Dual-layer Patch Research Articles

Knowledge-Based Neural Network for Thinned Array Modeling With Active Element Patterns

To speed up the process for designing finite thinned arrays, an efficient artificial neural network (ANN) model considering mutual coupling effects is proposed in this communication. Array elements are divided into three categories based on the active element pattern (AEP) technique, and subarrays are constructed to extract the AEP of each category of elements as training samples. The proposed model including parallel ANN branches takes into account the mutual coupling between elements and avoids the calculation of the radiation pattern of the entire array. To improve modeling performance, furthermore, a prior knowledge input technique is used to reduce the complexity of the input–output relationship that an ANN has to learn. The existing knowledge is obtained by back propagation (BP) ANN modeling. Once the knowledge-based model is well trained, it is repeatedly called by the genetic algorithm (GA) for the optimal solution as a substitute for the full-wave simulation. Numerical examples of a U-shaped slot thinned array and a dual-layer patch thinned array are utilized to verify the efficiency of the proposed scheme.

A novel two-layer, intradural and extradural patch graft approach to treating dural defects and tears: illustrative case.

BACKGROUNDDural tears must be quickly addressed to avoid the development of positional headaches and pseudomeningoceles, among other complications. However, sizeable areas of friable or absent dura create unique challenges when attempting to achieve a watertight seal. We have developed a two-layer subdural and epidural fibrous patch technique to treat expansive or challenging dural tears as a result of our experience treating spinal fluid leaks.OBSERVATIONSThe authors present the treatment of a large necrotic (5 × 1.5 cm) dural defect refractory to initial attempts at standard primary repair with dural patch grafting and requiring a revision with a dual-layer patch to manage persistent cerebrospinal fluid leakage.LESSONSThe use of a two-layer (subdural and epidural) patch is both a safe and effective dural repair technique for creating a watertight seal in challenging large areas in which the dura may be damaged, scarred, or absent. We also propose that this technique may be able to be used for smaller challenging tears, as well as potentially for repairs of large blood vessels or other fluid-filled structures in the body.

Dual-layer everted saphenous vein patch for pediatric femoral artery repair following ECMO decannulation

Decannulation from pediatric veno-arterial extracorporeal membrane oxygenation (VA-ECMO) involves the removal of large arterial perfusion cannulas from relatively small lower extremity arteries. While these challenging repairs are frequently performed by general pediatric surgeons, there is little standardization with regard to vascular techniques within the pediatric surgery training paradigm, resulting in variability in the repair of these arteriotomies and potential future consequences for lower extremity perfusion and growth. Herein we present a technique for repair of large common femoral arteriotomies following removal of ECMO perfusion cannulas utilizing a dual-layer patch of ipsilateral saphenous vein harvested via the arterial cutdown incision. This vein segment is everted to maximize endothelial surface area of the patch and dual layered to provide additional support against aneurysmal degeneration. The described technique is an effective repair of arteriotomy following VA-ECMO decannulation, which minimizes vascular complications and is an accessible technique to those without advanced vascular surgical training. Level of EvidenceLevel IV; operative technique description with small case series.

A novel conformal DBF receiving phased array on satellite application

A novel digital beam forming conformal phased array employed for satellite communication is introduced. A hemispherical shaped structure is designed for arranging the antenna elements, and the dual-layer patch antenna element is adopted to achieve broadband circular polarization. Depending on the directions of incoming waves, the elements/RF channels projected over the surface of the hemispherical array are selectively operating for beam forming. The beam coverage with gain variation within 1.5 dB are achieved in the space from -75° to 75°. The RF-digital integrative technique is proposed to achieve multiple beams at the same time, so the tracking of several satellites using one set of antenna is achieved. Finally, a prototype is manufactured and tested to verify the beam forming capability of the conformal hemispherical array. The proposed antenna is helpful for extending the beam forming architecture in satellite communication, and is instructive for engineering research.

A Low-Profile Dual-Layer Patch Antenna with a Circular Polarizer Consisting of Dual Semicircular Resonators

In this paper, a circular polarizer comprising dual semicircular split-rings (DSSRs) is presented. By placing it above an elliptical radiator that radiates linearly polarized (LP) waves, dual-layer patch antennas capable of radiating right-hand (RH) or left-hand (LH) circularly polarized (CP) waves are achieved in terms of the different offset direction of the bottom splits of the DSSRs. Because of both the capacitive coupling to the radiator and the degenerate modes existing in the excited DSSRs, the DSSRs collaboratively result in a circularly polarized radiation, successfully converting incident LP waves into CP ones. Simulated results show that the impedance, axial ratio (AR), and gain frequency response of both proposed CP antennas are identical, with a simulated 3-dB AR bandwidth of 72 MHz covering 2.402–2.474 GHz and a gain enhanced by 3.9 dB. The proposed antennas were fabricated and measured, revealing an operational bandwidth of 65 MHz (2.345–2.41 GHz) and a peak gain up to 9 dBi. Moreover, a low profile of 0.063λ0 is maintained. The proposed CP antennas could be as a candidate for wireless target detection applications in terms of their identical frequency response property.

Wideband Patch Antenna Using Multiple Parasitic Patches and Its Array Application With Mutual Coupling Reduction

A dual-layer patch antenna using multiple parasitic patches for the bandwidth enhancement is presented. Two additional resonances can be obtained with the help of the parasitic patches of the antenna. Consequently, a wide impedance bandwidth of 17% ( $\vert \text{S}_{\mathbf {11}}\vert dB) can be achieved. Then, without the increase of the antenna array footprint, the combinations of two decoupling techniques (i.e., metalized via walls and short-circuited stepped-impedance structures as the neutralized networks) are adopted for mutual coupling reduction when the antenna element is extended to $2\times1$ , $2\times2$ , and even $4\times4$ array applications. To validate the design idea, a $2\times2$ antenna array is fabricated and tested, whose measured isolations between any two feeding ports are better than 28 dB within the frequency range of 3–4 GHz. The measured peak gain fluctuates from 12.6 to 13.6 dBi within the 10-dB impedance band of 3.35–3.95 GHz, and the cross-polarization levels in both the E- and H-planes are lower than −38 dB at the boresight direction.

A WIDEBAND FREQUENCY SELECTIVE SURFACE REFLECTOR FOR 4G/X-BAND/KU-BAND

A Frequency Selective Surface (FSS) reflector with wideband response for 4G/X-band/Ku-band is proposed. The wideband FSS reflector consists of cascaded dual-layer patch FSS which is etched on separ ...

Wideband dual-layer patch antenna fed by a modified L-strip

A wideband patch antenna is proposed. By using the dual-layer patch configuration and modified L-strip feed technique, the impedance bandwidth of the patch antenna for VSWR<1.2 is broadened to 22% with respect to 900 MHz, which is superior to the other available patch antennas. In addition, by means of the modified L-shaped strip, the high cross polarization levels of the proposed antenna are suppressed effectively. Simulation results are compared with the measurements, and a good agreement is obtained. The measurements show that the antenna has a low cross-polarization level (<-20dB) and an acceptable gain level (~9dBi) across the operating bandwidth. At last, a parametric study and a design guideline of the proposed antenna are also presented to facilitate the design and optimization processes for engineers.