FEASIBILITY STUDY FOR INTEGRATED ANTENNA-AMPLIFIER NETWORK

OPERATION OF A JAMMER TRANSMITTER FROM A SMALL PLATFORM (RPV OR JEEP) NECESSITATES THE USE OF ELECTRICALLY SHORT ANTENNAS SUCH AS SHORT WHIPS AND SMALL LOOPS. THE CONVENTIONAL APPROACH USES A POWER AMPLIFIER DESIGNED FOR A 50-OHM LOAD AND AN ANTENNA TUNER THAT MATCHES THE ANTENNA-INPUT IMPEDANCE TO OHMS. HOWEVER, THE RAPID FREQUENCY CHANGES REQUIRED BY JAMMERS PRECLUDE THE USE OF ANTENNA TUNING. THE PROPOSED PROGRAM IS A FEASIBILITY STUDY AND SYSTEM DESIGN FOR A NOVEL APPROACH THAT INTEGRATES THE POWER AMPLIFIER (PA), ANTENNA, AND MATCHING NETWORK. THE ANTENNA ITSELF IS OPTIMIZED TO THE EXTENT POSSIBLE (GIVEN SIZE CONSTRAINTS) FOR MINIMUM VSWR. THE FILTER/MATCHING NETWORK ATTENUATES HARMONICS FROM THE PA AND BRINGS THE VSWR TO A REASONABLE LEVEL (E.G., <2:1) WITHIN ITS FREQUENCY BAND. A PIN-DIODE NETWORK SELECTS THE APPROPRIATE FILTER/MATCHING NETWORK FOR THE FREQUENCY OF OPERATION. AN OVERRATED PA DELIVERS THE SPECIFIED POWER INTO THE APPROXIMATELY MATCHED LOAD IMPEDANCE. THE FET PA ACHIEVES MAXIMUM EFFICIENCY BY OPERATING IN CLASS D AT HF AND SATURATED CLASS C AT VHF. A SWITCHING REGULATOR AND CONTROL UNIT MAINTAIN THE SPECIFIED OUTPUT POWER AND MAXIMUM EFFICIENCY IN SPITE OF VARIATIONS IN ITS LOAD IMPEDANCE.