Читать книгу Fundamentals of Terahertz Devices and Applications - Группа авторов - Страница 21

The equivalent current distributions on the aperture, using the incident field is defined as in (2.21 and 2.22) and the phase relation derived in (2.1), can then be written as follows:

(2.50)

(2.51)

where r ′ (θ′) is given by (2.5) and tan θ′ = ρ′/z′ where . The vectorial components of these equivalent current distributions can be also expressed in Cartesian coordinates using and .

With these equations, we have determined the surface currents on the lens aperture, and thus, the far field patterns in the reference system used in Figure 2.6 can be obtained using the following expressions:

(2.52)

Figure 2.6 Reference system for the evaluation of the far fields radiated by the elliptical lens antenna.

(2.53)

where and ; and η₀ is the intrinsic impedance of free space.