We present a new approach to designing V-band Bull’s eye antenna so as to produce multiple beams, which are either fixed or discretely steerable. Bull’s eye antennas comprise concentric rings around a subwavelength aperture. Beam deflection is accomplished by adjusting the effective spacing of the rings, which we explain in terms of the coupling angle to free space and surface waves. We show th...

The interaction between a modulated, intense electron beam and a single-mode rf cavity is discussed. A formalism is described which accounts for steady-state and transient beam loading, input/output waveguide coupling, and finite Q effects. A circuit equation is analyzed for shorttime behavior. Algorithms are presented for designing detuned structures to ensure longitudinal stability in relativ...

Abstract Smart antennas are examined as a promising technology in wireless communication systems. In the development of smart antenna technology, Adaptive beam-forming is most important aspect. uses various algorithms to identify signals desired direction and separate interference from undesired/unwanted direction. this paper, Proposed Beam-forming Algorithm offers better solution for reducing ...

multiple input multiple output (mimo) radars are new generation of array radars that employ orthogonal waveforms for their transmit probing signals. despite of several advantages, this strategy results in transmission of uniform power in all angle of array’s viewing field. therefore, possibility of transmit beamforming and achieving coherent processing gain will be lost. many efforts have been ...

The problem of designing an atom interferometer with optimum sensitivity to de Broglie wave phase shifts is revisited. Because van der Waals interactions affect how efficiently material gratings work as beam splitters, we find the optimum open fraction for each of the gratings in a three-grating Mach Zehnder atom interferometer depends on the van der Waals interaction strength as well as the at...

Active integrated antennas (AIA’s) provide a new paradigm for designing modern microwave and millimeter-wave architecture with desirable features such as compactness, light weight, low cost, low profile, minimum power consumption, and multiple functionality. This paper reviews recent research and development related to this emerging technology with emphasis on its applications in high-efficienc...

We have grown high quality magnetite microcrystals free from antiphase boundaries on Ru(0001) by reactive molecular beam epitaxy, conserving bulk magnetic properties below 20 nm thickness. Magnetization vector maps are obtained by X-ray spectromicroscopy and compared with micromagnetic simulations. The observed domain configurations are dictated purely by shape anisotropy, overcoming the possib...