JPS5637703A - Reflector antenna - Google Patents

Abstract

PURPOSE:To give suppression to the retroradiation caused at the periphery of the shadow boundary and the diffracted wave, by providing the electric wave diffusing plate at the tip of the masking shield and at the same time attaching the electric wave absorber onto the inner wall of the masking shield. CONSTITUTION:The electric wave absorber 5 is attached onto the inner wall of the masking shield 4 in an appropriate width to absorb the spill-over power of the primary radiator 3 which contributes to the radiation property around the shadow boundary. Thus the radiation property can be suppressed at the shadow boundary and its periphery. And both the lengths (h) and (l) of the shield 4 obtained from the equation 1 and the electric wave diffusing plate 6 obtained from the equation 2 are effective to the entire circumference of the shield 4 and the outer circumference frame 7 in case when the radiation property of the radiator 3 is in the rotational symmetry. As a result, the electric field can be reduced at both tips of the shield 4 and the frame 7, and accordingly the retroradiation property can be suppressed. In the equations, D shows the aperture diameter of the relector 2, lambda is the wavelength, i=3, 5..., L=(H<2>+h<2>)<1/2>, and H is the height of the frame 7 respectively.