Patent ID: 7973616
Filing Date: 2011-07-05
Classification: H01P

Abstract:
1. A short slot directional coupler comprising: a dielectric substrate having both surfaces each covered by a metal film; a first via-hole string and a second via-hole string, each of which has via-holes penetrating through the substrate, and formed so that a distance between the first via-hole string and the second via-hole string is narrow at a center of the string and wider along directions of both ends of the string; and a pair of third via-hole strings each having via-holes penetrating through the substrate, and formed between parts adjacent to both ends of the first via-hole string and parts adjacent to both ends of the second via-hole string to form a first post-wall waveguide along with the first via-hole string and a second post-wall waveguide along with the second via-hole string, wherein each via-hole interval in the first via-hole string, the second via-hole string and the third via-hole string is set to a value not more than 90% in an area on which each width of the first post-wall waveguide, the second post-wall waveguide and third post wall waveguides defined by the first via-hole string and the second via hole string satisfies a following equation: where f 0 represents an operating frequency, ∈ r represents a relative conductivity of the substrate, and c represents a light velocity.