The Federal Communications Commission recently set forth a mandate for signal spectrum separation among incompatible Enhanced Specialized Mobile Radio (ESMR) technologies. In response, K&L Microwave Inc., a part of Dover Corp.'s Microwave Products Group, Salisbury, Md., (www.klmicrowave.com) has released the WSD-00420 800-MHz rebanding duplexer. It keeps several communication signals from interfering with each other, especially critical when they are from equipment used by emergency personnel such as police, firefighters, and medical technicians.

“Commercial wireless systems have propagated wildly in the recent past,” says K&L's vice president of advanced engineering and R&D Rafi Hershtig. “Many of these devices operate on the 800-MHz band, which is the same band that public-safety organizations use. Here, the close proximity of numerous antennas coupled with ‘line-of-sight’ scenarios can potentially saturate the noise floor level of the transceivers, consequently escalating the problem of dropped calls.”

The WSD-00420 receive filter operates between 817 and 824 MHz, while its transmit filter operates between 862 and 869 MHz. The duplexer's downlink-transmit filter allows a sharp roll-off into guard and expansion bands below 862 MHz, thus mitigating the ESMR downlink out-of-band emission.