed for antenna size reduction are described by an equivalent circuit model. Human-body phantom solution is used for antenna characterization. The antenna, located at the outermost layer, serves not only as a good radiating unit, but also as the EMI protecting, mechanically supporting, packaging layer of the endoscope system.

Dual Micropores in Glass Substrates for Ion Channel and Gap Junction Recording

Despite the commercial success of automated high-throughput patch clamp technologies, instruments on the market typically cannot match the quality of single-channel recordings obtained by traditional patch clamp experiments with glass micropipettes. In automated approaches that use suction to position a cell to a micropore, the inner surface of the pore can be contaminated with proteins in solution prior to seal formation. Traditional patch clamping avoids this problem by applying a positive pressure to the micropipette prior to contacting the cell membrane, which enables significantly higher electrical seal resistances. This research aims to develop a universal platform for high-quality transport assays on glass chips that circumvents the problem of surface contamination and takes advantage of the high seal resistances and low capacitive current noise realized with glass substrates. Femtosecond laser ablation is used to fabricate a pair of micropores in close proximity to each other (distance < 5 µm) in glass, while the access channels to these pores are kept separate. This configuration makes it possible to use one pore for automated positioning of a cell by suction, while the other pore is kept clean by applying positive pressure. Once the cell is pre-positioned onto the first pore, suction may be applied to the second pore to establish a high quality seal that could be used to interrogate individual transmembrane transporter proteins and single ion channel proteins. In addition, this dual micropore configuration may enable the first automated gap junction recordings, bypassing the difficulties of manually positioning two micropipettes.

Evaluation and Measurement Method for Texture Depth of Exposed-Aggregate Cement Concrete Pavement Surface Based on Digital Imaging Technique

In order to study the surface characteristics of exposed-aggregate cement concrete pavement, the measurement mechanism of surface texture depth was analyzed by using digital image technique. Based on the principle of least square and Table curve 3D software, two-dimensional digital image of road surface was reconstructed into three-dimensional space surface and a method of evaluating and measuring pavement surface texture depth was put forward. With this method， digital image samples were calculated and the results were compared with the results of conventional measurement method. The results indicate that exposed-aggregate cement concrete pavement has excellent road characteristics; there is a good correlation between the digital image technique and the traditional sand patch method and the relative error is less than 7 percent. Thus, the digital image technique is feasible in evaluating and measuring pavement surface texture depth.

Single Center Experience With Modified Eversion Carotid Endarterectomy

Transaortic endarterectomy is a well-described technique for surgical revascularization of orificial atherosclerotic renovascular disease. Adopting this technique to carotid endarterectomy (CEA), modified eversion carotid endarterectomy (MECE), uses a traditional longitudinal arteriotomy that is confined to the bulb. This obviates the need for patch closure, simplifies the procedure, and permits easy conversion to traditional patch closure carotid endarterectomy (PCEA) for technical defects. We compared the safety and efficacy of this technique with PCEA. Three vascular surgeons performed 223 CEAs between July 2004 and December 2008 at a tertiary teaching hospital. Outcomes measured included perioperative stroke rate, morbidity rate, mortality rate, and late restenosis. The incidence of moderate (60-79%) and severe (≥80%) restenosis was examined at <6 weeks, 1 year, and ≥2 years after operation. All patients included in this study underwent follow-up for >12 months. Data were analyzed with Student's t-test (p < 0.05 = significant). CEA was performed for symptomatic disease in 40.4% (90/223) of patients. One surgeon performed MECE in 73.3% (99/135) of his patients during this period; the remaining patients (n = 124) underwent traditional PCEA. Intraoperative completion duplex ultrasound was performed for all patients. In 5.1% (5/99) of the patients, MECE was converted to PCEA for residual flaps. Intraoperative carotid cross-clamping time was significantly shorter in the MECE group (29.2 minutes vs. 52.2 minutes, p < 0.05). For patients in the PCEA group, the overall mortality rate was 1.8% (4/223), and perioperative stroke rate was 1.4% (3/223). Overall morbidity was 7.2%, which was similar between the two groups. Late restenosis rate on duplex scan was 7.1% (1.0% severe stenosis), early occlusion occurred in one patient with PCEA, and the reintervention rate was 1.0% (2/196). The incidence of late restenosis was similar between the MECE and PCEA group (8.4% vs. 6.2%, p = 0.55). Mean follow-up was 26.3 months for the MECE group and 29.4 months for the PCEA group. MECE is a safer alternative to conventional endarterectomy with a restenosis rate comparable with PCEA, offers the potential advantage of shorter clamping time, and obviates the need for patch closure.