Effect of Mutual Coupling within Elements of Array-Units Beyond Full Wavelength Element Spacing for Linear Arrays

In application of Array-units instead of primary radiating elements in Linear Arrays, mutual coupling within the elements of the Array-units were ignored. Since the element spacing within the Array-Units are much more smaller than the inter-element spacing of the main array, mutual coupling within the Array-units is of major concern. The major attraction of the concept of Linear Array of Array-units, is the ability to shape the Linear Array element's radiating pattern to any desired form. However, mutual coupling within the primary elements of the Array-unit, will modify its final output radiating pattern. The present work employs Array-units of two dipole elements to study the effect of mutual coupling within the elements of the Array-unit on the Array Pattern of Linear arrays beyond full wavelength element spacing. The attraction for this system is the application of pattern multiplication principle and the simplicity of Linear Array analysis. Instead, the concept of array-unit as elements of linear array, introduces non-uniform spacing as spacing within the array-unit elements are different from the spacing within the elements of the linear array. In addition, it provides the possibility of introducing phase shift between the array-unit and the linear array direction. This is possible since the phase shift within the elements of array-unit can be different from the elements of the linear array. We will investigate and quantify the effects of mutual coupling within the array-unit on grating lobe suppression, array beamwidth, and side-lobe levels.