From Eq. (8), the far fields are calculated in spherical coordinates as In the calculation of the far fields, we have used the normalized sizes fa and h/f, and the normalized frequency F(=k/kcn = l-n-a/kp'o„). F is proportional to frequency, F = I corresponding to cut-off. Figure 7 shows the radiation field pattern from the obliquely-cut type antenna. Incident mode is TE01 with F = 1.5 (a = 41.8°) and f/a = 1. In the E-plane the beam is sharpened as the reflector is made deeper and tj is improved. But in the H-plane the beam width does not change. Figure 8 shows the radiation field pattern from the stair-cut type. In this case h/f = 1 and 7? = 100% . The greater the focal distance is, the wider the width of the source in the E-plane is and the sharper the beam. But the beam width in the H-plane does not change. Compared in Fig. 9 are (a) the stair-cut type (F = 55, f/a = 2.0, h/f = 1.0) and (b) the obliquely-cut type (F = 1.55, f/a = 1.19, h/f = 4.53). The aperture width in the E-plane is about (a) 8« and (b) 10a, respectively (see Fig. 10). Half-value angles in the E-plane are (a) 7° (6°), (b) 9° (9°), and those in the H-plane are (a) 18° (17°), (b) 20° (23°). The values in the parentheses are measured half-value angles. Although the
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