Microwave tomographic imaging technology using a bifocusing operator has been developed in order to detect the internal voids/objects inside concrete structures. The imaging system consists of several cylindrical or planar array antennas for transmitting and receiving signals, and a numerical focusing operator is applied to the external signals both in transmitting and in receiving fields. An i...

A method is presented which optimizes weights of general planar 1D and 2D symmetric full and sparse arrays. The objective is to nd a weighting of the array elements which gives the minimum sidelobe level of the array pattern in a speci ed region the stopband. The sidelobe level is controlled on a discrete set of points from this region. The method minimizes the Chebyshev norm of the sidelobe le...

The proposed wideband shorted planar inverted cone antenna (SPICA) has been described as a two element antenna array in this paper. The two element array by this antenna with proper phase of excitation and spacing between the elements provide superdirective array characteristic. This array gives peak endfire directivity from 3.502 dBi to 10.3 dBi and radiation efficiency above 98% in the operat...

In this paper, we reviewed RF MEMS research efforts in planar structures and phased arrays. For planar transceivers, we have demonstrated several RF MEMS devices in order to establish building blocks in integrated millimeterwave systems. For phased-array applications, we have demonstrated two architectures for beam forming and steering without solid-state phase shifters.

In this paper, the lensing functions and imaging abilities of a quasi-periodic nanohole array in a metal screen have been theoretically investigated and demonstrated. Such an optical binary mask with nanoholes designed in an aperiodic arrangement can function as an ultra-thin planar optical lens, imaging complex structures composed of multiple light sources at tens of wavelengths away from the ...

Recently, superresolution techniques for Direction of arrival (DOA) estimation, such as MUSIC (MUltiple SIgnal Classification) algorithm [1], have become indispensable. By the assumption of an ideal array antenna, following problems are caused in an actual measurement. Array elements often have gain and phase errors, and mutual coupling effects cannot be also ignored in general, which degrade p...

The Indian Regional Navigation Satellite System (IRNSS) has recently (May 2016) become fully-operational and has been provided with the operational name of NavIC (Navigation with Indian Constellation). It has been developed by the Indian Space Research Organization (ISRO) with the objective of offering positioning, navigation and timing (PNT) to the users in its service area. This contribution ...

Recently, much attention has been focused on beams carrying orbital angular momentum (OAM) for radio communication. Here we experimentally demonstrate a planar-spiral phase plate (planar-SPP) for generating arbitrary mixed OAM beams. This proposed planar-SPP uses the concept of transmit array antenna having a perforated substrate to control the outputting phase for generating beams carrying OAM...

We study problems in computational geometry from the viewpoint of adaptive algorithms. Adaptive algorithms have been extensively studied for the sorting problem, and in this paper we generalize the framework to geometric problems. To this end, we think of geometric problems as permutation (or rearranging) problems of arrays, and define the “presortedness” as a distance from the input array to t...

Geometry-based stochastic model (GBSM) that describes the excess delay, direction of arrival, and direction of departure of multipath has been used extensively in multiple-input and multiple-output (MIMO) channel modeling. Many two dimensional and very few three dimensional (3D) GBSMs with linear array antennas have appeared in the literature. The models lack properties of the 3D channel for du...