ABSTRACT
It is instructive to look at a plot of G(r) (see Figure 3-9, which shows G(r) for a sinc2r power pattern). We shall adopt the 3-db half-width r½ as the unit of distance.
The full width at half-maximum, denoted by d½ in Figure 3-8, is commonly taken to be the resolution of the radiometer. We can see from equation (21) that G(r½)=½G
(0) when r½ 2=2w2 ln(2). The 3-db half-width is 2r½. Figure 3-9 is a plot of the
relative power contained within a radius r of the center, where r is measured in units of r½; r=1 corresponds to the 3-db radius of the pattern (which is one-half of the 3-
db beamwidth). We can see that only 76% of the power is contained within this contour: almost one -quarter of the power comes from outside the 3-db contour.
