Abstract: A method and apparatus are disclosed for combining digital sidebands with an FM analog signal for IBOC transmission by a single antenna. Specifically, a high power filter combiner for combining an FM analog and a digital signal of the same channel, or frequency, is disclosed. The combiner has two inputs that respectively receive an FM analog and a digital signal to be transmitted in the same FM channel. The combiner has mild tuned filters interposed between the inputs and the output which are tuned to pass the FM analog signal while reflecting the digital signal such that the passed FM analog signal and the reflected digital signal combine as IBOC, i.e., an FM analog signal with digital sideband signals. The combined IBOC signal is provided at an output of the combiner, capable for transmission through a single antenna.

Abstract: A multiple-section bandpass filter for broadcast communications includes adjacent waveguide segments with a perpendicular connecting segment between them to form a U-shaped signal path. The waveguide cavities of the segments may be extruded and rectangular in cross section, and have a groundplane spacing that allows signal propagation between filter sections by evanescent coupling. Resonators in each of the adjacent segments have a separation that establishes the coupling bandwidths without the need for passive decoupling structures. A cross coupling conductor between the adjacent segments provides a capacitive or inductive coupling between them. A decoupling structure may be located in the connecting segment.

Abstract: A method for optimizing the segment lengths of a segmented transmission line, comprising the steps of modeling the electrical performance of the segmented transmission line, and evaluating the model for incremental changes in electrical performance, selecting a set of segment lengths which meets a set of predefined optimization criteria. The predefined optimization criteria is, for example, minimum peak VSWR.

Abstract: A waveguide for high power radio frequency transmission, comprising a tubular member having an ellipsoidal cross section and relatively uniform wall thickness having a ratio of major to minor axes between about 1.5 to 2.0 and a minimum minor axis of about 20 cm.

Abstract: A high power Gysel multinode power network for an RF signal, having a plurality of RF ports, a plurality of RF isolation loads, each load being connected through a coaxial transmission line to a respective RF port, a combined port, comprising a first hub having a plurality of first radiating arms, each radiating arm comprising a coaxial transmission line extending to one of said RF ports, a node, comprising a second hub having a plurality of second radiating arms, each radiating arm comprising a coaxial transmission line extending to one of said RF isolation loads; and a common heat sink for dissipating heat from said plurality of RF isolation loads.