The electromagnetic cavity is made from a U-shaped hollow rectangular tube (2) at its two ends (38,40) each having two openings (4,6 and 8,10) on the same axis (12). Approximately half way between them a rectangular opening in the wall (50) communicates with a second hollow rectangular tube (16,22) at the remote signal introduction end (30). For electrical equalisation of the arm lengths, the second tube embraces the first (58) and is slid along it before brazing in position.
展开▼
