The present invention relates to three-gate Y power circulators for ultra-high frequencies.
Such circulators are constructed from sections of wave-guides associated together so that the whole presents a plane of symmetry parallel to two parallel planes containing either the large sides of all the wave-guide sections (common plane H), or the small sides (common plane E). The volume common to the three guides forms a resonating cavity. Non-reciprocity is provided by placing in this cavity a certain volume of gyromagnetic material subjected to a magnetizing field. Compensating, at least partially, the mismatching of impedances due to the gyromagnetic material is known. The U.S. Pat. No. 3,136,962 filed on Apr. 4, 1960 shows a circulator having n paths according to these two arrangements and indicates that the gyromagnetic material is in the form of two chips made from a gyromagnetic material lying on the conducting wall of the cavity, the matching being provided by a dielectric cylinder placed on one of the gyromagnetic chips. This structure, symmetrical, particularly interesting in the case of circulators having more than three gates, is also used in the structures having three paths.
Furthermore, it is known from U.S. Pat. No. 3,491,313 filed on Nov. 29, 1967 that the wall of the cavity may be pierced to introduce therein the pole pieces of the magnet used to bias the gyromagnetic material so as to reduce the reluctance of the magnetizing circuit on the gyromagnetic chips. Matching is provided by a prismatic metal member.
It is also known that the decoupling between the gates of a circulator decreases when the power of the incident wave exceeds a threshold which depends on the frequency of the wave and on the way in which the circulator is constructed.