Cosite Electromagnetic Interference (EMI) is a major concern for communication systems. Well-defined spectrum management procedures are usually effective in minimizing EMI , however, Frequency-hopping (FH) systems add a new dimension (time) to the EMI problems. The cosite operation of multiple frequency-hopping radios can cause severe EMI problems that result in a significant reduction in range for the collocated systems. Recent developments in comb-filter architecture for RF distribution systems indicate that this technology offers a unique solution to cosite EMI. This technology, Comb Limiter Combiner and Comb Linear Amplifier Combiner (CLIC / CLAC) was successfully demonstrated last year for Single Channel Ground and Airborne Radio System (SINCGARS). The CLIC / CLAC architecture demonstrated that 16 SINCGARS radios can be connected to one transmit antenna and one receive antenna without EMI. The transfer of this technology from VHF to UHF and beyond for is promising. Analysis and testing are required to determine component specifications and system parameters required to achieve cosite compatibility for various size platforms. The proposed effort is to demonstrate the scalability of this architecture for VHF (88 MHz - 200 MHz) and UHF (225 to 450 MHz) line of sight and satellite communications. Benefits Legacy Platforms With Multiple Cosite SINCGARS Systems (i.e., LPD-17, LHA, LHD, LAV, TOC, etc.). CLIC / CLAC performance indicates a significant performance improvement over that of the current frequency hopping SINCGARS multicoupler, the TD-1456, due to a reduction of intermodulation products as well as avoidance of any prioritization scheme for frequency deconfliction. The present multicoupler limits the use of one SINCGARS FH in any four SINCGARS associated with one multicoupler on Navy and Army platforms. CLIC / CLAC uses two antennas (one transmit and one receive) for up to 16 radios. The present system requires four antennas for 16 radios. Navy Platforms That Require Incorporation of Multiple Cosite EPLRS systems (i.e., LHA, LHD, etc.). CLIC / CLAC performance at VHF indicates portability of this technology to UHF and above. Several Navy ships have the requirement for incorporation of multiple (four) EPLRS systems. The projected cost to incorporate the antennas exceeds $800K per antenna for each ship (total cost will exceed $3.2M for antennas alone with no cosite EMI mitigation taken into account). CLIC / CLAC has the potential to mitigate cosite EMI, while reducing the antenna count to two ($1.6M total cost of antenna). CLIC / CLAC unit cost for UHF is estimated to be less than $500K and will result in ship savings of at least $1.1M per ship-installation. Joint Tactical Radio System (JTRS), a software-controlled radio will span the frequency range of 2 MHz to 2 GHz. Incorporation of this radio as a one-for-one replacement of legacy radios will result in severe cosite EMI for legacy frequency hopping systems such as SINCGARS, HAVE QUICK II, and EPLRS. RF distribution has been identified as the major risk associated with the JTRS program. CLIC / CLAC has the potential to mitigate cosite EMI resulting from several legacy waveforms being transmitted simultaneously on the same platform, from the smallest (i.e., LAV) to the largest (i.e., CVN) Keywords RF Distribution, Cosite EMI, CLIC / CLAC, JTRS, comb-filter architecture, SINCGARS, HAVE QUICK, EPLRS
