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Owing to abundant spectrum resources, millimeter wave (mmwave) communication promises to provide Gbps data rates, which, however, may be restricted by large path-loss. Thus, antenna arrays are commonly used along with beam alignment (BA) as an important step to achieve the array gain. Efficient BA relies on the beam training codebook design. In this paper, we propose a new hierarchical codebook to...
A methodology for expedited simulation-based design of microstrip linear antenna arrays is presented. Our approach utilizes response-corrected array factor model as well as surrogate-based optimization of the array elements for simultaneous control of both the radiation and reflection responses of the array. The technique is demonstrated using a 16-element array of slot-fed microstrip patch antennas.
A new search algorithm for phased array radar which is based on radio frequency stealth is proposed in this paper. When there is no indication information, parameters including the dwelling time and the average power are optimized by sequential quadratic programming (SQP), and a minimum energy cost model is set up by using Grey Relational Grade (GRG). The surveillance area is divided into several...
RF stealth technology is one of the most significant ways to guarantee the radar's survivability. The RF stealth algorithm of MIMO radar in searching mode is obtained to improve the RF stealth performance. This algorithm is based on the RF stealth optimization model which sets the number of subarrays, average power, dwell time and search frame period as controllable parameters, the interception factor...
We used the interior-point optimization algorithm to perform static RF shimming of three overlapped dual-row magnetic resonance imaging (MRI) arrays. These had radiative elements of axial lengths 80, 100, and 110 mm respectively. We evaluated the robustness of the static shims thus obtained. The head-and-torso model was located at different axial positions, including one where the distance between...
We present a numerical investigation of the RF fields generated inside a human head by single and dual-row loop arrays. For a uniform circular polarization (CP) mode excitation, a dual-row array has no advantage for human brain excitation. Significant improvement of B1+ homogeneity with a simultaneous increase of coverage in the axial direction can be obtained by using a dual-row array together with...
We present numerical investigation for a set of loop array geometry/load configurations obtained by RF circuit and frequency domain 3-D EM co-simulation. This is a very powerful and fast method for array coil investigation, since one multi-port 3-D EM simulation, which can be calculated in a reasonable time, is sufficient for obtaining the array transmit properties with several tuning/feeding/decoupling...
We present a numerical investigation of the near radiofrequency fields generated by a set of multi-row multichannel MRI loop array at 300 and 400 MHz using RF circuit and frequency domain 3-D EM co-simulation. Significant improvement of B1+ homogeneity with a simultaneous increase of coverage in the axial direction can be obtained by using a multi-row array together with a static volume RF shim. At...
The simulation presented hereafter show that active AFSR may be a good alternative to direct radiating arrays receive antennas on the secondary coverages considered. It offers the possibility to have a lower number of controls, while fulfilling the specification, even in case of failure.
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