A beam-shape loss formula for a statistically located target

1968 ◽  
Vol 56 (3) ◽  
pp. 360-361 ◽  
Author(s):  
J.R. Pace
Keyword(s):  
Beam Shape ◽  
Shape Loss ◽  
Loss Formula

scholarly journals Beam-shape loss for multiple-beam digital array radars

2019 ◽  
Vol 2019 (19) ◽  
pp. 5593-5596
Author(s):  
Yuan Yao ◽  
Guangxin Wu
Keyword(s):  
Beam Shape ◽  
Multiple Beam ◽  
Shape Loss

scholarly journals MIMO Radar Array Antenna with Transmit-Receive Subarrays

2020 ◽  
Vol 13 (6) ◽  
pp. 189-198
Author(s):  
Syahfrizal Tahcfulloh ◽  
Keyword(s):  
Performance Improvement ◽  
Phased Array ◽  
Mimo Radar ◽  
Interference Effects ◽  
Sidelobe Level ◽  
Beam Shape ◽  
Waveform Diversity ◽  
Half Power ◽  
Simulation And Evaluation ◽  
Shape Loss

Unlike the PMIMO radar, the transmit-receive (Tx-Rx) subarrays MIMO (TRSM) radar uses overlaping subarrays in Tx and Rx array so that it simultaneously combines the main advantage of the phased array radar (PA) i.e., high directional coherent gain, and the main advantage of the MIMO radar i.e., high waveform diversity gain. This paper has derived the radar performance formula such that Tx-Rx gain and SINR. The approach aims to overcome the beam shape loss, increase the transmit-receive gain, minimize the maximum peak sidelobe levels, narrow the half power beamwidth, increase directivity, and increase signal-to-noise-plus-interference ratio (SINR). This radar's performance is compared to the PMIMO radar in various methods such as equal subarrays, unequal subarrays, and optimum partitioning, the PA radar, and the MIMO radar. The numerical simulation and evaluation results show that the proposed radar has several advantages such as lowest the peak sidelobe level, narrow the half power beamwidth, and high directivity, so it is very robust against interference effects. When compared to the OPPM radar, as representative of the best-performing radars, this radar has an average performance improvement of MPSLL, directivity, and HPBW which are 21.5 dB, 2 dB, and 0.45 deg, respectively.

Study on MEMS Thermal Microactuators with Pedestal-Type Beam Shape and Au Electroplating

2013 ◽  
Vol 133 (4) ◽  
pp. 100-104 ◽  
Author(s):  
Kuniyuki Ochiai ◽  
Takahiro Osada ◽  
Hideo Muro
Keyword(s):  
Beam Shape

scholarly journals Optimized beam shaping assembly for a 2.1-MeV proton-accelerator-based neutron source for boron neutron capture therapy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pablo Torres-Sánchez ◽  
Ignacio Porras ◽  
Nataliya Ramos-Chernenko ◽  
Fernando Arias de Saavedra ◽  
Javier Praena
Keyword(s):  
Boron Neutron Capture Therapy ◽  
Neutron Capture ◽  
Beam Shaping ◽  
Proton Accelerator ◽  
Neutron Capture Therapy ◽  
Beam Shape ◽  
New Era ◽  
Boron Neutron Capture ◽  
Optimal Beam ◽  
Beam Shaping Assembly

AbstractBoron Neutron Capture Therapy (BNCT) is facing a new era where different projects based on accelerators instead of reactors are under development. The new facilities can be placed at hospitals and will increase the number of clinical trials. The therapeutic effect of BNCT can be improved if a optimized epithermal neutron spectrum is obtained, for which the beam shape assembly is a key ingredient. In this paper we propose an optimal beam shaping assembly suited for an affordable low energy accelerator. The beam obtained with the device proposed accomplishes all the IAEA recommendations for proton energies between 2.0 and 2.1 MeV. In addition, there is an overall improvement of the figures of merit with respect to BNCT facilities and previous proposals of new accelerator-based facilities.

ORIENTATING MANIPULATION OF CYLINDRICAL PARTICLES WITH OPTICAL TWEEZERS

2008 ◽  
Vol 17 (04) ◽  
pp. 387-394 ◽  
Author(s):  
XIUDONG SUN ◽  
XUECONG LI ◽  
JIANLONG ZHANG
Keyword(s):  
Escherichia Coli ◽  
Carbon Nanotubes ◽  
Laser Beam ◽  
Optical Tweezers ◽  
Optical Trap ◽  
Polarization Direction ◽  
Beam Shape ◽  
E Coli ◽  
Potential Applications ◽  
Cylindrical Particles

Orientating manipulations of cylindrical particles were performed by optical tweezers. Vertical and horizontal manipulations of Escherichia coli (E. coli) were carried out by changing the trapping depth and the focused laser beam shape. It was found that carbon nanotubes bundles (CNTBs) could be rotated in the linear polarized optical trap until it orientated its long axis along the linear polarization direction of the laser beam. However, E.coli could not be orientated in this way. Corresponding mechanisms were discussed based on the anisomeric electric characters of CNTBs. These orientation technologies of cylindrical objects with optical trap have potential applications in assembling nano-electric devices.

Circular aerial arrays for radio astronomy

1961 ◽  
Vol 262 (1308) ◽  
pp. 84-99 ◽  
Keyword(s):  
Radio Astronomy ◽  
Side Lobe ◽  
Correction Function ◽  
Side Lobe Level ◽  
Circular Aperture ◽  
Circular Array ◽  
Polar Diagram ◽  
Beam Shape ◽  
Correction Process ◽  
Dimensional Distribution

A new type of aerial array suitable for high-resolution observations in radio astronomy is explored theoretically. The array consists of a large number of aerial elements equally Spaced round a circle and electrically connected in phase. The power polar diagram is calculated for the cases when the circle is effectively continuous, and when the separation between adjacent elements is appreciable. In both cases the side-lobe level is rather high for most radio astronomical purposes, for which a process of aerial correction is required. The function of the correction process is to readjust the relative weights of the different spatial Fourier components to provide a suitable beam shape. A general method of aerial correction is developed in which the two dimensional distribution of brightness directly recorded by scanning is cross-correlated with a circularly symmetrical correction function , a process which is desirably performed in the instrument itself. The correction process allows one to convert the polar diagram of a ring-shaped array into (for example) the diagram of a uniform circular aperture of the same radius. The principal theoretical characteristics of the circular array are briefly compared with those of the Mills cross. It is found that while the process of aerial correction or ‘tapering’ is technically more straightforward in the cross, the circular array has the following advantages: (1) the length of transmission line (and hence attenuation) between each element and receiver is halved; (2) the number of elements required to gain the same information is reduced, approximately in the ratio 4: π ; (3) the beam possesses circular or elliptical symmetry; and (4) the system offers the possibility of direct phase and amplitude calibration with the aid of a transmitter situated on a central tower.

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