scholarly journals Effective Aperture of Antenna Directivity Bounding and its Radiation Aperture

2018 ◽  
Vol 3 (5) ◽  
pp. 1
Author(s):  
Javeed Ahammed ◽  
R. P. Singh ◽  
M. Satya Sai Ram
Keyword(s):  
Effective Aperture ◽  
Antenna Directivity

scholarly journals An overview of the Planck mission

2010 ◽  
Vol 6 (S274) ◽  
pp. 268-273
Author(s):  
N. Mandolesi ◽  
C. Burigana ◽  
A. Gruppuso ◽  
P. Procopio ◽  
S. Ricciardi
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Analysis Pipeline ◽  
Sky Surveys ◽  
Flight Data ◽  
Compact Source ◽  
Effective Aperture ◽  
Successful Launch ◽  
Scientific Results ◽  
Data Analysis Pipeline

AbstractThis paper provides an overview of the ESA Planck mission and its scientific promises. Planck is equipped with a 1.5–m effective aperture telescope with two actively-cooled instruments observing the sky in nine frequency channels from 30 GHz to 857 GHz: the Low Frequency Instrument (LFI) operating at 20 K with pseudo-correlation radiometers, and the High Frequency Instrument (HFI) with bolometers operating at 100 mK. After the successful launch in May 2009, Planck has already mapped the sky twice (at the time of writing this review) with the expected behavior and it is planned to complete at least two further all-sky surveys. The first scientific results, consisting of an Early Release Compact Source Catalog (ERCSC) and in about twenty papers on instrument performance in flight, data analysis pipeline, and main astrophysical results, will be released on January 2011. The first publications of the main cosmological implications are expected in 2012.

Adaptive Aperture Aided Antenna Design for SISO-MIMO Systems using Fuzzy C-Mean Clustering

2015 ◽  
Vol 4 (3) ◽  
pp. 33-47
Author(s):  
Parismita A Kashyap ◽  
Kandarpa Kumar Sarma
Keyword(s):  
Mimo Systems ◽  
High Reliability ◽  
Multiple Input Multiple Output ◽  
Multipath Fading ◽  
Time Instant ◽  
Antenna Structure ◽  
Single Input Single Output ◽  
Single Time ◽  
Effective Aperture ◽  
Transmitting Antenna

One of the most relevant themes of wireless communication is to achieve better spectral efficiency and provide high reliability while providing rich-content data services despite the existence of several serious challenges. A few of them are multipath fading, multi-user interference, co-channel interference (CCI), inter symbol interference (ISI) etc to name a few. Several techniques have already been developed and deployed to eliminate the fading effects. One of the less explored techniques which have been adopted and discussed in this chapter is based on the structure of the transmitting antenna. The physical dimension of the antenna is varied as per the fading condition by adopting a dynamic process which adjusts the structure to provide the best quality of service (QoS). Two types of antenna set-ups are considered - Single Input-Single Output (SISO) and Multiple Input-Multiple Output (MIMO). The transmitting antenna in this system adaptively updates its aperture to improve the system performance and at the same time optimizes the driving power of the antenna as per requirement. The system changes the effective aperture of the transmitting antenna in high data rate, time varying Rayleigh channels to adapt to a previously set Bit error Rate (BER). However, in a real time environment the BER keeps on changing based on the channel condition. It is difficult to attain a fixed value of BER and hence even more difficult to model the antenna structure for a single time instant. As a result there exist a number of effective aperture dimensions for various BER in a single time instant. Out of the various values, two specific limits of the effective aperture of the transmitting antenna needs to be decided. Fuzzy C-Mean (FCM) Clustering method being one of the most popular and efficient clustering technique is used to set two limits of the aperture within which a particular threshold of the BER is obtained at one particular instant of time. The results derived show the effectiveness of the entire system.

scholarly journals Direction Finding of Coherent Sources Using a MIMO Array of Triaxial Velocity Sensors

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Yuwei Song ◽  
Guoping Hu ◽  
Guimei Zheng
Keyword(s):  
Cross Correlation ◽  
Correlation Coefficients ◽  
Direction Finding ◽  
Covariance Matrices ◽  
Smoothing Algorithm ◽  
Arbitrary Configuration ◽  
Effective Aperture ◽  
Vector Sensors ◽  
Coherent Sources ◽  
Simulation Results

In the received side, triaxial velocity sensors of MIMO array are used to solve the problem of coherent source direction-finding in this paper. A new velocity field smoothing algorithm is presented to decorrelate coherent sources. The identically oriented velocity sensors of whole array are divided into three subarrays. Then, the covariance matrices of the three subarrays are smoothed to restore the rank of source covariance matrix (SCM). Lastly, the cross-correlation coefficients of the SCM after smoothing processing are calculated to analyze the performance of decorrelation. The proposed decorrelation algorithm (1) does not need the information of locations of velocity vector sensors; (2) is suitable for arbitrary configuration array; and (3) has no loss of array effective aperture. Simulation results prove the effectiveness of the proposed algorithm.

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