This paper is a review of amateur-built high-directivity wire antennas, for wireless local area network (WLAN), operating at 2.4-GHz frequency range. Those antennas can be deployed for range extension and interference reduction, for example. Covered in this review are a biquad antenna with reflector, Yagi-Uda antenna, and helical antenna. The distinctive feature of these antennas is their ease ...

This paper introduces a novel variation of the vee dipole antenna consisting of two coplanar vee dipoles with a common feed point. It is referred to as a double-vee dipole. Radiation characteristics of the double-vee dipole antenna are investigated numerically and experimentally. It is shown that the double-vee dipole can provide significantly higher directivity and lower sidelobes and back rad...

Forward and backward terahertz emission by ionizing two-color laser pulses in gas is investigated by means of a simple semianalytical model based on Jefimenko's equations and rigorous Maxwell simulations in one and two dimensions. We find the emission in the backward direction has a much smaller spectral bandwidth than in the forward direction and explain this by interference effects. Forward t...

OBJECTIVE Arterial hemodynamics and vascular calcification are associated with increased risk for cardiovascular disease, but their inter-relations remain unclear. We sought to examine the associations of arterial stiffness, pressure pulsatility, and wave reflection with arterial calcification in individuals free of prevalent cardiovascular disease. APPROACH AND RESULTS Framingham Heart Study...

A new type of highly-directional ultrasonic range sensor is designed, fabricated, and tested in this paper. To improve directivity, the parametric acoustic array, a nonlinear effect of media between two intensive waves, is applied to an ultrasonic range sensor. Additionally, a new type of the stepped-plate transducer is applied for generating high amplitude waves consisting of two frequencies. ...

A novel design of patch antenna is presented with double U slot structure on patch with ground irregularities. As a result tri-band response is achieved with gain reaching 0.785 to 3.75dB respectively and directivity of 5.5 to 5.6dBi. Coaxial cable is mounted with patch as medium of power. The antenna has shown minimum mismatch loss with 0 to 5% with high bandwidth response of 37 to 1200MHZ. Th...

We show that the enhanced directivity phenomenon for light passing through a subwavelength aperture in a silver film with corrugations on the exit face, is due to a leaky wave that decays exponentially from the aperture. We show quantitatively that the field along the interface of the silver film is dominated by the leaky wave, and that the radiation of the leaky wave, supported by the periodic...

Side lobe and directivity of antenna array is main problem in radar and communication field. This paper describes linear antenna array radiation pattern in adaptive beam forming using genetic algorithm. Unlike Simple GA (SGA), Genetic Algorithm is an iterative stochastic optimizer that works on the population values based on the fitness value. This improves the performance of the maximum reduct...

This paper considers a dual-hop cooperative satellite-unmanned aerial vehicle (UAV) communication system including satellite (S) and group of cluster headers (CHs) which are respectively with uniformly distributed UAVs. Specifically, the CHs serve as decode-and-forward relays to forward information transmitted by S Moreover, free-space optical (FSO) radio frequency (RF) technologies adopted ove...