The Bistatic Scattered Field

THE BISTATIC SCATTERED FIELD FROM A FINITE ARRAY... 

A plane wave is incident broadside to this array—that is, at 0°. The bistatic scattered field is obtained from the SPLAT program in the entire range fi om —90° to 270°. Furthermore, we show the bistatic fields for various load conditions of the active elements. 

Furthermore, in Fig. 5.3 we show the bistatic scattered field when Zl = 195 + 7 75ohms—that is, conjugate-matched. We also repeat the case Zl = 315 ohms to facilitate comparisons. 

It is, however, very instructive to observe how the field is scattered in all directions when the incident field is arriving from a fixed direction. Thus, we show at the top of Figs. 5.26 through 5.29 the bistatic scattered field at / = 5.7, 7.8, 10.0, and 12.0 GHz, respectively, for a typical triad (no. 25). 

ON THE BISTATIC SCATTERED FIELD FROM A LARGE ARRAY Bistatic Field from Triad 25. Normal Incidence... 

Fig. 5.28 Top The bistatic scattered field from a single typical triad (no. 25). Bottom The bIstatic scattered field from the entire array of 50 triads. Normal angle of incidence, f = 10.0GHz.

Next, in Figs. 5.31 through 5.34 we show the bistatic scattered field for the same array as above but for angle of incidence equal to -30°. At the top we... 

Fig. 8.1 The bistatic scattered field from a parabolic cylinder for an incident plane wave along boresight that is, ats = 0°. There is no feed that is, this shows the scattering from the parabolic surface itself referred to as reflector scattering.

The Bistatic Scattered Field as a Function of Angle of Incidence... 

Figures 8.5 through 8.9 show the bistatic scattered field for a parabolic cylinder with a low RCS feed. The frequency is fixed at the center frequency 9.0 GHz...

Similarly, we show in Fig. 8.6 the bistatic scattered field when the incident signal is at 2.5° from boresight. We observe in this case that the incident direction just clears the location circle of the dipoles while we in Fig. 8.7 with 6 = 3.75° are well outside this circle. At 0 = 5.0° and 10.0° shown in Figs. 8.8 and 8.9, respectively, we clear the feed to the extent that we basically obtain reflector scattering only. All in all this movie shows a gradual change from 0 = 0° to 9 = 10° without any particular surprises. 

Fig. 8.17 Out-of-band reduction. An FSS radome covering the entire reflector aperture. The bistatic scattered field is obtained when the radome is opaque.

Furthermore, in Chapter 5 we expanded our investigation to also include edge effects and showed that zero RCS is still possible. It was done rigorously by calculating the bistatic scattered field from each triad composed of a column of active elements and two columns of passive elements acting as reflectors. When conjugate-matched, the backscatter from such a triad was equal to zero. 

---