Multiple cavity square prism filter transmitter combiner with shared square walls and tuning controls mounted on rectangular end walls

摘要

A transmitter combiner includes a plurality of adjacent square prism filters, each of which shares at least one square wall with another of filters. Tuning of the individual square prism filters is accomplished by adjusting the position of tuning rods located in the high electric field region of each cavity. Tuning of each filter is achieved by rotating a control rod perpendicular to and extending through a rectangular end wall to pivot the tuning rod in that filter. In one embodiment of the invention, the control rod extends through a conductive tube attached along a square wall of the filter and perpendicular to the rectangular wall. In another embodiment of the invention, the control rod extends from the center of the rectangular wall and supports the tuning element near the center of the cavity. Temperature compensation is accomplished by variation in the length of the control rod as a function of temperature to compensate for changes in the dimensions of the cavity with the temperature thereof. In another embodiment of the invention, a bi-metal element shielded from electromagnetic energy in the cavity by a conductive tube causes pivoting of a small tuning rod.