Final answer:
Designing a Dolph-Tchebyscheff broadside array involves calculating the amplitude distribution for N=10 elements with d=0.8λ to achieve -30dB sidelobes, plotting the array pattern, and labeling FNBW and HPBW. The directivity is computed based on the array factor.
Step-by-step explanation:
To design a Dolph-Tchebyscheff broadside array with N = 10 elements and an element spacing of d = 0.8λ, having a sidelobe level of -30dB, we start by determining the necessary parameters to achieve the requested sidelobe level. This involves using specific equations and tables that relate to the Chebyshev polynomial and the array factor. After determining the amplitude distribution of the array elements, we can plot the array pattern. The pattern will show a main lobe where the directivity is maximum and sidelobes with the specified level of -30dB.
The sketch of the rectangular plot should depict the array pattern with clear indications of the First Null Beam Width (FNBW) and the Half-Power Beam Width (HPBW). These can be annotated in degrees directly on the plot. The directivity of the array is computed based on the array factor, which is a function of the number of elements, their spacing, and the amplitude distribution prescribed by the Dolph-Tchebyscheff design method.
To compute the directivity, we would typically use the formula 'Directivity (D) = 4π / solid angle subtended by the main beam', but specifics on this calculation vary based on the exact pattern achieved through the Dolph-Tchebyscheff method. It is recommended to reference detailed array antenna design texts or computational tools for precision.