This study investigated the effects of a peer feedback tool and a reflection tool on social and cognitive performance during computer supported collaborative learning (CSCL). A CSCL-environment was augmented with a peer feedback tool (Radar) and a reflection tool (Reflector) in order to make group members aware of both their individual and their group behavior. Radar visualizes how group member...

In this work, a wideband airborne reflector-based ground penetrating radar (GPR) is designed and proposed. The proposed GPR consists of 15 discrete panels, each panel supported by single multi-rotor unmanned aerial vehicle (UAV). A lightweight, Vivaldi antenna was developed as the feed structure. operates within frequency range 100-500 MHz has bandwidth 387 MHz. will possess penetration depth 2...

Various all-dielectric electromagnetic crystal (EMXT) based THz components, including filter/reflector, waveguide, antenna, and transition structure to planar circuits are proposed and simulated. Several of them have been fabricated via a THz rapid prototyping technique, and the measurements show very good consistency with the simulations. Potential integrated THz micro-systems could be constru...

Antenna with a Reflector Tadashi Takano 1, , Takehiro Imura , and Midori Okumura 3 1 JAXA, The Institute of Space and Astronautical Science 3-1-1 Yoshino-dai, Sagamihara 229-8510Japan, [email protected] 2 Electronics Engineering Department, University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Japan 3 Electronics Engineering Department, Tokai University 1117 Kita-kaname, Hiratsuka 259-1...

One form of Impulse Radiating Antenna (IRA) combines the technologies of the Balanced Transmission-line Wave (BTW) sensor with TEM-fed paraboloidal reflector antennas. The behavior of the IRA was calculated using a combination of the Method of Moments, using the NEC Code, and Geometrical Optics. The results of NEC compare favorably to both high and low frequency asymptotes. The frequency domain...

The Eleven antenna has constant beam width, constant phase center location, and low spillover over a decade bandwidth. Therefore, it can feed a reflector for high aperture efficiency (also called feed efficiency). It is equally important that the feed efficiency and its subefficiencies not be degraded significantly by installing the feed in a cryostat. The MIT Haystack Observatory, with guidanc...

In this research, the novel concept of a resonance-based reflector (RBR) was proposed, and a ring-shaped RBR was utilized to design a unidirectional antenna with low-profile and broadband characteristics. Research found the ring operates as two half-wavelength (λ/2) resonators. Then, the resonance effect transforms the reflection phase of the ring RBR, and achieves a reflection phase of 0° < ϕ ...

Printed reflectarrays combine certain advantages of reflector antennas and phased arrays. One major hurdle in the designing of reflectarrays is the compensation of phase difference between various elements. This paper presents reviews of various techniques for phase compensation, like using variable sizes of the patch, adding stubs of variable lengths and use of variable size slots on the groun...

-For high frequency and VHF point-to-point communication, the V-antenna reflector and the V-shaped antenna array are useful because of high gain, low cost, easy manoeuvering and simple geometry. The theoretical analysis for the radiation characteristics of a plane, twodimensional, V-shaped antenna array have been presented taking into account the mutual inductive coupling effect among the radia...

Abstract—This paper describes a wideband double-dipole Yagi-Uda antenna fed by a microstrip-slot coplanar stripline transition. The conventional dipole driver of a Yagi-Uda antenna is replaced by two parallel dipoles with different lengths to achieve multi-resonances, and a small, tapered ground plane is used to allow flexibility in the placement of a pair of reflectors for effective reflection...