Radiation Pattern Of Linear Array Research Articles

Compressive Sensing for Millimeter Wave Antenna Array Diagnosis

The radiation pattern of an antenna array depends on the excitation weights and the geometry of the array. Due to wind and atmospheric conditions, outdoor millimeter wave antenna elements are subject to full or partial blockages from a plethora of particles like dirt, salt, ice, and water droplets. Handheld devices are also subject to blockages from random finger placement and/or finger prints. These blockages cause absorption and scattering to the signal incident on the array, modify the array geometry, and distort the far-field radiation pattern of the array. This paper studies the effects of blockages on the far-field radiation pattern of linear arrays and proposes several array diagnosis techniques for millimeter wave antenna arrays. The proposed techniques jointly estimate the locations of the blocked antennas and the induced attenuation and phase-shifts given knowledge of the angles of arrival/departure. Numerical results show that the proposed techniques provide satisfactory results in terms of fault detection with reduced number of measurements (diagnosis time) provided that the number of blockages is small compared to the array size.

Synthesis and Analysis of Linear Array Radiation Patterns of Tompilz Projectors

This work aimed to synthesize, from computer simulations, radiation patterns of linear arrays of acoustic projectors of the piston type (Tompilz). This paper also has the focus to analyze the behavior of these radiation patterns when varying some parameters and characteristics of the array and radiating elements. For the array, it was considered the influence of variations related to the number of elements and the distance between them. For the elements, it was analyzed the changes in the diagrams when the product between the radius of the projector's head and the acoustic wavenumber was varied. These parameters were chosen because of his notorious influence in the shape of radiation patterns. Also, it was investigated the influence of radiation on patterns of multipath and Doppler spread, as well as the efficiency of a LMS (Least Mean Square) filter applied in the received signal. These results find application in the design of linear arrays of projectors and the development of beamforming techniques.

An iterative method for array pattern synthesis

The authors propose a novel iterative method for synthesizing radiation patterns of linear arrays with arbitrary sidelobe envelopes, with nonisotropic elements, and with nonuniform spacing between elements. Various design examples are presented and compared with other methods. It is shown that the proposed iterative method converges rapidly and yields superior results over other methods.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Exact analysis of radiation patterns using the expansion of the Fourier sum

The time required to compute radiation patterns of linear arrays given in a form of a Fourier sum depends on the number of array elements. In this communication, a fast algorithm for computing Fourier sums is presented. The radiation pattern given by this sum can be replaced by an infinite series whose terms depend on the envelope of the excitation function, w(x), and its derivatives at the edges of the linear array. In cases when w(x) has a few nonzero derivatives, this infinite series can be replaced by a finite sum which can be evaluated more rapidly than the original Fourier sum, making the method especially suitable for real-time applications. The effect of critical point is also investigated. Some sample case studies are included.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Monolithic millimeter-wave IMPATT oscillator and active antenna

A single-chip millimeter-wave transmitter module in which GaAs IMPATT diodes are monolithically integrated with a microstrip resonator and a loop antenna is discussed. Devices operating at 43.3 GHz produce 27-mW CW output power with 7.2% conversion efficiency. Radiation patterns of linear arrays of such radiating elements were determined as a function of interelement spacing and number of elements. The oscillator chip was also directly coupled to and power combined in waveguides, producing an inexpensive millimeter-wave source. >