the r&s®fd221 and r&s®fu221 filters are an essential part of radio equipment. they are used at radio sites where the reciprocal influence of neighboring radio systems must be selectively restricted. selective restriction is the only way multiple radio systems can be simultaneously operated in very tight spaces. as a result, sustainable, higher quality radio links that are more reliable can be achieved.
the frequency-agile r&s®fd221 and r&s®fu221 filters protect the operator's radio system against third-party rf interference. the filters work in both the transmit and receive directions.
a wide variety of radio installations can be the source of unwanted rf interference. frequent sources include broadcasting, microwave link and radar applications because they often operate with high transmit power. the filters protect the operator's radio system against such interference in the receive direction.
in the transmit direction, the filters protect sensitive third-party radio applications, such as navigation and radiomonitoring equipment, against the operator's out-ofband rf signals.
the filter effect in the receive and transmit directions also lets operators make economic use of their frequency bands. the frequency spacing between useful channels is substantially reduced, making it easier to install the required antennas. the physical spacing between the antenna sites is significantly reduced because the filters substantially increase the rf decoupling.
the highly selective filters are mechanically rugged and therefore can be used on board ships and semi-mobile facilities as well as in ground installations.