Simple method for pattern nulling by phase perturbation

Antenna Array Pattern Nulling by Phase Perturbations using Invasive Weed Optimization

Low side lobe levels and asymmetrical multiple nulls in specified directions need to be achieved for increasing the efficiency of antenna arrays used in communication systems. Nature inspired algorithms like Invasive Weed Optimization (IWO) algorithm may be applied for synthesis of linear antenna arrays to estimate the element phase excitations for achieving nulls in undesired directions. Sever...

The Importance of Phase in Nulling Interferometry and a Three-telescope Closure-phase Nulling Interferometer Concept

We discuss the theory of the Bracewell nulling interferometer and explicitly demonstrate that the phase of the ‘‘white light’’ null fringe is the same as the phase of the bright output from an ordinary stellar interferometer. As a consequence, a ‘‘closure phase’’ exists for a nulling interferometer with three or more telescopes. We calculate the phase offset as a function of baseline length for...

Birefringent Achromatic Phase Shifters for Nulling Interferometry and Phase Coronagraphy

Achromatic Phase Shifters are mandatory components in the field of nulling interferometry and phase coronagraphy. Indeed, in order to detect faint objects (e.g. exo-planets) around a central bright star, one must attenuate the latter by all means. To do this, the most efficient way is to “create” a destructive interference on the blinding light. This technique is called nulling and is common to...

modeling loss data by phase-type distribution

بیمه گران همیشه بابت خسارات بیمه نامه های تحت پوشش خود نگران بوده و روش هایی را جستجو می کنند که بتوانند داده های خسارات گذشته را با هدف اتخاذ یک تصمیم بهینه مدل بندی نمایند. در این پژوهش توزیع های فیزتایپ در مدل بندی داده های خسارات معرفی شده که شامل استنباط آماری مربوطه و استفاده از الگوریتم em در برآورد پارامترهای توزیع است. در پایان امکان استفاده از این توزیع در مدل بندی داده های گروه بندی ...

Linear Array Pattern Synthesis for Wide Band Sector Nulling