V. M. Gavrilov, V. J. Smirnov
Perspectivity of application of the focused electromagnetic fields in radiotempreturelocation, remote research of environments, medicine have made an actual problem of formation of focal area with operated parameters to means of focused antenna array (FAA).
By using of specially developed program computer research of possibility of creation of the FAA, focused in a near field, with the rarefied number of radiators in flat radiating surface is carried out. Definition of a configuration of the rarefied FAA as much as possible keeping focusing properties in comparison with an initial antenna array was the purpose of researches. As the initial flat antenna array with number of radiators 11×11, located in knots of a square grid was considered. It was necessary that the diagramme of orientation coincides with the diagramme of orientation of an element of Gjujgens. Focus influence (f) and a array step (L) for the sizes of focal area was investigated: its lengths (Δz0,5) which was defined in a plane of polarization in size of displacement on a focal axis concerning a focal point at reduction of amplitude of a field on 3 dB; and its width (Δx0,5) which was defined similarly in a plane passing through a focal point of perpendicularly focal axis. As the array alternative initial, were considered rarefied FAA with a crosswise and contour arrangement of radiators in surface. From result following, that the minimal length corresponds to full filling of radiating surface: Δz0,5=2,7λ (if L=2,5λ; f=15λ), Δz0,5=7,2λ (if L=2,5λ; f=30λ). Using rarefied array lead to increasing of the focal area length, less whit crosswise surface filling: in 1,22 times (as if L=2,5λ; f=15λ, so if f=30λ), more with contour surface filling: in 2,44 times (if L=2,5λ; f=15λ), and in 1,63 times (if L=2,5λ; f=30λ). The focal area width with full filling of radiating surface: Δx0,5=0,64λ (if L=2,5λ; f=15λ), Δx0,5=1,1λ (if L=2,5λ; f=30λ) – decrease with contour surface filling: in 1,23 times (if L=2,5λ; f=15λ), or in 1,31 times (if L=2,5λ; f=30λ), and increase with crosswise surface filling: in 1,34 times (if L=2,5λ; f=15λ), or in 1,36 times (if L=2,5λ; f=30λ). Thus, the rarefied phased antenna array focused in a near field, allow at insignificant increase in the sizes of focal area (in the resulted example for a crosswise array in 1,22 times in an orthogonal plane) essentially to reduce number of radiators in radiating surface (for a crosswise array in 5,76 times) that considerably raises their economic efficiency.