Antenna and transmission support equipment manufacturer Bext says that cross-coupling combiners are designed to maximize performance by allowing users to combine very closely-spaced frequencies with excellent separation while minimizing insertion loss.
It says that in standard designed-combiners the traditional method used is to combine closely-spaced frequencies is by using a high number of RF filters, which has the undesired side effects of critical tuning, high insertion loss, bulky size and heavy weight due to the extensive number of RF filters necessary.
The cross-coupling combiner design used by Bext in a new series of FM combiners to be seen at the NAB Show accomplishes better performance by the use of an additional out-of-phase coupling which, when properly designed, creates a very sharp cutoff without generating high insertion losses, or needing a more limited number of RF filters when compared to standard RF combiners. By using this design, Bext is able to offer combiners capable of putting two or more stations on the same antenna with good isolation among the transmitters, even when the RF spacing between them is as close as 400 kHz.
NAB Show Booth: N5434