www.gusucode.com > phased 案例源码 matlab代码程序 > phased/ULAGratingLobe1Example.m

    %% Create Grating Lobe Diagram for ULA
% Plot the grating lobe diagram for a 4-element uniform
% linear array having element spacing less than one-half
% wavelength. Grating lobes are plotted in u-v coordinates.
%%
% Assume the operating frequency of the array is 3 GHz and the
% spacing between elements is 0.45 of the wavelength. All
% elements are isotropic antenna elements. Steer the array in the direction
% 45 degrees in azimuth and 0 degrees in elevation.

% Copyright 2015 The MathWorks, Inc.


c = physconst('LightSpeed');
f = 3e9;
lambda = c/f;
sIso = phased.IsotropicAntennaElement;
sULA = phased.ULA('Element',sIso,'NumElements',4,...
    'ElementSpacing',0.45*lambda);
plotGratingLobeDiagram(sULA,f,[45;0],c);

%%
% The main lobe of the array is indicated by a filled black
% circle. The grating lobes in the visible and nonvisible regions are
% indicated by empty black circles. The
% visible region is defined by the direction
% cosine limits between [-1,1] and is marked by the two vertical
% black lines. Because the array spacing is less than
% one-half wavelength, there are no grating
% lobes in the visible region of space. There are an infinite
% number of grating lobes in the nonvisible regions, but only those
% in the range [-3,3] are shown.
%%
% The grating-lobe free region, shown in green, is the range of
% directions of the main lobe for which there are no grating
% lobes in the visible region. In this case, it coincides with 
% the visible region.
%%
% The white area of the diagram indicates a region where no grating lobes are 
% possible.