MILLI-WAVE ZONE RADIO REFLECTION PLATE

PURPOSE:To raise the efficiency of a reflected wave by providing a step which makes the mutual reflection wave phase the same between odd order Fresnel zones and even order Fresnel zones on a reflection plate surface. CONSTITUTION:A level difference of (lambda/4)/cos/(theta/2) is provided between first and third order Fresnel zones F1, F3 of the odd order Fresnel zones and a second order Fresnel zone F2 of the even order Fresnel zones. That is, when light is made incident perpendicularly to the surface of the reflection plate, the step is made to be lambda/4. For example, as a figure (b) shows, a reflection plate part 12 with lambda/4 thickness is provided at a reflection base plate 11, and a reflection plate part 13 with thickness of lambda/4 is provided on that reflection plate part 12. By forming the first order Fresnel zone F1 by the surface of the reflection plate part 13, the second order Fresnel zone F2 by the surface of the reflection plate part 12, and the third order Fresnel zone F3 on the reflection base plate 11, the step of lambda/4 can be provided. Also, the reflection base plate 11 and the reflection plate parts 12, 13 can be constituted of conductive metallic plates.